diff options
Diffstat (limited to 'src/crypt/crypt_sha256.c')
| -rw-r--r-- | src/crypt/crypt_sha256.c | 322 |
1 files changed, 322 insertions, 0 deletions
diff --git a/src/crypt/crypt_sha256.c b/src/crypt/crypt_sha256.c new file mode 100644 index 00000000..2dc27ee7 --- /dev/null +++ b/src/crypt/crypt_sha256.c @@ -0,0 +1,322 @@ +/* + * public domain sha256 crypt implementation + * + * original sha crypt design: http://people.redhat.com/drepper/SHA-crypt.txt + * in this implementation at least 32bit int is assumed, + * key length is limited, the $5$ prefix is mandatory, '\n' and ':' is rejected + * in the salt and rounds= setting must contain a valid iteration count, + * on error "*" is returned. + */ +#include <ctype.h> +#include <stdlib.h> +#include <stdio.h> +#include <string.h> +#include <stdint.h> + +/* public domain sha256 implementation based on fips180-3 */ + +struct sha256 { + uint64_t len; /* processed message length */ + uint32_t h[8]; /* hash state */ + uint8_t buf[64]; /* message block buffer */ +}; + +static uint32_t ror(uint32_t n, int k) { return (n >> k) | (n << (32-k)); } +#define Ch(x,y,z) (z ^ (x & (y ^ z))) +#define Maj(x,y,z) ((x & y) | (z & (x | y))) +#define S0(x) (ror(x,2) ^ ror(x,13) ^ ror(x,22)) +#define S1(x) (ror(x,6) ^ ror(x,11) ^ ror(x,25)) +#define R0(x) (ror(x,7) ^ ror(x,18) ^ (x>>3)) +#define R1(x) (ror(x,17) ^ ror(x,19) ^ (x>>10)) + +static const uint32_t K[64] = { +0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5, +0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174, +0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da, +0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967, +0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, +0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070, +0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3, +0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2 +}; + +static void processblock(struct sha256 *s, const uint8_t *buf) +{ + uint32_t W[64], t1, t2, a, b, c, d, e, f, g, h; + int i; + + for (i = 0; i < 16; i++) { + W[i] = (uint32_t)buf[4*i]<<24; + W[i] |= (uint32_t)buf[4*i+1]<<16; + W[i] |= (uint32_t)buf[4*i+2]<<8; + W[i] |= buf[4*i+3]; + } + for (; i < 64; i++) + W[i] = R1(W[i-2]) + W[i-7] + R0(W[i-15]) + W[i-16]; + a = s->h[0]; + b = s->h[1]; + c = s->h[2]; + d = s->h[3]; + e = s->h[4]; + f = s->h[5]; + g = s->h[6]; + h = s->h[7]; + for (i = 0; i < 64; i++) { + t1 = h + S1(e) + Ch(e,f,g) + K[i] + W[i]; + t2 = S0(a) + Maj(a,b,c); + h = g; + g = f; + f = e; + e = d + t1; + d = c; + c = b; + b = a; + a = t1 + t2; + } + s->h[0] += a; + s->h[1] += b; + s->h[2] += c; + s->h[3] += d; + s->h[4] += e; + s->h[5] += f; + s->h[6] += g; + s->h[7] += h; +} + +static void pad(struct sha256 *s) +{ + unsigned r = s->len % 64; + + s->buf[r++] = 0x80; + if (r > 56) { + memset(s->buf + r, 0, 64 - r); + r = 0; + processblock(s, s->buf); + } + memset(s->buf + r, 0, 56 - r); + s->len *= 8; + s->buf[56] = s->len >> 56; + s->buf[57] = s->len >> 48; + s->buf[58] = s->len >> 40; + s->buf[59] = s->len >> 32; + s->buf[60] = s->len >> 24; + s->buf[61] = s->len >> 16; + s->buf[62] = s->len >> 8; + s->buf[63] = s->len; + processblock(s, s->buf); +} + +static void sha256_init(struct sha256 *s) +{ + s->len = 0; + s->h[0] = 0x6a09e667; + s->h[1] = 0xbb67ae85; + s->h[2] = 0x3c6ef372; + s->h[3] = 0xa54ff53a; + s->h[4] = 0x510e527f; + s->h[5] = 0x9b05688c; + s->h[6] = 0x1f83d9ab; + s->h[7] = 0x5be0cd19; +} + +static void sha256_sum(struct sha256 *s, uint8_t md[20]) +{ + int i; + + pad(s); + for (i = 0; i < 8; i++) { + md[4*i] = s->h[i] >> 24; + md[4*i+1] = s->h[i] >> 16; + md[4*i+2] = s->h[i] >> 8; + md[4*i+3] = s->h[i]; + } +} + +static void sha256_update(struct sha256 *s, const void *m, unsigned long len) +{ + const uint8_t *p = m; + unsigned r = s->len % 64; + + s->len += len; + if (r) { + if (len < 64 - r) { + memcpy(s->buf + r, p, len); + return; + } + memcpy(s->buf + r, p, 64 - r); + len -= 64 - r; + p += 64 - r; + processblock(s, s->buf); + } + for (; len >= 64; len -= 64, p += 64) + processblock(s, p); + memcpy(s->buf, p, len); +} + +static unsigned char b64[] = +"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"; + +static char *to64(char *s, unsigned int u, int n) +{ + while (--n >= 0) { + *s++ = b64[u % 64]; + u /= 64; + } + return s; +} + +/* key limit is not part