UTIL: Add HMAC-SHA-1 function

1 files changed, 88 insertions, 0 deletions

diff --git a/src/util/crypto/nss/nss_hmac_sha1.c b/src/util/crypto/nss/nss_hmac_sha1.c
new file mode 100644
index 00000000..6faa09ae
--- /dev/null
+++ b/src/util/crypto/nss/nss_hmac_sha1.c
@@ -0,0 +1,88 @@
+/*
+    Authors:
+        Jan Cholasta <jcholast@redhat.com>
+
+    Copyright (C) 2012 Red Hat
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+/*
+    NSS does not provide public API for HMAC, so we implement it ourselves.
+
+    See RFC 2104 for details on the algorithm.
+*/
+
+#include "util/util.h"
+#include "util/crypto/sss_crypto.h"
+#include "util/crypto/nss/nss_util.h"
+
+#include <sechash.h>
+
+#define HMAC_SHA1_BLOCKSIZE 64
+
+int sss_hmac_sha1(const unsigned char *key,
+                  size_t key_len,
+                  const unsigned char *in,
+                  size_t in_len,
+                  unsigned char *out)
+{
+    int ret;
+    unsigned char ikey[HMAC_SHA1_BLOCKSIZE], okey[HMAC_SHA1_BLOCKSIZE];
+    size_t i;
+    HASHContext *sha1;
+    unsigned char hash[SSS_SHA1_LENGTH];
+    unsigned int res_len;
+
+    ret = nspr_nss_init();
+    if (ret != EOK) {
+        return ret;
+    }
+
+    sha1 = HASH_Create(HASH_AlgSHA1);
+    if (!sha1) {
+        return ENOMEM;
+    }
+
+    if (key_len > HMAC_SHA1_BLOCKSIZE) {
+        /* keys longer than blocksize are shortened */
+        HASH_Begin(sha1);
+        HASH_Update(sha1, key, key_len);
+        HASH_End(sha1, ikey, &res_len, SSS_SHA1_LENGTH);
+        memset(ikey + SSS_SHA1_LENGTH, 0, HMAC_SHA1_BLOCKSIZE - SSS_SHA1_LENGTH);
+    } else {
+        /* keys shorter than blocksize are zero-padded */
+        memcpy(ikey, key, key_len);
+        memset(ikey + key_len, 0, HMAC_SHA1_BLOCKSIZE - key_len);
+    }
+
+    /* HMAC(key, msg) = HASH(key XOR opad, HASH(key XOR ipad, msg)) */
+    for (i = 0; i < HMAC_SHA1_BLOCKSIZE; i++) {
+        okey[i] = ikey[i] ^ 0x5c;
+        ikey[i] ^= 0x36;
+    }
+
+    HASH_Begin(sha1);
+    HASH_Update(sha1, ikey, HMAC_SHA1_BLOCKSIZE);
+    HASH_Update(sha1, in, in_len);
+    HASH_End(sha1, hash, &res_len, SSS_SHA1_LENGTH);
+
+    HASH_Begin(sha1);
+    HASH_Update(sha1, okey, HMAC_SHA1_BLOCKSIZE);
+    HASH_Update(sha1, hash, SSS_SHA1_LENGTH);
+    HASH_End(sha1, out, &res_len, SSS_SHA1_LENGTH);
+
+    HASH_Destroy(sha1);
+
+    return EOK;
+}