diff --git a/mdc.h b/mdc.h
index a84996e0..c3e8d2ce 100644
--- a/mdc.h
+++ b/mdc.h
@@ -13,46 +13,47 @@
 NAMESPACE_BEGIN(CryptoPP)
 
 //! \class MDC_Info
+//! \tparam B BlockCipher derived class
 //! \brief MDC_Info cipher information
-template <class T>
-struct MDC_Info : public FixedBlockSize<T::DIGESTSIZE>, public FixedKeyLength<T::BLOCKSIZE>
+template <class B>
+struct MDC_Info : public FixedBlockSize<B::DIGESTSIZE>, public FixedKeyLength<B::BLOCKSIZE>
 {
-	static std::string StaticAlgorithmName() {return std::string("MDC/")+T::StaticAlgorithmName();}
+	static std::string StaticAlgorithmName() {return std::string("MDC/")+B::StaticAlgorithmName();}
 };
 
-
-//! \class MDC
 //! \brief MDC cipher
+//! \tparam T HashTransformation derived class
 //! \details MDC() is a construction by Peter Gutmann to turn an iterated hash function into a PRF
 //! \sa <a href="http://www.weidai.com/scan-mirror/cs.html#MDC">MDC</a>
-template <class T>
-class MDC : public MDC_Info<T>
+template <class H>
+class MDC : public MDC_Info<H>
 {
 	//! \class Enc
 	//! \brief MDC cipher encryption operation
-	class CRYPTOPP_NO_VTABLE Enc : public BlockCipherImpl<MDC_Info<T> >
+	class CRYPTOPP_NO_VTABLE Enc : public BlockCipherImpl<MDC_Info<H> >
 	{
-		typedef typename T::HashWordType HashWordType;
+		typedef typename H::HashWordType HashWordType;
 
 	public:
 		void UncheckedSetKey(const byte *userKey, unsigned int length, const NameValuePairs &params)
 		{
+			CRYPTOPP_UNUSED(params);
 			this->AssertValidKeyLength(length);
 			memcpy_s(m_key, m_key.size(), userKey, this->KEYLENGTH);
-			T::CorrectEndianess(Key(), Key(), this->KEYLENGTH);
+			m_hash.CorrectEndianess(Key(), Key(), this->KEYLENGTH);
 		}
 
 		void ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
 		{
-			T::CorrectEndianess(Buffer(), (HashWordType *)inBlock, this->BLOCKSIZE);
-			T::Transform(Buffer(), Key());
+			m_hash.CorrectEndianess(Buffer(), (HashWordType *)inBlock, this->BLOCKSIZE);
+			H::Transform(Buffer(), Key());
 			if (xorBlock)
 			{
-				T::CorrectEndianess(Buffer(), Buffer(), this->BLOCKSIZE);
+				m_hash.CorrectEndianess(Buffer(), Buffer(), this->BLOCKSIZE);
 				xorbuf(outBlock, xorBlock, m_buffer, this->BLOCKSIZE);
 			}
 			else
-				T::CorrectEndianess((HashWordType *)outBlock, Buffer(), this->BLOCKSIZE);
+				m_hash.CorrectEndianess((HashWordType *)outBlock, Buffer(), this->BLOCKSIZE);
 		}
 
 		bool IsPermutation() const {return false;}
@@ -65,12 +66,13 @@ class MDC : public MDC_Info<T>
 		HashWordType *Buffer() const {return (HashWordType *)m_buffer.data();}
 
 		// VC60 workaround: bug triggered if using FixedSizeAllocatorWithCleanup
-		FixedSizeSecBlock<byte, MDC_Info<T>::KEYLENGTH, AllocatorWithCleanup<byte> > m_key;
-		mutable FixedSizeSecBlock<byte, MDC_Info<T>::BLOCKSIZE, AllocatorWithCleanup<byte> > m_buffer;
+		FixedSizeSecBlock<byte, MDC_Info<H>::KEYLENGTH, AllocatorWithCleanup<byte> > m_key;
+		mutable FixedSizeSecBlock<byte, MDC_Info<H>::BLOCKSIZE, AllocatorWithCleanup<byte> > m_buffer;
+		mutable H m_hash;
 	};
 
 public:
-	//! use BlockCipher interface
+	// use BlockCipher interface
 	typedef BlockCipherFinal<ENCRYPTION, Enc> Encryption;
 };
 
diff --git a/randpool.cpp b/randpool.cpp
index a7d2efdf..39afd72f 100644
--- a/randpool.cpp
+++ b/randpool.cpp
@@ -12,15 +12,21 @@
 #include "aes.h"
 #include "sha.h"
 #include "hrtimer.h"
-#include <time.h>
+#include "trap.h"
+
+// OldRandomPool
+#include "mdc.h"
+#include "modes.h"
+
+#include <ctime>
 
