sha1_generic.c

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/*
 * Cryptographic API.
 *
 * SHA1 Secure Hash Algorithm.
 *
 * Derived from cryptoapi implementation, adapted for in-place
 * scatterlist interface.
 *
 * Copyright (c) Alan Smithee.
 * Copyright (c) Andrew McDonald <[email protected]>
 * Copyright (c) Jean-Francois Dive <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 */
#include <crypto/internal/hash.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/cryptohash.h>
#include <linux/types.h>
#include <crypto/sha.h>
#include <asm/byteorder.h>

static int sha1_init(struct shash_desc *desc)
{
    struct sha1_state *sctx = shash_desc_ctx(desc);

    *sctx = (struct sha1_state){
        .state = { SHA1_H0, SHA1_H1, SHA1_H2, SHA1_H3, SHA1_H4 },
    };

    return 0;
}

int crypto_sha1_update(struct shash_desc *desc, const u8 *data,
            unsigned int len)
{
    struct sha1_state *sctx = shash_desc_ctx(desc);
    unsigned int partial, done;
    const u8 *src;

    partial = sctx->count % SHA1_BLOCK_SIZE;
    sctx->count += len;
    done = 0;
    src = data;

    if ((partial + len) >= SHA1_BLOCK_SIZE) {
        u32 temp[SHA_WORKSPACE_WORDS];

        if (partial) {
            done = -partial;
            memcpy(sctx->buffer + partial, data,
                   done + SHA1_BLOCK_SIZE);
            src = sctx->buffer;
        }

        do {
            sha_transform(sctx->state, src, temp);
            done += SHA1_BLOCK_SIZE;
            src = data + done;
        } while (done + SHA1_BLOCK_SIZE <= len);

        memset(temp, 0, sizeof(temp));
        partial = 0;
    }
    memcpy(sctx->buffer + partial, src, len - done);

    return 0;
}
EXPORT_SYMBOL(crypto_sha1_update);


/* Add padding and return the message digest. */
static int sha1_final(struct shash_desc *desc, u8 *out)
{
    struct sha1_state *sctx = shash_desc_ctx(desc);
    __be32 *dst = (__be32 *)out;
    u32 i, index, padlen;
    __be64 bits;
    static const u8 padding[64] = { 0x80, };

    bits = cpu_to_be64(sctx->count << 3);

    /* Pad out to 56 mod 64 */
    index = sctx->count & 0x3f;
    padlen = (index < 56) ? (56 - index) : ((64+56) - index);
    crypto_sha1_update(desc, padding, padlen);

    /* Append length */
    crypto_sha1_update(desc, (const u8 *)&bits, sizeof(bits));

    /* Store state in digest */
    for (i = 0; i < 5; i++)
        dst[i] = cpu_to_be32(sctx->state[i]);

    /* Wipe context */
    memset(sctx, 0, sizeof *sctx);

    return 0;
}

static int sha1_export(struct shash_desc *desc, void *out)
{
    struct sha1_state *sctx = shash_desc_ctx(desc);

    memcpy(out, sctx, sizeof(*sctx));
    return 0;
}

static int sha1_import(struct shash_desc *desc, const void *in)
{
    struct sha1_state *sctx = shash_desc_ctx(desc);

    memcpy(sctx, in, sizeof(*sctx));
    return 0;
}

static struct shash_alg alg = {
    .digestsize =   SHA1_DIGEST_SIZE,
    .init       =   sha1_init,
    .update     =   crypto_sha1_update,
    .final      =   sha1_final,
    .export     =   sha1_export,
    .import     =   sha1_import,
    .descsize   =   sizeof(struct sha1_state),
    .statesize  =   sizeof(struct sha1_state),
    .base       =   {
        .cra_name   =   "sha1",
        .cra_driver_name=   "sha1-generic",
        .cra_flags  =   CRYPTO_ALG_TYPE_SHASH,
        .cra_blocksize  =   SHA1_BLOCK_SIZE,
        .cra_module =   THIS_MODULE,
    }
};

static int __init sha1_generic_mod_init(void)
{
    return crypto_register_shash(&alg);
}

static void __exit sha1_generic_mod_fini(void)
{
    crypto_unregister_shash(&alg);
}

module_init(sha1_generic_mod_init);
module_exit(sha1_generic_mod_fini);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("SHA1 Secure Hash Algorithm");

MODULE_ALIAS("sha1");