| /* |
| * 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; |
| } |