milos-linux/crypto/hctr2.c

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crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
// SPDX-License-Identifier: GPL-2.0
/*
* HCTR2 length-preserving encryption mode
*
* Copyright 2021 Google LLC
*/
/*
* HCTR2 is a length-preserving encryption mode that is efficient on
* processors with instructions to accelerate AES and carryless
* multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM
* processors with the ARMv8 crypto extensions.
*
* For more details, see the paper: "Length-preserving encryption with HCTR2"
* (https://eprint.iacr.org/2021/1441.pdf)
*/
lib/crypto: gf128hash: Rename polyval module to gf128hash Currently, the standalone GHASH code is coupled with crypto_shash. This has resulted in unnecessary complexity and overhead, as well as the code being unavailable to library code such as the AES-GCM library. Like was done with POLYVAL, it needs to find a new home in lib/crypto/. GHASH and POLYVAL are closely related and can each be implemented in terms of each other. Optimized code for one can be reused with the other. But also since GHASH tends to be difficult to implement directly due to its unnatural bit order, most modern GHASH implementations (including the existing arm, arm64, powerpc, and x86 optimized GHASH code, and the new generic GHASH code I'll be adding) actually reinterpret the GHASH computation as an equivalent POLYVAL computation, pre and post-processing the inputs and outputs to map to/from POLYVAL. Given this close relationship, it makes sense to group the GHASH and POLYVAL code together in the same module. This gives us a wide range of options for implementing them, reusing code between the two and properly utilizing whatever instructions each architecture provides. Thus, GHASH support will be added to the library module that is currently called "polyval". Rename it to an appropriate name: "gf128hash". Rename files, options, functions, etc. where appropriate to reflect the upcoming sharing with GHASH. (Note: polyval_kunit is not renamed, as ghash_kunit will be added alongside it instead.) Acked-by: Ard Biesheuvel <ardb@kernel.org> Link: https://lore.kernel.org/r/20260319061723.1140720-2-ebiggers@kernel.org Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2026-03-18 23:17:02 -07:00
#include <crypto/gf128hash.h>
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
#include <crypto/internal/cipher.h>
#include <crypto/internal/skcipher.h>
#include <crypto/scatterwalk.h>
#include <linux/module.h>
#define BLOCKCIPHER_BLOCK_SIZE 16
/*
* The specification allows variable-length tweaks, but Linux's crypto API
* currently only allows algorithms to support a single length. The "natural"
* tweak length for HCTR2 is 16, since that fits into one POLYVAL block for
* the best performance. But longer tweaks are useful for fscrypt, to avoid
* needing to derive per-file keys. So instead we use two blocks, or 32 bytes.
*/
#define TWEAK_SIZE 32
struct hctr2_instance_ctx {
struct crypto_cipher_spawn blockcipher_spawn;
struct crypto_skcipher_spawn xctr_spawn;
};
struct hctr2_tfm_ctx {
struct crypto_cipher *blockcipher;
struct crypto_skcipher *xctr;
struct polyval_key poly_key;
struct polyval_elem hashed_tweaklens[2];
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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u8 L[BLOCKCIPHER_BLOCK_SIZE];
};
struct hctr2_request_ctx {
u8 first_block[BLOCKCIPHER_BLOCK_SIZE];
u8 xctr_iv[BLOCKCIPHER_BLOCK_SIZE];
struct scatterlist *bulk_part_dst;
struct scatterlist *bulk_part_src;
struct scatterlist sg_src[2];
struct scatterlist sg_dst[2];
struct polyval_elem hashed_tweak;
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
/*
* skcipher sub-request size is unknown at compile-time, so it needs to
* go after the members with known sizes.
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
*/
union {
struct polyval_ctx poly_ctx;
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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struct skcipher_request xctr_req;
} u;
};
/*
* The input data for each HCTR2 hash step begins with a 16-byte block that
* contains the tweak length and a flag that indicates whether the input is evenly
* divisible into blocks. Since this implementation only supports one tweak
* length, we precompute the two hash states resulting from hashing the two
* possible values of this initial block. This reduces by one block the amount of
* data that needs to be hashed for each encryption/decryption
*
* These precomputed hashes are stored in hctr2_tfm_ctx.
