reduce risk of reusing random numbers after VM state rollback

modes.cpp

@@ -24,15 +24,6 @@ void Modes_TestInstantiations()
 }
 #endif
 
-void CipherModeBase::GetNextIV(byte *IV)
-{
-	if (!IsForwardTransformation())
-		throw NotImplemented("CipherModeBase: GetNextIV() must be called on an encryption object");
-
-	m_cipher->ProcessBlock(m_register);
-	memcpy(IV, m_register, BlockSize());
-}
-
 void CTR_ModePolicy::SeekToIteration(lword iterationCount)
 {
 	int carry=0;
@@ -45,11 +36,6 @@ void CTR_ModePolicy::SeekToIteration(lword iterationCount)
 	}
 }
 
-void CTR_ModePolicy::CipherGetNextIV(byte *IV)
-{
-	IncrementCounterByOne(IV, m_counterArray, BlockSize());
-}
-
 inline void CTR_ModePolicy::ProcessMultipleBlocks(byte *output, const byte *input, size_t n)
 {
 	unsigned int s = BlockSize(), j = 0;

modes.h

@@ -40,7 +40,6 @@ public:
 	unsigned int OptimalDataAlignment() const {return BlockSize();}
 
 	unsigned int IVSize() const {return BlockSize();}
-	void GetNextIV(byte *IV);
 	virtual IV_Requirement IVRequirement() const =0;
 
 protected:
@@ -64,7 +63,6 @@ class CRYPTOPP_NO_VTABLE ModePolicyCommonTemplate : public CipherModeBase, publi
 {
 	unsigned int GetAlignment() const {return m_cipher->BlockAlignment();}
 	void CipherSetKey(const NameValuePairs &params, const byte *key, size_t length);
-	void CipherGetNextIV(byte *IV) {CipherModeBase::GetNextIV(IV);}
 };
 
 template <class POLICY_INTERFACE>
@@ -137,7 +135,6 @@ private:
 		assert(iterationCount == 1);
 		assert(m_cipher->IsForwardTransformation());	// OFB mode needs the "encrypt" direction of the underlying block cipher, even to decrypt
 		m_cipher->ProcessBlock(keystreamBuffer);
-		memcpy_s(m_register, m_register.size(), keystreamBuffer, BlockSize());
 	}
 	void CipherResynchronize(byte *keystreamBuffer, const byte *iv)
 	{
@@ -150,10 +147,10 @@ class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE CTR_ModePolicy : public ModePolicyCommonTe
 public:
 	bool IsRandomAccess() const {return true;}
 	IV_Requirement IVRequirement() const {return UNIQUE_IV;}
-	void CipherGetNextIV(byte *IV);
 	static const char * CRYPTOPP_API StaticAlgorithmName() {return "CTR";}
 
 private:
+	unsigned int GetAlignment() const {return m_cipher->BlockAlignment();}
 	unsigned int GetBytesPerIteration() const {return BlockSize();}
 	unsigned int GetIterationsToBuffer() const {return m_cipher->OptimalNumberOfParallelBlocks();}
 	void WriteKeystream(byte *buffer, size_t iterationCount)

pubkey.h

@@ -1033,13 +1033,23 @@ public:
 		ma.m_empty = true;
 		Integer e(representative, representative.size());
 
-		Integer r;
+		// hash message digest into random number k to prevent reusing the same k on a different messages
+		// after virtual machine rollback
+		if (rng.CanIncorporateEntropy())
+			rng.IncorporateEntropy(representative, representative.size());
+		Integer k(rng, 1, params.GetSubgroupOrder()-1);
+		Integer r, s;
+		r = params.ConvertElementToInteger(params.ExponentiateBase(k));
+		alg.Sign(params, key.GetPrivateExponent(), k, e, r, s);
+
+		/*
+		Integer r, s;
 		if (this->MaxRecoverableLength() > 0)
 			r.Decode(ma.m_semisignature, ma.m_semisignature.size());
 		else
 			r.Decode(ma.m_presignature, ma.m_presignature.size());
-		Integer s;
 		alg.Sign(params, key.GetPrivateExponent(), ma.m_k, e, r, s);
+		*/
 
