Add constructor from keypair for EDDSA25519Signer.

core/crypto/EdDSA25519.cpp

@@ -28,6 +28,11 @@ size_t EDDSA25519Verifier::GetSignatureLen() const
     return EDDSA25519_SIGNATURE_LENGTH;
 }
 
+EDDSA25519Signer::EDDSA25519Signer(const uint8_t* signingPrivateKey, const uint8_t* signingPublicKey)
+{
+    std::memcpy(m_PrivateKey, signingPrivateKey, EDDSA25519_PRIVATE_KEY_LENGTH);
+    std::memcpy(m_PublicKey, signingPublicKey, EDDSA25519_PUBLIC_KEY_LENGTH);
+}
 
 EDDSA25519Signer::EDDSA25519Signer(const uint8_t* signingPrivateKey)
 {

core/crypto/EdDSA25519.h

@@ -29,9 +29,15 @@ class EDDSA25519Signer : public Signer {
 public:
 
     /**
-     * @todo allow passing the public key too as an optimization
+     * Construct from a key pair.
      */
-    EDDSA25519Signer(const uint8_t * signingPrivateKey);
+    EDDSA25519Signer(const uint8_t* signingPrivateKey, const uint8_t* signingPublicKey);
+
+    /**
+     * Construct from a private key.
+     * The corresponding public key will be computed from it.
+     */
+    EDDSA25519Signer(const uint8_t* signingPrivateKey);
 
     /**
      * @todo do not pass random number generator, EdDSA does not require a random