Bouncy Castle PGP Decryption Issue

Question

I\'ve had a application using Bouncy Castle for PGP decryption which has run without any issues for the past 8 months or so, and the past 2 days all of a sudden an issue has com

Answer 1

This could be important (Source: http://www.opensourcejavaphp.net/csharp/itextsharp/PgpPublicKeyEncryptedData.cs.html) :

It explains the value of your keyData.Algorithm being different, but the why I am still unsure of. It is most likely the input file that is the case. It could be different (client using a different key?)

private static IBufferedCipher GetKeyCipher(
            PublicKeyAlgorithmTag algorithm)
        {
            try
            {
                switch (algorithm)
                {
                    case PublicKeyAlgorithmTag.RsaEncrypt:
                    case PublicKeyAlgorithmTag.RsaGeneral:
                        return CipherUtilities.GetCipher("RSA//PKCS1Padding");
                    case PublicKeyAlgorithmTag.ElGamalEncrypt:
                    case PublicKeyAlgorithmTag.ElGamalGeneral:
                        return CipherUtilities.GetCipher("ElGamal/ECB/PKCS1Padding");
                    default:
                        throw new PgpException("unknown asymmetric algorithm: " + algorithm);
                }
            }
            catch (PgpException e)
            {
                throw e;
            }
            catch (Exception e)
            {
                throw new PgpException("Exception creating cipher", e);
            }
        }