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/* $OpenBSD: bcrypt.c,v 1.57 2016/08/26 08:25:02 guenther Exp $ */
/*
* Copyright (c) 2014 Ted Unangst <tedu@openbsd.org>
* Copyright (c) 1997 Niels Provos <provos@umich.edu>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/* 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, password)
* state := ExpandKey (state, 0, salt)
* 4. ctext := "OrpheanBeholderScryDoubt"
* 5. REPEAT 64:
* ctext := Encrypt_ECB (state, ctext);
* 6. RETURN Concatenate (salt, ctext);
*
*/
#include <sys/types.h>
#include <blf.h>
#include <ctype.h>
#include <errno.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.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_WORDS 6 /* Ciphertext words */
#define BCRYPT_MINLOGROUNDS 4 /* we have log2(rounds) in salt */
#define BCRYPT_SALTSPACE (7 + (BCRYPT_MAXSALT * 4 + 2) / 3 + 1)
#define BCRYPT_HASHSPACE 61
char *bcrypt_gensalt(u_int8_t);
static int encode_base64(char *, const u_int8_t *, size_t);
static int decode_base64(u_int8_t *, size_t, const char *);
/*
* Generates a salt for this version of crypt.
*/
static int
bcrypt_initsalt(int log_rounds, uint8_t *salt, size_t saltbuflen)
{
uint8_t csalt[BCRYPT_MAXSALT];
if (saltbuflen < BCRYPT_SALTSPACE) {
errno = EINVAL;
return -1;
}
arc4random_buf(csalt, sizeof(csalt));
if (log_rounds < 4)
log_rounds = 4;
else if (log_rounds > 31)
log_rounds = 31;
snprintf(salt, saltbuflen, "$2b$%2.2u$", log_rounds);
encode_base64(salt + 7, csalt, sizeof(csalt));
return 0;
}
/*
* the core bcrypt function
*/
static int
bcrypt_hashpass(const char *key, const char *salt, char *encrypted,
size_t encryptedlen)
{
blf_ctx state;
u_int32_t rounds, i, k;
u_int16_t j;
size_t key_len;
u_int8_t salt_len, logr, minor;
u_int8_t ciphertext[4 * BCRYPT_WORDS] = "OrpheanBeholderScryDoubt";
u_int8_t csalt[BCRYPT_MAXSALT];
u_int32_t cdata[BCRYPT_WORDS];
if (encryptedlen < BCRYPT_HASHSPACE)
goto inval;
/* Check and discard "$" identifier */
if (salt[0] != '$')
goto inval;
salt += 1;
if (salt[0] != BCRYPT_VERSION)
goto inval;
/* Check for minor versions */
switch ((minor = salt[1])) {
case 'a':
key_len = (u_int8_t)(strlen(key) + 1);
break;
case 'b':
/* strlen() returns a size_t, but the function calls
* below result in implicit casts to a narrower integer
* type, so cap key_len at the actual maximum supported
* length here to avoid integer wraparound */
key_len = strlen(key);
if (key_len > 72)
key_len = 72;
key_len++; /* include the NUL */
break;
default:
goto inval;
}
if (salt[2] != '$')
goto inval;
/* Discard version + "$" identifier */
salt += 3;
/* Check and parse num rounds */
if (!isdigit((unsigned char)salt[0]) ||
!isdigit((unsigned char)salt[1]) || salt[2] != '$')
goto inval;
logr = (salt[1] - '0') + ((salt[0] - '0') * 10);
if (logr < BCRYPT_MINLOGROUNDS || logr > 31)
goto inval;
/* Computer power doesn't increase linearly, 2^x should be fine */
rounds = 1U << logr;
/* Discard num rounds + "$" identifier */
salt += 3;
if (strlen(salt) * 3 / 4 < BCRYPT_MAXSALT)
goto inval;
/* We dont want the base64 salt but the raw data */
if (decode_base64(csalt, BCRYPT_MAXSALT, salt))
goto inval;
salt_len = BCRYPT_MAXSALT;
/* 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_WORDS; i++)
cdata[i] = Blowfish_stream2word(ciphertext, 4 * BCRYPT_WORDS, &j);
/* Now do the encryption */
for (k = 0; k < 64; k++)
blf_enc(&state, cdata, BCRYPT_WORDS / 2);
for (i = 0; i < BCRYPT_WORDS; 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;
