Swift

JWE using PBES2 Key Wrapping

See more JSON Web Encryption (JWE) Examples

Demonstrates how to create and decrypt a JWE that using PBES2 key wrapping.

This example demonstrates PBES2 with HMAC SHA-256 and A128KW wrapping. It is also possible to do the following by simply changing the "alg" parameter:

• PBES2 with HMAC SHA-384 and A192KW wrapping
• PBES2 with HMAC SHA-512 and A256KW wrapping

Note: This example requires Chilkat v9.5.0.66 or greater.

Swift

func chilkatTest() {
    var success: Bool = false

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

    // Note: This example requires Chilkat v9.5.0.66 or greater.

    var plaintext: String? = "Live long and prosper."

    let jwe = CkoJwe()!

    // First build the JWE Protected Header..
    let jweProtHdr = CkoJsonObject()!
    jweProtHdr.appendString(name: "alg", value: "PBES2-HS256+A128KW")
    jweProtHdr.appendString(name: "enc", value: "A128GCM")

    // PBES2 requires two additional parameters:
    // 1) A random salt parameter ("p2s") containing 8 or more bytes in base64url format.
    // 2) An iteration count parameter ("p2c").  A minimum count of 1000 is recommended.
    //    The iteration count is intended to make the PBES2 computation more expensive (time consuming)
    //    to prevent brute-force attacks.
    let prng = CkoPrng()!
    jweProtHdr.appendString(name: "p2s", value: prng.genRandom(numBytes: 16, encoding: "base64url"))
    jweProtHdr.appendString(name: "p2c", value: "1000")

    print("JWE Protected Header: \(jweProtHdr.emit()!)")
    print("--")

    // Don't forget to actually provide the protected header to the JWE object:
    jwe.setProtectedHeader(json: jweProtHdr)

    // Set the PBES2 password
    var recipientIndex: Int = 0
    jwe.setPassword(index: recipientIndex, password: "top secret")

    // Encrypt and return the JWE:
    var strJwe: String? = jwe.encrypt(content: plaintext, charset: "utf-8")
    if jwe.lastMethodSuccess != true {
        print("\(jwe.lastErrorText!)")
        return
    }

    // Show the JWE we just created:
    print("\(strJwe!)")

    // Decrypt the JWE.
    let jwe2 = CkoJwe()!
    success = jwe2.load(jwe: strJwe)
    if success != true {
        print("\(jwe2.lastErrorText!)")
        return
    }

    // Set the PBES2 password
    jwe2.setPassword(index: recipientIndex, password: "top secret")

    // Decrypt.
    var originalPlaintext: String? = jwe2.decrypt(index: 0, charset: "utf-8")
    if jwe2.lastMethodSuccess != true {
        print("\(jwe2.lastErrorText!)")
        return
    }

    print("original text: ")
    print("\(originalPlaintext!)")

    // Sample output:

    // JWE Protected Header: {"alg":"PBES2-HS256+A128KW","enc":"A128GCM","p2s":"z39rTEfRy1T1Yn_D1mZRlg","p2c":"1000"}
    // --
    // eyJhbGciOiJQQkVTMi1IUzI1NitBMTI4S1ciLCJlbmMiOiJBMTI4R0NNIiwicDJzIjoiejM5clRFZlJ5MVQxWW5fRDFtWlJsZyIsInAyYyI6IjEwMDAifQ.koYt6PrFmYwcwdcT7ZcvXHA1d-Xez5h4.luGlbvEnZp-7IsBOj42Yhw.YMTcfLf8Qe4zazozGV2OAu3cUdQ8Kg.rWub47ESWkc6IqZJTvSTmg
    // original text: 
    // Live long and prosper.

}