*/
static void hctr2_hash_tweaklens(struct hctr2_tfm_ctx *tctx)
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
{
struct polyval_ctx ctx;
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
for (int has_remainder = 0; has_remainder < 2; has_remainder++) {
const __le64 tweak_length_block[2] = {
cpu_to_le64(TWEAK_SIZE * 8 * 2 + 2 + has_remainder),
};
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
polyval_init(&ctx, &tctx->poly_key);
polyval_update(&ctx, (const u8 *)&tweak_length_block,
sizeof(tweak_length_block));
static_assert(sizeof(tweak_length_block) == POLYVAL_BLOCK_SIZE);
polyval_export_blkaligned(
&ctx, &tctx->hashed_tweaklens[has_remainder]);
}
memzero_explicit(&ctx, sizeof(ctx));
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
}
static int hctr2_setkey(struct crypto_skcipher *tfm, const u8 *key,
unsigned int keylen)
{
struct hctr2_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
u8 hbar[BLOCKCIPHER_BLOCK_SIZE];
int err;
crypto_cipher_clear_flags(tctx->blockcipher, CRYPTO_TFM_REQ_MASK);
crypto_cipher_set_flags(tctx->blockcipher,
crypto_skcipher_get_flags(tfm) &
CRYPTO_TFM_REQ_MASK);
err = crypto_cipher_setkey(tctx->blockcipher, key, keylen);
if (err)
return err;
crypto_skcipher_clear_flags(tctx->xctr, CRYPTO_TFM_REQ_MASK);
crypto_skcipher_set_flags(tctx->xctr,
crypto_skcipher_get_flags(tfm) &
CRYPTO_TFM_REQ_MASK);
err = crypto_skcipher_setkey(tctx->xctr, key, keylen);
if (err)
return err;
memset(hbar, 0, sizeof(hbar));
crypto_cipher_encrypt_one(tctx->blockcipher, hbar, hbar);
memset(tctx->L, 0, sizeof(tctx->L));
tctx->L[0] = 0x01;
crypto_cipher_encrypt_one(tctx->blockcipher, tctx->L, tctx->L);
static_assert(sizeof(hbar) == POLYVAL_BLOCK_SIZE);
polyval_preparekey(&tctx->poly_key, hbar);
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
memzero_explicit(hbar, sizeof(hbar));
hctr2_hash_tweaklens(tctx);
return 0;
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
}
static void hctr2_hash_tweak(struct skcipher_request *req)
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
const struct hctr2_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
struct hctr2_request_ctx *rctx = skcipher_request_ctx(req);
struct polyval_ctx *poly_ctx = &rctx->u.poly_ctx;
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
bool has_remainder = req->cryptlen % POLYVAL_BLOCK_SIZE;
polyval_import_blkaligned(poly_ctx, &tctx->poly_key,
&tctx->hashed_tweaklens[has_remainder]);
polyval_update(poly_ctx, req->iv, TWEAK_SIZE);
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
// Store the hashed tweak, since we need it when computing both
// H(T || N) and H(T || V).
