patched CryptoPP Crypto++ to add support for AES-256-CBC with W3C padding scheme (based on readium/readium-lcp-client#26 )

Author: danielweck

filters.cpp

@@ -701,6 +701,7 @@ void StreamTransformationFilter::LastPut(const byte *inString, size_t length)
 
 	case PKCS_PADDING:
 	case ONE_AND_ZEROS_PADDING:
+	case W3C_PADDING:
 		unsigned int s;
 		s = m_cipher.MandatoryBlockSize();
 		CRYPTOPP_ASSERT(s > 1);
@@ -735,6 +736,13 @@ void StreamTransformationFilter::LastPut(const byte *inString, size_t length)
 					throw InvalidCiphertext("StreamTransformationFilter: invalid PKCS #7 block padding found");
 				length = s-pad;
 			}
+			else if (m_padding == W3C_PADDING)
+			{
+				byte pad = space[s - 1];
+				if (pad < 1 || pad > s)
+					throw InvalidCiphertext("StreamTransformationFilter: invalid W3C block padding found");
+				length = s - pad;
+			}
 			else
 			{
 				while (length > 1 && space[length-1] == 0)

filters.h

@@ -480,6 +480,8 @@ struct BlockPaddingSchemeDef
 		PKCS_PADDING,
 		//! \brief 1 and 0's padding added to a block
 		ONE_AND_ZEROS_PADDING,
+		//! \brief [Random bytes (0 ~ N-2) and padding's length (N-1)]'s padding to a block
+		W3C_PADDING,
 		//! \brief Default padding scheme
 		DEFAULT_PADDING
 	};