 		size_t rLen = alg.RLen(params);
 		r.Encode(signature, rLen);
@@ -1054,11 +1064,17 @@ public:
 protected:
 	void RestartMessageAccumulator(RandomNumberGenerator &rng, PK_MessageAccumulatorBase &ma) const
 	{
+		// k needs to be generated before hashing for signature schemes with recovery
+		// but to defend against VM rollbacks we need to generate k after hashing.
+		// so this code is commented out, since no DL-based signature scheme with recovery
+		// has been implemented in Crypto++ anyway
+		/*
 		const DL_ElgamalLikeSignatureAlgorithm<T> &alg = this->GetSignatureAlgorithm();
 		const DL_GroupParameters<T> &params = this->GetAbstractGroupParameters();
 		ma.m_k.Randomize(rng, 1, params.GetSubgroupOrder()-1);
 		ma.m_presignature.New(params.GetEncodedElementSize(false));
 		params.ConvertElementToInteger(params.ExponentiateBase(ma.m_k)).Encode(ma.m_presignature, ma.m_presignature.size());
+		*/
 	}
 };
 

randpool.cpp

@@ -1,99 +1,59 @@
 // randpool.cpp - written and placed in the public domain by Wei Dai
-// The algorithm in this module comes from PGP's randpool.c
+// RandomPool used to follow the design of randpool in PGP 2.6.x,
+// but as of version 5.5 it has been redesigned to reduce the risk
+// of reusing random numbers after state rollback (which may occur
+// when running in a virtual machine like VMware).
 
 #include "pch.h"
 
 #ifndef CRYPTOPP_IMPORTS
 
 #include "randpool.h"
-#include "mdc.h"
+#include "aes.h"
 #include "sha.h"
-#include "modes.h"
+#include "hrtimer.h"
+#include <time.h>
 
 NAMESPACE_BEGIN(CryptoPP)
 
-typedef MDC<SHA> RandomPoolCipher;
-
-RandomPool::RandomPool(unsigned int poolSize)
-	: pool(poolSize), key(RandomPoolCipher::DEFAULT_KEYLENGTH)
+RandomPool::RandomPool()
+	: m_pCipher(new AES::Encryption), m_keySet(false)
 {
-	assert(poolSize > key.size());
-
-	addPos=0;
-	getPos=poolSize;
-	memset(pool, 0, poolSize);
-	memset(key, 0, key.size());
 }
 
-void RandomPool::Stir()
+void RandomPool::IncorporateEntropy(const byte *input, size_t length)
 {
-	CFB_Mode<RandomPoolCipher>::Encryption cipher;
+	SHA256 hash;
+	hash.Update(m_key, 32);
+	hash.Update(input, length);
+	hash.Final(m_key);
+	m_keySet = false;
+}
 
