Commit fd36de57 authored by Eric Biggers's avatar Eric Biggers
Browse files

crypto: polyval - Remove the polyval crypto_shash 



Remove polyval support from crypto_shash.  It no longer has any user now
that the HCTR2 code uses the POLYVAL library instead.

Reviewed-by: default avatarArd Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20251109234726.638437-8-ebiggers@kernel.org


Signed-off-by: default avatarEric Biggers <ebiggers@kernel.org>
parent d35abc0b

crypto/Kconfig

+0 −10
Original line number Diff line number Diff line
@@ -948,16 +948,6 @@ config CRYPTO_MICHAEL_MIC 
	  This algorithm is required for TKIP, but it should not be used for

	  other purposes because of the weakness of the algorithm.



config CRYPTO_POLYVAL

	tristate

	select CRYPTO_HASH

	select CRYPTO_LIB_GF128MUL

	help

	  POLYVAL hash function for HCTR2



	  This is used in HCTR2.  It is not a general-purpose

	  cryptographic hash function.



config CRYPTO_RMD160

	tristate "RIPEMD-160"

	select CRYPTO_HASH

crypto/Makefile

+0 −1
Original line number Diff line number Diff line
@@ -172,7 +172,6 @@ jitterentropy_rng-y := jitterentropy.o jitterentropy-kcapi.o 
obj-$(CONFIG_CRYPTO_JITTERENTROPY_TESTINTERFACE) += jitterentropy-testing.o

obj-$(CONFIG_CRYPTO_BENCHMARK) += tcrypt.o

obj-$(CONFIG_CRYPTO_GHASH) += ghash-generic.o

obj-$(CONFIG_CRYPTO_POLYVAL) += polyval-generic.o

obj-$(CONFIG_CRYPTO_USER_API) += af_alg.o

obj-$(CONFIG_CRYPTO_USER_API_HASH) += algif_hash.o

obj-$(CONFIG_CRYPTO_USER_API_SKCIPHER) += algif_skcipher.o

crypto/polyval-generic.c

deleted100644 → 0
+0 −205
Original line number Diff line number Diff line 
// 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 <crypto/gf128mul.h>

#include <crypto/internal/hash.h>

#include <crypto/polyval.h>

#include <crypto/utils.h>

#include <linux/errno.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/string.h>

#include <linux/unaligned.h>



struct polyval_tfm_ctx {

	struct gf128mul_4k *gf128;

};



struct polyval_desc_ctx {

	union {

		u8 buffer[POLYVAL_BLOCK_SIZE];

		be128 buffer128;

	};

};



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]);

}



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_generic_init(struct shash_desc *desc)

{

	struct polyval_desc_ctx *dctx = shash_desc_ctx(desc);



	memset(dctx, 0, sizeof(*dctx));



	return 0;

}



static int polyval_generic_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 tmp[POLYVAL_BLOCK_SIZE];



	do {

		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;

	} while (srclen >= POLYVAL_BLOCK_SIZE);



	return srclen;

}



static int polyval_finup(struct shash_desc *desc, const u8 *src,

			 unsigned int len, u8 *dst)

{

	struct polyval_desc_ctx *dctx = shash_desc_ctx(desc);



	if (len) {

		u8 tmp[POLYVAL_BLOCK_SIZE] = {};



		memcpy(tmp, src, len);

		polyval_generic_update(desc, tmp, POLYVAL_BLOCK_SIZE);

	}

	copy_and_reverse(dst, dctx->buffer);

	return 0;

}



static int polyval_export(struct shash_desc *desc, void *out)

{

	struct polyval_desc_ctx *dctx = shash_desc_ctx(desc);



	copy_and_reverse(out, dctx->buffer);

	return 0;

}



static int polyval_import(struct shash_desc *desc, const void *in)

{

	struct polyval_desc_ctx *dctx = shash_desc_ctx(desc);



	copy_and_reverse(dctx->buffer, in);

	return 0;

}



static void polyval_exit_tfm(struct crypto_shash *tfm)

{

	struct polyval_tfm_ctx *ctx = crypto_shash_ctx(tfm);



	gf128mul_free_4k(ctx->gf128);

}



static struct shash_alg polyval_alg = {

	.digestsize	= POLYVAL_DIGEST_SIZE,

	.init		= polyval_generic_init,

	.update		= polyval_generic_update,

	.finup		= polyval_finup,

	.setkey		= polyval_setkey,

	.export		= polyval_export,

	.import		= polyval_import,

	.exit_tfm	= polyval_exit_tfm,

	.statesize	= sizeof(struct polyval_desc_ctx),

	.descsize	= sizeof(struct polyval_desc_ctx),

	.base		= {

		.cra_name		= "polyval",

		.cra_driver_name	= "polyval-generic",

		.cra_priority		= 100,

		.cra_flags		= CRYPTO_AHASH_ALG_BLOCK_ONLY,

		.cra_blocksize		= POLYVAL_BLOCK_SIZE,

		.cra_ctxsize		= sizeof(struct polyval_tfm_ctx),

		.cra_module		= THIS_MODULE,

	},

};



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);

}



module_init(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");