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Added OpenBSD bcrypt implementation
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hntrmrrs committed Nov 3, 2008
1 parent b0db48b commit dabe98d82a740fdf3f494aae5e4f0d2c26a45211
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/* $OpenBSD: bcrypt.c,v 1.24 2008/04/02 19:54:05 millert Exp $ */

/*
* Copyright 1997 Niels Provos <provos@physnet.uni-hamburg.de>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Niels Provos.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

/* This password hashing algorithm was designed by David Mazieres
* <dm@lcs.mit.edu> and works as follows:
*
* 1. state := InitState ()
* 2. state := ExpandKey (state, salt, password) 3.
* REPEAT rounds:
* state := ExpandKey (state, 0, salt)
* state := ExpandKey(state, 0, password)
* 4. ctext := "OrpheanBeholderScryDoubt"
* 5. REPEAT 64:
* ctext := Encrypt_ECB (state, ctext);
* 6. RETURN Concatenate (salt, ctext);
*
*/

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <string.h>
#include <pwd.h>
#include <blf.h>

/* This implementation is adaptable to current computing power.
* You can have up to 2^31 rounds which should be enough for some
* time to come.
*/

#define BCRYPT_VERSION '2'
#define BCRYPT_MAXSALT 16 /* Precomputation is just so nice */
#define BCRYPT_BLOCKS 6 /* Ciphertext blocks */
#define BCRYPT_MINROUNDS 16 /* we have log2(rounds) in salt */

char *bcrypt_gensalt(u_int8_t);

static void encode_salt(char *, u_int8_t *, u_int16_t, u_int8_t);
static void encode_base64(u_int8_t *, u_int8_t *, u_int16_t);
static void decode_base64(u_int8_t *, u_int16_t, u_int8_t *);

static char encrypted[_PASSWORD_LEN];
static char gsalt[7 + (BCRYPT_MAXSALT * 4 + 2) / 3 + 1];
static char error[] = ":";

const static u_int8_t Base64Code[] =
"./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

const static u_int8_t index_64[128] = {
255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 0, 1, 54, 55,
56, 57, 58, 59, 60, 61, 62, 63, 255, 255,
255, 255, 255, 255, 255, 2, 3, 4, 5, 6,
7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,
255, 255, 255, 255, 255, 255, 28, 29, 30,
31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
41, 42, 43, 44, 45, 46, 47, 48, 49, 50,
51, 52, 53, 255, 255, 255, 255, 255
};
#define CHAR64(c) ( (c) > 127 ? 255 : index_64[(c)])

static void
decode_base64(u_int8_t *buffer, u_int16_t len, u_int8_t *data)
{
u_int8_t *bp = buffer;
u_int8_t *p = data;
u_int8_t c1, c2, c3, c4;
while (bp < buffer + len) {
c1 = CHAR64(*p);
c2 = CHAR64(*(p + 1));

/* Invalid data */
if (c1 == 255 || c2 == 255)
break;

*bp++ = (c1 << 2) | ((c2 & 0x30) >> 4);
if (bp >= buffer + len)
break;

c3 = CHAR64(*(p + 2));
if (c3 == 255)
break;

*bp++ = ((c2 & 0x0f) << 4) | ((c3 & 0x3c) >> 2);
if (bp >= buffer + len)
break;

c4 = CHAR64(*(p + 3));
if (c4 == 255)
break;
*bp++ = ((c3 & 0x03) << 6) | c4;

p += 4;
}
}

static void
encode_salt(char *salt, u_int8_t *csalt, u_int16_t clen, u_int8_t logr)
{
salt[0] = '$';
salt[1] = BCRYPT_VERSION;
salt[2] = 'a';
salt[3] = '$';

snprintf(salt + 4, 4, "%2.2u$", logr);

encode_base64((u_int8_t *) salt + 7, csalt, clen);
}
/* Generates a salt for this version of crypt.
Since versions may change. Keeping this here
seems sensible.
*/

char *
bcrypt_gensalt(u_int8_t log_rounds)
{
u_int8_t csalt[BCRYPT_MAXSALT];
u_int16_t i;
u_int32_t seed = 0;

for (i = 0; i < BCRYPT_MAXSALT; i++) {
if (i % 4 == 0)
seed = arc4random();
csalt[i] = seed & 0xff;
seed = seed >> 8;
}

if (log_rounds < 4)
log_rounds = 4;
else if (log_rounds > 31)
log_rounds = 31;

encode_salt(gsalt, csalt, BCRYPT_MAXSALT, log_rounds);
return gsalt;
}
/* We handle $Vers$log2(NumRounds)$salt+passwd$
i.e. $2$04$iwouldntknowwhattosayetKdJ6iFtacBqJdKe6aW7ou */

char *
bcrypt(const char *key, const char *salt)
{
blf_ctx state;
u_int32_t rounds, i, k;
u_int16_t j;
u_int8_t key_len, salt_len, logr, minor;
u_int8_t ciphertext[4 * BCRYPT_BLOCKS] = "OrpheanBeholderScryDoubt";
u_int8_t csalt[BCRYPT_MAXSALT];
u_int32_t cdata[BCRYPT_BLOCKS];
int n;

