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-rw-r--r--crypto/polyval-generic.c245
1 files changed, 0 insertions, 245 deletions
diff --git a/crypto/polyval-generic.c b/crypto/polyval-generic.c
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--- a/crypto/polyval-generic.c
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-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * POLYVAL: hash function for HCTR2.
- *
- * Copyright (c) 2007 Nokia Siemens Networks - Mikko Herranen <mh1@iki.fi>
- * Copyright (c) 2009 Intel Corp.
- * Author: Huang Ying <ying.huang@intel.com>
- * Copyright 2021 Google LLC
- */
-
-/*
- * Code based on crypto/ghash-generic.c
- *
- * POLYVAL is a keyed hash function similar to GHASH. POLYVAL uses a different
- * modulus for finite field multiplication which makes hardware accelerated
- * implementations on little-endian machines faster. POLYVAL is used in the
- * kernel to implement HCTR2, but was originally specified for AES-GCM-SIV
- * (RFC 8452).
- *
- * For more information see:
- * Length-preserving encryption with HCTR2:
- * https://eprint.iacr.org/2021/1441.pdf
- * AES-GCM-SIV: Nonce Misuse-Resistant Authenticated Encryption:
- * https://datatracker.ietf.org/doc/html/rfc8452
- *
- * Like GHASH, POLYVAL is not a cryptographic hash function and should
- * not be used outside of crypto modes explicitly designed to use POLYVAL.
- *
- * This implementation uses a convenient trick involving the GHASH and POLYVAL
- * fields. This trick allows multiplication in the POLYVAL field to be
- * implemented by using multiplication in the GHASH field as a subroutine. An
- * element of the POLYVAL field can be converted to an element of the GHASH
- * field by computing x*REVERSE(a), where REVERSE reverses the byte-ordering of
- * a. Similarly, an element of the GHASH field can be converted back to the
- * POLYVAL field by computing REVERSE(x^{-1}*a). For more information, see:
- * https://datatracker.ietf.org/doc/html/rfc8452#appendix-A
- *
- * By using this trick, we do not need to implement the POLYVAL field for the
- * generic implementation.
- *
- * Warning: this generic implementation is not intended to be used in practice
- * and is not constant time. For practical use, a hardware accelerated
- * implementation of POLYVAL should be used instead.
- *
- */
-
-#include <asm/unaligned.h>
-#include <crypto/algapi.h>
-#include <crypto/gf128mul.h>
-#include <crypto/polyval.h>
-#include <crypto/internal/hash.h>
-#include <linux/crypto.h>
-#include <linux/init.h>
-#include <linux/kernel.h>
-#include <linux/module.h>
-
-struct polyval_tfm_ctx {
- struct gf128mul_4k *gf128;
-};
-
-struct polyval_desc_ctx {
- union {
- u8 buffer[POLYVAL_BLOCK_SIZE];
- be128 buffer128;
- };
- u32 bytes;
-};
-
-static void copy_and_reverse(u8 dst[POLYVAL_BLOCK_SIZE],
- const u8 src[POLYVAL_BLOCK_SIZE])
-{
- u64 a = get_unaligned((const u64 *)&src[0]);
- u64 b = get_unaligned((const u64 *)&src[8]);
-
- put_unaligned(swab64(a), (u64 *)&dst[8]);
- put_unaligned(swab64(b), (u64 *)&dst[0]);
-}
-
-/*
- * Performs multiplication in the POLYVAL field using the GHASH field as a
- * subroutine. This function is used as a fallback for hardware accelerated
- * implementations when simd registers are unavailable.
- *
- * Note: This function is not used for polyval-generic, instead we use the 4k
- * lookup table implementation for finite field multiplication.
- */
-void polyval_mul_non4k(u8 *op1, const u8 *op2)
-{
- be128 a, b;
-
- // Assume one argument is in Montgomery form and one is not.
- copy_and_reverse((u8 *)&a, op1);
- copy_and_reverse((u8 *)&b, op2);
- gf128mul_x_lle(&a, &a);
- gf128mul_lle(&a, &b);
- copy_and_reverse(op1, (u8 *)&a);
-}
-EXPORT_SYMBOL_GPL(polyval_mul_non4k);
-
-/*
- * Perform a POLYVAL update using non4k multiplication. This function is used
- * as a fallback for hardware accelerated implementations when simd registers
- * are unavailable.
- *
- * Note: This function is not used for polyval-generic, instead we use the 4k
- * lookup table implementation of finite field multiplication.
