2 * public domain sha256 crypt implementation
4 * original sha crypt design: http://people.redhat.com/drepper/SHA-crypt.txt
5 * in this implementation at least 32bit int is assumed,
6 * key length is limited, the $5$ prefix is mandatory, '\n' and ':' is rejected
7 * in the salt and rounds= setting must contain a valid iteration count,
8 * on error "*" is returned.
16 /* public domain sha256 implementation based on fips180-3 */
19 uint64_t len; /* processed message length */
20 uint32_t h[8]; /* hash state */
21 uint8_t buf[64]; /* message block buffer */
24 static uint32_t ror(uint32_t n, int k) { return (n >> k) | (n << (32-k)); }
25 #define Ch(x,y,z) (z ^ (x & (y ^ z)))
26 #define Maj(x,y,z) ((x & y) | (z & (x | y)))
27 #define S0(x) (ror(x,2) ^ ror(x,13) ^ ror(x,22))
28 #define S1(x) (ror(x,6) ^ ror(x,11) ^ ror(x,25))
29 #define R0(x) (ror(x,7) ^ ror(x,18) ^ (x>>3))
30 #define R1(x) (ror(x,17) ^ ror(x,19) ^ (x>>10))
32 static const uint32_t K[64] = {
33 0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
34 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
35 0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
36 0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
37 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
38 0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
39 0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
40 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
43 static void processblock(struct sha256 *s, const uint8_t *buf)
45 uint32_t W[64], t1, t2, a, b, c, d, e, f, g, h;
48 for (i = 0; i < 16; i++) {
49 W[i] = (uint32_t)buf[4*i]<<24;
50 W[i] |= (uint32_t)buf[4*i+1]<<16;
51 W[i] |= (uint32_t)buf[4*i+2]<<8;
55 W[i] = R1(W[i-2]) + W[i-7] + R0(W[i-15]) + W[i-16];
64 for (i = 0; i < 64; i++) {
65 t1 = h + S1(e) + Ch(e,f,g) + K[i] + W[i];
66 t2 = S0(a) + Maj(a,b,c);
86 static void pad(struct sha256 *s)
88 unsigned r = s->len % 64;
92 memset(s->buf + r, 0, 64 - r);
94 processblock(s, s->buf);
96 memset(s->buf + r, 0, 56 - r);
98 s->buf[56] = s->len >> 56;
99 s->buf[57] = s->len >> 48;
100 s->buf[58] = s->len >> 40;
101 s->buf[59] = s->len >> 32;
102 s->buf[60] = s->len >> 24;
103 s->buf[61] = s->len >> 16;
104 s->buf[62] = s->len >> 8;
106 processblock(s, s->buf);
109 static void sha256_init(struct sha256 *s)
112 s->h[0] = 0x6a09e667;
113 s->h[1] = 0xbb67ae85;
114 s->h[2] = 0x3c6ef372;
115 s->h[3] = 0xa54ff53a;
116 s->h[4] = 0x510e527f;
117 s->h[5] = 0x9b05688c;
118 s->h[6] = 0x1f83d9ab;
119 s->h[7] = 0x5be0cd19;
122 static void sha256_sum(struct sha256 *s, uint8_t *md)
127 for (i = 0; i < 8; i++) {
128 md[4*i] = s->h[i] >> 24;
129 md[4*i+1] = s->h[i] >> 16;
130 md[4*i+2] = s->h[i] >> 8;
135 static void sha256_update(struct sha256 *s, const void *m, unsigned long len)
137 const uint8_t *p = m;
138 unsigned r = s->len % 64;
143 memcpy(s->buf + r, p, len);
146 memcpy(s->buf + r, p, 64 - r);
149 processblock(s, s->buf);
151 for (; len >= 64; len -= 64, p += 64)
153 memcpy(s->buf, p, len);
156 static const unsigned char b64[] =
157 "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
159 static char *to64(char *s, unsigned int u, int n)
168 /* key limit is not part of the original design, added for DoS protection.
