n_md5.c

/*
 * https://opensource.apple.com/source/cvs/cvs-19/cvs/lib/md5.c
 *
 * This code implements the MD5 message-digest algorithm.
 * The algorithm is due to Ron Rivest.  This code was
 * written by Colin Plumb in 1993, no copyright is claimed.
 * This code is in the public domain; do with it what you wish.
 *
 * Equivalent code is available from RSA Data Security, Inc.
 * This code has been tested against that, and is equivalent,
 * except that you don't need to include two pages of legalese
 * with every copy.
 *
 * To compute the message digest of a chunk of bytes, declare an
 * MD5Context structure, pass it to NoteMD5Init, call NoteMD5Update as
 * needed on buffers full of bytes, and then call NoteMD5Final, which
 * will fill a supplied 16-byte array with the digest.
 */

/* This code was modified in 1997 by Jim Kingdon of Cyclic Software to
   not require an integer type which is exactly 32 bits.  This work
   draws on the changes for the same purpose by Tatu Ylonen
   <ylo@cs.hut.fi> as part of SSH, but since I didn't actually use
   that code, there is no copyright issue.  I hereby disclaim
   copyright in any changes I have made; this code remains in the
   public domain.  */

#include <string.h>
#include "n_lib.h"

// Forwards
void n_htoa8(unsigned char n, unsigned char *p);
static void putu32 (unsigned long data, unsigned char *addr);
static unsigned long getu32 (const unsigned char *addr);

/* Little-endian byte-swapping routines.  Note that these do not
   depend on the size of datatypes such as unsigned long, nor do they require
   us to detect the endianness of the machine we are running on.  It
   is possible they should be macros for speed, but I would be
   surprised if they were a performance bottleneck for MD5.  */

static unsigned long getu32 (const unsigned char *addr)
{
    return (((((unsigned long)addr[3] << 8) | addr[2]) << 8)
            | addr[1]) << 8 | addr[0];
}

static void putu32 (unsigned long data, unsigned char *addr)
{
    addr[0] = (unsigned char)data;
    addr[1] = (unsigned char)(data >> 8);
    addr[2] = (unsigned char)(data >> 16);
    addr[3] = (unsigned char)(data >> 24);
}

/* Convert an 8-bit number to 2 hex digits, null-terminating it */
void n_htoa8(unsigned char n, unsigned char *p)
{
    unsigned char nibble = (n >> 4) & 0xf;
    if (nibble >= 10) {
        *p++ = 'a' + (nibble-10);
    } else {
        *p++ = '0' + nibble;
    }
    nibble = n & 0xf;
    if (nibble >= 10) {
        *p++ = 'a' + (nibble-10);
    } else {
        *p++ = '0' + nibble;
    }
    *p = '\0';
}

/*
 * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
 * initialization constants.
 */
void NoteMD5Init(NoteMD5Context *ctx)
{
    memset(ctx, 0, sizeof(NoteMD5Context));

    ctx->buf[0] = 0x67452301;
    ctx->buf[1] = 0xefcdab89;
    ctx->buf[2] = 0x98badcfe;
    ctx->buf[3] = 0x10325476;

    ctx->bits[0] = 0;
    ctx->bits[1] = 0;
}

/*
 * Update context to reflect the concatenation of another buffer full
 * of bytes.
 */
void NoteMD5Update(NoteMD5Context *ctx, unsigned char const *buf, unsigned long len)
{
    unsigned long t;

    /* Update bitcount */

    t = ctx->bits[0];
    if ((ctx->bits[0] = (t + ((unsigned long)len << 3)) & 0xffffffff) < t) {
        ctx->bits[1]++;    /* Carry from low to high */
    }
    ctx->bits[1] += len >> 29;

    t = (t >> 3) & 0x3f;  /* Bytes already in shsInfo->data */

    /* Handle any leading odd-sized chunks */

    if ( t ) {
        unsigned char *p = ctx->in + t;

        t = 64-t;
        if (len < t) {
            memcpy(p, buf, len);
            return;
        }
        memcpy(p, buf, t);
        NoteMD5Transform(ctx->buf, ctx->in);
        buf += t;
        len -= t;
    }

    /* Process data in 64-byte chunks */

    while (len >= 64) {
        memcpy(ctx->in, buf, 64);
        NoteMD5Transform(ctx->buf, ctx->in);
        buf += 64;
        len -= 64;
    }

    /* Handle any remaining bytes of data. */

    memcpy(ctx->in, buf, len);
}

/*
 * Final wrapup - pad to 64-byte boundary with the bit pattern
 * 1 0* (64-bit count of bits processed, MSB-first)
 */
void NoteMD5Final(unsigned char *digest, NoteMD5Context *ctx)
{
    unsigned count;
    unsigned char *p;

    /* Compute number of bytes mod 64 */
    count = (ctx->bits[0] >> 3) & 0x3F;

    /* Set the first char of padding to 0x80.  This is safe since there is
       always at least one byte free */
    p = ctx->in + count;
    *p++ = 0x80;

