add sha256/sha512 crypt

based on versions sent to the list by nsz, with some simplification
and debloating. i'd still like to get them a bit smaller, or ideally
merge them into a single file with most of the code being shared, but
that can be done later.

1 files changed, 322 insertions, 0 deletions

diff --git a/src/misc/crypt_sha256.c b/src/misc/crypt_sha256.c
new file mode 100644
index 00000000..95e79b6e
--- /dev/null
+++ b/src/misc/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);
+}
+
+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;
+}
+
+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];
+	}
+}
+
+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;
+}