2 files changed, 120 insertions, 0 deletions
diff --git a/emsa2.cpp b/emsa2.cpp
new file mode 100755
index 0000000..ef8672e
--- /dev/null
+++ b/emsa2.cpp
@@ -0,0 +1,34 @@
+// emsa2.cpp - written and placed in the public domain by Wei Dai
+
+#include "pch.h"
+#include "emsa2.h"
+
+#ifndef CRYPTOPP_IMPORTS
+
+NAMESPACE_BEGIN(CryptoPP)
+
+void EMSA2Pad::ComputeMessageRepresentative(RandomNumberGenerator &rng, 
+	const byte *recoverableMessage, unsigned int recoverableMessageLength,
+	HashTransformation &hash, HashIdentifier hashIdentifier, bool messageEmpty,
+	byte *representative, unsigned int representativeBitLength) const
+{
+	assert(representativeBitLength >= MinRepresentativeBitLength(hashIdentifier.second, hash.DigestSize()));
+
+	if (representativeBitLength % 8 != 7)
+		throw PK_SignatureScheme::InvalidKeyLength("EMSA2: EMSA2 requires a key length that is a multiple of 8");
+
+	unsigned int digestSize = hash.DigestSize();
+	unsigned int representativeByteLength = BitsToBytes(representativeBitLength);
+
+	representative[0] = messageEmpty ? 0x4b : 0x6b;
+	memset(representative+1, 0xbb, representativeByteLength-digestSize-4);	// pad with 0xbb
+	byte *afterP2 = representative+representativeByteLength-digestSize-3;
+	afterP2[0] = 0xba;
+	hash.Final(afterP2+1);
+	representative[representativeByteLength-2] = *hashIdentifier.first;
+	representative[representativeByteLength-1] = 0xcc;
+}
+
+NAMESPACE_END
+
+#endif
diff --git a/emsa2.h b/emsa2.h
new file mode 100755
index 0000000..774e756
--- /dev/null
+++ b/emsa2.h
@@ -0,0 +1,86 @@
+#ifndef CRYPTOPP_EMSA2_H
+#define CRYPTOPP_EMSA2_H
+
+/** \file
+	This file contains various padding schemes for public key algorithms.
+*/
+
+#include "cryptlib.h"
+#include "pubkey.h"
+
+#ifdef CRYPTOPP_IS_DLL
+#include "sha.h"
+#endif
+
+NAMESPACE_BEGIN(CryptoPP)
+
+template <class H> class EMSA2HashId
+{
+public:
+	static const byte id;
+};
+
+template <class BASE>
+class EMSA2HashIdLookup : public BASE
+{
+public:
+	struct HashIdentifierLookup
+	{
+		template <class H> struct HashIdentifierLookup2
+		{
+			static HashIdentifier Lookup()
+			{
+				return HashIdentifier(&EMSA2HashId<H>::id, 1);
+			}
+		};
+	};
+};
+
+// EMSA2HashId can be instantiated with the following classes.
+class SHA1;
+class RIPEMD160;
+class RIPEMD128;
+class SHA256;
+class SHA384;
+class SHA512;
+class Whirlpool;
+class SHA224;
+// end of list
+
+#ifdef CRYPTOPP_IS_DLL
+CRYPTOPP_DLL_TEMPLATE_CLASS EMSA2HashId<SHA1>;
+CRYPTOPP_DLL_TEMPLATE_CLASS EMSA2HashId<SHA224>;
+CRYPTOPP_DLL_TEMPLATE_CLASS EMSA2HashId<SHA256>;
+CRYPTOPP_DLL_TEMPLATE_CLASS EMSA2HashId<SHA384>;
+CRYPTOPP_DLL_TEMPLATE_CLASS EMSA2HashId<SHA512>;
+#endif
+
+//! _
+class CRYPTOPP_DLL EMSA2Pad : public EMSA2HashIdLookup<PK_DeterministicSignatureMessageEncodingMethod>
+{
+public:
+	static const char * CRYPTOPP_API StaticAlgorithmName() {return "EMSA2";}
+	
+	unsigned int MinRepresentativeBitLength(unsigned int hashIdentifierLength, unsigned int digestLength) const
+		{return 8*digestLength + 31;}
+
+	void ComputeMessageRepresentative(RandomNumberGenerator &rng, 
+		const byte *recoverableMessage, unsigned int recoverableMessageLength,
+		HashTransformation &hash, HashIdentifier hashIdentifier, bool messageEmpty,
+		byte *representative, unsigned int representativeBitLength) const;
+};
+
+//! EMSA2, for use with RWSS and RSA_ISO
+/*! Only the following hash functions are supported by this signature standard:
+	\dontinclude emsa2.h
+	\skip EMSA2HashId can be instantiated
+	\until end of list
+*/
+struct P1363_EMSA2 : public SignatureStandard
+{
+	typedef EMSA2Pad SignatureMessageEncodingMethod;
+};
+
+NAMESPACE_END
+
+#endif