(Unicode C++) JWE using AES Key Wrap and AES_128_CBC_HMAC_SHA_256

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.

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#include <CkJweW.h>
#include <CkJsonObjectW.h>
#include <CkStringBuilderW.h>

void ChilkatSample(void)
    {
    // 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.

    bool success;
    const wchar_t *plaintext = L"Live long and prosper.";

    CkJweW jwe;

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

    wprintf(L"JWE Protected Header: %s\n",jweProtHdr.emit());
    wprintf(L"--\n");

    // 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:
    const wchar_t *aesWrappingKey = L"GawgguFyGrWKav7AX4VKUg";
    jwe.SetWrappingKey(0,aesWrappingKey,L"base64url");

    // Encrypt and return the JWE:
    const wchar_t *strJwe = jwe.encrypt(plaintext,L"utf-8");
    if (jwe.get_LastMethodSuccess() != true) {
        wprintf(L"%s\n",jwe.lastErrorText());
        return;
    }

    // Show the JWE we just created:
    wprintf(L"%s\n",strJwe);

    // Decrypt the JWE that was just produced.
    // 1) Load the JWE.
    // 2) Set the AES wrapping key.
    // 3) Decrypt.
    CkJweW jwe2;
    success = jwe2.LoadJwe(strJwe);
    if (success != true) {
        wprintf(L"%s\n",jwe2.lastErrorText());
        return;
    }

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

    // Decrypt.
    const wchar_t *originalPlaintext = jwe2.decrypt(0,L"utf-8");
    if (jwe2.get_LastMethodSuccess() != true) {
        wprintf(L"%s\n",jwe2.lastErrorText());
        return;
    }

    wprintf(L"original text: \n");
    wprintf(L"%s\n",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.

    CkStringBuilderW sbJwe;
    sbJwe.Append(L"eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.");
    sbJwe.Append(L"6KB707dM9YTIgHtLvtgWQ8mKwboJW3of9locizkDTHzBC2IlrT1oOQ.");
    sbJwe.Append(L"AxY8DCtDaGlsbGljb3RoZQ.");
    sbJwe.Append(L"KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY.");
    sbJwe.Append(L"U0m_YmjN04DJvceFICbCVQ");

    success = jwe2.LoadJweSb(sbJwe);
    if (success != true) {
        wprintf(L"%s\n",jwe2.lastErrorText());
        return;
    }

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

    // Decrypt.
    originalPlaintext = jwe2.decrypt(0,L"utf-8");
    if (jwe2.get_LastMethodSuccess() != true) {
        wprintf(L"%s\n",jwe2.lastErrorText());
        return;
    }

    wprintf(L"%s\n",originalPlaintext);
    }