Sample code for 30+ languages & platforms
Swift

Send Encrypted Email with a Selected Algorithm (AES, 3DES, etc.)

Sends an encrypted email using the recipient's digital certificate from a .cer file, and chooses 3DES for the encryption algorithm. (It is also possible to send AES encrypted email w/ 128-bit, 192-bit, or 256-bit encryption simply by setting the Pkcs7CryptAlg and Pkcs7KeyLength properties.)

Chilkat Swift Downloads

Swift

func chilkatTest() {
    var success: Bool = false

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // The mailman object is used for sending and receiving email.
    let mailman = CkoMailMan()!

    // Set the SMTP server.
    mailman.smtpHost = "smtp.mymailserver.com"

    // Load the .cer file into a certificate object.
    // When sending S/MIME encrypted email, it is the recipient's
    // certificate that is used for encryption.  Only the public key
    // is needed to encrypt.  The recipient is the only
    // one possessing the private key, and therefore is the only
    // one able to decrypt.
    let cert = CkoCert()!
    success = cert.load(fromFile: "cknotes.cer")
    if success != true {
        print("\(cert.lastErrorText!)")
        return
    }

    // Create a new email object
    let email = CkoEmail()!

    email.subject = "This email is encrypted"
    email.body = "This is a digitally encrypted mail"
    email.from = "Chilkat Support <support@chilkatsoft.com>"
    success = email.add(to: "Chilkat Blog", emailAddress: "admin@cknotes.com")

    // Indicate that the email is to be sent encrypted.
    email.sendEncrypted = true

    // Specify the certificate to be used for encryption.
    success = email.setEncryptCert(cert: cert)

    // If desired, specify the encryption algorithm to be used.
    // The Pkcs7CryptAlg property can be set to "aes", "des", "3des", or "rc2"
    email.pkcs7CryptAlg = "3des"

    // If desired, set the key length (in bits) for the encryption algorithm:
    // The possible values allowed depend on the Pkcs7CryptAlg property. 
    // For "aes", the key length may be 128, 192, or 256. 
    // For "3des" the key length must be 192. 
    // For "des" the key length must be 40. 
    // For "rc2" the key length can be 40, 56, 64, or 128.
    email.pkcs7KeyLength = 192

    success = mailman.sendEmail(email: email)
    if success != true {
        print("\(mailman.lastErrorText!)")
    }
    else {
        print("Mail Sent!")
    }


}