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/* $OpenBSD: bcrypt.c,v 1.48 2015/01/05 13:10:10 tedu Exp $ */
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/*
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* Copyright (c) 2014 Ted Unangst <tedu@openbsd.org>
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* Copyright (c) 1997 Niels Provos <provos@umich.edu>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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/* This password hashing algorithm was designed by David Mazieres
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* <dm@lcs.mit.edu> and works as follows:
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*
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* 1. state := InitState ()
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* 2. state := ExpandKey (state, salt, password)
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* 3. REPEAT rounds:
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* state := ExpandKey (state, 0, password)
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* state := ExpandKey (state, 0, salt)
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* 4. ctext := "OrpheanBeholderScryDoubt"
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* 5. REPEAT 64:
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* ctext := Encrypt_ECB (state, ctext);
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* 6. RETURN Concatenate (salt, ctext);
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*
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*/
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#include <sys/types.h>
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#include <blf.h>
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#include <ctype.h>
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#include <pwd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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/* This implementation is adaptable to current computing power.
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* You can have up to 2^31 rounds which should be enough for some
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* time to come.
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*/
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#define BCRYPT_VERSION '2'
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#define BCRYPT_MAXSALT 16 /* Precomputation is just so nice */
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#define BCRYPT_BLOCKS 6 /* Ciphertext blocks */
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#define BCRYPT_MINLOGROUNDS 4 /* we have log2(rounds) in salt */
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#define BCRYPT_SALTSPACE (7 + (BCRYPT_MAXSALT * 4 + 2) / 3 + 1)
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#define BCRYPT_HASHSPACE 61
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char *bcrypt_gensalt(u_int8_t);
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static int encode_base64(char *, const u_int8_t *, size_t);
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static int decode_base64(u_int8_t *, size_t, const char *);
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/*
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* Generates a salt for this version of crypt.
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*/
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static int
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bcrypt_initsalt(int log_rounds, uint8_t *salt, size_t saltbuflen)
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{
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uint8_t csalt[BCRYPT_MAXSALT];
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if (saltbuflen < BCRYPT_SALTSPACE)
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return -1;
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arc4random_buf(csalt, sizeof(csalt));
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if (log_rounds < 4)
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log_rounds = 4;
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else if (log_rounds > 31)
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log_rounds = 31;
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snprintf(salt, saltbuflen, "$2b$%2.2u$", log_rounds);
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encode_base64(salt + 7, csalt, sizeof(csalt));
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return 0;
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}
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/*
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* the core bcrypt function
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*/
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static int
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bcrypt_hashpass(const char *key, const char *salt, char *encrypted,
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size_t encryptedlen)
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{
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blf_ctx state;
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u_int32_t rounds, i, k;
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u_int16_t j;
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size_t key_len;
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u_int8_t salt_len, logr, minor;
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u_int8_t ciphertext[4 * BCRYPT_BLOCKS] = "OrpheanBeholderScryDoubt";
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u_int8_t csalt[BCRYPT_MAXSALT];
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u_int32_t cdata[BCRYPT_BLOCKS];
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if (encryptedlen < BCRYPT_HASHSPACE)
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return -1;
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/* Check and discard "$" identifier */
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if (salt[0] != '$')
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return -1;
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salt += 1;
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if (salt[0] != BCRYPT_VERSION)
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return -1;
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/* Check for minor versions */
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switch ((minor = salt[1])) {
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case 'a':
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key_len = (u_int8_t)(strlen(key) + 1);
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break;
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case 'b':
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/* strlen() returns a size_t, but the function calls
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* below result in implicit casts to a narrower integer
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* type, so cap key_len at the actual maximum supported
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* length here to avoid integer wraparound */
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key_len = strlen(key);
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if (key_len > 72)
