source: bootcd/isolinux/syslinux-6.03/com32/libutil/sha1hash.c

/*
SHA-1 in C
By Steve Reid <sreid@sea-to-sky.net>
100% Public Domain

-----------------
Modified 7/98
By James H. Brown <jbrown@burgoyne.com>
Still 100% Public Domain

Corrected a problem which generated improper hash values on 16 bit machines
Routine SHA1Update changed from
        void SHA1Update(SHA1_CTX* context, unsigned char* data, unsigned int
len)
to
        void SHA1Update(SHA1_CTX* context, unsigned char* data, unsigned
long len)

The 'len' parameter was declared an int which works fine on 32 bit machines.
However, on 16 bit machines an int is too small for the shifts being done
against
it.  This caused the hash function to generate incorrect values if len was
greater than 8191 (8K - 1) due to the 'len << 3' on line 3 of SHA1Update().

Since the file IO in main() reads 16K at a time, any file 8K or larger would
be guaranteed to generate the wrong hash (e.g. Test Vector #3, a million
"a"s).

I also changed the declaration of variables i & j in SHA1Update to
unsigned long from unsigned int for the same reason.

These changes should make no difference to any 32 bit implementations since
an
int and a long are the same size in those environments.

--
I also corrected a few compiler warnings generated by Borland C.
1. Added #include <process.h> for exit() prototype
2. Removed unused variable 'j' in SHA1Final
3. Changed exit(0) to return(0) at end of main.

ALL changes I made can be located by searching for comments containing 'JHB'
-----------------
Modified 8/98
By Steve Reid <sreid@sea-to-sky.net>
Still 100% public domain

1- Removed #include <process.h> and used return() instead of exit()
2- Fixed overwriting of finalcount in SHA1Final() (discovered by Chris Hall)
3- Changed email address from steve@edmweb.com to sreid@sea-to-sky.net

-----------------
Modified 4/01
By Saul Kravitz <Saul.Kravitz@celera.com>
Still 100% PD
Modified to run on Compaq Alpha hardware.

-----------------
Modified 2/03
By H. Peter Anvin <hpa@zytor.com>
Still 100% PD
Modified to run on any hardware with <inttypes.h> and <netinet/in.h>
Changed the driver program

*/

/*
Test Vectors (from FIPS PUB 180-1)
"abc"
  A9993E36 4706816A BA3E2571 7850C26C 9CD0D89D
"abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq"
  84983E44 1C3BD26E BAAE4AA1 F95129E5 E54670F1
A million repetitions of "a"
  34AA973C D4C4DAA4 F61EEB2B DBAD2731 6534016F
*/

/* #define SHA1HANDSOFF  */

#include <stdio.h>
#include <string.h>
#include <inttypes.h>
#include <netinet/in.h>         /* For htonl/ntohl/htons/ntohs */

#include "sha1.h"

#define rol(value, bits) (((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) (block->l[i] = ntohl(block->l[i]))
#define blk(i) (block->l[i&15] = rol(block->l[(i+13)&15]^block->l[(i+8)&15] \
    ^block->l[(i+2)&15]^block->l[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);

#ifdef VERBOSE                  /* SAK */
void SHAPrintContext(SHA1_CTX * context, char *msg)
{
    printf("%s (%d,%d) %x %x %x %x %x\n",
           msg,
           context->count[0], context->count[1],
           context->state[0],
           context->state[1],
           context->state[2], context->state[3], context->state[4]);
}
#endif

/* Hash a single 512-bit block. This is the core of the algorithm. */

void SHA1Transform(uint32_t state[5], const unsigned char buffer[64])
{
    uint32_t a, b, c, d, e;
    typedef union {
        unsigned char c[64];
        uint32_t l[16];
    } CHAR64LONG16;
    CHAR64LONG16 *block;
#ifdef SHA1HANDSOFF
    static unsigned char workspace[64];
    block = (CHAR64LONG16 *) workspace;
    memcpy(block, buffer, 64);
#else
    block = (CHAR64LONG16 *) buffer;
#endif
    /* 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;
}

