r16287@catbus: nickm | 2007-10-31 00:53:53 -0400

 HMAC-SHA-1 implementation, with unit tests based on vectors from RVFC2202.  Steven's stuff will need this.


svn:r12289

2 files changed, 52 insertions, 1 deletions

diff --git a/src/common/crypto.c b/src/common/crypto.c
index 6c1dae9a73..8762840a54 100644
--- a/src/common/crypto.c
+++ b/src/common/crypto.c
@@ -1261,7 +1261,7 @@ void
 crypto_digest_get_digest(crypto_digest_env_t *digest,
                          char *out, size_t out_len)
 {
-  static unsigned char r[DIGEST_LEN];
+  static unsigned char r[DIGEST_LEN]; /*XXXXX020 why static? */
   SHA_CTX tmpctx;
   tor_assert(digest);
   tor_assert(out);
@@ -1297,6 +1297,54 @@ crypto_digest_assign(crypto_digest_env_t *into,
   memcpy(into,from,sizeof(crypto_digest_env_t));
 }
 
+/**DOCDOC */
+#define DIGEST_BLOCKSIZE 64
+
+/** Compute the HMAC-SHA-1 of the <b>msg_len</b> bytes in <b>msg</b>, using
+ * the <b>key</b> of length <b>key_len</b>.  Store the DIGEST_LEN-byte result
+ * in <b>hmac_out</b>.
+ */
+void
+crypto_hmac_sha1(char *hmac_out,
+                 const char *key, size_t key_len,
+                 const char *msg, size_t msg_len)
+{
+  SHA_CTX sha;
+  uint8_t K[DIGEST_BLOCKSIZE], D[DIGEST_LEN], K_SHORT[DIGEST_LEN];
+  const uint8_t *real_key;
+  unsigned int i;
+
+  if (key_len > DIGEST_BLOCKSIZE) {
+    SHA1((const unsigned char*)key, key_len, K_SHORT);
+    key_len = DIGEST_LEN;
+    real_key = K_SHORT;
+  } else {
+    real_key = (const uint8_t*)key;
+  }
+
+  memset(K, 0, sizeof(K));
+  memcpy(K, real_key, key_len);
+  for (i=0; i < sizeof(K); ++i)
+    K[i] ^= 0x36;
+  SHA1_Init(&sha);
+  SHA1_Update(&sha, K, sizeof(K));
+  SHA1_Update(&sha, msg, msg_len);
+  SHA1_Final(D, &sha);
+
+  /*
+  memset(K, 0, sizeof(K));
+  memcpy(K, real_key, key_len);
+  for (i=0; i < sizeof(K); ++i)
+    K[i] ^= 0x5c;
+  */
+  for (i=0; i < sizeof(K); ++i)
+    K[i] ^= (0x36 ^ 0x5c);
+  SHA1_Init(&sha);
+  SHA1_Update(&sha, K, sizeof(K));
+  SHA1_Update(&sha, D, sizeof(D));
+  SHA1_Final((unsigned char*)hmac_out, &sha);
+}
+
 /* DH */
 
 /** Shared P parameter for our DH key exchanged. */
diff --git a/src/common/crypto.h b/src/common/crypto.h
index 09cbbe704a..610ea460d7 100644
--- a/src/common/crypto.h
+++ b/src/common/crypto.h
@@ -146,6 +146,9 @@ void crypto_digest_get_digest(crypto_digest_env_t *digest,
 crypto_digest_env_t *crypto_digest_dup(const crypto_digest_env_t *digest);
 void crypto_digest_assign(crypto_digest_env_t *into,
                           const crypto_digest_env_t *from);
+void crypto_hmac_sha1(char *hmac_out,
+                      const char *key, size_t key_len,
+                      const char *msg, size_t msg_len);
 
 /* Key negotiation */
 crypto_dh_env_t *crypto_dh_new(void);