crypt-gensalt.c

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/*
 * Written by Solar Designer and placed in the public domain.
 * See crypt_blowfish.c for more information.
 *
 * contrib/pgcrypto/crypt-gensalt.c
 *
 * This file contains salt generation functions for the traditional and
 * other common crypt(3) algorithms, except for bcrypt which is defined
 * entirely in crypt_blowfish.c.
 *
 * Put bcrypt generator also here as crypt-blowfish.c
 * may not be compiled always.        -- marko
 */
 
#include "postgres.h"
 
#include "px-crypt.h"
 
typedef unsigned int BF_word;
 
static unsigned char _crypt_itoa64[64 + 1] =
"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
 
char *
_crypt_gensalt_traditional_rn(unsigned long count,
                              const char *input, int size, char *output, int output_size)
{
    if (size < 2 || output_size < 2 + 1 || (count && count != 25))
    {
        if (output_size > 0)
            output[0] = '\0';
        return NULL;
    }
 
    output[0] = _crypt_itoa64[(unsigned int) input[0] & 0x3f];
    output[1] = _crypt_itoa64[(unsigned int) input[1] & 0x3f];
    output[2] = '\0';
 
    return output;
}
 
char *
_crypt_gensalt_extended_rn(unsigned long count,
                           const char *input, int size, char *output, int output_size)
{
    unsigned long value;
 
/* Even iteration counts make it easier to detect weak DES keys from a look
 * at the hash, so they should be avoided */
    if (size < 3 || output_size < 1 + 4 + 4 + 1 ||
        (count && (count > 0xffffff || !(count & 1))))
    {
        if (output_size > 0)
            output[0] = '\0';
        return NULL;
    }
 
    if (!count)
        count = 725;
 
    output[0] = '_';
    output[1] = _crypt_itoa64[count & 0x3f];
    output[2] = _crypt_itoa64[(count >> 6) & 0x3f];
    output[3] = _crypt_itoa64[(count >> 12) & 0x3f];
    output[4] = _crypt_itoa64[(count >> 18) & 0x3f];
    value = (unsigned long) (unsigned char) input[0] |
        ((unsigned long) (unsigned char) input[1] << 8) |
        ((unsigned long) (unsigned char) input[2] << 16);
    output[5] = _crypt_itoa64[value & 0x3f];
    output[6] = _crypt_itoa64[(value >> 6) & 0x3f];
    output[7] = _crypt_itoa64[(value >> 12) & 0x3f];
    output[8] = _crypt_itoa64[(value >> 18) & 0x3f];
    output[9] = '\0';
 
    return output;
}
 
char *
_crypt_gensalt_md5_rn(unsigned long count,
                      const char *input, int size, char *output, int output_size)
{
    unsigned long value;
 
    if (size < 3 || output_size < 3 + 4 + 1 || (count && count != 1000))
    {
        if (output_size > 0)
            output[0] = '\0';
        return NULL;
    }
 
    output[0] = '$';
    output[1] = '1';
    output[2] = '$';
    value = (unsigned long) (unsigned char) input[0] |
        ((unsigned long) (unsigned char) input[1] << 8) |
        ((unsigned long) (unsigned char) input[2] << 16);
    output[3] = _crypt_itoa64[value & 0x3f];
    output[4] = _crypt_itoa64[(value >> 6) & 0x3f];
    output[5] = _crypt_itoa64[(value >> 12) & 0x3f];
    output[6] = _crypt_itoa64[(value >> 18) & 0x3f];
    output[7] = '\0';
 
    if (size >= 6 && output_size >= 3 + 4 + 4 + 1)
    {
        value = (unsigned long) (unsigned char) input[3] |
            ((unsigned long) (unsigned char) input[4] << 8) |
            ((unsigned long) (unsigned char) input[5] << 16);
        output[7] = _crypt_itoa64[value & 0x3f];
        output[8] = _crypt_itoa64[(value >> 6) & 0x3f];
        output[9] = _crypt_itoa64[(value >> 12) & 0x3f];
        output[10] = _crypt_itoa64[(value >> 18) & 0x3f];
        output[11] = '\0';
    }
 
    return output;
}
 
 
 
static unsigned char BF_itoa64[64 + 1] =
"./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
 