-	for (int i=0; i<2; i++)
+void RandomPool::GenerateIntoBufferedTransformation(BufferedTransformation &target, const std::string &channel, lword size)
+{
+	if (size > 0)
 	{
-		cipher.SetKeyWithIV(key, key.size(), pool.end()-cipher.IVSize());
-		cipher.ProcessString(pool, pool.size());
-		memcpy(key, pool, key.size());
+		if (!m_keySet)
+			m_pCipher->SetKey(m_key, 32);
+
+		Timer timer;
+		TimerWord tw = timer.GetCurrentTimerValue();
+		CRYPTOPP_COMPILE_ASSERT(sizeof(tw) <= 16);
+		*(TimerWord *)m_seed.data() += tw;
+
+		time_t t = time(NULL);
+		CRYPTOPP_COMPILE_ASSERT(sizeof(t) <= 8);
+		*(time_t *)(m_seed.data()+8) += t;
+
+		do
+		{
+			m_pCipher->ProcessBlock(m_seed);
+			size_t len = UnsignedMin(16, size);
+			target.ChannelPut(channel, m_seed, len);
+			size -= len;
+		} while (size > 0);
 	}
-
-	addPos = 0;
-	getPos = key.size();
-}
-
-size_t RandomPool::Put2(const byte *inString, size_t length, int messageEnd, bool blocking)
-{
-	size_t t;
-
-	while (length > (t = pool.size() - addPos))
-	{
-		xorbuf(pool+addPos, inString, t);
-		inString += t;
-		length -= t;
-		Stir();
-	}
-
-	if (length)
-	{
-		xorbuf(pool+addPos, inString, length);
-		addPos += length;
-		getPos = pool.size(); // Force stir on get
-	}
-
-	return 0;
-}
-
-size_t RandomPool::TransferTo2(BufferedTransformation &target, lword &transferBytes, const std::string &channel, bool blocking)
-{
-	if (!blocking)
-		throw NotImplemented("RandomPool: nonblocking transfer is not implemented by this object");
-
-	lword size = transferBytes;
-
-	while (size > 0)
-	{
-		if (getPos == pool.size())
-			Stir();
-		size_t t = UnsignedMin(pool.size() - getPos, size);
-		target.ChannelPut(channel, pool+getPos, t);
-		size -= t;
-		getPos += t;
-	}
-
-	return 0;
-}
-
-byte RandomPool::GenerateByte()
-{
-	if (getPos == pool.size())
-		Stir();
-
-	return pool[getPos++];
-}
-
-void RandomPool::GenerateBlock(byte *outString, size_t size)
-{
-	ArraySink sink(outString, size);
-	TransferTo(sink, size);
 }
 
 NAMESPACE_END

randpool.h

@@ -7,38 +7,25 @@
 NAMESPACE_BEGIN(CryptoPP)
 
 //! Randomness Pool
-/*! This class can be used to generate
-	pseudorandom bytes after seeding the pool with
-	the Put() methods */
-class CRYPTOPP_DLL RandomPool : public RandomNumberGenerator,
-				   public Bufferless<BufferedTransformation>
+/*! This class can be used to generate cryptographic quality
+	pseudorandom bytes after seeding the pool with IncorporateEntropy() */
+class CRYPTOPP_DLL RandomPool : public RandomNumberGenerator, public NotCopyable
 {
 public:
-	//! poolSize must be greater than 16
-	RandomPool(unsigned int poolSize=384);
+	RandomPool();
 
-	size_t Put2(const byte *begin, size_t length, int messageEnd, bool blocking);
+	bool CanIncorporateEntropy() const {return true;}
+	void IncorporateEntropy(const byte *input, size_t length);
+	void GenerateIntoBufferedTransformation(BufferedTransformation &target, const std::string &channel, lword size);
 
-	bool AnyRetrievable() const {return true;}
-	lword MaxRetrievable() const {return ULONG_MAX;}
-
-	size_t TransferTo2(BufferedTransformation &target, lword &transferBytes, const std::string &channel=NULL_CHANNEL, bool blocking=true);
-	size_t CopyRangeTo2(BufferedTransformation &target, lword &begin, lword end=LWORD_MAX, const std::string &channel=NULL_CHANNEL, bool blocking=true) const
-	{
-		throw NotImplemented("RandomPool: CopyRangeTo2() is not supported by this store");
-	}
-
-	byte GenerateByte();
-	void GenerateBlock(byte *output, size_t size);
-
-	void IsolatedInitialize(const NameValuePairs &parameters) {}
-
-protected:
-	void Stir();
+	// for backwards compatibility. use RandomNumberSource, RandomNumberStore, and RandomNumberSink for other BufferTransformation functionality
+	void Put(const byte *input, size_t length) {IncorporateEntropy(input, length);}
 
 private:
-	SecByteBlock pool, key;
-	size_t addPos, getPos;
+	FixedSizeSecBlock<byte, 32> m_key;
+	FixedSizeSecBlock<byte, 16> m_seed;
+	member_ptr<BlockCipher> m_pCipher;
+	bool m_keySet;
 };
 
