MIME S/MIME Encryption Algorithm Properties

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Demonstrates the properties that control S/MIME encryption: Pkcs7CryptAlg (the symmetric content-encryption algorithm), Pkcs7KeyLength (the content-encryption key length in bits), OaepPadding (whether RSAES-OAEP key transport is used instead of RSAES-PKCS1-v1_5), and the OAEP hash settings OaepHash and OaepMgfHash. The properties are configured before calling Encrypt.

bool success = false;

Chilkat.Mime mime = new Chilkat.Mime();
success = mime.SetBodyFromPlainText("This message will be encrypted.");
if (success == false) {
    Debug.WriteLine(mime.LastErrorText);
    return;
}

//  Pkcs7CryptAlg is the symmetric content-encryption algorithm.  Supported values are aes, aes-gcm,
//  des, 3des, and rc2.  The default is aes.
mime.Pkcs7CryptAlg = "aes";

//  Pkcs7KeyLength is the content-encryption key length in bits.  The default is 128.
mime.Pkcs7KeyLength = 256;

//  OaepPadding selects the RSA key-transport padding.  The default is false (RSAES-PKCS1-v1_5).
//  Set true to use RSAES-OAEP, in which case the OAEP hash settings apply.
mime.OaepPadding = true;
mime.OaepHash = "sha256";
mime.OaepMgfHash = "sha256";

//  Load the recipient certificate (public key is sufficient for encrypting).
Chilkat.Cert cert = new Chilkat.Cert();
success = cert.LoadFromFile("qa_data/recipient.cer");
if (success == false) {
    Debug.WriteLine(cert.LastErrorText);
    return;
}

//  Encrypt using the algorithm settings configured above.
success = mime.Encrypt(cert);
if (success == false) {
    Debug.WriteLine(mime.LastErrorText);
    return;
}

Debug.WriteLine("Encrypted with " + mime.Pkcs7CryptAlg + " " + Convert.ToString(mime.Pkcs7KeyLength) + "-bit key.");