static_assert(TWEAK_SIZE % POLYVAL_BLOCK_SIZE == 0);
polyval_export_blkaligned(poly_ctx, &rctx->hashed_tweak);
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
}
static void hctr2_hash_message(struct skcipher_request *req,
struct scatterlist *sgl,
u8 digest[POLYVAL_DIGEST_SIZE])
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
{
static const u8 padding = 0x1;
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
struct hctr2_request_ctx *rctx = skcipher_request_ctx(req);
struct polyval_ctx *poly_ctx = &rctx->u.poly_ctx;
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
const unsigned int bulk_len = req->cryptlen - BLOCKCIPHER_BLOCK_SIZE;
struct sg_mapping_iter miter;
int i;
int n = 0;
sg_miter_start(&miter, sgl, sg_nents(sgl),
SG_MITER_FROM_SG | SG_MITER_ATOMIC);
for (i = 0; i < bulk_len; i += n) {
sg_miter_next(&miter);
n = min_t(unsigned int, miter.length, bulk_len - i);
polyval_update(poly_ctx, miter.addr, n);
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
}
sg_miter_stop(&miter);
if (req->cryptlen % BLOCKCIPHER_BLOCK_SIZE)
polyval_update(poly_ctx, &padding, 1);
polyval_final(poly_ctx, digest);
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
}
static int hctr2_finish(struct skcipher_request *req)
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
const struct hctr2_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
struct hctr2_request_ctx *rctx = skcipher_request_ctx(req);
struct polyval_ctx *poly_ctx = &rctx->u.poly_ctx;
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
u8 digest[POLYVAL_DIGEST_SIZE];
// U = UU ^ H(T || V)
// or M = MM ^ H(T || N)
polyval_import_blkaligned(poly_ctx, &tctx->poly_key,
&rctx->hashed_tweak);
hctr2_hash_message(req, rctx->bulk_part_dst, digest);
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
crypto_xor(rctx->first_block, digest, BLOCKCIPHER_BLOCK_SIZE);
// Copy U (or M) into dst scatterlist
scatterwalk_map_and_copy(rctx->first_block, req->dst,
0, BLOCKCIPHER_BLOCK_SIZE, 1);
return 0;
}
static void hctr2_xctr_done(void *data, int err)
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
{
struct skcipher_request *req = data;
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
if (!err)
err = hctr2_finish(req);
skcipher_request_complete(req, err);
}
static int hctr2_crypt(struct skcipher_request *req, bool enc)
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
const struct hctr2_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
struct hctr2_request_ctx *rctx = skcipher_request_ctx(req);
u8 digest[POLYVAL_DIGEST_SIZE];
int bulk_len = req->cryptlen - BLOCKCIPHER_BLOCK_SIZE;
// Requests must be at least one block
if (req->cryptlen < BLOCKCIPHER_BLOCK_SIZE)
return -EINVAL;
// Copy M (or U) into a temporary buffer
scatterwalk_map_and_copy(rctx->first_block, req->src,
0, BLOCKCIPHER_BLOCK_SIZE, 0);
// Create scatterlists for N and V
rctx->bulk_part_src = scatterwalk_ffwd(rctx->sg_src, req->src,
BLOCKCIPHER_BLOCK_SIZE);
rctx->bulk_part_dst = scatterwalk_ffwd(rctx->sg_dst, req->dst,
BLOCKCIPHER_BLOCK_SIZE);
// MM = M ^ H(T || N)
// or UU = U ^ H(T || V)
hctr2_hash_tweak(req);
hctr2_hash_message(req, rctx->bulk_part_src, digest);
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
crypto_xor(digest, rctx->first_block, BLOCKCIPHER_BLOCK_SIZE);
// UU = E(MM)
// or MM = D(UU)
if (enc)
crypto_cipher_encrypt_one(tctx->blockcipher, rctx->first_block,
digest);
else
crypto_cipher_decrypt_one(tctx->blockcipher, rctx->first_block,
digest);
// S = MM ^ UU ^ L
crypto_xor(digest, rctx->first_block, BLOCKCIPHER_BLOCK_SIZE);
crypto_xor_cpy(rctx->xctr_iv, digest, tctx->L, BLOCKCIPHER_BLOCK_SIZE);
// V = XCTR(S, N)
// or N = XCTR(S, V)
skcipher_request_set_tfm(&rctx->u.xctr_req, tctx->xctr);
skcipher_request_set_crypt(&rctx->u.xctr_req, rctx->bulk_part_src,
rctx->bulk_part_dst, bulk_len,
rctx->xctr_iv);
