password hashing algorithm using blowfish

src/lib/libc/crypt/bcrypt.c

@@ -0,0 +1,300 @@
+/* $OpenBSD: bcrypt.c,v 1.1 1997/02/13 16:31:16 provos Exp $ */
+/*
+ * Copyright 1997 Niels Provos <provos@physnet.uni-hamburg.de>
+ *
+ * Modification and redistribution in source and binary forms is
+ * permitted provided that due credit is given to the author and the
+ * OpenBSD project (for instance by leaving this copyright notice
+ * intact).
+ */
+
+/* This password hashing algorithm was designed by David Mazieres
+ * <dm@lcs.mit.edu> and works as follows:
+ *
+ * 1. state := InitState ()
+ * 2. state := ExpandKey (state, salt, password) 3.
+ * REPEAT rounds:
+ *	state := ExpandKey (state, 0, salt)
+ *      state := ExpandKey(state, 0, password)
+ * 4. ctext := "OpenBSDbcrypthashfunc"
+ * 5. REPEAT 64:
+ * 	ctext := Encrypt_ECB (state, ctext);
+ * 6. RETURN Concatenate (salt, ctext);
+ *
+ */
+
+#ifdef TEST
+#include <stdio.h>
+#endif
+
+#include <stdlib.h>
+#include <time.h>
+#include <sys/types.h>
+#include <string.h>
+#include <pwd.h>
+#include <blf.h>
+
+/* This implementation is adaptable to current computing power.
+ * You can have up to 2^31 rounds which should be enough for some
+ * time to come.
+ */
+
+#define BCRYPT_VERSION '2'
+#define BCRYPT_MAXSALT 16	/* Precomputation is just so nice */
+#define BCRYPT_BLOCKS 6		/* Ciphertext blocks */
+#define BCRYPT_MINROUNDS 16	/* we have log2(rounds) in salt */
+
+char   *bcrypt_gensalt __P((u_int8_t));
+
+static void encode_salt __P((char *, u_int8_t *, u_int16_t, u_int8_t));
+static void encode_base64 __P((u_int8_t *, u_int8_t *, u_int16_t));
+static void decode_base64 __P((u_int8_t *, u_int16_t, u_int8_t *));
+
+static char    encrypted[_PASSWORD_LEN];
+static char    gsalt[BCRYPT_MAXSALT * 4 / 3 + 1];
+static char    error[] = ":";
+
+const static u_int8_t Base64Code[] =
+"./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
+
+const static u_int8_t index_64[128] =
+{
+	255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+	255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+	255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+	255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+	255, 255, 255, 255, 255, 255, 0, 1, 54, 55,
+	56, 57, 58, 59, 60, 61, 62, 63, 255, 255,
+	255, 255, 255, 255, 255, 2, 3, 4, 5, 6,
+	7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
+	17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,
+	255, 255, 255, 255, 255, 255, 28, 29, 30,
+	31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
+	41, 42, 43, 44, 45, 46, 47, 48, 49, 50,
+	51, 52, 53, 255, 255, 255, 255, 255
+};
+#define CHAR64(c)  ( (c) > 127 ? 255 : index_64[(c)])
+
+static void
+decode_base64(buffer, len, data)
+	u_int8_t *buffer;
+	u_int16_t len;
+	u_int8_t *data;
+{
+	u_int8_t *bp = buffer;
+	u_int8_t *p = data;
+	u_int8_t c1, c2, c3, c4;
+	while (bp < buffer + len) {
+		c1 = CHAR64(*p);
+		c2 = CHAR64(*(p + 1));
+
+		/* Invalid data */
+		if (c1 == 255 || c2 == 255)
+			break;
+
+		*bp++ = (c1 << 2) | ((c2 & 0x30) >> 4);
+		if (bp >= buffer + len)
+			break;
+
+		c3 = CHAR64(*(p + 2));
+		if (c3 == 255)
+			break;
+
+		*bp++ = ((c2 & 0x0f) << 4) | ((c3 & 0x3c) >> 2);
+		if (bp >= buffer + len)
+			break;
+
+		c4 = CHAR64(*(p + 3));
+		if (c4 == 255)
+			break;
+		*bp++ = ((c3 & 0x03) << 6) | c4;
+
+		p += 4;
+	}
+}
+
+static void
+encode_salt(salt, csalt, clen, logr)
+	char   *salt;
+	u_int8_t *csalt;
+	u_int16_t clen;
+	u_int8_t logr;
+{
+	salt[0] = '$';
+	salt[1] = BCRYPT_VERSION;
+	salt[2] = '$';
+
+	snprintf(salt + 3, 4, "%2.2u$", logr);
+
+	encode_base64((u_int8_t *) salt + 6, csalt, clen);
+}
+/* Generates a salt for this version of crypt.
+   Since versions may change. Keeping this here
+   seems sensible.
