SecureDecode() Method

Visual Basic (Declaration)
Visual Basic (Usage)
C#
Managed Extensions for C++
C++/CLI

Public Overloads Function SecureDecode() As SignerInfoCollection

Dim instance As MailMessage
Dim value As SignerInfoCollection
 
value = instance.SecureDecode()

public SignerInfoCollection SecureDecode()

public: SignerInfoCollection* SecureDecode();

public:
SignerInfoCollection^ SecureDecode();

Return Value

System.Security.Cryptography.Pkcs.SignerInfoCollection containing the signing certificate and additional information found in the signed message.

If IsSecure is true, this method verifies and/or decrypts the S/MIME message in place. If successful, IsSecure returns false. If unsuccessful, an Exception is thrown; decryption may succeed before signer verification throws an exception, so the message may be partially decoded if an exception is thrown.

This method will search the "MY" certificate store for a valid decrypting certificate as necessary, and imports the message's signing certificates into the "AddressBook" certificate store where they may subsequently be used by SecureEncrypt

To verify the digital signature or validate the certificate, call SignerInfo.CheckSignature(Boolean) on each member of the returned System.Security.Cryptography.Pkcs.SignerInfoCollection.

Use SecureDecode(X509Certificate2Collection,Boolean) if additional control is desired.

This example demonstrates decoding an SMIME message that was either signed, encrypted or both.

C#

using System.Security.Cryptography.X509Certificates;
using System.Security.Cryptography.Pkcs;

private MailMessage getDecodedMessage(MailMessage message)
{
    //Load the decrypting certificate from an exported certificate file (may also be loaded from an X509Store)
    X509Certificate2 decryptingCertificate = new X509Certificate2(Application.StartupPath + "\\myCertificate.pfx");
    //Decode the message and import the signing certificate into the AddressBook certificate Store
    //(If the decrypting certificate is already present in the "MY" certificate store, 
    //the parameterless SecureDecode() may be used instead.)
    SignerInfoCollection signatories = message.SecureDecode(new X509Certificate2Collection(decryptingCertificate), true);
    //Optionally verify the signature and validate the certificate
    foreach (SignerInfo signator in signatories)
        signator.CheckSignature(false);
    return message;
}

Visual Basic

Imports System.Security.Cryptography.X509Certificates
Imports System.Security.Cryptography.Pkcs

Private Function getDecodedMessage(ByVal message As MailMessage) As MailMessage
    'Load the decrypting certificate from an exported certificate file (may also be loaded from an X509Store)
    Dim decryptingCertificate As New X509Certificate2(Application.StartupPath & "\myCertificate.pfx")
    'Decode the message and import the signing certificate into the AddressBook certificate Store
    '(If the decrypting certificate is already present in the "MY" certificate store, 
    'the parameterless SecureDecode() may be used instead.)
    Dim signatories As SignerInfoCollection = message.SecureDecode(New X509Certificate2Collection(decryptingCertificate), True)
    'Optionally verify the signature and validate the certificate
    For Each signator As SignerInfo In signatories
        signator.CheckSignature(False)
    Next signator
    Return message
End Function

Reference

MailMessage Class
MailMessage Members
Overload List