method ECDH.prototype.getPrivateKeyECDH.prototype.getPrivateKey(): BufferIf encoding is specified, a string is returned; otherwise a Buffer is returned. Return TypeBufferThe EC Diffie-Hellman in the specified encoding. ECDH.prototype.getPrivateKey(encoding: BinaryToTextEncoding): stringParametersencoding: BinaryToTextEncodingReturn Typestring