Swift

JWE with DEFLATE Compression

See more JSON Web Encryption (JWE) Examples

Demonstrates how to DEFLATE ("zip") compress the JWE payload prior to encryption.

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.

    // Create some plaintext to be encrypted.
    // This example will demonstrate with and without DEFLATE (zip) compression.
    let sbPlainText = CkoStringBuilder()!
    var bCrLf: Bool = true
    var line: String? = "Live long and prosper."
    sbPlainText.appendLine(str: line, crlf: bCrLf)
    sbPlainText.appendLine(str: line, crlf: bCrLf)
    sbPlainText.appendLine(str: line, crlf: bCrLf)
    sbPlainText.appendLine(str: line, crlf: bCrLf)

    // The text to be encrypted:
    print("\(sbPlainText.getAsString()!)")

    let jwe = CkoJwe()!

    // Build the JWE Protected Header: {"alg":"A128KW","enc":"A128CBC-HS256","zip":"DEF"}
    // The "zip":"DEF" parameter indicates that the plaintext payload should
    // be compressed prior to encryption.
    let jweProtHdr = CkoJsonObject()!
    jweProtHdr.appendString(name: "alg", value: "A128KW")
    jweProtHdr.appendString(name: "enc", value: "A128CBC-HS256")
    jweProtHdr.appendString(name: "zip", value: "DEF")
    jwe.setProtectedHeader(json: jweProtHdr)

    // Set the AES key wrap key:
    var aesWrappingKey: String? = "GawgguFyGrWKav7AX4VKUg"
    jwe.setWrappingKey(index: 0, encodedKey: aesWrappingKey, encoding: "base64url")

    // Encrypt and return the JWE in sbJweCompressed:
    let sbJweCompressed = CkoStringBuilder()!
    success = jwe.encryptSb(contentSb: sbPlainText, charset: "utf-8", jweSb: sbJweCompressed)
    if success != true {
        print("\(jwe.lastErrorText!)")
        return
    }

    // Show the compressed JWE:
    print("\(sbJweCompressed.getAsString()!)")
    print("size of compressed JWE: \(sbJweCompressed.length.intValue)")

    // Now create a JWE without compression.
    jweProtHdr.delete(name: "zip")
    // Make sure to update the shared protected header:
    jwe.setProtectedHeader(json: jweProtHdr)

    let sbJweUncompressed = CkoStringBuilder()!
    success = jwe.encryptSb(contentSb: sbPlainText, charset: "utf-8", jweSb: sbJweUncompressed)
    if success != true {
        print("\(jwe.lastErrorText!)")
        return
    }

    // Show the uncompressed JWE:
    print("\(sbJweUncompressed.getAsString()!)")
    print("size of uncompressed JWE: \(sbJweUncompressed.length.intValue)")

    // Decrypting is the same whether compression is used or not.
    // The "zip" header in the JWE indicates that the payload should be 
    // automatically decompressed (inflated) after decrypting.
    let jwe2 = CkoJwe()!
    success = jwe2.loadSb(sb: sbJweCompressed)
    if success != true {
        print("\(jwe2.lastErrorText!)")
        return
    }

    // Set the AES wrap key.
    jwe2.setWrappingKey(index: 0, encodedKey: aesWrappingKey, encoding: "base64url")

    // Decrypt (also automatically decompresses).
    let sbOriginalText = CkoStringBuilder()!
    success = jwe2.decryptSb(index: 0, charset: "utf-8", contentSb: sbOriginalText)
    if success != true {
        print("\(jwe2.lastErrorText!)")
        return
    }

    print("original text from compressed JWE: ")
    print("\(sbOriginalText.getAsString()!)")

    // -----------------------------------------------------------
    // Do the same with the uncompressed JWE

    success = jwe2.loadSb(sb: sbJweUncompressed)
    if success != true {
        print("\(jwe2.lastErrorText!)")
        return
    }

    // Set the AES wrap key.
    jwe2.setWrappingKey(index: 0, encodedKey: aesWrappingKey, encoding: "base64url")

    // Decrypt.
    sbOriginalText.clear()
    success = jwe2.decryptSb(index: 0, charset: "utf-8", contentSb: sbOriginalText)
    if success != true {
        print("\(jwe2.lastErrorText!)")
        return
    }

    print("original text from uncompressed JWE: ")
    print("\(sbOriginalText.getAsString()!)")

    // ------------------------------------------------
    // The output of this example is:
    // (Note: Your output data will be different because the content encryption key is randomly generated.)

    // eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2IiwiemlwIjoiREVGIn0.xuW-pEAIdEUFnk10m8ocursvktO8Of9ByCCAt6LgKkkOtCWCUn1kQw.zpGj-9WVni3cQxyOuZbcGA.0hzP1myua3oYpUHwCIY_3edBUREbUpLaX6wYuJduOdI.Ppc6aEO3y3B8BJ1FKMPjlA
    // size of compressed JWE: 212
    // eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.N4KeyC7nnSFkieJOyE24_zKeuV_m7v5UKoJb1TgV4Yc_r2RzUPNvyA.6AEdyXSCKx-iMmUJyypSLg.QpixfyrwhGpmwUDp623viik4smPav7vwPLiC2r-V-jwnSfEH3mxWu6DbrIz3mixaqATwynmEBzVPxvS9jTXpSAGCnniib4_0WoPl3r_wF5tlsKOEe--jpNso-DKd1Tp8jJxj3JkFWt3IRnUUKGj17g.sBfDwFc5fzpaI-UW8-SW4g
    // size of uncompressed JWE: 303
    // original text from compressed JWE: 
    // Live long and prosper.
    // Live long and prosper.
    // Live long and prosper.
    // Live long and prosper.
    // 
    // original text from uncompressed JWE: 
    // Live long and prosper.
    // Live long and prosper.
    // Live long and prosper.
    // Live long and prosper.
    // 

}