Make AuthenticatedSymmetricCipher::AlgorithmName non-pure

Also see https://stackoverflow.com/q/49658309/608639

cryptest.nmake

@@ -60,8 +60,8 @@ LD = link.exe
 AR = lib.exe
 RM = del.exe
 
-# C4231 and C4505 are needed for VS2008 and below. Lots of noise...
-CXXFLAGS = /nologo /W4 /wd4231 /wd4505 /wd4511 /wd4156 /D_MBCS /Zi /TP /GR /EHsc
+# C4231 is needed for VS2008 and below. Lots of noise...
+CXXFLAGS = /nologo /W4 /wd4231 /wd4511 /wd4156 /D_MBCS /Zi /TP /GR /EHsc
 LDFLAGS = /nologo /SUBSYSTEM:CONSOLE
 ARFLAGS = /nologo
 LDLIBS =

cryptlib.cpp

@@ -268,6 +268,12 @@ bool AuthenticatedSymmetricCipher::DecryptAndVerify(byte *message, const byte *m
 	return TruncatedVerify(mac, macLength);
 }
 
+std::string AuthenticatedSymmetricCipher::AlgorithmName() const
+{
+	// Squash C4505 on Visual Studio 2008 and friends
+	return "Unknown";
+}
+
 unsigned int RandomNumberGenerator::GenerateBit()
 {
 	return GenerateByte() & 1;

cryptlib.h

@@ -1313,7 +1313,7 @@ public:
 	/// \details The standard algorithm name can be a name like \a AES or \a AES/GCM. Some algorithms
 	///   do not have standard names yet. For example, there is no standard algorithm name for
 	///   Shoup's ECIES.
-	virtual std::string AlgorithmName() const =0;
+	virtual std::string AlgorithmName() const;
 
 protected:
 	const Algorithm & GetAlgorithm() const