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+#ifndef CRYPTOPP_RW_H
+#define CRYPTOPP_RW_H
+
+/** \file
+	This file contains classes that implement the
+	Rabin-Williams signature schemes as defined in IEEE P1363.
+*/
+
+#include "pubkey.h"
+#include "integer.h"
+
+NAMESPACE_BEGIN(CryptoPP)
+
+const word IFSSR_R = 6;
+const word IFSSA_R = 12;
+
+//! .
+template <word r>
+class RWFunction : virtual public TrapdoorFunction, public PublicKey
+{
+	typedef RWFunction ThisClass;
+
+public:
+	void Initialize(const Integer &n)
+		{m_n = n;}
+
+	void BERDecode(BufferedTransformation &bt);
+	void DEREncode(BufferedTransformation &bt) const;
+
+	Integer ApplyFunction(const Integer &x) const;
+	Integer PreimageBound() const {return m_n;}
+	Integer ImageBound() const {return ++(m_n>>1);}
+
+	bool Validate(RandomNumberGenerator &rng, unsigned int level) const;
+	bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const;
+	void AssignFrom(const NameValuePairs &source);
+
+	const Integer& GetModulus() const {return m_n;}
+	void SetModulus(const Integer &n) {m_n = n;}
+
+protected:
+	Integer m_n;
+};
+
+//! .
+template <word r>
+class InvertibleRWFunction : public RWFunction<r>, public TrapdoorFunctionInverse, public PrivateKey
+{
+	typedef InvertibleRWFunction ThisClass;
+
+public:
+	void Initialize(const Integer &n, const Integer &p, const Integer &q, const Integer &u)
+		{m_n = n; m_p = p; m_q = q; m_u = u;}
+	// generate a random private key
+	void Initialize(RandomNumberGenerator &rng, unsigned int modulusBits)
+		{GenerateRandomWithKeySize(rng, modulusBits);}
+
+	void BERDecode(BufferedTransformation &bt);
+	void DEREncode(BufferedTransformation &bt) const;
+
+	Integer CalculateInverse(const Integer &x) const;
+
+	// GeneratibleCryptoMaterial
+	bool Validate(RandomNumberGenerator &rng, unsigned int level) const;
+	bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const;
+	void AssignFrom(const NameValuePairs &source);
+	/*! parameters: (ModulusSize) */
+	void GenerateRandom(RandomNumberGenerator &rng, const NameValuePairs &alg);
+
+	const Integer& GetPrime1() const {return m_p;}
+	const Integer& GetPrime2() const {return m_q;}
+	const Integer& GetMultiplicativeInverseOfPrime2ModPrime1() const {return m_u;}
+
+	void SetPrime1(const Integer &p) {m_p = p;}
+	void SetPrime2(const Integer &q) {m_q = q;}
+	void SetMultiplicativeInverseOfPrime2ModPrime1(const Integer &u) {m_u = u;}
+
+protected:
+	Integer m_p, m_q, m_u;
+};
+
+//! .
+class EMSA2Pad : public PK_PaddingAlgorithm
+{
+public:
+	static const char *StaticAlgorithmName() {return "EMSA2";}
+	
+	unsigned int MaxUnpaddedLength(unsigned int paddedLength) const {return (paddedLength+1)/8-2;}
+
+	void Pad(RandomNumberGenerator &rng, const byte *raw, unsigned int inputLength, byte *padded, unsigned int paddedLength) const;
+	DecodingResult Unpad(const byte *padded, unsigned int paddedLength, byte *raw) const;
+};
+
+//! .
+template <class H>
+class EMSA2DecoratedHashModule : public HashTransformationWithDefaultTruncation
+{
+public:
+	EMSA2DecoratedHashModule() : empty(true) {}
+	void Update(const byte *input, unsigned int length)
+		{h.Update(input, length); empty = empty && length==0;}
+	unsigned int DigestSize() const;
+	void Final(byte *digest);
+	void Restart() {h.Restart(); empty=true;}
+
+private:
+	H h;
+	bool empty;
+};
+
+template <class H> struct EMSA2DigestDecoration
+{
+	static const byte decoration;
+};
+
+//! EMSA2, for use with RW
+/*! The following hash functions are supported: SHA, RIPEMD160. */
+struct P1363_EMSA2 : public SignatureStandard
+{
+	template <class H> struct SignaturePaddingAlgorithm {typedef EMSA2Pad type;};
+	template <class H> struct DecoratedHashingAlgorithm {typedef EMSA2DecoratedHashModule<H> type;};
+};
+
+template<> struct CryptoStandardTraits<P1363_EMSA2> : public P1363_EMSA2 {};
+
+// EMSA2DecoratedHashModule can be instantiated with the following two classes.
+class SHA;
+class RIPEMD160;
+
+template <class H>
+void EMSA2DecoratedHashModule<H>::Final(byte *digest)
+{
+	digest[0] = empty ? 0x4b : 0x6b;
+	h.Final(digest+1);
+	digest[DigestSize()-1] = EMSA2DigestDecoration<H>::decoration;
+	empty=true;
+}
+
+template <class H>
+unsigned int EMSA2DecoratedHashModule<H>::DigestSize() const
+{
+	return h.DigestSize() + 2;
+}
+
+//! .
+template <word r>
+struct RW
+{
+	static std::string StaticAlgorithmName() {return "RW";}
+	typedef RWFunction<r> PublicKey;
+	typedef InvertibleRWFunction<r> PrivateKey;
+};
+
+//! RW
+template <class H, class STANDARD = P1363_EMSA2>
+struct RWSSA : public TF_SSA<STANDARD, H, RW<IFSSA_R> >
+{
+};
+
+NAMESPACE_END
+
+#endif