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/* SHA256 and SHA512-based Unix crypt implementation.
* Released into the Public Domain by Ulrich Drepper <drepper@redhat.com>.
*/
/* 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;
}
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