 NAMESPACE_BEGIN(CryptoPP)
 
 RandomPool::RandomPool()
 	: m_pCipher(new AES::Encryption), m_keySet(false)
 {
-	memset(m_key, 0, m_key.SizeInBytes());
-	memset(m_seed, 0, m_seed.SizeInBytes());
+	::memset(m_key, 0, m_key.SizeInBytes());
+	::memset(m_seed, 0, m_seed.SizeInBytes());
 }
 
 void RandomPool::IncorporateEntropy(const byte *input, size_t length)
@@ -51,8 +57,8 @@ void RandomPool::GenerateIntoBufferedTransformation(BufferedTransformation &targ
 		// UBsan finding: signed integer overflow: 1876017710 + 1446085457 cannot be represented in type 'long int'
 		// *(time_t *)(m_seed.data()+8) += t;
 		word64 tt1 = 0, tt2 = (word64)t;
-		memcpy(&tt1, m_seed.data()+8, 8);
-		memcpy(m_seed.data()+8, &(tt2 += tt1), 8);
+		::memcpy(&tt1, m_seed.data()+8, 8);
+		::memcpy(m_seed.data()+8, &(tt2 += tt1), 8);
 
 		// Wipe the intermediates
 		*((volatile TimerWord*)&tw) = 0;
@@ -69,6 +75,89 @@ void RandomPool::GenerateIntoBufferedTransformation(BufferedTransformation &targ
 	}
 }
 
+// OldRandomPool is provided for backwards compatibility for a migration path
+typedef MDC<SHA1> OldRandomPoolCipher;
+
+OldRandomPool::OldRandomPool(unsigned int poolSize)
+        : pool(poolSize), key(OldRandomPoolCipher::DEFAULT_KEYLENGTH), addPos(0), getPos(poolSize)
+{
+	CRYPTOPP_ASSERT(poolSize > key.size());
+	::memset(pool, 0, poolSize);
+	::memset(key, 0, key.size());
+}
+
+void OldRandomPool::Stir()
+{
+	CFB_Mode<OldRandomPoolCipher>::Encryption cipher;
+
+	for (int i=0; i<2; i++)
+	{
+		cipher.SetKeyWithIV(key, key.size(), pool.end()-cipher.IVSize());
+		cipher.ProcessString(pool, pool.size());
+		::memcpy(key, pool, key.size());
+	}
+
+	addPos = 0;
+	getPos = key.size();
+}
+
+size_t OldRandomPool::Put2(const byte *inString, size_t length, int messageEnd, bool blocking)
+{
+	CRYPTOPP_UNUSED(messageEnd); CRYPTOPP_UNUSED(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 OldRandomPool::TransferTo2(BufferedTransformation &target, lword &transferBytes, const std::string &channel, bool blocking)
+{
+	if (!blocking)
+		throw NotImplemented("OldRandomPool: 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 OldRandomPool::GenerateByte()
+{
+	if (getPos == pool.size())
+		Stir();
+
+	return pool[getPos++];
+}
+
+void OldRandomPool::GenerateBlock(byte *outString, size_t size)
+{
+	ArraySink sink(outString, size);
+	TransferTo(sink, size);
+}
+
 NAMESPACE_END
 
 #endif
diff --git a/randpool.h b/randpool.h
index 3214e3c0..37dda408 100644
--- a/randpool.h
+++ b/randpool.h
@@ -1,4 +1,5 @@
 // randpool.h - originally written and placed in the public domain by Wei Dai
+//              OldRandPool added by JW in August, 2017.
 
