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POBouncy castle error: Unable to cast object of type RsaPrivateCrtKeyParameters to type ElGamalKeyParameters
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copied!<p>I am having difficulties with decryption of a GPG file using Bouncy Castle. I have the encrypted file and I have a private key and the password for the private key. I can successfully decrypt the file using the desktop software GPG4win Kleopatra so I have the correct private key and the gpg file is valid.</p> <p>However when our application reaches the line of code which attempts to decrypt the data with Bouncy Castle, I receive this error:</p> <pre><code>Unable to cast object of type 'Org.BouncyCastle.Crypto.Parameters.RsaPrivateCrtKeyParameters' to type 'Org.BouncyCastle.Crypto.Parameters.ElGamalKeyParameters'. </code></pre> <p>I am decrypting the same file using the same private key with Kleopatra so this has got to be something I can resolve by perhaps changing the private key file to the expected format or setting some options in Bouncy Castle.</p> <p>The private key file is a plain text file beginning with the lines:</p> <pre><code>-----BEGIN PGP PRIVATE KEY BLOCK----- Version: GnuPG v2.0.17 (MingW32) </code></pre> <p>Here is a flattened out version of the decryption code. Apologies if I have missed anything out:</p> <pre><code>PgpEncryptionKeys encryptionKeys = new PgpEncryptionKeys(publicKey, privateKey, passPhrase); Stream encryptedStream = new StreamReader(encryptedFileName).BaseStream; Stream encodedFile = PgpUtilities.GetDecoderStream(inputStream); PgpObjectFactory factory = new PgpObjectFactory(encodedFile); PgpObject pgpObject = factory.NextPgpObject(); PgpEncryptedDataList encryptedDataList; if (pgpObject is PgpEncryptedDataList) { encryptedDataList = (PgpEncryptedDataList)pgpObject; } else { encryptedDataList = (PgpEncryptedDataList)factory.NextPgpObject(); } PgpPublicKeyEncryptedData myEncryptedData = null; PgpPublicKeyEncryptedData publicKeyED = null; foreach (PgpPublicKeyEncryptedData encryptedData in encryptedDataList.GetEncryptedDataObjects()) { if (encryptedData != null) { myEncryptedData = encryptedData; break; } } Stream clearStream = myEncryptedData.GetDataStream(privateKey); PgpObjectFactory clearFactory = new PgpObjectFactory(clearStream); PgpObject message = clearFactory.NextPgpObject(); if (message is PgpCompressedData) { message = ProcessCompressedMessage(message); PgpLiteralData literalData = (PgpLiteralData)message; using (Stream outputFile = File.Create(outputFilePath)) { using (Stream literalDataStream = literalData.GetInputStream()) { Streams.PipeAll(literalDataStream, outputFile); } } } </code></pre> <p>The exception occurs on this line:</p> <pre><code>Stream clearStream = myEncryptedData.GetDataStream(privateKey); </code></pre> <p>I hope you can suggest something for me to try. I can provide any further details I might have missed.</p> <p>Thanks!</p>

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