    /* Bytes of padding needed to make 64 bytes */
    count = 64 - 1 - count;

    /* Pad out to 56 mod 64 */
    if (count < 8) {
        /* Two lots of padding:  Pad the first block to 64 bytes */
        memset(p, 0, count);
        NoteMD5Transform(ctx->buf, ctx->in);

        /* Now fill the next block with 56 bytes */
        memset(ctx->in, 0, 56);
    } else {
        /* Pad block to 56 bytes */
        memset(p, 0, count-8);
    }

    /* Append length in bits and transform */
    putu32(ctx->bits[0], ctx->in + 56);
    putu32(ctx->bits[1], ctx->in + 60);

    NoteMD5Transform(ctx->buf, ctx->in);
    putu32(ctx->buf[0], digest);
    putu32(ctx->buf[1], digest + 4);
    putu32(ctx->buf[2], digest + 8);
    putu32(ctx->buf[3], digest + 12);
    memset(ctx, 0, sizeof(NoteMD5Context)); /* In case it's sensitive */
}

/* The four core functions - F1 is optimized somewhat */

/* #define F1(x, y, z) (x & y | ~x & z) */
#define F1(x, y, z) (z ^ (x & (y ^ z)))
#define F2(x, y, z) F1(z, x, y)
#define F3(x, y, z) (x ^ y ^ z)
#define F4(x, y, z) (y ^ (x | ~z))

/* This is the central step in the MD5 algorithm. */
#define MD5STEP(f, w, x, y, z, data, s) \
  ( w += f(x, y, z) + data, w &= 0xffffffff, w = w<<s | w>>(32-s), w += x )

/*
 * The core of the MD5 algorithm, this alters an existing MD5 hash to
 * reflect the addition of 16 longwords of new data.  NoteMD5Update blocks
 * the data and converts bytes into longwords for this routine.
 */
void NoteMD5Transform(unsigned long buf[4], const unsigned char inraw[64])
{
    register unsigned long a, b, c, d;
    unsigned long in[16];
    int i;

    for (i = 0; i < 16; ++i) {
        in[i] = getu32 (inraw + 4 * i);
    }

    a = buf[0];
    b = buf[1];
    c = buf[2];
    d = buf[3];

    MD5STEP(F1, a, b, c, d, in[ 0]+0xd76aa478,  7);
    MD5STEP(F1, d, a, b, c, in[ 1]+0xe8c7b756, 12);
    MD5STEP(F1, c, d, a, b, in[ 2]+0x242070db, 17);
    MD5STEP(F1, b, c, d, a, in[ 3]+0xc1bdceee, 22);
    MD5STEP(F1, a, b, c, d, in[ 4]+0xf57c0faf,  7);
    MD5STEP(F1, d, a, b, c, in[ 5]+0x4787c62a, 12);
    MD5STEP(F1, c, d, a, b, in[ 6]+0xa8304613, 17);
    MD5STEP(F1, b, c, d, a, in[ 7]+0xfd469501, 22);
    MD5STEP(F1, a, b, c, d, in[ 8]+0x698098d8,  7);
    MD5STEP(F1, d, a, b, c, in[ 9]+0x8b44f7af, 12);
    MD5STEP(F1, c, d, a, b, in[10]+0xffff5bb1, 17);
    MD5STEP(F1, b, c, d, a, in[11]+0x895cd7be, 22);
    MD5STEP(F1, a, b, c, d, in[12]+0x6b901122,  7);
    MD5STEP(F1, d, a, b, c, in[13]+0xfd987193, 12);
    MD5STEP(F1, c, d, a, b, in[14]+0xa679438e, 17);
    MD5STEP(F1, b, c, d, a, in[15]+0x49b40821, 22);

    MD5STEP(F2, a, b, c, d, in[ 1]+0xf61e2562,  5);
    MD5STEP(F2, d, a, b, c, in[ 6]+0xc040b340,  9);
    MD5STEP(F2, c, d, a, b, in[11]+0x265e5a51, 14);
    MD5STEP(F2, b, c, d, a, in[ 0]+0xe9b6c7aa, 20);
    MD5STEP(F2, a, b, c, d, in[ 5]+0xd62f105d,  5);
    MD5STEP(F2, d, a, b, c, in[10]+0x02441453,  9);
    MD5STEP(F2, c, d, a, b, in[15]+0xd8a1e681, 14);
    MD5STEP(F2, b, c, d, a, in[ 4]+0xe7d3fbc8, 20);
    MD5STEP(F2, a, b, c, d, in[ 9]+0x21e1cde6,  5);
    MD5STEP(F2, d, a, b, c, in[14]+0xc33707d6,  9);
    MD5STEP(F2, c, d, a, b, in[ 3]+0xf4d50d87, 14);
    MD5STEP(F2, b, c, d, a, in[ 8]+0x455a14ed, 20);
    MD5STEP(F2, a, b, c, d, in[13]+0xa9e3e905,  5);
    MD5STEP(F2, d, a, b, c, in[ 2]+0xfcefa3f8,  9);
    MD5STEP(F2, c, d, a, b, in[ 7]+0x676f02d9, 14);
    MD5STEP(F2, b, c, d, a, in[12]+0x8d2a4c8a, 20);