- */
-void polyval_update_non4k(const u8 *key, const u8 *in,
- size_t nblocks, u8 *accumulator)
-{
- while (nblocks--) {
- crypto_xor(accumulator, in, POLYVAL_BLOCK_SIZE);
- polyval_mul_non4k(accumulator, key);
- in += POLYVAL_BLOCK_SIZE;
- }
-}
-EXPORT_SYMBOL_GPL(polyval_update_non4k);
-
-static int polyval_setkey(struct crypto_shash *tfm,
- const u8 *key, unsigned int keylen)
-{
- struct polyval_tfm_ctx *ctx = crypto_shash_ctx(tfm);
- be128 k;
-
- if (keylen != POLYVAL_BLOCK_SIZE)
- return -EINVAL;
-
- gf128mul_free_4k(ctx->gf128);
-
- BUILD_BUG_ON(sizeof(k) != POLYVAL_BLOCK_SIZE);
- copy_and_reverse((u8 *)&k, key);
- gf128mul_x_lle(&k, &k);
-
- ctx->gf128 = gf128mul_init_4k_lle(&k);
- memzero_explicit(&k, POLYVAL_BLOCK_SIZE);
-
- if (!ctx->gf128)
- return -ENOMEM;
-
- return 0;
-}
-
-static int polyval_init(struct shash_desc *desc)
-{
- struct polyval_desc_ctx *dctx = shash_desc_ctx(desc);
-
- memset(dctx, 0, sizeof(*dctx));
-
- return 0;
-}
-
-static int polyval_update(struct shash_desc *desc,
- const u8 *src, unsigned int srclen)
-{
- struct polyval_desc_ctx *dctx = shash_desc_ctx(desc);
- const struct polyval_tfm_ctx *ctx = crypto_shash_ctx(desc->tfm);
- u8 *pos;
- u8 tmp[POLYVAL_BLOCK_SIZE];
- int n;
-
- if (dctx->bytes) {
- n = min(srclen, dctx->bytes);
- pos = dctx->buffer + dctx->bytes - 1;
-
- dctx->bytes -= n;
- srclen -= n;
-
- while (n--)
- *pos-- ^= *src++;
-
- if (!dctx->bytes)
- gf128mul_4k_lle(&dctx->buffer128, ctx->gf128);
- }
-
- while (srclen >= POLYVAL_BLOCK_SIZE) {
- copy_and_reverse(tmp, src);
- crypto_xor(dctx->buffer, tmp, POLYVAL_BLOCK_SIZE);
- gf128mul_4k_lle(&dctx->buffer128, ctx->gf128);
- src += POLYVAL_BLOCK_SIZE;
- srclen -= POLYVAL_BLOCK_SIZE;
- }
-
- if (srclen) {
- dctx->bytes = POLYVAL_BLOCK_SIZE - srclen;
- pos = dctx->buffer + POLYVAL_BLOCK_SIZE - 1;
- while (srclen--)
- *pos-- ^= *src++;
- }
-
- return 0;
-}
-
-static int polyval_final(struct shash_desc *desc, u8 *dst)
-{
- struct polyval_desc_ctx *dctx = shash_desc_ctx(desc);
- const struct polyval_tfm_ctx *ctx = crypto_shash_ctx(desc->tfm);
-
- if (dctx->bytes)
- gf128mul_4k_lle(&dctx->buffer128, ctx->gf128);
- copy_and_reverse(dst, dctx->buffer);
- return 0;
-}
-
-static void polyval_exit_tfm(struct crypto_tfm *tfm)
-{
- struct polyval_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
-
- gf128mul_free_4k(ctx->gf128);
-}
-
-static struct shash_alg polyval_alg = {
- .digestsize = POLYVAL_DIGEST_SIZE,
- .init = polyval_init,
- .update = polyval_update,
- .final = polyval_final,
- .setkey = polyval_setkey,
- .descsize = sizeof(struct polyval_desc_ctx),
- .base = {
- .cra_name = "polyval",
- .cra_driver_name = "polyval-generic",
- .cra_priority = 100,
- .cra_blocksize = POLYVAL_BLOCK_SIZE,
- .cra_ctxsize = sizeof(struct polyval_tfm_ctx),
- .cra_module = THIS_MODULE,
- .cra_exit = polyval_exit_tfm,
- },
-};
-
-static int __init polyval_mod_init(void)
-{
- return crypto_register_shash(&polyval_alg);
-}
-
-static void __exit polyval_mod_exit(void)
-{
- crypto_unregister_shash(&polyval_alg);
-}
-
-subsys_initcall(polyval_mod_init);
-module_exit(polyval_mod_exit);
-
-MODULE_LICENSE("GPL");
-MODULE_DESCRIPTION("POLYVAL hash function");
-MODULE_ALIAS_CRYPTO("polyval");
-MODULE_ALIAS_CRYPTO("polyval-generic");
generated by cgit (git 2.34.1) at 2025-12-21 18:32:34 +0000