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(C#) Decrypt S/MIME and Verify S/MIME SignaturesC# example to decrypt S/MIME and verify S/MIME signatures. The S/MIME is unwrapped to get the original MIME prior to signing/encrypting. Note: This example requires Chilkat v11.0.0 or greater.
bool success = false; // This example requires the Chilkat API to have been previously unlocked. // See Global Unlock Sample for sample code. Chilkat.Mime mime = new Chilkat.Mime(); // Load an S/MIME message from a file: success = mime.LoadMimeFile("signedMime.txt"); if (success == false) { Debug.WriteLine(mime.LastErrorText); return; } // The ContainsEncryptedParts/ContainsSignedParts methods // can be called to determine if the MIME is encrypted and/or signed: bool isEncrypted = mime.ContainsEncryptedParts(); bool isSigned = mime.ContainsSignedParts(); // We don't want the "unwrap extras". You'll see what those // are in a few moments... mime.UnwrapExtras = false; // To verify the signature, call UnwrapSecurity. This will // verify the signature(s) and decrypt the S/MIME and restore // the MIME to the unsigned/unencrypted state. // The results of what was found are present in the MIME object's // properties, as well as extra header fields that are added // to the unwrapped MIME. success = mime.UnwrapSecurity(); if (success != true) { // UnwrapSecurity returns true if all signatures were // verified and all parts decrypted. Debug.WriteLine(mime.LastErrorText); return; } // The mime.UnwrapExtras property controls whether or not // these additional fields are added to the unwrapped MIME: // // X-NumPartsSigned: 1 // X-SignaturesValid: yes // X-NumPartsEncrypted: 1 // X-Decrypted: no // // The X-NumPartsSigned/X-SignaturesValid headers are added // if the MIME was signed. // // The X-NumPartsEncrypted/X-Decrypted headers are added // if the MIME was encrypted. // // If the MIME was signed, get the certificate used for signing. if (isSigned == true) { Chilkat.Cert signerCert = new Chilkat.Cert(); // The NumSignerCerts property indicates how many certificates // were used for signing. This example will assume the value is 1. // To get the 1st signer cert, call LastSignerCert with an index of 0: success = mime.LastSignerCert(0,signerCert); if (success == true) { Debug.WriteLine("**** Signer Cert: " + signerCert.SubjectCN); } } // If the MIME was encrypted, get the certificate used for decryption if (isEncrypted == true) { // The NumDecryptCerts property indicates how many certificates // were used for decrypting. This example will assume the value is 1. // To get the 1st decrypt cert, call LastDecryptCert with an index of 0: Chilkat.Cert decryptCert = new Chilkat.Cert(); success = mime.LastDecryptCert(0,decryptCert); if (success == true) { Debug.WriteLine("**** Decrypt Cert: " + decryptCert.SubjectCN); } } // Display the unwrapped MIME: Debug.WriteLine(mime.GetMime()); // Save the unwrapped MIME to a file: success = mime.SaveMime("unwrappedMime.txt"); |
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