Add bcrypt_pbkdf to libsa, from libutil. This will soon allow the boot

loader to support softraid crypto volumes using bcrypt pbkdf.

2 files changed, 189 insertions, 0 deletions

diff --git a/sys/lib/libsa/bcrypt_pbkdf.c b/sys/lib/libsa/bcrypt_pbkdf.c
new file mode 100644
index 00000000000..4020ada74a4
--- /dev/null
+++ b/sys/lib/libsa/bcrypt_pbkdf.c
@@ -0,0 +1,167 @@
+/* $OpenBSD: bcrypt_pbkdf.c,v 1.1 2016/09/10 18:26:28 jsing Exp $ */
+/*
+ * Copyright (c) 2013 Ted Unangst <tedu@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <lib/libsa/stand.h>
+#include <sys/param.h>
+ 
+#include "bcrypt_pbkdf.h"
+#include "blowfish.h"
+#include "sha2.h"
+
+#define	MINIMUM(a,b) (((a) < (b)) ? (a) : (b))
+
+/*
+ * pkcs #5 pbkdf2 implementation using the "bcrypt" hash
+ *
+ * The bcrypt hash function is derived from the bcrypt password hashing
+ * function with the following modifications:
+ * 1. The input password and salt are preprocessed with SHA512.
+ * 2. The output length is expanded to 256 bits.
+ * 3. Subsequently the magic string to be encrypted is lengthened and modifed
+ *    to "OxychromaticBlowfishSwatDynamite"
+ * 4. The hash function is defined to perform 64 rounds of initial state
+ *    expansion. (More rounds are performed by iterating the hash.)
+ *
+ * Note that this implementation pulls the SHA512 operations into the caller
+ * as a performance optimization.
+ *
+ * One modification from official pbkdf2. Instead of outputting key material
+ * linearly, we mix it. pbkdf2 has a known weakness where if one uses it to
+ * generate (e.g.) 512 bits of key material for use as two 256 bit keys, an
+ * attacker can merely run once through the outer loop, but the user
+ * always runs it twice. Shuffling output bytes requires computing the
+ * entirety of the key material to assemble any subkey. This is something a
+ * wise caller could do; we just do it for you.
+ */
+
+#define BCRYPT_WORDS 8
+#define BCRYPT_HASHSIZE (BCRYPT_WORDS * 4)
+
+static void
+bcrypt_hash(uint8_t *sha2pass, uint8_t *sha2salt, uint8_t *out)
+{
+	blf_ctx state;
+	uint8_t ciphertext[BCRYPT_HASHSIZE] =
+	    "OxychromaticBlowfishSwatDynamite";
+	uint32_t cdata[BCRYPT_WORDS];
+	int i;
+	uint16_t j;
+	size_t shalen = SHA512_DIGEST_LENGTH;
+
+	/* key expansion */
+	Blowfish_initstate(&state);
+	Blowfish_expandstate(&state, sha2salt, shalen, sha2pass, shalen);
+	for (i = 0; i < 64; i++) {
+		Blowfish_expand0state(&state, sha2salt, shalen);
+		Blowfish_expand0state(&state, sha2pass, shalen);
+	}
+
+	/* encryption */
+	j = 0;
+	for (i = 0; i < BCRYPT_WORDS; i++)
+		cdata[i] = Blowfish_stream2word(ciphertext, sizeof(ciphertext),
+		    &j);
+	for (i = 0; i < 64; i++)
+		blf_enc(&state, cdata, sizeof(cdata) / sizeof(uint64_t));
+
+	/* copy out */
+	for (i = 0; i < BCRYPT_WORDS; i++) {