+ */
+
+char   *
+bcrypt_gensalt(log_rounds)
+	u_int8_t log_rounds;
+{
+	u_int8_t csalt[BCRYPT_MAXSALT];
+	u_int16_t i;
+	u_int32_t seed = 0;
+	(void) srandom((int) time((time_t *) NULL));
+	for (i = 0; i < BCRYPT_MAXSALT; i++) {
+		if (i % 4 == 0)
+			seed = random();
+		csalt[i] = seed & 0xff;
+		seed = seed >> 8;
+	}
+
+	if (log_rounds < 4)
+		log_rounds = 4;
+
+	encode_salt(gsalt, csalt, BCRYPT_MAXSALT, log_rounds);
+	return gsalt;
+}
+/* We handle $Vers$log2(NumRounds)$salt+passwd$
+   i.e. $2$04$iwouldntknowwhattosayetKdJ6iFtacBqJdKe6aW7ou */
+
+char   *
+bcrypt(key, salt)
+	char   *key;
+	char   *salt;
+{
+	blf_ctx state;
+	u_int32_t rounds, i, k;
+	u_int16_t j;
+	u_int8_t key_len, salt_len, logr;
+	u_int8_t ciphertext[4 * BCRYPT_BLOCKS] = "OpenBSDbcrypthashfunc";
+	u_int8_t csalt[BCRYPT_MAXSALT];
+	u_int32_t cdata[BCRYPT_BLOCKS];
+	/* Discard "$" identifier */
+	salt++;
+
+	if (*salt > BCRYPT_VERSION) {
+		/* How do I handle errors ? Return ':' */
+		return error;
+	}
+	/* Discard version + "$" identifier */
+	salt += 2;
+
+	if (*(salt + 2) != '$')
+		/* Out of sync with passwd entry */
+		return error;
+
+	/* Computer power doesnt increase linear, 2^x should be fine */
+	if ((rounds = (u_int32_t) 1 << (logr = atoi(salt))) < BCRYPT_MINROUNDS)
+		return error;
+
+	/* Discard num rounds + "$" identifier */
+	salt += 3;
+
+	/* We dont want the base64 salt but the raw data */
+	decode_base64(csalt, BCRYPT_MAXSALT, (u_int8_t *) salt);
+	salt_len = BCRYPT_MAXSALT;
+	key_len = strlen(key);
+
+	/* Setting up S-Boxes and Subkeys */
+	Blowfish_initstate(&state);
+	Blowfish_expandstate(&state, csalt, salt_len,
+	    (u_int8_t *) key, key_len);
+	for (k = 0; k < rounds; k++) {
+		Blowfish_expand0state(&state, (u_int8_t *) key, key_len);
+		Blowfish_expand0state(&state, csalt, salt_len);
+	}
+
+	/* This can be precomputed later */
+	j = 0;
+	for (i = 0; i < BCRYPT_BLOCKS; i++)
+		cdata[i] = Blowfish_stream2word(ciphertext, 4 * BCRYPT_BLOCKS, &j);
+
+	/* Now do the encryption */
+	for (k = 0; k < 64; k++)
+		blf_enc(&state, cdata, BCRYPT_BLOCKS / 2);
+
+	for (i = 0; i < BCRYPT_BLOCKS; i++) {
+		ciphertext[4 * i + 3] = cdata[i] & 0xff;
+		cdata[i] = cdata[i] >> 8;
+		ciphertext[4 * i + 2] = cdata[i] & 0xff;
+		cdata[i] = cdata[i] >> 8;
+		ciphertext[4 * i + 1] = cdata[i] & 0xff;
+		cdata[i] = cdata[i] >> 8;
+		ciphertext[4 * i + 0] = cdata[i] & 0xff;
+	}
+
+
+	encrypted[0] = '$';
+	encrypted[1] = BCRYPT_VERSION;
+	encrypted[2] = '$';
+
+	snprintf(encrypted + 3, 4, "%2.2u$", logr);
+
+	encode_base64((u_int8_t *) encrypted + 6, csalt, BCRYPT_MAXSALT);
+	encode_base64((u_int8_t *) encrypted + strlen(encrypted), ciphertext,
+	    4 * BCRYPT_BLOCKS);
+	return encrypted;
+}
+
+static void
+encode_base64(buffer, data, len)
+	u_int8_t *buffer;
+	u_int8_t *data;
+	u_int16_t len;
+{
+	u_int8_t *bp = buffer;
+	u_int8_t *p = data;
+	u_int8_t c1, c2;
+	while (p < data + len) {
+		c1 = *p++;
+		*bp++ = Base64Code[(c1 >> 2)];
+		c1 = (c1 & 0x03) << 4;
+		c2 = *p++;
+		if (p >= data + len) {
+			*bp++ = Base64Code[c1];
+			break;
+		}
+		c1 |= (c2 >> 4) & 0x0f;
+		*bp++ = Base64Code[c1];
+		c1 = (c2 & 0x0f) << 2;
+		c2 = *p++;
+		if (p >= data + len) {
+			*bp++ = Base64Code[c1];
+			break;
+		}
+		c1 |= (c2 >> 6) & 0x03;
+		*bp++ = Base64Code[c1];
+		*bp++ = Base64Code[c2 & 0x3f];
+	}
+	*bp = '\0';
+}
+#ifdef TEST
+void
+main()
+{
+	char    blubber[73];
+	char    salt[100];
+	char   *p;
+	salt[0] = '$';
+	salt[1] = BCRYPT_VERSION;
+	salt[2] = '$';
+
+	snprintf(salt + 3, 4, "%2.2u$", 5);
+
+	printf("24 bytes of salt: ");
+	fgets(salt + 6, 94, stdin);
+	salt[99] = 0;
+	printf("72 bytes of password: ");
+	fpurge(stdin);
+	fgets(blubber, 73, stdin);
+	blubber[72] = 0;
+
+	p = crypt(blubber, salt);
+	printf("Passwd entry: %s\n\n", p);
+
+	p = bcrypt_gensalt(5);
+	printf("Generated salt: %s\n", p);
+	p = crypt(blubber, p);
+	printf("Passwd entry: %s\n", p);
+}
+#endif