Fixed CTR rekey. Rewrote IV Included CTR mode encryption/decryption

[silc.git] / lib / silcske / silcske.c

diff --git a/lib/silcske/silcske.c b/lib/silcske/silcske.c
index 4db209868986ccd79ca41180a0d734e9423479e4..4a407490c4f91305c27b60a01351f04381a2ae0d 100644 (file)
--- a/lib/silcske/silcske.c
+++ b/lib/silcske/silcske.c
@@ -3312,6 +3312,12 @@ SilcBool silc_ske_set_keys(SilcSKE ske,
       return FALSE;
   }
 
+  /* Allocate hash */
+  if (ret_hash) {
+    if (!silc_hash_alloc(silc_hash_get_name(prop->hash), ret_hash))
+      return FALSE;
+  }
+
   /* Set key material */
   memset(iv, 0, sizeof(iv));
   if (ske->responder) {
@@ -3320,10 +3326,22 @@ SilcBool silc_ske_set_keys(SilcSKE ske,
                          keymat->enc_key_len, TRUE);
 
       if (silc_cipher_get_mode(*ret_send_key) == SILC_CIPHER_MODE_CTR) {
-        memcpy(iv, ske->hash, 4);
-        memcpy(iv + 4, keymat->receive_iv, iv_included ? 4 : 8);
+       /* Counter mode */
+       if (!ske->rekeying) {
+         /* Set IV. */
+         memcpy(iv, ske->hash, 4);
+         if (!iv_included)
+           memcpy(iv + 4, keymat->receive_iv, 8);
+       } else {
+         /* Rekey, recompute the truncated hash value. */
+         silc_hash_make(prop->hash, keymat->receive_iv, 8, iv);
+         if (!iv_included)
+           memcpy(iv + 4, keymat->receive_iv, 8);
+       }
+
         silc_cipher_set_iv(*ret_send_key, iv);
       } else {
+       /* Other modes */
        silc_cipher_set_iv(*ret_send_key, keymat->receive_iv);
       }
     }
@@ -3332,10 +3350,22 @@ SilcBool silc_ske_set_keys(SilcSKE ske,
                          keymat->enc_key_len, FALSE);
 
       if (silc_cipher_get_mode(*ret_receive_key) == SILC_CIPHER_MODE_CTR) {
-        memcpy(iv, ske->hash, 4);
-        memcpy(iv + 4, keymat->send_iv, iv_included ? 4 : 8);
+       /* Counter mode */
+       if (!ske->rekeying) {
+         /* Set IV. */
+         memcpy(iv, ske->hash, 4);
+         if (!iv_included)
+           memcpy(iv + 4, keymat->send_iv, 8);
+       } else {
+         /* Rekey, recompute the truncated hash value. */
+         silc_hash_make(prop->hash, keymat->send_iv, 8, iv);
+         if (!iv_included)
+           memcpy(iv + 4, keymat->send_iv, 8);
+       }
+
         silc_cipher_set_iv(*ret_receive_key, iv);
       } else {
+       /* Other modes */
        silc_cipher_set_iv(*ret_receive_key, keymat->send_iv);
       }
     }
@@ -3351,10 +3381,22 @@ SilcBool silc_ske_set_keys(SilcSKE ske,
                          keymat->enc_key_len, TRUE);
 
       if (silc_cipher_get_mode(*ret_send_key) == SILC_CIPHER_MODE_CTR) {
-        memcpy(iv, ske->hash, 4);
-        memcpy(iv + 4, keymat->send_iv, iv_included ? 4 : 8);
+       /* Counter mode */
+       if (!ske->rekeying) {
+         /* Set IV. */
+         memcpy(iv, ske->hash, 4);
+         if (!iv_included)
+           memcpy(iv + 4, keymat->send_iv, 8);
+       } else {
+         /* Rekey, recompute the truncated hash value. */
+         silc_hash_make(prop->hash, keymat->send_iv, 8, iv);
+         if (!iv_included)
+           memcpy(iv + 4, keymat->send_iv, 8);
+       }
+
        silc_cipher_set_iv(*ret_send_key, iv);
       } else {
+       /* Other modes */
        silc_cipher_set_iv(*ret_send_key, keymat->send_iv);
       }
     }
@@ -3363,10 +3405,23 @@ SilcBool silc_ske_set_keys(SilcSKE ske,
                          keymat->enc_key_len, FALSE);
 
       if (silc_cipher_get_mode(*ret_receive_key) == SILC_CIPHER_MODE_CTR) {
-        memcpy(iv, ske->hash, 4);
-        memcpy(iv + 4, keymat->receive_iv, iv_included ? 4 : 8);
+       /* Counter mode */
+       if (!ske->rekeying) {
+         /* Set IV.  If IV Included flag was negotiated we only set the
+            truncated hash value. */
+         memcpy(iv, ske->hash, 4);
+         if (!iv_included)
+           memcpy(iv + 4, keymat->receive_iv, 8);
+       } else {
+         /* Rekey, recompute the truncated hash value. */
+         silc_hash_make(prop->hash, keymat->receive_iv, 8, iv);
+         if (!iv_included)
+           memcpy(iv + 4, keymat->receive_iv, 8);
+       }
+
        silc_cipher_set_iv(*ret_receive_key, iv);
       } else {
+       /* Other modes */
        silc_cipher_set_iv(*ret_receive_key, keymat->receive_iv);
       }
     }
@@ -3378,12 +3433,6 @@ SilcBool silc_ske_set_keys(SilcSKE ske,
                        keymat->hmac_key_len);
   }
 
-  /* Allocate hash */
-  if (ret_hash) {
-    if (!silc_hash_alloc(silc_hash_get_name(prop->hash), ret_hash))
-      return FALSE;
-  }
-
   return TRUE;
 }