(JavaScript) JWE Using Flattened JWE JSON Serialization

This example duplicates the example A.5 in RFC 7516 for JSON Web Encryption (JWE).

This example demonstrates using the flattened JWE JSON Serialization syntax. This example demonstrates the capability for encrypting the plaintext to a single recipient in a flattened JSON structure.

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

Note

This example is intended for running within a Chilkat.Js embedded JavaScript engine. All Chilkat JavaScript examples require Chilkat v11.4.0 or greater.

var 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.

var plaintext = "Live long and prosper.";

var jwe = new CkJwe();

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

// We have a single recipient that uses AES Key Wrap to encrypt the CEK.
// 
//      {"alg":"A128KW","kid":"7"}

var jweRecipientHdr = new CkJsonObject();
jweRecipientHdr.AppendString("alg","A128KW");
jweRecipientHdr.AppendString("kid","7");
var recipientIndex = 0;
jwe.SetRecipientHeader(recipientIndex,jweRecipientHdr);

// Set the Shared Unprotected Header:  {"jku":"https://server.example.com/keys.jwks"}
var jweUnprotHdr = new CkJsonObject();
jweUnprotHdr.AppendString("jku","https://server.example.com/keys.jwks");
jwe.SetUnprotectedHeader(jweUnprotHdr);

// Set the AES key wrapping key.
var aesWrappingKey = "GawgguFyGrWKav7AX4VKUg";
recipientIndex = 0;
jwe.SetWrappingKey(recipientIndex,aesWrappingKey,"base64url");

// OK.. everything has been specified.
// Now encrypt.  
// Indicate that we prefer the flattened JSON serialization.
jwe.PreferFlattened = true;
var strJwe = jwe.Encrypt(plaintext,"utf-8");
if (jwe.LastMethodSuccess !== true) {
    console.log(jwe.LastErrorText);
    return;
}

// The JWE is produced in the most compact form possible (a single line).
// Let's load it into a JSON object and examine in a non-compact pretty-printed format:
var jsonTemp = new CkJsonObject();
jsonTemp.Load(strJwe);
jsonTemp.EmitCompact = false;
console.log(jsonTemp.Emit());

// The JWE looks like this:
// (Note: Because of random values used in the encryption process, your encrypted results will be different.)

// 	{ 
// 	  "protected": "eyJlbmMiOiJBMTI4Q0JDLUhTMjU2In0",
// 	  "unprotected": { 
// 	    "jku": "https://server.example.com/keys.jwks"
// 	  },
// 	  "header": { 
// 	    "alg": "A128KW",
// 	    "kid": "7"
// 	  },
// 	  "encrypted_key": "FW7z9VxOvnF2ClicvUT4HTeqcdyh90C6qytfEFJsOb77FOwTfYrc3w",
// 	  "iv": "O6Ly5-eML3zTs-_fNX3D5Q",
// 	  "ciphertext": "Q8NLmeac9JhLh0CQPuG_7D9wVDb55eToCh0g5-FQ4M0",
// 	  "tag": "slzlo6-J9C7wSDF4dh_kBg"
// 	} 

// Now decrypt......................................

// First, load the JWE..
var jwe2 = new CkJwe();
success = jwe2.LoadJwe(strJwe);
if (success !== true) {
    console.log(jwe2.LastErrorText);
    return;
}

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

// Decrypt
var originalPlaintext = jwe2.Decrypt(recipientIndex,"utf-8");
if (jwe2.LastMethodSuccess !== true) {
    console.log(jwe2.LastErrorText);
    return;
}

console.log("original text decrypted with AES key wrap key: ");
console.log(originalPlaintext);

// ---------------------------------------------------------------------------------
// It should also be possible to decrypt the flattened JWE as shown in RFC 7516, Appendix A.5
// because it was produced using the same key.

var sbJwe = new CkStringBuilder();

sbJwe.Append("{");
sbJwe.Append("\"protected\":");
sbJwe.Append("\"eyJlbmMiOiJBMTI4Q0JDLUhTMjU2In0\",");
sbJwe.Append("\"unprotected\":");
sbJwe.Append("{\"jku\":\"https://server.example.com/keys.jwks\"},");
sbJwe.Append("\"header\":");
sbJwe.Append("{\"alg\":\"A128KW\",\"kid\":\"7\"},");
sbJwe.Append("\"encrypted_key\":");
sbJwe.Append("\"6KB707dM9YTIgHtLvtgWQ8mKwboJW3of9locizkDTHzBC2IlrT1oOQ\",");
sbJwe.Append("\"iv\":");
sbJwe.Append("\"AxY8DCtDaGlsbGljb3RoZQ\",");
sbJwe.Append("\"ciphertext\":");
sbJwe.Append("\"KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY\",");
sbJwe.Append("\"tag\":");
sbJwe.Append("\"Mz-VPPyU4RlcuYv1IwIvzw\"");
sbJwe.Append("}");

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

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

originalPlaintext = jwe2.Decrypt(recipientIndex,"utf-8");
if (jwe2.LastMethodSuccess !== true) {
    console.log(jwe2.LastErrorText);
    return;
}

console.log("original text decrypted from published flattened JWE: ");
console.log(originalPlaintext);

// The output:

// original text decrypted with AES key wrap key: 
// Live long and prosper.
// original text decrypted from published flattened JWE: 
// Live long and prosper.