Improve RSADigestEngine, using Poco::Crypto::DigestEngine to calculate

the hash before signing. That way we can then support RSA signatures
with any hash supported by OpenSSL, not only MD5 and SHA1. It was also
required a new method on DigestEngine to obtain the NID (numeric ID) of
the algorithm, to be used on the OpenSSL RSA_sign call.

Crypto/include/Poco/Crypto/DigestEngine.h

@@ -67,6 +67,9 @@ public:
 	const std::string& algorithm() const;
 		/// Returns the name of the digest algorithm.
 	
+	int nid() const;
+		/// Returns the NID (OpenSSL object identifier) of the digest algorithm.
+
 	// DigestEngine
 	std::size_t digestLength() const;
 	void reset();

Crypto/include/Poco/Crypto/RSADigestEngine.h

@@ -43,8 +43,7 @@
 #include "Poco/Crypto/Crypto.h"
 #include "Poco/Crypto/RSAKey.h"
 #include "Poco/DigestEngine.h"
-#include "Poco/MD5Engine.h"
+#include "Poco/Crypto/DigestEngine.h"
-#include "Poco/SHA1Engine.h"
 #include <openssl/rsa.h>
 #include <istream>
 #include <ostream>
@@ -58,10 +57,10 @@ class Crypto_API RSADigestEngine: public Poco::DigestEngine
 	/// This class implements a Poco::DigestEngine that can be
 	/// used to compute a secure digital signature.
 	///
-	/// First another Poco::DigestEngine (Poco::MD5Engine
+	/// First another Poco::Crypto::DigestEngine is created and
-	/// or Poco::SHA1Engine) is used to compute a cryptographic
+	/// used to compute a cryptographic hash of the data to be
-	/// hash of the data to be signed. Then, the hash value is
+	/// signed. Then, the hash value is encrypted, using
-	/// encrypted, using the RSA private key.
+	/// the RSA private key.
 	///
 	/// To verify a signature, pass it to the verify() 
 	/// member function. It will decrypt the signature
@@ -75,9 +74,19 @@ public:
 		DIGEST_SHA1
 	};
 	
+	//@ deprecated
 	RSADigestEngine(const RSAKey& key, DigestType digestType = DIGEST_SHA1);
 		/// Creates the RSADigestEngine with the given RSA key,
-		/// using the SHA-1 hash algorithm.
+		/// using the MD5 or SHA-1 hash algorithm.
+		/// Kept for backward compatibility
+
+	RSADigestEngine(const RSAKey& key, const std::string &name);
+		/// Creates the RSADigestEngine with the given RSA key,
+		/// using the hash algorithm with the given name
+		/// (e.g., "MD5", "SHA1", "SHA256", "SHA512", etc.).
+		/// See the OpenSSL documentation for a list of supported digest algorithms.
+		///
+		/// Throws a Poco::NotFoundException if no algorithm with the given name exists.
 
 	~RSADigestEngine();
 		/// Destroys the RSADigestEngine.
@@ -113,12 +122,9 @@ protected:
 
 private:
 	RSAKey _key;
-	Poco::DigestEngine& _engine;
+	Poco::Crypto::DigestEngine _engine;
-	int _type;
 	Poco::DigestEngine::Digest _digest;
 	Poco::DigestEngine::Digest _signature;
-	Poco::MD5Engine _md5Engine;
-	Poco::SHA1Engine _sha1Engine;
 };
 
 

Crypto/src/DigestEngine.cpp

@@ -57,6 +57,10 @@ DigestEngine::~DigestEngine()
 	EVP_MD_CTX_destroy(_ctx);
 }
 
+int DigestEngine::nid() const
+{
+	return EVP_MD_nid(_ctx->digest);
+}
 
 std::size_t DigestEngine::digestLength() const
 {

Crypto/src/RSADigestEngine.cpp

@@ -36,6 +36,7 @@
 
 #include "Poco/Crypto/RSADigestEngine.h"
 #include <openssl/pem.h>
+#include <openssl/evp.h>
 