static void
BF_encode(char *dst, const BF_word *src, int size)
{
    const unsigned char *sptr = (const unsigned char *) src;
    const unsigned char *end = sptr + size;
    unsigned char *dptr = (unsigned char *) dst;
    unsigned int c1,
                c2;
 
    do
    {
        c1 = *sptr++;
        *dptr++ = BF_itoa64[c1 >> 2];
        c1 = (c1 & 0x03) << 4;
        if (sptr >= end)
        {
            *dptr++ = BF_itoa64[c1];
            break;
        }
 
        c2 = *sptr++;
        c1 |= c2 >> 4;
        *dptr++ = BF_itoa64[c1];
        c1 = (c2 & 0x0f) << 2;
        if (sptr >= end)
        {
            *dptr++ = BF_itoa64[c1];
            break;
        }
 
        c2 = *sptr++;
        c1 |= c2 >> 6;
        *dptr++ = BF_itoa64[c1];
        *dptr++ = BF_itoa64[c2 & 0x3f];
    } while (sptr < end);
}
 
char *
_crypt_gensalt_blowfish_rn(unsigned long count,
                           const char *input, int size, char *output, int output_size)
{
    if (size < 16 || output_size < 7 + 22 + 1 ||
        (count && (count < 4 || count > 31)))
    {
        if (output_size > 0)
            output[0] = '\0';
        return NULL;
    }
 
    if (!count)
        count = 5;
 
    output[0] = '$';
    output[1] = '2';
    output[2] = 'a';
    output[3] = '$';
    output[4] = '0' + count / 10;
    output[5] = '0' + count % 10;
    output[6] = '$';
 
    BF_encode(&output[7], (const BF_word *) input, 16);
    output[7 + 22] = '\0';
 
    return output;
}
 
/*
 * Helper for _crypt_gensalt_sha256_rn and _crypt_gensalt_sha512_rn
 */
static char *
_crypt_gensalt_sha(unsigned long count,
                   const char *input, int size, char *output, int output_size)
{
    char       *s_ptr = output;
    unsigned int result_bufsize = PX_SHACRYPT_SALT_BUF_LEN;
    int         rc;
 
    /* output buffer must be allocated with PX_MAX_SALT_LEN bytes */
    if (PX_MAX_SALT_LEN < result_bufsize)
        ereport(ERROR,
                errcode(ERRCODE_SYNTAX_ERROR),
                errmsg("invalid size of salt"));
 
    /*
     * Care must be taken to not exceed the buffer size allocated for the
     * input character buffer.
     */
    if ((PX_SHACRYPT_SALT_MAX_LEN != size) || (output_size < size))
        ereport(ERROR,
                errcode(ERRCODE_INTERNAL_ERROR),
                errmsg("invalid length of salt buffer"));
 
    /* Skip magic bytes, set by callers */
    s_ptr += 3;
    if ((rc = pg_snprintf(s_ptr, 18, "rounds=%lu$", count)) <= 0)
        ereport(ERROR,
                errcode(ERRCODE_INTERNAL_ERROR),
                errmsg("cannot format salt string"));
 
    /* s_ptr should now be positioned at the start of the salt string */
    s_ptr += rc;
 
    /*
     * Normalize salt string
     *
     * size of input buffer was checked above to not exceed
     * PX_SHACRYPT_SALT_LEN_MAX.
     */
    for (int i = 0; i < size; i++)
    {
        *s_ptr = _crypt_itoa64[input[i] & 0x3f];
        s_ptr++;
    }
 
    /* We're done */
    return output;
}
 
/* gen_list->gen function for sha512 */
char *
_crypt_gensalt_sha512_rn(unsigned long count,
                         char const *input, int size,
                         char *output, int output_size)
{
    memset(output, 0, output_size);
    /* set magic byte for sha512crypt */
    output[0] = '$';
    output[1] = '6';
    output[2] = '$';
 
    return _crypt_gensalt_sha(count, input, size, output, output_size);
}
 
/* gen_list->gen function for sha256 */
char *
_crypt_gensalt_sha256_rn(unsigned long count,
                         const char *input, int size,
                         char *output, int output_size)
{
    memset(output, 0, output_size);
    /* set magic byte for sha256crypt */
    output[0] = '$';
    output[1] = '5';
    output[2] = '$';
 
    return _crypt_gensalt_sha(count, input, size, output, output_size);
}