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crypto: sha256 - implement base layer for SHA-256

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To reduce the number of copies of boilerplate code throughout
the tree, this patch implements generic glue for the SHA-256
algorithm. This allows a specific arch or hardware implementation
to only implement the special handling that it needs.

The users need to supply an implementation of

  void (sha256_block_fn)(struct sha256_state *sst, u8 const *src, int blocks)

and pass it to the SHA-256 base functions. For easy casting between the
prototype above and existing block functions that take a 'u32 state[]'
as their first argument, the 'state' member of struct sha256_state is
moved to the base of the struct.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Ard Biesheuvel 2015-04-09 12:55:34 +02:00 committed by Herbert Xu
parent c4d5b9ffa3
commit 11b8d5ef91
2 changed files with 129 additions and 1 deletions
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2
include/crypto/sha.h
View file

@ -71,8 +71,8 @@ struct sha1_state {
};
struct sha256_state {
u64 count;
u32 state[SHA256_DIGEST_SIZE / 4];
u64 count;
u8 buf[SHA256_BLOCK_SIZE];
};

128
include/crypto/sha256_base.h Normal file
View file

@ -0,0 +1,128 @@
/*
* sha256_base.h - core logic for SHA-256 implementations
*
* Copyright (C) 2015 Linaro Ltd <ard.biesheuvel@linaro.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <crypto/internal/hash.h>
#include <crypto/sha.h>
#include <linux/crypto.h>
#include <linux/module.h>
#include <asm/unaligned.h>
typedef void (sha256_block_fn)(struct sha256_state *sst, u8 const *src,
int blocks);
static inline int sha224_base_init(struct shash_desc *desc)
{
struct sha256_state *sctx = shash_desc_ctx(desc);
sctx->state[0] = SHA224_H0;
sctx->state[1] = SHA224_H1;
sctx->state[2] = SHA224_H2;
sctx->state[3] = SHA224_H3;
sctx->state[4] = SHA224_H4;
sctx->state[5] = SHA224_H5;
sctx->state[6] = SHA224_H6;
sctx->state[7] = SHA224_H7;
sctx->count = 0;
return 0;
}
static inline int sha256_base_init(struct shash_desc *desc)
{
struct sha256_state *sctx = shash_desc_ctx(desc);
sctx->state[0] = SHA256_H0;
sctx->state[1] = SHA256_H1;
sctx->state[2] = SHA256_H2;
sctx->state[3] = SHA256_H3;
sctx->state[4] = SHA256_H4;
sctx->state[5] = SHA256_H5;
sctx->state[6] = SHA256_H6;
sctx->state[7] = SHA256_H7;
sctx->count = 0;
return 0;
}
static inline int sha256_base_do_update(struct shash_desc *desc,
const u8 *data,
unsigned int len,
sha256_block_fn *block_fn)
{
struct sha256_state *sctx = shash_desc_ctx(desc);
unsigned int partial = sctx->count % SHA256_BLOCK_SIZE;
sctx->count += len;
if (unlikely((partial + len) >= SHA256_BLOCK_SIZE)) {
int blocks;
if (partial) {
int p = SHA256_BLOCK_SIZE - partial;
memcpy(sctx->buf + partial, data, p);
data += p;
len -= p;
block_fn(sctx, sctx->buf, 1);
}
blocks = len / SHA256_BLOCK_SIZE;
len %= SHA256_BLOCK_SIZE;
if (blocks) {
block_fn(sctx, data, blocks);
data += blocks * SHA256_BLOCK_SIZE;
}
partial = 0;
}
if (len)
memcpy(sctx->buf + partial, data, len);
return 0;
}
static inline int sha256_base_do_finalize(struct shash_desc *desc,
sha256_block_fn *block_fn)
{
const int bit_offset = SHA256_BLOCK_SIZE - sizeof(__be64);
struct sha256_state *sctx = shash_desc_ctx(desc);
__be64 *bits = (__be64 *)(sctx->buf + bit_offset);
unsigned int partial = sctx->count % SHA256_BLOCK_SIZE;
sctx->buf[partial++] = 0x80;
if (partial > bit_offset) {
memset(sctx->buf + partial, 0x0, SHA256_BLOCK_SIZE - partial);
partial = 0;
block_fn(sctx, sctx->buf, 1);
}
memset(sctx->buf + partial, 0x0, bit_offset - partial);
*bits = cpu_to_be64(sctx->count << 3);
block_fn(sctx, sctx->buf, 1);
return 0;
}
static inline int sha256_base_finish(struct shash_desc *desc, u8 *out)
{
unsigned int digest_size = crypto_shash_digestsize(desc->tfm);
struct sha256_state *sctx = shash_desc_ctx(desc);
__be32 *digest = (__be32 *)out;
int i;
for (i = 0; digest_size > 0; i++, digest_size -= sizeof(__be32))
put_unaligned_be32(sctx->state[i], digest++);
*sctx = (struct sha256_state){};
return 0;
}