| @@ -0,0 +1,251 @@ |
| + | /* SHA256 and SHA512-based Unix crypt implementation. |
| + | * Released into the Public Domain by Ulrich Drepper <[email protected]>. |
| + | */ |
| + | |
| + | /* Prefix for optional rounds specification. */ |
| + | static const char str_rounds[] = "rounds=%u$"; |
| + | |
| + | /* Maximum salt string length. */ |
| + | #define SALT_LEN_MAX 16 |
| + | /* Default number of rounds if not explicitly specified. */ |
| + | #define ROUNDS_DEFAULT 5000 |
| + | /* Minimum number of rounds. */ |
| + | #define ROUNDS_MIN 1000 |
| + | /* Maximum number of rounds. */ |
| + | #define ROUNDS_MAX 999999999 |
| + | |
| + | static char * |
| + | NOINLINE |
| + | sha_crypt(/*const*/ char *key_data, /*const*/ char *salt_data) |
| + | { |
| + | void (*sha_begin)(void *ctx) FAST_FUNC; |
| + | void (*sha_hash)(const void *buffer, size_t len, void *ctx) FAST_FUNC; |
| + | void* (*sha_end)(void *resbuf, void *ctx) FAST_FUNC; |
| + | int _32or64; |
| + | |
| + | char *result, *resptr; |
| + | |
| + | /* btw, sha256 needs [32] and uint32_t only */ |
| + | unsigned char alt_result[64] __attribute__((__aligned__(__alignof__(uint64_t)))); |
| + | unsigned char temp_result[64] __attribute__((__aligned__(__alignof__(uint64_t)))); |
| + | union { |
| + | sha256_ctx_t x; |
| + | sha512_ctx_t y; |
| + | } ctx; |
| + | union { |
| + | sha256_ctx_t x; |
| + | sha512_ctx_t y; |
| + | } alt_ctx; |
| + | unsigned salt_len; |
| + | unsigned key_len; |
| + | unsigned cnt; |
| + | unsigned rounds; |
| + | char *cp; |
| + | char is_sha512; |
| + | |
| + | /* Analyze salt, construct already known part of result */ |
| + | cnt = strlen(salt_data) + 1 + 43 + 1; |
| + | is_sha512 = salt_data[1]; |
| + | if (is_sha512 == '6') |
| + | cnt += 43; |
| + | result = resptr = xzalloc(cnt); /* will provide NUL terminator */ |
| + | *resptr++ = '$'; |
| + | *resptr++ = is_sha512; |
| + | *resptr++ = '$'; |
| + | rounds = ROUNDS_DEFAULT; |
| + | salt_data += 3; |
| + | if (strncmp(salt_data, str_rounds, 7) == 0) { |
| + | /* 7 == strlen("rounds=") */ |
| + | char *endp; |
| + | unsigned srounds = bb_strtou(salt_data + 7, &endp, 10); |
| + | if (*endp == '$') { |
| + | salt_data = endp + 1; |
| + | rounds = srounds; |
| + | if (rounds < ROUNDS_MIN) |
| + | rounds = ROUNDS_MIN; |
| + | if (rounds > ROUNDS_MAX) |
| + | rounds = ROUNDS_MAX; |
| + | } |
| + | } |
| + | salt_len = strchrnul(salt_data, '$') - salt_data; |
| + | if (salt_len > SALT_LEN_MAX) |
| + | salt_len = SALT_LEN_MAX; |
| + | /* xstrdup assures suitable alignment; also we will use it |
| + | as a scratch space later. */ |
| + | salt_data = xstrndup(salt_data, salt_len); |
| + | if (rounds != ROUNDS_DEFAULT) /* add "rounds=NNNNN$" */ |
| + | resptr += sprintf(resptr, str_rounds, rounds); |
| + | strcpy(resptr, salt_data); |
| + | resptr += salt_len; |
| + | *resptr++ = '$'; |
| + | /* key data doesn't need much processing */ |
| + | key_len = strlen(key_data); |
| + | key_data = xstrdup(key_data); |
| + | |
| + | /* Which flavor of SHAnnn ops to use? */ |
| + | sha_begin = (void*)sha256_begin; |
| + | sha_hash = (void*)sha256_hash; |
| + | sha_end = (void*)sha256_end; |
| + | _32or64 = 32; |
| + | if (is_sha512 == '6') { |
| + | sha_begin = (void*)sha512_begin; |
| + | sha_hash = (void*)sha512_hash; |
| + | sha_end = (void*)sha512_end; |
| + | _32or64 = 64; |
| + | } |
| + | |
| + | /* Add KEY, SALT. */ |
| + | sha_begin(&ctx); |
| + | sha_hash(key_data, key_len, &ctx); |
