/// <summary>Return the decrypted session data for the packet.</summary>
 private static byte[] GetSessionData(SymmetricKeyEncSessionPacket keyData, ReadOnlySpan <byte> rawPassword)
 {
     byte[] key = Array.Empty <byte>();
     try
     {
         key = new byte[PgpUtilities.GetKeySize(keyData.EncAlgorithm) / 8];
         S2kBasedEncryption.MakeKey(rawPassword, keyData.S2k.HashAlgorithm, keyData.S2k.GetIV(), keyData.S2k.IterationCount, key);
         if (keyData.SecKeyData?.Length > 0)
         {
             using var keyCipher    = PgpUtilities.GetSymmetricAlgorithm(keyData.EncAlgorithm);
             using var keyDecryptor = new ZeroPaddedCryptoTransform(keyCipher.CreateDecryptor(key, new byte[(keyCipher.BlockSize + 7) / 8]));
             return(keyDecryptor.TransformFinalBlock(keyData.SecKeyData, 0, keyData.SecKeyData.Length));
         }
         else
         {
             var sessionData = new byte[key.Length + 1];
             sessionData[0] = (byte)keyData.EncAlgorithm;
             key.CopyTo(sessionData, 1);
             return(sessionData);
         }
     }
     finally
     {
         CryptographicOperations.ZeroMemory(key);
     }
 }
        /// <summary>Add a PBE encryption method to the encrypted object.</summary>
        public void AddMethod(ReadOnlySpan <byte> rawPassPhrase, PgpHashAlgorithm s2kDigest)
        {
            S2k s2k = PgpUtilities.GenerateS2k(s2kDigest, 0x60);

            byte[] key = new byte[PgpUtilities.GetKeySize(defAlgorithm) / 8];
            S2kBasedEncryption.MakeKey(rawPassPhrase, s2kDigest, s2k.GetIV(), s2k.IterationCount, key);
            methods.Add(new PbeMethod(defAlgorithm, s2k, key));
        }