/* Discard "$" identifier */
salt++;

if (*salt > BCRYPT_VERSION) {
/* How do I handle errors ? Return ':' */
return error;
}

/* Check for minor versions */
if (salt[1] != '$') {
switch (salt[1]) {
case 'a':
/* 'ab' should not yield the same as 'abab' */
minor = salt[1];
salt++;
break;
default:
return error;
}
} else
minor = 0;

/* Discard version + "$" identifier */
salt += 2;

if (salt[2] != '$')
/* Out of sync with passwd entry */
return error;

/* Computer power doesn't increase linear, 2^x should be fine */
n = atoi(salt);
if (n > 31 || n < 0)
return error;
logr = (u_int8_t)n;
if ((rounds = (u_int32_t) 1 << logr) < BCRYPT_MINROUNDS)
return error;

/* Discard num rounds + "$" identifier */
salt += 3;

if (strlen(salt) * 3 / 4 < BCRYPT_MAXSALT)
return error;

/* We dont want the base64 salt but the raw data */
decode_base64(csalt, BCRYPT_MAXSALT, (u_int8_t *) salt);
salt_len = BCRYPT_MAXSALT;
key_len = strlen(key) + (minor >= 'a' ? 1 : 0);

/* Setting up S-Boxes and Subkeys */
Blowfish_initstate(&state);
Blowfish_expandstate(&state, csalt, salt_len,
(u_int8_t *) key, key_len);
for (k = 0; k < rounds; k++) {
Blowfish_expand0state(&state, (u_int8_t *) key, key_len);
Blowfish_expand0state(&state, csalt, salt_len);
}

/* This can be precomputed later */
j = 0;
for (i = 0; i < BCRYPT_BLOCKS; i++)
cdata[i] = Blowfish_stream2word(ciphertext, 4 * BCRYPT_BLOCKS, &j);

/* Now do the encryption */
for (k = 0; k < 64; k++)
blf_enc(&state, cdata, BCRYPT_BLOCKS / 2);

for (i = 0; i < BCRYPT_BLOCKS; i++) {
ciphertext[4 * i + 3] = cdata[i] & 0xff;
cdata[i] = cdata[i] >> 8;
ciphertext[4 * i + 2] = cdata[i] & 0xff;
cdata[i] = cdata[i] >> 8;
ciphertext[4 * i + 1] = cdata[i] & 0xff;
cdata[i] = cdata[i] >> 8;
ciphertext[4 * i + 0] = cdata[i] & 0xff;
}


i = 0;
encrypted[i++] = '$';
encrypted[i++] = BCRYPT_VERSION;
if (minor)
encrypted[i++] = minor;
encrypted[i++] = '$';

snprintf(encrypted + i, 4, "%2.2u$", logr);

encode_base64((u_int8_t *) encrypted + i + 3, csalt, BCRYPT_MAXSALT);
encode_base64((u_int8_t *) encrypted + strlen(encrypted), ciphertext,
4 * BCRYPT_BLOCKS - 1);
memset(&state, 0, sizeof(state));
memset(ciphertext, 0, sizeof(ciphertext));
memset(csalt, 0, sizeof(csalt));
memset(cdata, 0, sizeof(cdata));
return encrypted;
}

static void
encode_base64(u_int8_t *buffer, u_int8_t *data, u_int16_t len)
{
u_int8_t *bp = buffer;
u_int8_t *p = data;
u_int8_t c1, c2;
while (p < data + len) {
c1 = *p++;
*bp++ = Base64Code[(c1 >> 2)];
c1 = (c1 & 0x03) << 4;
if (p >= data + len) {
*bp++ = Base64Code[c1];
break;
}
c2 = *p++;
c1 |= (c2 >> 4) & 0x0f;
*bp++ = Base64Code[c1];
c1 = (c2 & 0x0f) << 2;
if (p >= data + len) {
*bp++ = Base64Code[c1];
break;
}
c2 = *p++;
c1 |= (c2 >> 6) & 0x03;
*bp++ = Base64Code[c1];
*bp++ = Base64Code[c2 & 0x3f];
}
*bp = '\0';
}
#if 0
void
main()
{
char blubber[73];
char salt[100];
char *p;
salt[0] = '$';
salt[1] = BCRYPT_VERSION;
salt[2] = '$';

snprintf(salt + 3, 4, "%2.2u$", 5);

printf("24 bytes of salt: ");
fgets(salt + 6, sizeof(salt) - 6, stdin);
salt[99] = 0;
printf("72 bytes of password: ");
fpurge(stdin);
fgets(blubber, sizeof(blubber), stdin);
blubber[72] = 0;

p = crypt(blubber, salt);
printf("Passwd entry: %s\n\n", p);

p = bcrypt_gensalt(5);
printf("Generated salt: %s\n", p);
p = crypt(blubber, p);
printf("Passwd entry: %s\n", p);
}
#endif

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