+		out[4 * i + 3] = (cdata[i] >> 24) & 0xff;
+		out[4 * i + 2] = (cdata[i] >> 16) & 0xff;
+		out[4 * i + 1] = (cdata[i] >> 8) & 0xff;
+		out[4 * i + 0] = cdata[i] & 0xff;
+	}
+
+	/* zap */
+	explicit_bzero(ciphertext, sizeof(ciphertext));
+	explicit_bzero(cdata, sizeof(cdata));
+	explicit_bzero(&state, sizeof(state));
+}
+
+int
+bcrypt_pbkdf(const char *pass, size_t passlen, const uint8_t *salt, size_t saltlen,
+    uint8_t *key, size_t keylen, unsigned int rounds)
+{
+	SHA2_CTX ctx;
+	uint8_t sha2pass[SHA512_DIGEST_LENGTH];
+	uint8_t sha2salt[SHA512_DIGEST_LENGTH];
+	uint8_t out[BCRYPT_HASHSIZE];
+	uint8_t tmpout[BCRYPT_HASHSIZE];
+	uint8_t countsalt[4];
+	size_t i, j, amt, stride;
+	uint32_t count;
+	size_t origkeylen = keylen;
+
+	/* nothing crazy */
+	if (rounds < 1)
+		return -1;
+	if (passlen == 0 || saltlen == 0 || keylen == 0 ||
+	    keylen > sizeof(out) * sizeof(out))
+		return -1;
+	stride = (keylen + sizeof(out) - 1) / sizeof(out);
+	amt = (keylen + stride - 1) / stride;
+
+	/* collapse password */
+	SHA512Init(&ctx);
+	SHA512Update(&ctx, pass, passlen);
+	SHA512Final(sha2pass, &ctx);
+
+
+	/* generate key, sizeof(out) at a time */
+	for (count = 1; keylen > 0; count++) {
+		countsalt[0] = (count >> 24) & 0xff;
+		countsalt[1] = (count >> 16) & 0xff;
+		countsalt[2] = (count >> 8) & 0xff;
+		countsalt[3] = count & 0xff;
+
+		/* first round, salt is salt */
+		SHA512Init(&ctx);
+		SHA512Update(&ctx, salt, saltlen);
+		SHA512Update(&ctx, countsalt, sizeof(countsalt));
+		SHA512Final(sha2salt, &ctx);
+		bcrypt_hash(sha2pass, sha2salt, tmpout);
+		memcpy(out, tmpout, sizeof(out));
+
+		for (i = 1; i < rounds; i++) {
+			/* subsequent rounds, salt is previous output */
+			SHA512Init(&ctx);
+			SHA512Update(&ctx, tmpout, sizeof(tmpout));
+			SHA512Final(sha2salt, &ctx);
+			bcrypt_hash(sha2pass, sha2salt, tmpout);
+			for (j = 0; j < sizeof(out); j++)
+				out[j] ^= tmpout[j];
+		}
+
+		/*
+		 * pbkdf2 deviation: output the key material non-linearly.
+		 */
+		amt = MINIMUM(amt, keylen);
+		for (i = 0; i < amt; i++) {
+			size_t dest = i * stride + (count - 1);
+			if (dest >= origkeylen)
+				break;
+			key[dest] = out[i];
+		}
+		keylen -= i;
+	}
+
+	/* zap */
+	explicit_bzero(&ctx, sizeof(ctx));
+	explicit_bzero(out, sizeof(out));
+
+	return 0;
+}
diff --git a/sys/lib/libsa/bcrypt_pbkdf.h b/sys/lib/libsa/bcrypt_pbkdf.h
new file mode 100644
index 00000000000..7fb8396a746
--- /dev/null
+++ b/sys/lib/libsa/bcrypt_pbkdf.h
@@ -0,0 +1,22 @@
+/* $OpenBSD: bcrypt_pbkdf.h,v 1.1 2016/09/10 18:26:28 jsing Exp $ */
+/*
+ * Copyright (c) 2013 Ted Unangst <tedu@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * pkcs #5 pbkdf2 implementation using the "bcrypt" hash
+ */
+int bcrypt_pbkdf(const char *, size_t, const uint8_t *, size_t,
+    uint8_t *, size_t, unsigned int);