169 * rounds limit has been lowered (versus the reference/spec), also for DoS
170 * protection. runtime is O(klen^2 + klen*rounds) */
173 #define ROUNDS_DEFAULT 5000
174 #define ROUNDS_MIN 1000
175 #define ROUNDS_MAX 9999999
177 /* hash n bytes of the repeated md message digest */
178 static void hashmd(struct sha256 *s, unsigned int n, const void *md)
182 for (i = n; i > 32; i -= 32)
183 sha256_update(s, md, 32);
184 sha256_update(s, md, i);
187 static char *sha256crypt(const char *key, const char *setting, char *output)
190 unsigned char md[32], kmd[32], smd[32];
191 unsigned int i, r, klen, slen;
192 char rounds[20] = "";
196 /* reject large keys */
197 klen = strnlen(key, KEY_MAX+1);
201 /* setting: $5$rounds=n$salt$ (rounds=n$ and closing $ are optional) */
202 if (strncmp(setting, "$5$", 3) != 0)
207 if (strncmp(salt, "rounds=", sizeof "rounds=" - 1) == 0) {
212 * this is a deviation from the reference:
213 * bad rounds setting is rejected if it is
215 * - unterminated (missing '$')
216 * - begins with anything but a decimal digit
217 * the reference implementation treats these bad
218 * rounds as part of the salt or parse them with
219 * strtoul semantics which may cause problems
220 * including non-portable hashes that depend on
221 * the host's value of ULONG_MAX.
223 salt += sizeof "rounds=" - 1;
226 u = strtoul(salt, &end, 10);
232 else if (u > ROUNDS_MAX)
236 /* needed when rounds is zero prefixed or out of bounds */
237 sprintf(rounds, "rounds=%u$", r);
240 for (i = 0; i < SALT_MAX && salt[i] && salt[i] != '$'; i++)
241 /* reject characters that interfere with /etc/shadow parsing */
242 if (salt[i] == '\n' || salt[i] == ':')
246 /* B = sha(key salt key) */
248 sha256_update(&ctx, key, klen);
249 sha256_update(&ctx, salt, slen);
250 sha256_update(&ctx, key, klen);
251 sha256_sum(&ctx, md);
253 /* A = sha(key salt repeat-B alternate-B-key) */
255 sha256_update(&ctx, key, klen);
256 sha256_update(&ctx, salt, slen);
257 hashmd(&ctx, klen, md);
258 for (i = klen; i > 0; i >>= 1)
260 sha256_update(&ctx, md, sizeof md);
262 sha256_update(&ctx, key, klen);
263 sha256_sum(&ctx, md);
265 /* DP = sha(repeat-key), this step takes O(klen^2) time */
267 for (i = 0; i < klen; i++)
268 sha256_update(&ctx, key, klen);
269 sha256_sum(&ctx, kmd);
271 /* DS = sha(repeat-salt) */
273 for (i = 0; i < 16 + md[0]; i++)
274 sha256_update(&ctx, salt, slen);
275 sha256_sum(&ctx, smd);
277 /* iterate A = f(A,DP,DS), this step takes O(rounds*klen) time */
278 for (i = 0; i < r; i++) {
281 hashmd(&ctx, klen, kmd);
283 sha256_update(&ctx, md, sizeof md);
285 sha256_update(&ctx, smd, slen);
287 hashmd(&ctx, klen, kmd);
289 sha256_update(&ctx, md, sizeof md);
291 hashmd(&ctx, klen, kmd);
292 sha256_sum(&ctx, md);
295 /* output is $5$rounds=n$salt$hash */
297 p += sprintf(p, "$5$%s%.*s$", rounds, slen, salt);
298 static const unsigned char perm[][3] = {
299 0,10,20,21,1,11,12,22,2,3,13,23,24,4,14,
300 15,25,5,6,16,26,27,7,17,18,28,8,9,19,29 };
301 for (i=0; i<10; i++) p = to64(p,
302 (md[perm[i][0]]<<16)|(md[perm[i][1]]<<8)|md[perm[i][2]], 4);
303 p = to64(p, (md[31]<<8)|md[30], 3);
308 char *__crypt_sha256(const char *key, const char *setting, char *output)
310 static const char testkey[] = "Xy01@#\x01\x02\x80\x7f\xff\r\n\x81\t !";
311 static const char testsetting[] = "$5$rounds=1234$abc0123456789$";
312 static const char testhash[] = "$5$rounds=1234$abc0123456789$3VfDjPt05VHFn47C/ojFZ6KRPYrOjj1lLbH.dkF3bZ6";
316 p = sha256crypt(key, setting, output);
317 /* self test and stack cleanup */
318 q = sha256crypt(testkey, testsetting, testbuf);
319 if (!p || q != testbuf || memcmp(testbuf, testhash, sizeof testhash))