(Swift) RSA Encrypt String to Encoded Result and Reverse

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Demonstrates how to RSA encrypt a string to a base64 encoded result, and the reverse.

Chilkat Downloads for the Swift Programming Language MAC OS X (Cocoa) Objective-C/Swift Libs iOS Objective-C/Swift Libs

func chilkatTest() {
    // The RSA public key is used for encryption, and the private key for decryption.

    // The public key's role is to make encryption accessible to anyone while ensuring that
    // only the private key holder can decrypt the messages.
    // The public key is designed to be widely distributed so anyone can use it to encrypt messages
    // intended for the owner of the private key.

    // Load our 2048-bit RSA public key.
    let pubKey = CkoPublicKey()!
    // In all Chilkat methods expecting a path, you pass either absolute or relative paths.
    var success: Bool = pubKey.load(fromFile: "rsaKeys/myTestRsaPublic.pem")
    if success == false {
        print("\(pubKey.lastErrorText!)")
        return
    }

    let rsa = CkoRsa()!

    // Tell RSA to use the public key.
    rsa.importPublicKeyObj(pubKey)

    // RSA encryption is for small amounts of data, on the order of 200 bytes or less.
    // The maximum number of bytes that can be RSA encrypted depends
    // on the RSA key size and padding scheme (OAEP padding vs PKCS#1 v1.5 padding).
    // For specific limits, see: RSA Encryption Maximum Number of Bytes

    // Encrypt the utf-8 byte representation of the string.
    rsa.charset = "utf-8"
    rsa.encodingMode = "base64"

    // Be Careful when Using non-us-ascii String Literals in Source Code
    var encryptedB64: String? = rsa.encryptStringENC("Élève français dîne à côté d’un café où l’on sert déjà du gâteau au chocolat et des éclairs délicieux", bUsePrivateKey: false)

    // ------------------------------------------------------------------------------------------------------------------------
    // Let's decrypt, which requires the matching private key...

    // Load the matching 2048-bit RSA private key.
    let privKey = CkoPrivateKey()!
    var password: String? = "secret"
    success = privKey.loadAnyFormatFile("rsaKeys/myTestRsaPrivate.pem", password: password)
    if success == false {
        print("\(privKey.lastErrorText!)")
        return
    }

    // Tell the RSA object to use the private key.
    rsa.importPrivateKeyObj(privKey)

    // Indicate that after decrypting the resultant decrypted bytes contains the utf-8 byte representation of the text.
    rsa.charset = "utf-8"
    rsa.encodingMode = "base64"
    var originalText: String? = rsa.decryptStringENC(encryptedB64, bUsePrivateKey: true)
    if success == false {
        print("\(rsa.lastErrorText!)")
        return
    }

    print("Original text = \(originalText!)")
    print("Success.")

}