 //! \file randpool.h
 //! \brief Class file for Randomness Pool
@@ -9,20 +10,9 @@
 //!   RandomPool was redesigned to reduce the risk of reusing random numbers after state
 //!   rollback (which may occur when running in a virtual machine like VMware or a hosted
 //!   environment).
-//! \details If you need the pre-Crypto++ 5.5 generator then you can find it with:
-//! <pre>
-//!    $ git clone https://github.com/weidai11/cryptopp cryptopp-ancient
-//!    $ cryptopp-ancient
-//!
-//!    # Checkout the RandomPool change
-//!    $ git checkout f41245df6fb9b85574260eca9cd32777e8ab5136
-//!
-//!    # Go back one more
-//!    git checkout HEAD~1
-//!
-//!    $ grep 'MDC<SHA1>' *.h *.cpp
-//!    randpool.cpp:typedef MDC<SHA1> RandomPoolCipher;
-//! </pre>
+//! \details If you need the pre-Crypto++ 5.5 generator then use OldRandomPool class. You
+//!   should migrate away from OldRandomPool at the earliest opportunity. Use RandomPool
+//!   or AutoSeededRandomPool instead.
 //! \since Crypto++ 4.0 (PGP 2.6.x style), Crypto++ 5.5 (AES-256 based)
 
 #ifndef CRYPTOPP_RANDPOOL_H
@@ -45,6 +35,9 @@ NAMESPACE_BEGIN(CryptoPP)
 //!   RandomPool was redesigned to reduce the risk of reusing random numbers after state
 //!   rollback (which may occur when running in a virtual machine like VMware or a hosted
 //!   environment).
+//! \details If you need the pre-Crypto++ 5.5 generator then use OldRandomPool class. You
+//!   should migrate away from OldRandomPool at the earliest opportunity. Use RandomPool
+//!   or AutoSeededRandomPool instead.
 //! \since Crypto++ 4.0 (PGP 2.6.x style), Crypto++ 5.5 (AES-256 based)
 class CRYPTOPP_DLL RandomPool : public RandomNumberGenerator, public NotCopyable
 {
@@ -56,7 +49,8 @@ public:
 	void IncorporateEntropy(const byte *input, size_t length);
 	void GenerateIntoBufferedTransformation(BufferedTransformation &target, const std::string &channel, lword size);
 
-	// for backwards compatibility. use RandomNumberSource, RandomNumberStore, and RandomNumberSink for other BufferTransformation functionality
+	// for backwards compatibility. use RandomNumberSource, RandomNumberStore, and
+	//   RandomNumberSink for other BufferTransformation functionality
 	void Put(const byte *input, size_t length) {IncorporateEntropy(input, length);}
 
 private:
@@ -66,6 +60,51 @@ private:
 	bool m_keySet;
 };
 
+//! \class OldRandomPool
+//! \brief Randomness Pool based on PGP 2.6.x with MDC
+//! \details If you need the pre-Crypto++ 5.5 generator then use OldRandomPool class. The
+//!   OldRandomPool class is always available so you dont need to define
+//!   CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY. However, you should migrate away from
+//!   OldRandomPool at the earliest opportunity. Use RandomPool or AutoSeededRandomPool instead.
+//! \deprecated This class uses an old style PGP 2.6.x with MDC. The generator risks reusing
+//!   random random numbers after state rollback. Migrate to RandomPool or AutoSeededRandomPool
+//!   at the earliest opportunity.
+//! \since Crypto++ 6.0 (PGP 2.6.x style)
+class CRYPTOPP_DLL OldRandomPool : public RandomNumberGenerator,
+                                   public Bufferless<BufferedTransformation>
+{
+public:
+	//! \brief Construct an OldRandomPool
+	//! \param poolSize internal pool size of the generator
+	//! \details poolSize must be greater than 16
+	OldRandomPool(unsigned int poolSize=384);
+
+	size_t Put2(const byte *begin, size_t length, int messageEnd, bool blocking);
+
+	bool AnyRetrievable() const {return true;}
+	lword MaxRetrievable() const {return ULONG_MAX;}
+
+	size_t TransferTo2(BufferedTransformation &target, lword &transferBytes, const std::string &channel=DEFAULT_CHANNEL, bool blocking=true);
+	size_t CopyRangeTo2(BufferedTransformation &target, lword &begin, lword end=LWORD_MAX, const std::string &channel=DEFAULT_CHANNEL, bool blocking=true) const
+	{
+		CRYPTOPP_UNUSED(target); CRYPTOPP_UNUSED(begin); CRYPTOPP_UNUSED(end);
+		CRYPTOPP_UNUSED(channel); CRYPTOPP_UNUSED(blocking);
+		throw NotImplemented("OldRandomPool: CopyRangeTo2() is not supported by this store");
+	}
+
+	byte GenerateByte();
+	void GenerateBlock(byte *output, size_t size);
+
+	void IsolatedInitialize(const NameValuePairs &parameters) {CRYPTOPP_UNUSED(parameters);}
+
+protected:
+	void Stir();
+
+private:
+	SecByteBlock pool, key;
+	size_t addPos, getPos;
+};
+
 NAMESPACE_END
 
