/* * Copyright (c) 2014 Ted Unangst <[email protected]> * Copyright (c) 1997 Niels Provos <[email protected]> * * 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. */ #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; WRAP(clock_gettime)(CLOCK_THREAD_CPUTIME_ID, &before); bcrypt_newhash("testpassword", r, buf, sizeof(buf)); WRAP(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);