decrypt Method

Decrypts the current message.

Syntax

def decrypt() -> None: ...

Remarks

on_decrypt decrypts the input data with the specified certificate. Certificates are specified by calling add_certificate or setting the certificates property.

If the certificate used to encrypt the message is not known ahead of time get_recipient_info may be called prior to calling on_decrypt to obtain information about the recipient (the entity the for which the message was encrypted). If get_recipient_info is called, the on_recipient_info event is fired with information about the recipient which may be used to load an appropriate decryption certificate.

The following properties are applicable when calling this method:

• certificates (Required)

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• input_file
• input_message

When a valid source is found the search stops. The order in which the output properties are checked is as follows:

• output_file
• output_message: The output data is written to this property if no other destination is specified.

Encrypt and Decrypt a message

Cms cms = new Cms();
cms.RecipientCerts.Add(new Certificate(CertStoreTypes.cstPublicKeyFile, @"C:\temp\test.cer", "", "*"));
cms.InputMessage = "My Data";
cms.Encrypt();

string encryptedMessage = cms.OutputMessage;

cms = new Cms();
cms.InputMessage = encryptedMessage;
cms.Certificates.Add(new Certificate(CertStoreTypes.cstPFXFile, @"C:\temp\test.pfx", "password", "*"));
cms.Decrypt();

string plaintextMessage = cms.OutputMessage;

Cms cms = new Cms();
cms.RecipientCerts.Add(new Certificate(CertStoreTypes.cstPublicKeyFile, @"C:\temp\test.cer", "", "*"));
cms.InputMessage = "My Data";
cms.OutputFormat = "DER";
cms.Encrypt();

byte[] encryptedMessage = cms.OutputMessageB; //Binary output

cms = new Cms();
cms.InputMessageB = encryptedMessage;
cms.Certificates.Add(new Certificate(CertStoreTypes.cstPFXFile, @"C:\temp\test.pfx", "password", "*"));
cms.Decrypt();

string plaintextMessage = cms.OutputMessage;

Cms cms = new Cms();
cms.RecipientCerts.Add(new Certificate(CertStoreTypes.cstPublicKeyFile, @"C:\temp\test.cer", "", "*"));
cms.RecipientCerts.Add(new Certificate(CertStoreTypes.cstPublicKeyFile, @"C:\temp\test2.cer", "", "*"));
cms.InputMessage = "My Data";
cms.Encrypt();

string encryptedMessage = cms.OutputMessage;

cms = new Cms();
cms.InputMessage = encryptedMessage;
cms.Certificates.Add(new Certificate(CertStoreTypes.cstPFXFile, @"C:\temp\test.pfx", "password", "*"));
cms.Decrypt();

string plaintextMessage = cms.OutputMessage;

Cms cms = new Cms();
cms.RecipientCerts.Add(new Certificate(CertStoreTypes.cstPublicKeyFile, @"C:\temp\test.cer", "", "*"));
cms.InputMessage = "My Data";
cms.Encrypt();

string encryptedMessage = cms.OutputMessage;

//If the recipient certificate is not known ahead of time the GetRecipientInfo method may be called
//to find information about the certificate.
cms = new Cms();
cms.InputMessage = encryptedMessage;
cms.OnRecipientInfo += (s, e) => {
  Console.WriteLine(e.SerialNumber);
  Console.WriteLine(e.Issuer);
  if (e.Issuer == "CN=100") //Identify the certificate to load based on event params
  {
    cms.Certificates.Add(new Certificate(CertStoreTypes.cstPFXFile, @"C:\temp\test.pfx", "password", "*"));
  }
};

cms.GetRecipientInfo();
cms.Decrypt();

string plaintextMessage = cms.OutputMessage;