| + | sha_hash(salt_data, salt_len, &ctx); |
| + | |
| + | /* Compute alternate SHA sum with input KEY, SALT, and KEY. |
| + | The final result will be added to the first context. */ |
| + | sha_begin(&alt_ctx); |
| + | sha_hash(key_data, key_len, &alt_ctx); |
| + | sha_hash(salt_data, salt_len, &alt_ctx); |
| + | sha_hash(key_data, key_len, &alt_ctx); |
| + | sha_end(alt_result, &alt_ctx); |
| + | |
| + | /* Add result of this to the other context. */ |
| + | /* Add for any character in the key one byte of the alternate sum. */ |
| + | for (cnt = key_len; cnt > _32or64; cnt -= _32or64) |
| + | sha_hash(alt_result, _32or64, &ctx); |
| + | sha_hash(alt_result, cnt, &ctx); |
| + | |
| + | /* Take the binary representation of the length of the key and for every |
| + | 1 add the alternate sum, for every 0 the key. */ |
| + | for (cnt = key_len; cnt != 0; cnt >>= 1) |
| + | if ((cnt & 1) != 0) |
| + | sha_hash(alt_result, _32or64, &ctx); |
| + | else |
| + | sha_hash(key_data, key_len, &ctx); |
| + | |
| + | /* Create intermediate result. */ |
| + | sha_end(alt_result, &ctx); |
| + | |
| + | /* Start computation of P byte sequence. */ |
| + | /* For every character in the password add the entire password. */ |
| + | sha_begin(&alt_ctx); |
| + | for (cnt = 0; cnt < key_len; ++cnt) |
| + | sha_hash(key_data, key_len, &alt_ctx); |
| + | sha_end(temp_result, &alt_ctx); |
| + | |
| + | /* NB: past this point, raw key_data is not used anymore */ |
| + | |
| + | /* Create byte sequence P. */ |
| + | #define p_bytes key_data /* reuse the buffer as it is of the key_len size */ |
| + | cp = p_bytes; /* was: ... = alloca(key_len); */ |
| + | for (cnt = key_len; cnt >= _32or64; cnt -= _32or64) { |
| + | cp = memcpy(cp, temp_result, _32or64); |
| + | cp += _32or64; |
| + | } |
| + | memcpy(cp, temp_result, cnt); |
| + | |
| + | /* Start computation of S byte sequence. */ |
| + | /* For every character in the password add the entire password. */ |
| + | sha_begin(&alt_ctx); |
| + | for (cnt = 0; cnt < 16 + alt_result[0]; ++cnt) |
| + | sha_hash(salt_data, salt_len, &alt_ctx); |
| + | sha_end(temp_result, &alt_ctx); |
| + | |
| + | /* NB: past this point, raw salt_data is not used anymore */ |
| + | |
| + | /* Create byte sequence S. */ |
| + | #define s_bytes salt_data /* reuse the buffer as it is of the salt_len size */ |
| + | cp = s_bytes; /* was: ... = alloca(salt_len); */ |
| + | for (cnt = salt_len; cnt >= _32or64; cnt -= _32or64) { |
| + | cp = memcpy(cp, temp_result, _32or64); |
| + | cp += _32or64; |
| + | } |
| + | memcpy(cp, temp_result, cnt); |
| + | |
| + | /* Repeatedly run the collected hash value through SHA to burn |
| + | CPU cycles. */ |
| + | for (cnt = 0; cnt < rounds; ++cnt) { |
| + | sha_begin(&ctx); |
| + | |
| + | /* Add key or last result. */ |
| + | if ((cnt & 1) != 0) |
| + | sha_hash(p_bytes, key_len, &ctx); |
| + | else |
| + | sha_hash(alt_result, _32or64, &ctx); |
| + | /* Add salt for numbers not divisible by 3. */ |
| + | if (cnt % 3 != 0) |
| + | sha_hash(s_bytes, salt_len, &ctx); |
| + | /* Add key for numbers not divisible by 7. */ |
| + | if (cnt % 7 != 0) |
| + | sha_hash(p_bytes, key_len, &ctx); |
| + | /* Add key or last result. */ |
| + | if ((cnt & 1) != 0) |
| + | sha_hash(alt_result, _32or64, &ctx); |
| + | else |
| + | sha_hash(p_bytes, key_len, &ctx); |
| + | |
| + | sha_end(alt_result, &ctx); |
| + | } |
| + | |
| + | |
| + | /* Append encrypted password to result buffer */ |
