(Swift) JWE using ECDH-ES+A256KW

See more JSON Web Encryption (JWE) Examples

{
    "kty": "EC",
    "d": "jZCffzVqJjryBH4EoaN0oD-TyLXrW2XHoDdIuPZnk8c",
    "use": "enc",
    "crv": "P-256",
    "kid": "evEK2thJMsWxBYRivXI8ykUf6n6zizLiLCGH3s58wKs",
    "x": "LOakgGvxWBsWbCPLY6Vq6OuBktIqG8POXFXe7ngQ2oM",
    "y": "voJvS6I-Mc4qqmEA_G2hLQqBck3a3vqaJbmzY7YPUD4",
    "alg": "ECDH-ES+A256KW"
}

Also shows how to decrypt.

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

func chilkatTest() {
    // This requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    var success: Bool

    // Create the following JSON:
    // {
    //     "kty": "EC",
    //     "d": "jZCffzVqJjryBH4EoaN0oD-TyLXrW2XHoDdIuPZnk8c",
    //     "use": "enc",
    //     "crv": "P-256",
    //     "kid": "evEK2thJMsWxBYRivXI8ykUf6n6zizLiLCGH3s58wKs",
    //     "x": "LOakgGvxWBsWbCPLY6Vq6OuBktIqG8POXFXe7ngQ2oM",
    //     "y": "voJvS6I-Mc4qqmEA_G2hLQqBck3a3vqaJbmzY7YPUD4",
    //     "alg": "ECDH-ES+A256KW"
    // }

    let json = CkoJsonObject()!
    json.update("kty", value: "EC")
    json.update("d", value: "jZCffzVqJjryBH4EoaN0oD-TyLXrW2XHoDdIuPZnk8c")
    json.update("use", value: "enc")
    json.update("crv", value: "P-256")
    json.update("kid", value: "evEK2thJMsWxBYRivXI8ykUf6n6zizLiLCGH3s58wKs")
    json.update("x", value: "LOakgGvxWBsWbCPLY6Vq6OuBktIqG8POXFXe7ngQ2oM")
    json.update("y", value: "voJvS6I-Mc4qqmEA_G2hLQqBck3a3vqaJbmzY7YPUD4")
    json.update("alg", value: "ECDH-ES+A256KW")

    let pubkey = CkoPublicKey()!

    success = pubkey.load(from: json.emit())
    if success == false {
        print("\(pubkey.lastErrorText!)")
        return
    }

    // Build our protected header:

    // 	{
    // 	  "alg": "ECDH-ES+A256KW",
    // 	  "enc": "A256GCM",
    // 	  "exp": 1621957030,
    // 	  "cty": "NJWT",
    // 	  "epk": {
    // 	    "kty": "EC",
    // 	    "x": "QLpJ_LpFx-6yJhsb4OvHwU1khLnviiOwYOvmf5clK7w"
    // 	    "y": "AJh7pJ3zZKDJkm8rbeG69GBooTosXJgSsvNFH0i3Vxnu"
    // 	    "crv": "BP-256"
    // 	  }
    // 	}

    // Use jwt only for getting the current date/time + 3600 seconds.
    let jwt = CkoJwt()!

    let jweProtHdr = CkoJsonObject()!
    jweProtHdr.update("alg", value: "ECDH-ES+A256KW")
    jweProtHdr.update("enc", value: "A256GCM")
    jweProtHdr.updateInt("exp", value: jwt.genNumericDate(3600).intValue)
    jweProtHdr.update("cty", value: "NJWT")
    jweProtHdr.update("epk.kty", value: "EC")
    jweProtHdr.update("epk.x", value: "LOakgGvxWBsWbCPLY6Vq6OuBktIqG8POXFXe7ngQ2oM")
    jweProtHdr.update("epk.y", value: "voJvS6I-Mc4qqmEA_G2hLQqBck3a3vqaJbmzY7YPUD4")
    jweProtHdr.update("epk.crv", value: "P-256")

    let jwe = CkoJwe()!
    jwe.setProtectedHeader(jweProtHdr)
    jwe.setPublicKey(0, pubKey: pubkey)

    var plainText: String? = "This is the text to be encrypted."
    var strJwe: String? = jwe.encrypt(plainText, charset: "utf-8")
    if jwe.lastMethodSuccess != true {
        print("\(jwe.lastErrorText!)")
        return
    }

    print("\(strJwe!)")

    // Let's decrypt...
    let privkey = CkoPrivateKey()!

    success = privkey.loadJwk(json.emit())
    if success == false {
        print("\(privkey.lastErrorText!)")
        return
    }

    let jwe2 = CkoJwe()!
    success = jwe2.load(strJwe)
    if success == false {
        print("\(jwe2.lastErrorText!)")
        return
    }

    jwe2.setPrivateKey(0, privKey: privkey)

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

    print("\(decryptedText!)")

}