FreeBSD/Linux Kernel Cross Reference
sys/crypto/md5.c

     /* 
      * Cryptographic API.
      *
      * MD5 Message Digest Algorithm (RFC1321).
      *
      * Derived from cryptoapi implementation, originally based on the
      * public domain implementation written by Colin Plumb in 1993.
      *
      * Copyright (c) Cryptoapi developers.
     * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
     * 
     * 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 <crypto/md5.h>
    #include <linux/init.h>
    #include <linux/module.h>
    #include <linux/string.h>
    #include <linux/types.h>
    #include <linux/cryptohash.h>
    #include <asm/byteorder.h>
    
    /* XXX: this stuff can be optimized */
    static inline void le32_to_cpu_array(u32 *buf, unsigned int words)
    {
            while (words--) {
                    __le32_to_cpus(buf);
                    buf++;
            }
    }
    
    static inline void cpu_to_le32_array(u32 *buf, unsigned int words)
    {
            while (words--) {
                    __cpu_to_le32s(buf);
                    buf++;
            }
    }
    
    static inline void md5_transform_helper(struct md5_state *ctx)
    {
            le32_to_cpu_array(ctx->block, sizeof(ctx->block) / sizeof(u32));
            md5_transform(ctx->hash, ctx->block);
    }
    
    static int md5_init(struct shash_desc *desc)
    {
            struct md5_state *mctx = shash_desc_ctx(desc);
    
            mctx->hash[0] = 0x67452301;
            mctx->hash[1] = 0xefcdab89;
            mctx->hash[2] = 0x98badcfe;
            mctx->hash[3] = 0x10325476;
            mctx->byte_count = 0;
    
            return 0;
    }
    
    static int md5_update(struct shash_desc *desc, const u8 *data, unsigned int len)
    {
            struct md5_state *mctx = shash_desc_ctx(desc);
            const u32 avail = sizeof(mctx->block) - (mctx->byte_count & 0x3f);
    
            mctx->byte_count += len;
    
            if (avail > len) {
                    memcpy((char *)mctx->block + (sizeof(mctx->block) - avail),
                           data, len);
                    return 0;
            }
    
            memcpy((char *)mctx->block + (sizeof(mctx->block) - avail),
                   data, avail);
    
            md5_transform_helper(mctx);
            data += avail;
            len -= avail;
    
            while (len >= sizeof(mctx->block)) {
                    memcpy(mctx->block, data, sizeof(mctx->block));
                    md5_transform_helper(mctx);
                    data += sizeof(mctx->block);
                    len -= sizeof(mctx->block);
            }
    
            memcpy(mctx->block, data, len);
    
            return 0;
    }
    
    static int md5_final(struct shash_desc *desc, u8 *out)
    {
            struct md5_state *mctx = shash_desc_ctx(desc);
            const unsigned int offset = mctx->byte_count & 0x3f;
            char *p = (char *)mctx->block + offset;
           int padding = 56 - (offset + 1);
   
           *p++ = 0x80;
           if (padding < 0) {
                   memset(p, 0x00, padding + sizeof (u64));
                   md5_transform_helper(mctx);
                   p = (char *)mctx->block;
                   padding = 56;
           }
   
           memset(p, 0, padding);
           mctx->block[14] = mctx->byte_count << 3;
           mctx->block[15] = mctx->byte_count >> 29;
           le32_to_cpu_array(mctx->block, (sizeof(mctx->block) -
                             sizeof(u64)) / sizeof(u32));
           md5_transform(mctx->hash, mctx->block);
           cpu_to_le32_array(mctx->hash, sizeof(mctx->hash) / sizeof(u32));
           memcpy(out, mctx->hash, sizeof(mctx->hash));
           memset(mctx, 0, sizeof(*mctx));
   
           return 0;
   }
   
   static int md5_export(struct shash_desc *desc, void *out)
   {
           struct md5_state *ctx = shash_desc_ctx(desc);
   
           memcpy(out, ctx, sizeof(*ctx));
           return 0;
   }
   
   static int md5_import(struct shash_desc *desc, const void *in)
   {
           struct md5_state *ctx = shash_desc_ctx(desc);
   
           memcpy(ctx, in, sizeof(*ctx));
           return 0;
   }
   
   static struct shash_alg alg = {
           .digestsize     =       MD5_DIGEST_SIZE,
           .init           =       md5_init,
           .update         =       md5_update,
           .final          =       md5_final,
           .export         =       md5_export,
           .import         =       md5_import,
           .descsize       =       sizeof(struct md5_state),
           .statesize      =       sizeof(struct md5_state),
           .base           =       {
                   .cra_name       =       "md5",
                   .cra_flags      =       CRYPTO_ALG_TYPE_SHASH,
                   .cra_blocksize  =       MD5_HMAC_BLOCK_SIZE,
                   .cra_module     =       THIS_MODULE,
           }
   };
   
   static int __init md5_mod_init(void)
   {
           return crypto_register_shash(&alg);
   }
   
   static void __exit md5_mod_fini(void)
   {
           crypto_unregister_shash(&alg);
   }
   
   module_init(md5_mod_init);
   module_exit(md5_mod_fini);
   
   MODULE_LICENSE("GPL");
   MODULE_DESCRIPTION("MD5 Message Digest Algorithm");

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