| + | //TODO: replace with something like |
| + | // bb_uuencode(cp, src, length, bb_uuenc_tbl_XXXbase64); |
| + | #define b64_from_24bit(B2, B1, B0, N) \ |
| + | do { \ |
| + | unsigned w = ((B2) << 16) | ((B1) << 8) | (B0); \ |
| + | resptr = to64(resptr, w, N); \ |
| + | } while (0) |
| + | if (is_sha512 == '5') { |
| + | b64_from_24bit(alt_result[0], alt_result[10], alt_result[20], 4); |
| + | b64_from_24bit(alt_result[21], alt_result[1], alt_result[11], 4); |
| + | b64_from_24bit(alt_result[12], alt_result[22], alt_result[2], 4); |
| + | b64_from_24bit(alt_result[3], alt_result[13], alt_result[23], 4); |
| + | b64_from_24bit(alt_result[24], alt_result[4], alt_result[14], 4); |
| + | b64_from_24bit(alt_result[15], alt_result[25], alt_result[5], 4); |
| + | b64_from_24bit(alt_result[6], alt_result[16], alt_result[26], 4); |
| + | b64_from_24bit(alt_result[27], alt_result[7], alt_result[17], 4); |
| + | b64_from_24bit(alt_result[18], alt_result[28], alt_result[8], 4); |
| + | b64_from_24bit(alt_result[9], alt_result[19], alt_result[29], 4); |
| + | b64_from_24bit(0, alt_result[31], alt_result[30], 3); |
| + | } else { |
| + | b64_from_24bit(alt_result[0], alt_result[21], alt_result[42], 4); |
| + | b64_from_24bit(alt_result[22], alt_result[43], alt_result[1], 4); |
| + | b64_from_24bit(alt_result[44], alt_result[2], alt_result[23], 4); |
| + | b64_from_24bit(alt_result[3], alt_result[24], alt_result[45], 4); |
| + | b64_from_24bit(alt_result[25], alt_result[46], alt_result[4], 4); |
| + | b64_from_24bit(alt_result[47], alt_result[5], alt_result[26], 4); |
| + | b64_from_24bit(alt_result[6], alt_result[27], alt_result[48], 4); |
| + | b64_from_24bit(alt_result[28], alt_result[49], alt_result[7], 4); |
| + | b64_from_24bit(alt_result[50], alt_result[8], alt_result[29], 4); |
| + | b64_from_24bit(alt_result[9], alt_result[30], alt_result[51], 4); |
| + | b64_from_24bit(alt_result[31], alt_result[52], alt_result[10], 4); |
| + | b64_from_24bit(alt_result[53], alt_result[11], alt_result[32], 4); |
| + | b64_from_24bit(alt_result[12], alt_result[33], alt_result[54], 4); |
| + | b64_from_24bit(alt_result[34], alt_result[55], alt_result[13], 4); |
| + | b64_from_24bit(alt_result[56], alt_result[14], alt_result[35], 4); |
| + | b64_from_24bit(alt_result[15], alt_result[36], alt_result[57], 4); |
| + | b64_from_24bit(alt_result[37], alt_result[58], alt_result[16], 4); |
| + | b64_from_24bit(alt_result[59], alt_result[17], alt_result[38], 4); |
| + | b64_from_24bit(alt_result[18], alt_result[39], alt_result[60], 4); |
| + | b64_from_24bit(alt_result[40], alt_result[61], alt_result[19], 4); |
| + | b64_from_24bit(alt_result[62], alt_result[20], alt_result[41], 4); |
| + | b64_from_24bit(0, 0, alt_result[63], 2); |
| + | } |
| + | /* *resptr = '\0'; - xzalloc did it */ |
| + | #undef b64_from_24bit |
| + | |
| + | /* Clear the buffer for the intermediate result so that people |
| + | attaching to processes or reading core dumps cannot get any |
| + | information. */ |
| + | memset(temp_result, 0, sizeof(temp_result)); |
| + | memset(alt_result, 0, sizeof(alt_result)); |
| + | memset(&ctx, 0, sizeof(ctx)); |
| + | memset(&alt_ctx, 0, sizeof(alt_ctx)); |
| + | memset(key_data, 0, key_len); /* also p_bytes */ |
| + | memset(salt_data, 0, salt_len); /* also s_bytes */ |
| + | free(key_data); |
| + | free(salt_data); |
| + | #undef p_bytes |
| + | #undef s_bytes |
| + | |
| + | return result; |
| + | } |