skcipher_request_set_callback(&rctx->u.xctr_req,
req->base.flags,
hctr2_xctr_done, req);
return crypto_skcipher_encrypt(&rctx->u.xctr_req) ?:
hctr2_finish(req);
}
static int hctr2_encrypt(struct skcipher_request *req)
{
return hctr2_crypt(req, true);
}
static int hctr2_decrypt(struct skcipher_request *req)
{
return hctr2_crypt(req, false);
}
static int hctr2_init_tfm(struct crypto_skcipher *tfm)
{
struct skcipher_instance *inst = skcipher_alg_instance(tfm);
struct hctr2_instance_ctx *ictx = skcipher_instance_ctx(inst);
struct hctr2_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
struct crypto_skcipher *xctr;
struct crypto_cipher *blockcipher;
int err;
xctr = crypto_spawn_skcipher(&ictx->xctr_spawn);
if (IS_ERR(xctr))
return PTR_ERR(xctr);
blockcipher = crypto_spawn_cipher(&ictx->blockcipher_spawn);
if (IS_ERR(blockcipher)) {
err = PTR_ERR(blockcipher);
goto err_free_xctr;
}
tctx->xctr = xctr;
tctx->blockcipher = blockcipher;
BUILD_BUG_ON(offsetofend(struct hctr2_request_ctx, u) !=
sizeof(struct hctr2_request_ctx));
crypto_skcipher_set_reqsize(
tfm, max(sizeof(struct hctr2_request_ctx),
offsetofend(struct hctr2_request_ctx, u.xctr_req) +
crypto_skcipher_reqsize(xctr)));
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
return 0;
err_free_xctr:
crypto_free_skcipher(xctr);
return err;
}
static void hctr2_exit_tfm(struct crypto_skcipher *tfm)
{
struct hctr2_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
crypto_free_cipher(tctx->blockcipher);
crypto_free_skcipher(tctx->xctr);
}
static void hctr2_free_instance(struct skcipher_instance *inst)
{
struct hctr2_instance_ctx *ictx = skcipher_instance_ctx(inst);
crypto_drop_cipher(&ictx->blockcipher_spawn);
crypto_drop_skcipher(&ictx->xctr_spawn);
kfree(inst);
}
static int hctr2_create_common(struct crypto_template *tmpl, struct rtattr **tb,
const char *xctr_name)
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
{
struct skcipher_alg_common *xctr_alg;
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
u32 mask;
struct skcipher_instance *inst;
struct hctr2_instance_ctx *ictx;
struct crypto_alg *blockcipher_alg;
char blockcipher_name[CRYPTO_MAX_ALG_NAME];
int len;
int err;
err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER, &mask);
if (err)
return err;
inst = kzalloc(sizeof(*inst) + sizeof(*ictx), GFP_KERNEL);
if (!inst)
return -ENOMEM;
ictx = skcipher_instance_ctx(inst);
/* Stream cipher, xctr(block_cipher) */
err = crypto_grab_skcipher(&ictx->xctr_spawn,
skcipher_crypto_instance(inst),
xctr_name, 0, mask);
if (err)
goto err_free_inst;
xctr_alg = crypto_spawn_skcipher_alg_common(&ictx->xctr_spawn);
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
err = -EINVAL;
if (strncmp(xctr_alg->base.cra_name, "xctr(", 5))
goto err_free_inst;
len = strscpy(blockcipher_name, xctr_alg->base.cra_name + 5,
sizeof(blockcipher_name));
if (len < 1)
goto err_free_inst;
if (blockcipher_name[len - 1] != ')')
goto err_free_inst;
blockcipher_name[len - 1] = 0;
/* Block cipher, e.g. "aes" */
err = crypto_grab_cipher(&ictx->blockcipher_spawn,
skcipher_crypto_instance(inst),
blockcipher_name, 0, mask);
if (err)
goto err_free_inst;
blockcipher_alg = crypto_spawn_cipher_alg(&ictx->blockcipher_spawn);
/* Require blocksize of 16 bytes */
err = -EINVAL;
if (blockcipher_alg->cra_blocksize != BLOCKCIPHER_BLOCK_SIZE)
goto err_free_inst;
/* Instance fields */
err = -ENAMETOOLONG;
if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME, "hctr2(%s)",
blockcipher_alg->cra_name) >= CRYPTO_MAX_ALG_NAME)
goto err_free_inst;
if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
"hctr2_base(%s,polyval-lib)",
xctr_alg->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
goto err_free_inst;
inst->alg.base.cra_blocksize = BLOCKCIPHER_BLOCK_SIZE;
inst->alg.base.cra_ctxsize = sizeof(struct hctr2_tfm_ctx);
inst->alg.base.cra_alignmask = xctr_alg->base.cra_alignmask;
