C#

JWE using "dir" Direct use of Shared Symmetric Key

See more JSON Web Encryption (JWE) Examples

Demonstrates how to create a JWE using the "dir" alg -- which is to directly use a shared symmetric key.

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..
Chilkat.JsonObject jweProtHdr = new Chilkat.JsonObject();
jweProtHdr.AppendString("alg","dir");
jweProtHdr.AppendString("enc","A128GCM");

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

// The JWE is to use 128-bit AES GCM encryption as specified by the "enc" parameter.
// Given that the "alg" = "dir", we are to directly specify the AES GCM key.
// (It is assumed that the decrypting side also has knowledge of the direct key to be used..)

// Our key will be these 16 hex bytes: 000102030405060708090A0B0C0D0E0F

// The SetWrappingKey method is also used for "dir" direct keys.
// However, if there are multiple recipients, they must all share the same CEK (Content Encryption Key),
// which is specified by calling SetWrappingKey with an index of 0.

int recipientIndex = 0;
jwe.SetWrappingKey(recipientIndex,"000102030405060708090A0B0C0D0E0F","hex");

// 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.
Chilkat.Jwe jwe2 = new Chilkat.Jwe();
success = jwe2.LoadJwe(strJwe);
if (success != true) {
    Debug.WriteLine(jwe2.LastErrorText);
    return;
}

jwe2.SetWrappingKey(0,"000102030405060708090A0B0C0D0E0F","hex");

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

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

// Sample output:
// eyJhbGciOiJkaXIiLCJlbmMiOiJBMTI4R0NNIn0..20HX5Huc7f1nQC4pBUtiCQ.axFZIxtZy5j0ifJQUzGXLKIpsBuxJA.eBrOC-NrsreN6JeGuOPk1g
// original text: 
// Live long and prosper.