crypto/sha1_generic.c

   1 /*
   2  * Cryptographic API.
   3  *
   4  * SHA1 Secure Hash Algorithm.
   5  *
   6  * Derived from cryptoapi implementation, adapted for in-place
   7  * scatterlist interface.
   8  *
   9  * Copyright (c) Alan Smithee.
  10  * Copyright (c) Andrew McDonald <andrew@mcdonald.org.uk>
  11  * Copyright (c) Jean-Francois Dive <jef@linuxbe.org>
  12  *
  13  * This program is free software; you can redistribute it and/or modify it
  14  * under the terms of the GNU General Public License as published by the Free
  15  * Software Foundation; either version 2 of the License, or (at your option)
  16  * any later version.
  17  *
  18  */
  19 #include <linux/init.h>
  20 #include <linux/module.h>
  21 #include <linux/mm.h>
  22 #include <linux/crypto.h>
  23 #include <linux/cryptohash.h>
  24 #include <linux/types.h>
  25 #include <crypto/sha.h>
  26 #include <asm/byteorder.h>
  27
  28 struct sha1_ctx {
  29         u64 count;
  30         u32 state[5];
  31         u8 buffer[64];
  32 };
  33
  34 static void sha1_init(struct crypto_tfm *tfm)
  35 {
  36         struct sha1_ctx *sctx = crypto_tfm_ctx(tfm);
  37         static const struct sha1_ctx initstate = {
  38           0,
  39           { SHA1_H0, SHA1_H1, SHA1_H2, SHA1_H3, SHA1_H4 },
  40           { 0, }
  41         };
  42
  43         *sctx = initstate;
  44 }
  45
  46 static void sha1_update(struct crypto_tfm *tfm, const u8 *data,
  47                         unsigned int len)
  48 {
  49         struct sha1_ctx *sctx = crypto_tfm_ctx(tfm);
  50         unsigned int partial, done;
  51         const u8 *src;
  52
  53         partial = sctx->count & 0x3f;
  54         sctx->count += len;
  55         done = 0;
  56         src = data;
  57
  58         if ((partial + len) > 63) {
  59                 u32 temp[SHA_WORKSPACE_WORDS];
  60
  61                 if (partial) {
  62                         done = -partial;
  63                         memcpy(sctx->buffer + partial, data, done + 64);
  64                         src = sctx->buffer;
  65                 }
  66
  67                 do {
  68                         sha_transform(sctx->state, src, temp);
  69                         done += 64;
  70                         src = data + done;
  71                 } while (done + 63 < len);
  72
  73                 memset(temp, 0, sizeof(temp));
  74                 partial = 0;
  75         }
  76         memcpy(sctx->buffer + partial, src, len - done);
  77 }
  78
  79
  80 /* Add padding and return the message digest. */
  81 static void sha1_final(struct crypto_tfm *tfm, u8 *out)
  82 {
  83         struct sha1_ctx *sctx = crypto_tfm_ctx(tfm);
  84         __be32 *dst = (__be32 *)out;
  85         u32 i, index, padlen;
  86         __be64 bits;
  87         static const u8 padding[64] = { 0x80, };
  88
  89         bits = cpu_to_be64(sctx->count << 3);
  90
  91         /* Pad out to 56 mod 64 */
  92         index = sctx->count & 0x3f;
  93         padlen = (index < 56) ? (56 - index) : ((64+56) - index);
  94         sha1_update(tfm, padding, padlen);
  95
  96         /* Append length */
  97         sha1_update(tfm, (const u8 *)&bits, sizeof(bits));
  98
  99         /* Store state in digest */
 100         for (i = 0; i < 5; i++)
 101                 dst[i] = cpu_to_be32(sctx->state[i]);
 102
 103         /* Wipe context */
 104         memset(sctx, 0, sizeof *sctx);
 105 }
 106
 107 static struct crypto_alg alg = {
 108         .cra_name       =       "sha1",
 109         .cra_driver_name=       "sha1-generic",
 110         .cra_flags      =       CRYPTO_ALG_TYPE_DIGEST,
 111         .cra_blocksize  =       SHA1_BLOCK_SIZE,
 112         .cra_ctxsize    =       sizeof(struct sha1_ctx),
 113         .cra_module     =       THIS_MODULE,
 114         .cra_alignmask  =       3,
 115         .cra_list       =       LIST_HEAD_INIT(alg.cra_list),
 116         .cra_u          =       { .digest = {
 117         .dia_digestsize =       SHA1_DIGEST_SIZE,
 118         .dia_init       =       sha1_init,
 119         .dia_update     =       sha1_update,
 120         .dia_final      =       sha1_final } }
 121 };
 122
 123 static int __init sha1_generic_mod_init(void)
 124 {
 125         return crypto_register_alg(&alg);
 126 }
 127
 128 static void __exit sha1_generic_mod_fini(void)
 129 {
 130         crypto_unregister_alg(&alg);
 131 }
 132
 133 module_init(sha1_generic_mod_init);
 134 module_exit(sha1_generic_mod_fini);
 135
 136 MODULE_LICENSE("GPL");
 137 MODULE_DESCRIPTION("SHA1 Secure Hash Algorithm");
 138
 139 MODULE_ALIAS("sha1");