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
inst->alg.base.cra_priority = (2 * xctr_alg->base.cra_priority +
blockcipher_alg->cra_priority) /
3;
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
inst->alg.setkey = hctr2_setkey;
inst->alg.encrypt = hctr2_encrypt;
inst->alg.decrypt = hctr2_decrypt;
inst->alg.init = hctr2_init_tfm;
inst->alg.exit = hctr2_exit_tfm;
inst->alg.min_keysize = xctr_alg->min_keysize;
inst->alg.max_keysize = xctr_alg->max_keysize;
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
inst->alg.ivsize = TWEAK_SIZE;
inst->free = hctr2_free_instance;
err = skcipher_register_instance(tmpl, inst);
if (err) {
err_free_inst:
hctr2_free_instance(inst);
}
return err;
}
static int hctr2_create_base(struct crypto_template *tmpl, struct rtattr **tb)
{
const char *xctr_name;
const char *polyval_name;
xctr_name = crypto_attr_alg_name(tb[1]);
if (IS_ERR(xctr_name))
return PTR_ERR(xctr_name);
polyval_name = crypto_attr_alg_name(tb[2]);
if (IS_ERR(polyval_name))
return PTR_ERR(polyval_name);
if (strcmp(polyval_name, "polyval") != 0 &&
strcmp(polyval_name, "polyval-lib") != 0)
return -ENOENT;
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
return hctr2_create_common(tmpl, tb, xctr_name);
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
}
static int hctr2_create(struct crypto_template *tmpl, struct rtattr **tb)
{
const char *blockcipher_name;
char xctr_name[CRYPTO_MAX_ALG_NAME];
blockcipher_name = crypto_attr_alg_name(tb[1]);
if (IS_ERR(blockcipher_name))
return PTR_ERR(blockcipher_name);
if (snprintf(xctr_name, CRYPTO_MAX_ALG_NAME, "xctr(%s)",
blockcipher_name) >= CRYPTO_MAX_ALG_NAME)
return -ENAMETOOLONG;
return hctr2_create_common(tmpl, tb, xctr_name);
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
}
static struct crypto_template hctr2_tmpls[] = {
{
/* hctr2_base(xctr_name, polyval_name) */
.name = "hctr2_base",
.create = hctr2_create_base,
.module = THIS_MODULE,
}, {
/* hctr2(blockcipher_name) */
.name = "hctr2",
.create = hctr2_create,
.module = THIS_MODULE,
}
};
static int __init hctr2_module_init(void)
{
return crypto_register_templates(hctr2_tmpls, ARRAY_SIZE(hctr2_tmpls));
}
static void __exit hctr2_module_exit(void)
{
return crypto_unregister_templates(hctr2_tmpls,
ARRAY_SIZE(hctr2_tmpls));
}
module_init(hctr2_module_init);
crypto: hctr2 - Add HCTR2 support Add support for HCTR2 as a template. HCTR2 is a length-preserving encryption mode that is efficient on processors with instructions to accelerate AES and carryless multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions. As a length-preserving encryption mode, HCTR2 is suitable for applications such as storage encryption where ciphertext expansion is not possible, and thus authenticated encryption cannot be used. Currently, such applications usually use XTS, or in some cases Adiantum. XTS has the disadvantage that it is a narrow-block mode: a bitflip will only change 16 bytes in the resulting ciphertext or plaintext. This reveals more information to an attacker than necessary. HCTR2 is a wide-block mode, so it provides a stronger security property: a bitflip will change the entire message. HCTR2 is somewhat similar to Adiantum, which is also a wide-block mode. However, HCTR2 is designed to take advantage of existing crypto instructions, while Adiantum targets devices without such hardware support. Adiantum is also designed with longer messages in mind, while HCTR2 is designed to be efficient even on short messages. HCTR2 requires POLYVAL and XCTR as components. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-05-20 18:14:55 +00:00
module_exit(hctr2_module_exit);
MODULE_DESCRIPTION("HCTR2 length-preserving encryption mode");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS_CRYPTO("hctr2");
MODULE_IMPORT_NS("CRYPTO_INTERNAL");