ccm.rb in sjcl-1.0.1

- old
+ new

@@ -1,15 +1,18 @@
 module SJCL::Mode
   module CCM
+    class TagAuthError < ::StandardError; end
+    class Error < ::StandardError; end
+
     NAME = "ccm"
 
     def self.encrypt(prf, plaintext, iv, adata=[], tlen=64)
       ccml = 2
       out = plaintext.dup
       ivl = SJCL::BitArray.bitLength(iv) / 8
       ol = SJCL::BitArray.bitLength(out) / 8
-      raise "ccm: IV must be at least 7 bytes" if ivl < 7
+      raise Error, "ccm: IV must be at least 7 bytes" if ivl < 7
       while ccml < 4 && ((ol & 0xFFFFFFFF) >> 8*ccml > 0)
         ccml += 1
       end
       ccml = 15 - ivl if ccml < 15 - ivl
       iv = SJCL::BitArray.clamp(iv,8*(15-ccml));
@@ -26,11 +29,11 @@
       ol = SJCL::BitArray.bitLength(ciphertext)
       out = SJCL::BitArray.clamp(ciphertext, ol - tlen)
       tag = SJCL::BitArray.bitSlice(ciphertext, ol - tlen)
 
       ol = (ol - tlen) / 8;
-      raise "ccm: iv must be at least 7 bytes" if (ivl < 7)
+      raise Error, "ccm: iv must be at least 7 bytes" if (ivl < 7)
 
       # compute the length of the length
       while ccml < 4 && ((ol & 0xFFFFFFFF) >> 8*ccml > 0)
         ccml += 1
       end
@@ -44,18 +47,18 @@
       out = ctrMode(prf, out, iv, tag, tlen, ccml)
 
       # check the tag
       tag2 = computeTag(prf, out[:data], iv, adata, tlen, ccml)
       if (!SJCL::BitArray.compare(out[:tag], tag2))
-        raise "ccm: tag doesn't match"
+        raise TagAuthError, "ccm: tag doesn't match"
       end
       return out[:data]
     end
 
     def self.computeTag(prf, plaintext, iv, adata, tlen, l)
       tlen /= 8
       if (tlen % 2 != 0 || tlen < 4 || tlen > 16)
-        raise "ccm: invalid tag length"
+        raise Error, "ccm: invalid tag length"
       end
 
       # mac the flags
       mac = [SJCL::BitArray.partial(8, (adata.length > 0 ? 1<<6 : 0) | ((tlen-2) << 2) | l-1)]
 