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 <crypto/internal/hash.h>
  20 #include <linux/init.h>
  21 #include <linux/module.h>
  22 #include <linux/mm.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 int sha1_init(struct shash_desc *desc)
  35 {
  36         struct sha1_ctx *sctx = shash_desc_ctx(desc);
  37
  38         static const struct sha1_ctx initstate = {
  39           0,
  40           { SHA1_H0, SHA1_H1, SHA1_H2, SHA1_H3, SHA1_H4 },
  41           { 0, }
  42         };
  43
  44         *sctx = initstate;
  45
  46         return 0;
  47 }
  48
  49 static int sha1_update(struct shash_desc *desc, const u8 *data,
  50                         unsigned int len)
  51 {
  52         struct sha1_ctx *sctx = shash_desc_ctx(desc);
  53         unsigned int partial, done;
  54         const u8 *src;
  55
  56         partial = sctx->count & 0x3f;
  57         sctx->count += len;
  58         done = 0;
  59         src = data;
  60
  61         if ((partial + len) > 63) {
  62                 u32 temp[SHA_WORKSPACE_WORDS];
  63
  64                 if (partial) {
  65                         done = -partial;
  66                         memcpy(sctx->buffer + partial, data, done + 64);
  67                         src = sctx->buffer;
  68                 }
  69
  70                 do {
  71                         sha_transform(sctx->state, src, temp);
  72                         done += 64;
  73                         src = data + done;
  74                 } while (done + 63 < len);
  75
  76                 memset(temp, 0, sizeof(temp));
  77                 partial = 0;
  78         }
  79         memcpy(sctx->buffer + partial, src, len - done);
  80
  81         return 0;
  82 }
  83
  84
  85 /* Add padding and return the message digest. */
  86 static int sha1_final(struct shash_desc *desc, u8 *out)
  87 {
  88         struct sha1_ctx *sctx = shash_desc_ctx(desc);
  89         __be32 *dst = (__be32 *)out;
  90         u32 i, index, padlen;
  91         __be64 bits;
  92         static const u8 padding[64] = { 0x80, };
  93
  94         bits = cpu_to_be64(sctx->count << 3);
  95
  96         /* Pad out to 56 mod 64 */
  97         index = sctx->count & 0x3f;
  98         padlen = (index < 56) ? (56 - index) : ((64+56) - index);
  99         sha1_update(desc, padding, padlen);
 100
 101         /* Append length */
 102         sha1_update(desc, (const u8 *)&bits, sizeof(bits));
 103
 104         /* Store state in digest */
 105         for (i = 0; i < 5; i++)
 106                 dst[i] = cpu_to_be32(sctx->state[i]);
 107
 108         /* Wipe context */
 109         memset(sctx, 0, sizeof *sctx);
 110
 111         return 0;
 112 }
 113
 114 static struct shash_alg alg = {
 115         .digestsize     =       SHA1_DIGEST_SIZE,
 116         .init           =       sha1_init,
 117         .update         =       sha1_update,
 118         .final          =       sha1_final,
 119         .descsize       =       sizeof(struct sha1_ctx),
 120         .base           =       {
 121                 .cra_name       =       "sha1",
 122                 .cra_driver_name=       "sha1-generic",
 123                 .cra_flags      =       CRYPTO_ALG_TYPE_SHASH,
 124                 .cra_blocksize  =       SHA1_BLOCK_SIZE,
 125                 .cra_module     =       THIS_MODULE,
 126         }
 127 };
 128
 129 static int __init sha1_generic_mod_init(void)
 130 {
 131         return crypto_register_shash(&alg);
 132 }
 133
 134 static void __exit sha1_generic_mod_fini(void)
 135 {
 136         crypto_unregister_shash(&alg);
 137 }
 138
 139 module_init(sha1_generic_mod_init);
 140 module_exit(sha1_generic_mod_fini);
 141
 142 MODULE_LICENSE("GPL");
 143 MODULE_DESCRIPTION("SHA1 Secure Hash Algorithm");
 144
 145 MODULE_ALIAS("sha1");