 #endif
diff --git a/validat1.cpp b/validat1.cpp
index be903af1..c1f14e37 100644
--- a/validat1.cpp
+++ b/validat1.cpp
@@ -718,6 +718,115 @@ bool TestRandomPool()
 	}
 #endif
 
+	// Old, PGP 2.6 style RandomPool. Added because users were still having problems
+	//  with it in 2017. The missing functionality was a barrier to upgrades.
+	std::cout << "\nTesting OldRandomPool generator...\n\n";
+	{
+		OldRandomPool prng;
+		static const unsigned int ENTROPY_SIZE = 32;
+
+		// https://github.com/weidai11/cryptopp/issues/452
+		byte result[32], expected[32] = {
+			0x58,0x3E,0x0A,0xAC,0x79,0x71,0x19,0x18,
+			0x51,0x97,0xC6,0x9B,0xEF,0x82,0x18,0x1E,
+			0x9C,0x0F,0x5C,0xEF,0xC7,0x89,0xB2,0x94,
+			0x04,0x96,0xD6,0xD9,0xA4,0x3B,0xB7,0xEC
+		};
+
+		SecByteBlock seed(0x00, 384);
+		prng.Put(seed, seed.size());
+
+		prng.GenerateBlock(result, sizeof(result));
+		fail = (0 != ::memcmp(result, expected, sizeof(expected)));
+
+		pass &= !fail;
+		if (fail)
+			std::cout << "FAILED:";
+		else
+			std::cout << "passed:";
+		std::cout << "  Expected sequence from PGP-style RandomPool (2007 version)\n";
+
+		MeterFilter meter(new Redirector(TheBitBucket()));
+		RandomNumberSource test(prng, 100000, true, new Deflator(new Redirector(meter)));
+
+		fail = false;
+		if (meter.GetTotalBytes() < 100000)
+			fail = true;
+
+		pass &= !fail;
+		if (fail)
+			std::cout << "FAILED:";
+		else
+			std::cout << "passed:";
+		std::cout << "  100000 generated bytes compressed to " << meter.GetTotalBytes() << " bytes by DEFLATE\n";
+
+		try
+		{
+			fail = false;
+			prng.DiscardBytes(100000);
+		}
+		catch (const Exception&)
+		{
+			fail = true;
+		}
+
+		pass &= !fail;
+		if (fail)
+			std::cout << "FAILED:";
+		else
+			std::cout << "passed:";
+		std::cout << "  discarded 10000 bytes" << std::endl;
+
+		try
+		{
+			fail = false;
+			if(prng.CanIncorporateEntropy())
+			{
+				SecByteBlock entropy(ENTROPY_SIZE);
+				GlobalRNG().GenerateBlock(entropy, entropy.SizeInBytes());
+
+				prng.IncorporateEntropy(entropy, entropy.SizeInBytes());
+				prng.IncorporateEntropy(entropy, entropy.SizeInBytes());
+				prng.IncorporateEntropy(entropy, entropy.SizeInBytes());
+				prng.IncorporateEntropy(entropy, entropy.SizeInBytes());
+			}
+		}
+		catch (const Exception& /*ex*/)
+		{
+			fail = true;
+		}
+
+		pass &= !fail;
+		if (fail)
+			std::cout << "FAILED:";
+		else
+			std::cout << "passed:";
+		std::cout << "  IncorporateEntropy with " << 4*ENTROPY_SIZE << " bytes\n";
+
+		try
+		{
+			// Miscellaneous for code coverage
+			fail = false;
+			word32 result = prng.GenerateWord32();
+			result = prng.GenerateWord32((result & 0xff), 0xffffffff - (result & 0xff));
+			prng.GenerateBlock(reinterpret_cast<byte*>(&result), 4);
+			prng.GenerateBlock(reinterpret_cast<byte*>(&result), 3);
+			prng.GenerateBlock(reinterpret_cast<byte*>(&result), 2);
+			prng.GenerateBlock(reinterpret_cast<byte*>(&result), 1);
+		}
+		catch (const Exception&)
+		{
+			fail = true;
+		}
+
+		pass &= !fail;
+		if (fail)
+			std::cout << "FAILED:";
+		else
+			std::cout << "passed:";
+		std::cout << "  GenerateWord32 and Crop\n";
+	}
+
 	return pass;
 }