}
snprintf(encrypted, 8, "$2%c$%2.2u$", minor, logr);
encode_base64(encrypted + 7, csalt, BCRYPT_MAXSALT);
encode_base64(encrypted + 7 + 22, ciphertext, 4 * BCRYPT_WORDS - 1);
explicit_bzero(&state, sizeof(state));
explicit_bzero(ciphertext, sizeof(ciphertext));
explicit_bzero(csalt, sizeof(csalt));
explicit_bzero(cdata, sizeof(cdata));
return 0;
inval:
errno = EINVAL;
return -1;
}
/*
* user friendly functions
*/
int
bcrypt_newhash(const char *pass, int log_rounds, char *hash, size_t hashlen)
{
char salt[BCRYPT_SALTSPACE];
if (bcrypt_initsalt(log_rounds, salt, sizeof(salt)) != 0)
return -1;
if (bcrypt_hashpass(pass, salt, hash, hashlen) != 0)
return -1;
explicit_bzero(salt, sizeof(salt));
return 0;
}
DEF_WEAK(bcrypt_newhash);
int
bcrypt_checkpass(const char *pass, const char *goodhash)
{
char hash[BCRYPT_HASHSPACE];
if (bcrypt_hashpass(pass, goodhash, hash, sizeof(hash)) != 0)
return -1;
if (strlen(hash) != strlen(goodhash) ||
timingsafe_bcmp(hash, goodhash, strlen(goodhash)) != 0) {
errno = EACCES;
return -1;
}
explicit_bzero(hash, sizeof(hash));
return 0;
}
DEF_WEAK(bcrypt_checkpass);
/*
* Measure this system's performance by measuring the time for 8 rounds.
* We are aiming for something that takes around 0.1s, but not too much over.
*/
int
_bcrypt_autorounds(void)
{
struct timespec before, after;
int r = 8;
char buf[_PASSWORD_LEN];
int duration;
clock_gettime(CLOCK_THREAD_CPUTIME_ID, &before);
bcrypt_newhash("testpassword", r, buf, sizeof(buf));
clock_gettime(CLOCK_THREAD_CPUTIME_ID, &after);
duration = after.tv_sec - before.tv_sec;
duration *= 1000000;
duration += (after.tv_nsec - before.tv_nsec) / 1000;
/* too quick? slow it down. */
while (r < 16 && duration <= 60000) {
r += 1;
duration *= 2;
}
/* too slow? speed it up. */
while (r > 6 && duration > 120000) {
r -= 1;
duration /= 2;
}
return r;
}
/*
* internal utilities
*/
static const u_int8_t Base64Code[] =
"./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
static const 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)])
/*
* read buflen (after decoding) bytes of data from b64data
*/
static int
decode_base64(u_int8_t *buffer, size_t len, const char *b64data)
{
u_int8_t *bp = buffer;
const u_int8_t *p = b64data;
u_int8_t c1, c2, c3, c4;
while (bp < buffer + len) {
c1 = CHAR64(*p);
/* Invalid data */
if (c1 == 255)
return -1;
c2 = CHAR64(*(p + 1));
if (c2 == 255)
return -1;
*bp++ = (c1 << 2) | ((c2 & 0x30) >> 4);
if (bp >= buffer + len)
break;
c3 = CHAR64(*(p + 2));
if (c3 == 255)
return -1;
*bp++ = ((c2 & 0x0f) << 4) | ((c3 & 0x3c) >> 2);
if (bp >= buffer + len)
break;
c4 = CHAR64(*(p + 3));
if (c4 == 255)
return -1;
*bp++ = ((c3 & 0x03) << 6) | c4;
p += 4;
}
return 0;
}
/*
* Turn len bytes of data into base64 encoded data.
* This works without = padding.
*/
static int
encode_base64(char *b64buffer, const u_int8_t *data, size_t len)
{
u_int8_t *bp = b64buffer;
const 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';
return 0;
}
/*
* classic interface
*/
char *
bcrypt_gensalt(u_int8_t log_rounds)
{
static char gsalt[BCRYPT_SALTSPACE];
bcrypt_initsalt(log_rounds, gsalt, sizeof(gsalt));
return gsalt;
}
char *
bcrypt(const char *pass, const char *salt)
{
static char gencrypted[BCRYPT_HASHSPACE];
if (bcrypt_hashpass(pass, salt, gencrypted, sizeof(gencrypted)) != 0)
return NULL;
return gencrypted;
}
DEF_WEAK(bcrypt);
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