Add eddsa from ref10 implementation (with some modifications).

core/crypto/SignatureBase.h

@@ -0,0 +1,29 @@
+#ifndef SIGNATUREBASE_H__
+#define SIGNATUREBASE_H__
+
+#include <cryptopp/osrng.h>
+
+namespace i2p {
+namespace crypto {
+
+class Verifier {
+public:
+    
+    virtual ~Verifier() {};
+    virtual bool Verify(const uint8_t * buf, size_t len, const uint8_t * signature) const = 0;
+    virtual size_t GetPublicKeyLen() const = 0;
+    virtual size_t GetSignatureLen() const = 0;
+    virtual size_t GetPrivateKeyLen() const { return GetSignatureLen()/2; };
+};
+
+class Signer {
+public:
+
+    virtual ~Signer() {};      
+    virtual void Sign(CryptoPP::RandomNumberGenerator& rnd, const uint8_t * buf, int len, uint8_t * signature) const = 0; 
+};
+
+
+}
+}
+#endif // SIGNATUREBASE_H__