of the original design, added for DoS protection. + * rounds limit has been lowered (versus the reference/spec), also for DoS + * protection. runtime is O(klen^2 + klen*rounds) */ +#define KEY_MAX 256 +#define SALT_MAX 16 +#define ROUNDS_DEFAULT 5000 +#define ROUNDS_MIN 1000 +#define ROUNDS_MAX 50000 + +/* hash n bytes of the repeated md message digest */ +static void hashmd(struct sha256 *s, unsigned int n, const void *md) +{ + unsigned int i; + + for (i = n; i > 32; i -= 32) + sha256_update(s, md, 32); + sha256_update(s, md, i); +} + +static char *sha256crypt(const char *key, const char *setting, char *output) +{ + struct sha256 ctx; + unsigned char md[32], kmd[32], smd[32]; + unsigned int i, r, klen, slen; + char rounds[20] = ""; + const char *salt; + char *p; + + /* reject large keys */ + klen = strnlen(key, KEY_MAX+1); + if (klen > KEY_MAX) + return 0; + + /* setting: $5$rounds=n$salt$ (rounds=n$ and closing $ are optional) */ + if (strncmp(setting, "$5$", 3) != 0) + return 0; + salt = setting + 3; + + r = ROUNDS_DEFAULT; + if (strncmp(salt, "rounds=", sizeof "rounds=" - 1) == 0) { + unsigned long u; + char *end; + + /* + * this is a deviation from the reference: + * bad rounds setting is rejected if it is + * - empty + * - unterminated (missing '$') + * - begins with anything but a decimal digit + * the reference implementation treats these bad + * rounds as part of the salt or parse them with + * strtoul semantics which may cause problems + * including non-portable hashes that depend on + * the host's value of ULONG_MAX. + */ + salt += sizeof "rounds=" - 1; + if (!isdigit(*salt)) + return 0; + u = strtoul(salt, &end, 10); + if (*end != '$') + return 0; + salt = end+1; + if (u < ROUNDS_MIN) + r = ROUNDS_MIN; + else if (u > ROUNDS_MAX) + r = ROUNDS_MAX; + else + r = u; + /* needed when rounds is zero prefixed or out of bounds */ + sprintf(rounds, "rounds=%u$", r); + } + + for (i = 0; i < SALT_MAX && salt[i] && salt[i] != '$'; i++) + /* reject characters that interfere with /etc/shadow parsing */ + if (salt[i] == '\n' || salt[i] == ':') + return 0; + slen = i; + + /* B = sha(key salt key) */ + sha256_init(&ctx); + sha256_update(&ctx, key, klen); + sha256_update(&ctx, salt, slen); + sha256_update(&ctx, key, klen); + sha256_sum(&ctx, md); + + /* A = sha(key salt repeat-B alternate-B-key) */ + sha256_init(&ctx); + sha256_update(&ctx, key, klen); + sha256_update(&ctx, salt, slen); + hashmd(&ctx, klen, md); + for (i = klen; i > 0; i >>= 1) + if (i & 1) + sha256_update(&ctx, md, sizeof md); + else + sha256_update(&ctx, key, klen); + sha256_sum(&ctx, md); + + /* DP = sha(repeat-key), this step takes O(klen^2) time */ + sha256_init(&ctx); + for (i = 0; i < klen; i++) + sha256_update(&ctx, key, klen); + sha256_sum(&ctx, kmd); + + /* DS = sha(repeat-salt) */ + sha256_init(&ctx); + for (i = 0; i < 16 + md[0]; i++) + sha256_update(&ctx, salt, slen); + sha256_sum(&ctx, smd); + + /* iterate A = f(A,DP,DS), this step takes O(rounds*klen) time */ + for (i = 0; i < r; i++) { + sha256_init(&ctx); + if (i % 2) + hashmd(&ctx, klen, kmd); + else + sha256_update(&ctx, md, sizeof md); + if (i % 3) + sha256_update(&ctx, smd, slen); + if (i % 7) + hashmd(&ctx, klen, kmd); + if (i % 2) + sha256_update(&ctx, md, sizeof md); + else + hashmd(&ctx, klen, kmd); + sha256_sum(&ctx, md); + } + + /* output is $5$rounds=n$salt$hash */ + p = output; + p += sprintf(p, "$5$%s%.*s$", rounds, slen, salt); + static const unsigned char perm[][3] = { + 0,10,20,21,1,11,12,22,2,3,13,23,24,4,14, + 15,25,5,6,16,26,27,7,17,18,28,8,9,19,29 }; + for (i=0; i<10; i++) p = to64(p, + (md[perm[i][0]]<<16)|(md[perm[i][1]]<<8)|md[perm[i][2]], 4); + p = to64(p, (md[31]<<8)|md[30], 3); + *p = 0; + return output; +} + +char *__crypt_sha256(const char *key, const char *setting, char *output) +{ + static const char testkey[] = "Xy01@#\x01\x02\x80\x7f\xff\r\n\x81\t !"; + static const char testsetting[] = "$5$rounds=1234$abc0123456789$"; + static const char testhash[] = "$5$rounds=1234$abc0123456789$3VfDjPt05VHFn47C/ojFZ6KRPYrOjj1lLbH.dkF3bZ6"; + char testbuf[128]; + char *p, *q; + + p = sha256crypt(key, setting, output); + /* self test and stack cleanup */ + q = sha256crypt(testkey, testsetting, testbuf); + if (!p || q != testbuf || memcmp(testbuf, testhash, sizeof testhash)) + return "*"; + return p; +} |