/* SHA1Init - Initialize new context */

void SHA1Init(SHA1_CTX * context)
{
    /* SHA1 initialization constants */
    context->state[0] = 0x67452301;
    context->state[1] = 0xEFCDAB89;
    context->state[2] = 0x98BADCFE;
    context->state[3] = 0x10325476;
    context->state[4] = 0xC3D2E1F0;
    context->count[0] = context->count[1] = 0;
}

/* Run your data through this. */

void SHA1Update(SHA1_CTX * context, const unsigned char *data, uint32_t len)
{                               /*
                                   JHB */
    uint32_t i, j;              /* JHB */

#ifdef VERBOSE
    SHAPrintContext(context, "before");
#endif
    j = (context->count[0] >> 3) & 63;
    if ((context->count[0] += len << 3) < (len << 3))
        context->count[1]++;
    context->count[1] += (len >> 29);
    if ((j + len) > 63) {
        memcpy(&context->buffer[j], data, (i = 64 - j));
        SHA1Transform(context->state, context->buffer);
        for (; i + 63 < len; i += 64) {
            SHA1Transform(context->state, &data[i]);
        }
        j = 0;
    } else
        i = 0;
    memcpy(&context->buffer[j], &data[i], len - i);
#ifdef VERBOSE
    SHAPrintContext(context, "after ");
#endif
}

/* Add padding and return the message digest. */

void SHA1Final(unsigned char digest[20], SHA1_CTX * context)
{
    uint32_t i;                 /* JHB */
    unsigned char finalcount[8];

    for (i = 0; i < 8; i++) {
        finalcount[i] = (unsigned char)((context->count[(i >= 4 ? 0 : 1)]
                                         >> ((3 - (i & 3)) * 8)) & 255);        /* Endian independent */
    }
    SHA1Update(context, (unsigned char *)"\200", 1);
    while ((context->count[0] & 504) != 448) {
        SHA1Update(context, (unsigned char *)"\0", 1);
    }
    SHA1Update(context, finalcount, 8); /* Should cause a SHA1Transform()
                                         */
    for (i = 0; i < 20; i++) {
        digest[i] = (unsigned char)
            ((context->state[i >> 2] >> ((3 - (i & 3)) * 8)) & 255);
    }
    /* Wipe variables */
    i = 0;                      /* JHB */
    memset(context->buffer, 0, 64);
    memset(context->state, 0, 20);
    memset(context->count, 0, 8);
    memset(finalcount, 0, 8);   /* SWR */
#ifdef SHA1HANDSOFF             /* make SHA1Transform overwrite it's own static vars */
    SHA1Transform(context->state, context->buffer);
#endif
}

/*************************************************************/

/* This is not quite the MIME base64 algorithm: it uses _ instead of /,
   and instead of padding the output with = characters we just make the
   output shorter. */
char *mybase64(uint8_t digest[20])
{
    static const char charz[] =
        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+_";
    uint8_t input[21];
    static char output[28];
    int i, j;
    uint8_t *p;
    char *q;
    uint32_t bv;

    memcpy(input, digest, 20);
    input[20] = 0;              /* Pad to multiple of 3 bytes */

    p = input;
    q = output;
    for (i = 0; i < 7; i++) {
        bv = (p[0] << 16) | (p[1] << 8) | p[2];
        p += 3;
        for (j = 0; j < 4; j++) {
            *q++ = charz[(bv >> 18) & 0x3f];
            bv <<= 6;
        }
    }
    *--q = '\0';                /* The last character is not significant */
    return output;
}

#ifdef FOR_TESTING_ONLY

int main(int argc, char **argv)
{
    int i;
    SHA1_CTX context;
    uint8_t digest[20], buffer[16384];
    FILE *file;

    if (argc < 2) {
        file = stdin;
    } else {
        if (!(file = fopen(argv[1], "rb"))) {
            fputs("Unable to open file.", stderr);
            return (-1);
        }
    }
    SHA1Init(&context);
    while (!feof(file)) {       /* note: what if ferror(file) */
        i = fread(buffer, 1, 16384, file);
        SHA1Update(&context, buffer, i);
    }
    SHA1Final(digest, &context);
    fclose(file);

    puts(mybase64(digest));

    return 0;
}

#endif