    MD5STEP(F3, a, b, c, d, in[ 5]+0xfffa3942,  4);
    MD5STEP(F3, d, a, b, c, in[ 8]+0x8771f681, 11);
    MD5STEP(F3, c, d, a, b, in[11]+0x6d9d6122, 16);
    MD5STEP(F3, b, c, d, a, in[14]+0xfde5380c, 23);
    MD5STEP(F3, a, b, c, d, in[ 1]+0xa4beea44,  4);
    MD5STEP(F3, d, a, b, c, in[ 4]+0x4bdecfa9, 11);
    MD5STEP(F3, c, d, a, b, in[ 7]+0xf6bb4b60, 16);
    MD5STEP(F3, b, c, d, a, in[10]+0xbebfbc70, 23);
    MD5STEP(F3, a, b, c, d, in[13]+0x289b7ec6,  4);
    MD5STEP(F3, d, a, b, c, in[ 0]+0xeaa127fa, 11);
    MD5STEP(F3, c, d, a, b, in[ 3]+0xd4ef3085, 16);
    MD5STEP(F3, b, c, d, a, in[ 6]+0x04881d05, 23);
    MD5STEP(F3, a, b, c, d, in[ 9]+0xd9d4d039,  4);
    MD5STEP(F3, d, a, b, c, in[12]+0xe6db99e5, 11);
    MD5STEP(F3, c, d, a, b, in[15]+0x1fa27cf8, 16);
    MD5STEP(F3, b, c, d, a, in[ 2]+0xc4ac5665, 23);

    MD5STEP(F4, a, b, c, d, in[ 0]+0xf4292244,  6);
    MD5STEP(F4, d, a, b, c, in[ 7]+0x432aff97, 10);
    MD5STEP(F4, c, d, a, b, in[14]+0xab9423a7, 15);
    MD5STEP(F4, b, c, d, a, in[ 5]+0xfc93a039, 21);
    MD5STEP(F4, a, b, c, d, in[12]+0x655b59c3,  6);
    MD5STEP(F4, d, a, b, c, in[ 3]+0x8f0ccc92, 10);
    MD5STEP(F4, c, d, a, b, in[10]+0xffeff47d, 15);
    MD5STEP(F4, b, c, d, a, in[ 1]+0x85845dd1, 21);
    MD5STEP(F4, a, b, c, d, in[ 8]+0x6fa87e4f,  6);
    MD5STEP(F4, d, a, b, c, in[15]+0xfe2ce6e0, 10);
    MD5STEP(F4, c, d, a, b, in[ 6]+0xa3014314, 15);
    MD5STEP(F4, b, c, d, a, in[13]+0x4e0811a1, 21);
    MD5STEP(F4, a, b, c, d, in[ 4]+0xf7537e82,  6);
    MD5STEP(F4, d, a, b, c, in[11]+0xbd3af235, 10);
    MD5STEP(F4, c, d, a, b, in[ 2]+0x2ad7d2bb, 15);
    MD5STEP(F4, b, c, d, a, in[ 9]+0xeb86d391, 21);

    buf[0] += a;
    buf[1] += b;
    buf[2] += c;
    buf[3] += d;

}

// Hash data and return its binary hash into an NOTE_MD5_HASH_SIZE buffer
void NoteMD5Hash(unsigned char* data, unsigned long len, unsigned char *retHash)
{
    NoteMD5Context context;
    NoteMD5Init(&context);
    NoteMD5Update(&context, data, len);
    NoteMD5Final(retHash, &context);
}

// Hash data and return it as a string into a buffer that is at least (16*2)+1 in length
void NoteMD5HashString(unsigned char *data, unsigned long len, char *strbuf, unsigned long buflen)
{
    unsigned char hash[NOTE_MD5_HASH_SIZE];
    NoteMD5Hash(data, len, hash);
    char hashstr[NOTE_MD5_HASH_SIZE*3] = {0};
    for (int i=0; i<NOTE_MD5_HASH_SIZE; i++) {
        n_htoa8(hash[i], (unsigned char *)&hashstr[i*2]);
    }
    hashstr[NOTE_MD5_HASH_SIZE*2+1] = 0;
    strlcpy(strbuf, hashstr, buflen);
}

// Convert a hash to string
void NoteMD5HashToString(unsigned char *hash, char *strbuf, unsigned long buflen)
{
    char hashstr[NOTE_MD5_HASH_SIZE*3] = {0};
    for (int i=0; i<NOTE_MD5_HASH_SIZE; i++) {
        n_htoa8(hash[i], (unsigned char *)&hashstr[i*2]);
    }
    strlcpy(strbuf, hashstr, buflen);
}