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key_len = 72;
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key_len++; /* include the NUL */
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break;
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default:
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return -1;
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}
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if (salt[2] != '$')
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return -1;
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/* Discard version + "$" identifier */
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salt += 3;
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/* Check and parse num rounds */
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if (!isdigit((unsigned char)salt[0]) ||
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!isdigit((unsigned char)salt[1]) || salt[2] != '$')
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return -1;
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logr = atoi(salt);
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if (logr < BCRYPT_MINLOGROUNDS || logr > 31)
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return -1;
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/* Computer power doesn't increase linearly, 2^x should be fine */
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rounds = 1U << logr;
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/* Discard num rounds + "$" identifier */
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salt += 3;
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if (strlen(salt) * 3 / 4 < BCRYPT_MAXSALT)
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return -1;
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/* We dont want the base64 salt but the raw data */
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if (decode_base64(csalt, BCRYPT_MAXSALT, salt))
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return -1;
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salt_len = BCRYPT_MAXSALT;
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/* Setting up S-Boxes and Subkeys */
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Blowfish_initstate(&state);
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Blowfish_expandstate(&state, csalt, salt_len,
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(u_int8_t *) key, key_len);
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for (k = 0; k < rounds; k++) {
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Blowfish_expand0state(&state, (u_int8_t *) key, key_len);
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Blowfish_expand0state(&state, csalt, salt_len);
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}
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/* This can be precomputed later */
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j = 0;
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for (i = 0; i < BCRYPT_BLOCKS; i++)
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cdata[i] = Blowfish_stream2word(ciphertext, 4 * BCRYPT_BLOCKS, &j);
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/* Now do the encryption */
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for (k = 0; k < 64; k++)
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blf_enc(&state, cdata, BCRYPT_BLOCKS / 2);
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for (i = 0; i < BCRYPT_BLOCKS; i++) {
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ciphertext[4 * i + 3] = cdata[i] & 0xff;
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cdata[i] = cdata[i] >> 8;
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ciphertext[4 * i + 2] = cdata[i] & 0xff;
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cdata[i] = cdata[i] >> 8;
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ciphertext[4 * i + 1] = cdata[i] & 0xff;
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cdata[i] = cdata[i] >> 8;
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ciphertext[4 * i + 0] = cdata[i] & 0xff;
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}
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snprintf(encrypted, 8, "$2%c$%2.2u$", minor, logr);
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encode_base64(encrypted + 7, csalt, BCRYPT_MAXSALT);
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encode_base64(encrypted + 7 + 22, ciphertext, 4 * BCRYPT_BLOCKS - 1);
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explicit_bzero(&state, sizeof(state));
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explicit_bzero(ciphertext, sizeof(ciphertext));
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explicit_bzero(csalt, sizeof(csalt));
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explicit_bzero(cdata, sizeof(cdata));
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return 0;
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}
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/*
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* user friendly functions
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*/
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int
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bcrypt_newhash(const char *pass, int log_rounds, char *hash, size_t hashlen)
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{
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char salt[BCRYPT_SALTSPACE];
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if (bcrypt_initsalt(log_rounds, salt, sizeof(salt)) != 0)
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return -1;
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if (bcrypt_hashpass(pass, salt, hash, hashlen) != 0)
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return -1;
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explicit_bzero(salt, sizeof(salt));
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return 0;
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}
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int
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bcrypt_checkpass(const char *pass, const char *goodhash)
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{
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char hash[BCRYPT_HASHSPACE];
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if (bcrypt_hashpass(pass, goodhash, hash, sizeof(hash)) != 0)
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return -1;
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if (strlen(hash) != strlen(goodhash) ||
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timingsafe_bcmp(hash, goodhash, strlen(goodhash)) != 0)
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return -1;
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explicit_bzero(hash, sizeof(hash));
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return 0;
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}
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/*
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* Measure this system's performance by measuring the time for 8 rounds.
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* We are aiming for something that takes between 0.25 and 0.5 seconds.