 NAMESPACE_END

salsa.cpp

@@ -17,17 +17,6 @@ void Salsa20_TestInstantiations()
 	Salsa20::Encryption x;
 }
 
-void Salsa20_Policy::CipherGetNextIV(byte *IV)
-{
-	word32 j6, j7;
-
-	j6 = m_state[14] + 1;
-	j7 = m_state[11] + (j6 == 0);
-
-	PutWord(false, LITTLE_ENDIAN_ORDER, IV, j6);
-	PutWord(false, LITTLE_ENDIAN_ORDER, IV+4, j7);
-}
-
 void Salsa20_Policy::CipherSetKey(const NameValuePairs &params, const byte *key, size_t length)
 {
 	m_rounds = params.GetIntValueWithDefault(Name::Rounds(), 20);
@@ -87,10 +76,20 @@ void Salsa20_Policy::OperateKeystream(KeystreamOperation operation, byte *output
 {
 	int i;
 #if CRYPTOPP_BOOL_SSE2_INTRINSICS_AVAILABLE
+	#define SSE2_QUARTER_ROUND(a, b, d, i)				{\
+		__m128i t = _mm_add_epi32(a, d);				\
+		b = _mm_xor_si128(b, _mm_slli_epi32(t, i));		\
+		b = _mm_xor_si128(b, _mm_srli_epi32(t, 32-i));}
+
 	if (HasSSE2())
 	{
 		__m128i *s = (__m128i *)m_state.data();
 
+#if CRYPTOPP_GCC_VERSION >= 40000 || _MSC_VER > 1400 || (defined(_MSC_VER) && CRYPTOPP_BOOL_X86)
+		// This code triggers an internal compiler error on MSVC 2005 when compiling 
+		// for x64 with optimizations on. hopefully it will get fixed in the next release.
+		// A bug report has been submitted at http://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=274123
+		// Also, GCC 3.4.4 generates incorrect code for x86 at -O2.
 		if (iterationCount >= 4)
 		{
 			__m128i ss[16];
@@ -139,11 +138,6 @@ void Salsa20_Policy::OperateKeystream(KeystreamOperation operation, byte *output
 
 				for (i=m_rounds; i>0; i-=2)
 				{
-					#define SSE2_QUARTER_ROUND(a, b, d, i)				{\
-						__m128i t = _mm_add_epi32(a, d);				\
-						b = _mm_xor_si128(b, _mm_slli_epi32(t, i));		\
-						b = _mm_xor_si128(b, _mm_srli_epi32(t, 32-i));}
-
 					#define QUARTER_ROUND(a, b, c, d)	\
 						SSE2_QUARTER_ROUND(a, b, d, 7)	\
 						SSE2_QUARTER_ROUND(b, c, a, 9)	\
@@ -205,6 +199,7 @@ void Salsa20_Policy::OperateKeystream(KeystreamOperation operation, byte *output
 				#undef SALSA_OUTPUT
 			} while ((iterationCount-=4) >= 4);
 		}
+#endif
 
 		if (!IsP4()) while (iterationCount)
 		{
@@ -333,6 +328,6 @@ void Salsa20_Policy::OperateKeystream(KeystreamOperation operation, byte *output
 		if (++m_state[8] == 0)
 			++m_state[5];
 	}
-}
+}	// see comment above if an internal compiler error occurs here
 
