Add OldRandomPool class (Issue 452)

RandomPool used to be a PGP-style deterministic generator and folks used it as a key generation function. At Crypto++ 5.5 the design changed to harden it agianst rollback attacks. The design change resulted in an upgrade barrier. That is, some folks are stuck at Crypto++ 4.2 or Crypto++ 5.2 because they must interoperate with existing software.

Below is the test program we used for the test vector. It was run against Crypto++ 5.4.

    RandomPool prng;
    SecByteBlock seed(0x00, 384), result(64);
    prng.Put(seed, seed.size());

    prng.GenerateBlock(result, result.size());
    HexEncoder encoder(new FileSink(std::cout));

    std::cout << "RandomPool: ";
    encoder.Put(result, sizeof(result));
    std::cout << std::endl;

1 files changed, 52 insertions, 15 deletions

diff --git a/randpool.h b/randpool.h
index 3214e3c0..a9c1a749 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 +60,49 @@ 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

+        {

+                throw NotImplemented("OldRandomPool: CopyRangeTo2() is not supported by this store");

+        }

+

+        byte GenerateByte();

+        void GenerateBlock(byte *output, size_t size);

+

+        void IsolatedInitialize(const NameValuePairs &parameters) {}

+

+protected:

+        void Stir();

+

+private:

+        SecByteBlock pool, key;

+        size_t addPos, getPos;

+};

+

 NAMESPACE_END

 

 #endif