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*/
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int
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bcrypt_autorounds(void)
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{
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struct timespec before, after;
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int r = 8;
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char buf[_PASSWORD_LEN];
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int duration;
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clock_gettime(CLOCK_THREAD_CPUTIME_ID, &before);
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bcrypt_newhash("testpassword", r, buf, sizeof(buf));
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clock_gettime(CLOCK_THREAD_CPUTIME_ID, &after);
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duration = after.tv_sec - before.tv_sec;
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duration *= 1000000;
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duration += (after.tv_nsec - before.tv_nsec) / 1000;
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/* too quick? slow it down. */
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while (r < 16 && duration <= 1000000 / 4) {
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r += 1;
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duration *= 2;
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}
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/* too slow? speed it up. */
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while (r > 4 && duration > 1000000 / 2) {
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r -= 1;
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duration /= 2;
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}
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return r;
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}
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/*
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* internal utilities
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*/
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static const u_int8_t Base64Code[] =
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"./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
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static const u_int8_t index_64[128] = {
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 0, 1, 54, 55,
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56, 57, 58, 59, 60, 61, 62, 63, 255, 255,
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255, 255, 255, 255, 255, 2, 3, 4, 5, 6,
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7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
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17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,
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255, 255, 255, 255, 255, 255, 28, 29, 30,
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31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
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41, 42, 43, 44, 45, 46, 47, 48, 49, 50,
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51, 52, 53, 255, 255, 255, 255, 255
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};
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#define CHAR64(c) ( (c) > 127 ? 255 : index_64[(c)])
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/*
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* read buflen (after decoding) bytes of data from b64data
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*/
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static int
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decode_base64(u_int8_t *buffer, size_t len, const char *b64data)
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{
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u_int8_t *bp = buffer;
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const u_int8_t *p = b64data;
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u_int8_t c1, c2, c3, c4;
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while (bp < buffer + len) {
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c1 = CHAR64(*p);
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/* Invalid data */
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if (c1 == 255)
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return -1;
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c2 = CHAR64(*(p + 1));
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if (c2 == 255)
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return -1;
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*bp++ = (c1 << 2) | ((c2 & 0x30) >> 4);
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if (bp >= buffer + len)
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break;
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c3 = CHAR64(*(p + 2));
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if (c3 == 255)
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return -1;
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*bp++ = ((c2 & 0x0f) << 4) | ((c3 & 0x3c) >> 2);
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if (bp >= buffer + len)
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break;
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c4 = CHAR64(*(p + 3));
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if (c4 == 255)
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return -1;
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*bp++ = ((c3 & 0x03) << 6) | c4;
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p += 4;
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}
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return 0;
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}
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/*
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* Turn len bytes of data into base64 encoded data.
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* This works without = padding.
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*/
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static int
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encode_base64(char *b64buffer, const u_int8_t *data, size_t len)
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{
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u_int8_t *bp = b64buffer;
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const u_int8_t *p = data;
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u_int8_t c1, c2;
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while (p < data + len) {
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c1 = *p++;
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*bp++ = Base64Code[(c1 >> 2)];
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c1 = (c1 & 0x03) << 4;
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if (p >= data + len) {
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*bp++ = Base64Code[c1];
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break;
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}
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c2 = *p++;
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c1 |= (c2 >> 4) & 0x0f;
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*bp++ = Base64Code[c1];
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c1 = (c2 & 0x0f) << 2;
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if (p >= data + len) {
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*bp++ = Base64Code[c1];
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break;
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}
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c2 = *p++;
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c1 |= (c2 >> 6) & 0x03;
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*bp++ = Base64Code[c1];
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*bp++ = Base64Code[c2 & 0x3f];
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}
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*bp = '\0';
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return 0;
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}
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/*
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* classic interface
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*/
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char *
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bcrypt_gensalt(u_int8_t log_rounds)
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{
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static char gsalt[BCRYPT_SALTSPACE];
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bcrypt_initsalt(log_rounds, gsalt, sizeof(gsalt));
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return gsalt;
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}
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char *
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bcrypt(const char *pass, const char *salt)
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{
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static char gencrypted[BCRYPT_HASHSPACE];
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static char gerror[2];
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/* How do I handle errors ? Return ':' */
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strlcpy(gerror, ":", sizeof(gerror));
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if (bcrypt_hashpass(pass, salt, gencrypted, sizeof(gencrypted)) != 0)
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return gerror;
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return gencrypted;
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}
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