 
 namespace Poco {
@@ -44,8 +45,13 @@ namespace Crypto {
 
 RSADigestEngine::RSADigestEngine(const RSAKey& key, DigestType digestType):
 	_key(key),
-	_engine(digestType == DIGEST_MD5 ? static_cast<Poco::DigestEngine&>(_md5Engine) : static_cast<Poco::DigestEngine&>(_sha1Engine)),
+	_engine(digestType == DIGEST_MD5 ? "MD5" : "SHA1")
-	_type(digestType == DIGEST_MD5 ? NID_md5 : NID_sha1)
+{
+}
+
+RSADigestEngine::RSADigestEngine(const RSAKey& key, const std::string &algorithm):
+	_key(key),
+	_engine(algorithm)
 {
 }
 
@@ -86,7 +92,7 @@ const DigestEngine::Digest& RSADigestEngine::signature()
 		digest();
 		_signature.resize(_key.size());
 		unsigned sigLen = static_cast<unsigned>(_signature.size());
-		RSA_sign(_type, &_digest[0], static_cast<unsigned>(_digest.size()), &_signature[0], &sigLen, _key.impl()->getRSA());
+		RSA_sign(_engine.nid(), &_digest[0], static_cast<unsigned>(_digest.size()), &_signature[0], &sigLen, _key.impl()->getRSA());
 		// truncate _sig to sigLen
 		if (sigLen < _signature.size())
 			_signature.resize(sigLen);
@@ -99,7 +105,7 @@ bool RSADigestEngine::verify(const DigestEngine::Digest& sig)
 {
 	digest();
 	DigestEngine::Digest sigCpy = sig; // copy becausse RSA_verify can modify sigCpy
-	int ret = RSA_verify(_type, &_digest[0], static_cast<unsigned>(_digest.size()), &sigCpy[0], static_cast<unsigned>(sigCpy.size()), _key.impl()->getRSA());
+	int ret = RSA_verify(_engine.nid(), &_digest[0], static_cast<unsigned>(_digest.size()), &sigCpy[0], static_cast<unsigned>(sigCpy.size()), _key.impl()->getRSA());
 	return ret != 0;
 }
 

Crypto/testsuite/src/RSATest.cpp

@@ -149,6 +149,26 @@ void RSATest::testSign()
 }
 
 
+void RSATest::testSignSha256()
+{
+	std::string msg("Test this sign message");
+	RSAKey key(RSAKey::KL_2048, RSAKey::EXP_LARGE);
+	RSADigestEngine eng(key,"SHA256");
+	eng.update(msg.c_str(), static_cast<unsigned>(msg.length()));
+	const Poco::DigestEngine::Digest& sig = eng.signature();
+	std::string hexDig = Poco::DigestEngine::digestToHex(sig);
+
+	// verify
+	std::ostringstream strPub;
+	key.save(&strPub);
+	std::string pubKey = strPub.str();
+	std::istringstream iPub(pubKey);
+	RSAKey keyPub(&iPub);
+	RSADigestEngine eng2(key,"SHA256");
+	eng2.update(msg.c_str(), static_cast<unsigned>(msg.length()));
+	assert (eng2.verify(sig));
+}
+
 void RSATest::testSignManipulated()
 {
 	std::string msg("Test this sign message");
@@ -244,6 +264,7 @@ CppUnit::Test* RSATest::suite()
 
 	CppUnit_addTest(pSuite, RSATest, testNewKeys);
 	CppUnit_addTest(pSuite, RSATest, testSign);
+	CppUnit_addTest(pSuite, RSATest, testSignSha256);
 	CppUnit_addTest(pSuite, RSATest, testSignManipulated);
 	CppUnit_addTest(pSuite, RSATest, testRSACipher);
 	CppUnit_addTest(pSuite, RSATest, testRSACipherLarge);

Crypto/testsuite/src/RSATest.h

@@ -48,6 +48,7 @@ public:
 
 	void testNewKeys();
 	void testSign();
+	void testSignSha256();
 	void testSignManipulated();
 	void testRSACipher();
 	void testRSACipherLarge();