FreeBSD/Linux Kernel Cross Reference
sys/crypto/sha1.c

     /*
      * Cryptographic API.
      *
      * SHA1 Secure Hash Algorithm.
      *
      * Derived from cryptoapi implementation, adapted for in-place
      * scatterlist interface.  Originally based on the public domain
      * implementation written by Steve Reid.
      *
     * Copyright (c) Alan Smithee.
     * Copyright (c) Andrew McDonald <andrew@mcdonald.org.uk>
     * Copyright (c) Jean-Francois Dive <jef@linuxbe.org>
     *
     * 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 <linux/init.h>
    #include <linux/module.h>
    #include <linux/mm.h>
    #include <linux/crypto.h>
    #include <asm/scatterlist.h>
    #include <asm/byteorder.h>
    
    #define SHA1_DIGEST_SIZE        20
    #define SHA1_HMAC_BLOCK_SIZE    64
    
    static inline u32 rol(u32 value, u32 bits)
    {
            return (((value) << (bits)) | ((value) >> (32 - (bits))));
    }
    
    /* blk0() and blk() perform the initial expand. */
    /* I got the idea of expanding during the round function from SSLeay */
    # define blk0(i) block32[i]
    
    #define blk(i) (block32[i&15] = rol(block32[(i+13)&15]^block32[(i+8)&15] \
        ^block32[(i+2)&15]^block32[i&15],1))
    
    /* (R0+R1), R2, R3, R4 are the different operations used in SHA1 */
    #define R0(v,w,x,y,z,i) z+=((w&(x^y))^y)+blk0(i)+0x5A827999+rol(v,5); \
                            w=rol(w,30);
    #define R1(v,w,x,y,z,i) z+=((w&(x^y))^y)+blk(i)+0x5A827999+rol(v,5); \
                            w=rol(w,30);
    #define R2(v,w,x,y,z,i) z+=(w^x^y)+blk(i)+0x6ED9EBA1+rol(v,5);w=rol(w,30);
    #define R3(v,w,x,y,z,i) z+=(((w|x)&y)|(w&x))+blk(i)+0x8F1BBCDC+rol(v,5); \
                            w=rol(w,30);
    #define R4(v,w,x,y,z,i) z+=(w^x^y)+blk(i)+0xCA62C1D6+rol(v,5);w=rol(w,30);
    
    struct sha1_ctx {
            u64 count;
            u32 state[5];
            u8 buffer[64];
    };
    
    /* Hash a single 512-bit block. This is the core of the algorithm. */
    static void sha1_transform(u32 *state, const u8 *in)
    {
            u32 a, b, c, d, e;
            u32 block32[16];
    
            /* convert/copy data to workspace */
            for (a = 0; a < sizeof(block32)/sizeof(u32); a++)
              block32[a] = be32_to_cpu (((const u32 *)in)[a]);
    
            /* Copy context->state[] to working vars */
            a = state[0];
            b = state[1];
            c = state[2];
            d = state[3];
            e = state[4];
    
            /* 4 rounds of 20 operations each. Loop unrolled. */
            R0(a,b,c,d,e, 0); R0(e,a,b,c,d, 1); R0(d,e,a,b,c, 2); R0(c,d,e,a,b, 3);
            R0(b,c,d,e,a, 4); R0(a,b,c,d,e, 5); R0(e,a,b,c,d, 6); R0(d,e,a,b,c, 7);
            R0(c,d,e,a,b, 8); R0(b,c,d,e,a, 9); R0(a,b,c,d,e,10); R0(e,a,b,c,d,11);
            R0(d,e,a,b,c,12); R0(c,d,e,a,b,13); R0(b,c,d,e,a,14); R0(a,b,c,d,e,15);
            R1(e,a,b,c,d,16); R1(d,e,a,b,c,17); R1(c,d,e,a,b,18); R1(b,c,d,e,a,19);
            R2(a,b,c,d,e,20); R2(e,a,b,c,d,21); R2(d,e,a,b,c,22); R2(c,d,e,a,b,23);
            R2(b,c,d,e,a,24); R2(a,b,c,d,e,25); R2(e,a,b,c,d,26); R2(d,e,a,b,c,27);
            R2(c,d,e,a,b,28); R2(b,c,d,e,a,29); R2(a,b,c,d,e,30); R2(e,a,b,c,d,31);
            R2(d,e,a,b,c,32); R2(c,d,e,a,b,33); R2(b,c,d,e,a,34); R2(a,b,c,d,e,35);
            R2(e,a,b,c,d,36); R2(d,e,a,b,c,37); R2(c,d,e,a,b,38); R2(b,c,d,e,a,39);
            R3(a,b,c,d,e,40); R3(e,a,b,c,d,41); R3(d,e,a,b,c,42); R3(c,d,e,a,b,43);
            R3(b,c,d,e,a,44); R3(a,b,c,d,e,45); R3(e,a,b,c,d,46); R3(d,e,a,b,c,47);
            R3(c,d,e,a,b,48); R3(b,c,d,e,a,49); R3(a,b,c,d,e,50); R3(e,a,b,c,d,51);
            R3(d,e,a,b,c,52); R3(c,d,e,a,b,53); R3(b,c,d,e,a,54); R3(a,b,c,d,e,55);
            R3(e,a,b,c,d,56); R3(d,e,a,b,c,57); R3(c,d,e,a,b,58); R3(b,c,d,e,a,59);
            R4(a,b,c,d,e,60); R4(e,a,b,c,d,61); R4(d,e,a,b,c,62); R4(c,d,e,a,b,63);
            R4(b,c,d,e,a,64); R4(a,b,c,d,e,65); R4(e,a,b,c,d,66); R4(d,e,a,b,c,67);
            R4(c,d,e,a,b,68); R4(b,c,d,e,a,69); R4(a,b,c,d,e,70); R4(e,a,b,c,d,71);
            R4(d,e,a,b,c,72); R4(c,d,e,a,b,73); R4(b,c,d,e,a,74); R4(a,b,c,d,e,75);
            R4(e,a,b,c,d,76); R4(d,e,a,b,c,77); R4(c,d,e,a,b,78); R4(b,c,d,e,a,79);
            /* Add the working vars back into context.state[] */
            state[0] += a;
            state[1] += b;
            state[2] += c;
           state[3] += d;
           state[4] += e;
           /* Wipe variables */
           a = b = c = d = e = 0;
           memset (block32, 0x00, sizeof block32);
   }
   
