Verify Message

Verifies the S/MIME signature of a MIME message.

Code

using DRIT.Mail.Rfc.Mime;
using DRIT.Mail.Rfc.SMime;

MimeMessage message = MimeMessage.Load("signed.eml");

var verifier = new SMimeVerifier();
SMimeVerificationResult result = verifier.Verify(message);

Console.WriteLine($"Status: {result.Status}");

foreach (SMimeSignatureInfo signature in result.Signatures)
{
    Console.WriteLine($"  Signer:     {signature.SignerCertificate?.Subject}");
    Console.WriteLine($"  Digest:     {signature.DigestAlgorithm}");
    Console.WriteLine($"  Valid from: {signature.SignerCertificate?.NotBefore}");
    Console.WriteLine($"  Valid to:   {signature.SignerCertificate?.NotAfter}");
}

Remarks

SMimeVerifier validates both detached (multipart/signed) and opaque (application/pkcs7-mime) S/MIME signatures. The signer certificate chain is validated against the system trust store by default.