C#

JWE using AES Key Wrap and AES_128_CBC_HMAC_SHA_256

See more JSON Web Encryption (JWE) Examples

This example duplicates the example A.3 in RFC 7516 for JSON Web Encryption (JWE).

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

C#

bool success = 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.

string plaintext = "Live long and prosper.";

Chilkat.Jwe jwe = new Chilkat.Jwe();

//  First build the JWE Protected Header: {"alg":"A128KW","enc":"A128CBC-HS256"}
Chilkat.JsonObject jweProtHdr = new Chilkat.JsonObject();
jweProtHdr.AppendString("alg","A128KW");
jweProtHdr.AppendString("enc","A128CBC-HS256");
jwe.SetProtectedHeader(jweProtHdr);

Debug.WriteLine("JWE Protected Header: " + jweProtHdr.Emit());
Debug.WriteLine("--");

//  The example A.3 in RFC 7516 uses the following 128-bit AES key,
//  specified in JWK (JSON Web Key) format:
//       {"kty":"oct",
//        "k":"GawgguFyGrWKav7AX4VKUg"
//       }
//  This is just a way of saying: The key type ("kty") is 
//  a bunch of octets ("k") in base64url encoding.
//  We can simply set the AES wrapping key like this:
string aesWrappingKey = "GawgguFyGrWKav7AX4VKUg";
jwe.SetWrappingKey(0,aesWrappingKey,"base64url");

//  Encrypt and return the JWE:
string strJwe = jwe.Encrypt(plaintext,"utf-8");
if (jwe.LastMethodSuccess != true) {
    Debug.WriteLine(jwe.LastErrorText);
    return;
}

//  Show the JWE we just created:
Debug.WriteLine(strJwe);

//  Decrypt the JWE that was just produced.
//  1) Load the JWE.
//  2) Set the AES wrapping key.
//  3) Decrypt.
Chilkat.Jwe jwe2 = new Chilkat.Jwe();
success = jwe2.LoadJwe(strJwe);
if (success != true) {
    Debug.WriteLine(jwe2.LastErrorText);
    return;
}

//  Set the AES wrap key.
jwe2.SetWrappingKey(0,aesWrappingKey,"base64url");

//  Decrypt.
string originalPlaintext = jwe2.Decrypt(0,"utf-8");
if (jwe2.LastMethodSuccess != true) {
    Debug.WriteLine(jwe2.LastErrorText);
    return;
}

Debug.WriteLine("original text: ");
Debug.WriteLine(originalPlaintext);

//  ---------------------------------------------------------------------------------
//  It should also be possible to decrypt the JWE as shown in RFC 7516, Appendix A.3.7
//  because it was produced using the same AES Wrap key.

Chilkat.StringBuilder sbJwe = new Chilkat.StringBuilder();
sbJwe.Append("eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.");
sbJwe.Append("6KB707dM9YTIgHtLvtgWQ8mKwboJW3of9locizkDTHzBC2IlrT1oOQ.");
sbJwe.Append("AxY8DCtDaGlsbGljb3RoZQ.");
sbJwe.Append("KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY.");
sbJwe.Append("U0m_YmjN04DJvceFICbCVQ");

success = jwe2.LoadJweSb(sbJwe);
if (success != true) {
    Debug.WriteLine(jwe2.LastErrorText);
    return;
}

jwe2.SetWrappingKey(0,aesWrappingKey,"base64url");

//  Decrypt.
originalPlaintext = jwe2.Decrypt(0,"utf-8");
if (jwe2.LastMethodSuccess != true) {
    Debug.WriteLine(jwe2.LastErrorText);
    return;
}

Debug.WriteLine(originalPlaintext);