   static void sha1_init(void *ctx)
   {
           struct sha1_ctx *sctx = ctx;
           static const struct sha1_ctx initstate = {
             0,
             { 0x67452301, 0xEFCDAB89, 0x98BADCFE, 0x10325476, 0xC3D2E1F0 },
             { 0, }
           };
   
           *sctx = initstate;
   }
   
   static void sha1_update(void *ctx, const u8 *data, unsigned int len)
   {
           struct sha1_ctx *sctx = ctx;
           unsigned int i, j;
   
           j = (sctx->count >> 3) & 0x3f;
           sctx->count += len << 3;
   
           if ((j + len) > 63) {
                   memcpy(&sctx->buffer[j], data, (i = 64-j));
                   sha1_transform(sctx->state, sctx->buffer);
                   for ( ; i + 63 < len; i += 64) {
                           sha1_transform(sctx->state, &data[i]);
                   }
                   j = 0;
           }
           else i = 0;
           memcpy(&sctx->buffer[j], &data[i], len - i);
   }
   
   
   /* Add padding and return the message digest. */
   static void sha1_final(void* ctx, u8 *out)
   {
           struct sha1_ctx *sctx = ctx;
           u32 i, j, index, padlen;
           u64 t;
           u8 bits[8] = { 0, };
           static const u8 padding[64] = { 0x80, };
   
           t = sctx->count;
           bits[7] = 0xff & t; t>>=8;
           bits[6] = 0xff & t; t>>=8;
           bits[5] = 0xff & t; t>>=8;
           bits[4] = 0xff & t; t>>=8;
           bits[3] = 0xff & t; t>>=8;
           bits[2] = 0xff & t; t>>=8;
           bits[1] = 0xff & t; t>>=8;
           bits[0] = 0xff & t;
   
           /* Pad out to 56 mod 64 */
           index = (sctx->count >> 3) & 0x3f;
           padlen = (index < 56) ? (56 - index) : ((64+56) - index);
           sha1_update(sctx, padding, padlen);
   
           /* Append length */
           sha1_update(sctx, bits, sizeof bits); 
   
           /* Store state in digest */
           for (i = j = 0; i < 5; i++, j += 4) {
                   u32 t2 = sctx->state[i];
                   out[j+3] = t2 & 0xff; t2>>=8;
                   out[j+2] = t2 & 0xff; t2>>=8;
                   out[j+1] = t2 & 0xff; t2>>=8;
                   out[j  ] = t2 & 0xff;
           }
   
           /* Wipe context */
           memset(sctx, 0, sizeof *sctx);
   }
   
   static struct crypto_alg alg = {
           .cra_name       =       "sha1",
           .cra_flags      =       CRYPTO_ALG_TYPE_DIGEST,
           .cra_blocksize  =       SHA1_HMAC_BLOCK_SIZE,
           .cra_ctxsize    =       sizeof(struct sha1_ctx),
           .cra_module     =       THIS_MODULE,
           .cra_list       =       LIST_HEAD_INIT(alg.cra_list),
           .cra_u          =       { .digest = {
           .dia_digestsize =       SHA1_DIGEST_SIZE,
           .dia_init       =       sha1_init,
           .dia_update     =       sha1_update,
           .dia_final      =       sha1_final } }
   };
   
   static int __init init(void)
   {
           return crypto_register_alg(&alg);
   }
   
   static void __exit fini(void)
   {
           crypto_unregister_alg(&alg);
   }
   
   module_init(init);
   module_exit(fini);
   
   MODULE_LICENSE("GPL");
   MODULE_DESCRIPTION("SHA1 Secure Hash Algorithm");

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