 NAMESPACE_END

salsa.h

@@ -18,7 +18,6 @@ class CRYPTOPP_NO_VTABLE Salsa20_Policy : public AdditiveCipherConcretePolicy<wo
 protected:
 	void CipherSetKey(const NameValuePairs &params, const byte *key, size_t length);
 	void OperateKeystream(KeystreamOperation operation, byte *output, const byte *input, size_t iterationCount);
-	void CipherGetNextIV(byte *IV);
 	void CipherResynchronize(byte *keystreamBuffer, const byte *IV);
 	bool IsRandomAccess() const {return true;}
 	void SeekToIteration(lword iterationCount);

seal.h

@@ -18,7 +18,6 @@ class CRYPTOPP_NO_VTABLE SEAL_Policy : public AdditiveCipherConcretePolicy<word3
 protected:
 	void CipherSetKey(const NameValuePairs &params, const byte *key, size_t length);
 	void OperateKeystream(KeystreamOperation operation, byte *output, const byte *input, size_t iterationCount);
-	void CipherGetNextIV(byte *IV) {PutWord(false, BIG_ENDIAN_ORDER, IV, m_outsideCounter+1);}
 	void CipherResynchronize(byte *keystreamBuffer, const byte *IV);
 	bool IsRandomAccess() const {return true;}
 	void SeekToIteration(lword iterationCount);

strciphr.h

@@ -73,7 +73,6 @@ struct CRYPTOPP_DLL CRYPTOPP_NO_VTABLE AdditiveCipherAbstractPolicy
 	virtual bool CanOperateKeystream() const {return false;}
 	virtual void OperateKeystream(KeystreamOperation operation, byte *output, const byte *input, size_t iterationCount) {assert(false);}
 	virtual void CipherSetKey(const NameValuePairs &params, const byte *key, size_t length) =0;
-	virtual void CipherGetNextIV(byte *iv) {throw NotImplemented("SimpleKeyingInterface: this object doesn't support GetNextIV()");}
 	virtual void CipherResynchronize(byte *keystreamBuffer, const byte *iv) {throw NotImplemented("SimpleKeyingInterface: this object doesn't support resynchronization");}
 	virtual bool IsRandomAccess() const =0;
 	virtual void SeekToIteration(lword iterationCount) {assert(!IsRandomAccess()); throw NotImplemented("StreamTransformation: this object doesn't support random access");}
@@ -133,10 +132,8 @@ template <class BASE = AbstractPolicyHolder<AdditiveCipherAbstractPolicy, TwoBas
 class CRYPTOPP_NO_VTABLE AdditiveCipherTemplate : public BASE
 {
 public:
-    byte GenerateByte();
 	void GenerateBlock(byte *output, size_t size);
     void ProcessData(byte *outString, const byte *inString, size_t length);
-	void GetNextIV(byte *iv) {this->AccessPolicy().CipherGetNextIV(iv);}
 	void Resynchronize(const byte *iv);
 	unsigned int OptimalBlockSize() const {return this->GetPolicy().GetOptimalBlockSize();}
 	unsigned int GetOptimalNextBlockSize() const {return (unsigned int)this->m_leftOver;}
@@ -170,7 +167,6 @@ public:
 	virtual bool CanIterate() const {return false;}
 	virtual void Iterate(byte *output, const byte *input, CipherDir dir, size_t iterationCount) {assert(false);}
 	virtual void CipherSetKey(const NameValuePairs &params, const byte *key, size_t length) =0;
-	virtual void CipherGetNextIV(byte *iv) {throw NotImplemented("SimpleKeyingInterface: this object doesn't support GetNextIV()");}
 	virtual void CipherResynchronize(const byte *iv) {throw NotImplemented("SimpleKeyingInterface: this object doesn't support resynchronization");}
 };
 
@@ -236,7 +232,6 @@ class CRYPTOPP_NO_VTABLE CFB_CipherTemplate : public BASE
 {
 public:
 	void ProcessData(byte *outString, const byte *inString, size_t length);
-	void GetNextIV(byte *iv) {this->AccessPolicy().CipherGetNextIV(iv);}
 	void Resynchronize(const byte *iv);
 	unsigned int OptimalBlockSize() const {return this->GetPolicy().GetBytesPerIteration();}
 	unsigned int GetOptimalNextBlockSize() const {return (unsigned int)m_leftOver;}