(MFC) JWE using A256GCMKW

This example demonstrates creating a JCE with AES GCM key wrap.

Chilkat C/C++ Library Downloads MS Visual C/C++ Libs

See Also: Using MFC CString in Chilkat

#include <CkJwe.h>
#include <CkJsonObject.h>
#include <CkPrng.h>

void ChilkatSample(void)
    {
    CkString strOut;

    // This requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    bool success;
    const char *plaintext = "My text to enrypt";

    CkJwe jwe;

    // First build the JWE Protected Header: 

    //         {
    //             "alg": "A256GCMKW",
    //             "kid": "18ec08e1-bfa9-4d95-b205-2b4dd1d4321d",
    //             "tag": "kfPduVQ3T3H6vnewt--ksw",
    //             "iv": "KkYT0GX_2jHlfqN_",
    //             "enc": "A128CBC-HS256"
    //         }

    CkJsonObject jweProtHdr;
    jweProtHdr.AppendString("alg","A256GCMKW");
    // kid is optional
    jweProtHdr.AppendString("kid","18ec08e1-bfa9-4d95-b205-2b4dd1d4321d");
    // tag is optional
    jweProtHdr.AppendString("tag","kfPduVQ3T3H6vnewt--ksw");
    jweProtHdr.AppendString("enc","A256GCM");
    // the iv should be 16 random chars.
    CkPrng prng;
    jweProtHdr.AppendString("iv",prng.randomString(16,true,true,true));
    jwe.SetProtectedHeader(jweProtHdr);

    strOut.append("JWE Protected Header: ");
    strOut.append(jweProtHdr.emit());
    strOut.append("\r\n");
    strOut.append("--");
    strOut.append("\r\n");

    // Given that we have 256-bit AES, our key should be 32 bytes.
    // The ascii string here is 32 bytes, therefore the 2nd arg is "ascii" to use these
    // ascii chars directly as the key.
    const char *aesWrappingKey = "2baf4f730f5e4542b428593ef9cceb0e";
    jwe.SetWrappingKey(0,aesWrappingKey,"ascii");

    // Encrypt and return the JWE:
    const char *strJwe = jwe.encrypt(plaintext,"utf-8");
    if (jwe.get_LastMethodSuccess() != true) {
        strOut.append(jwe.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Show the JWE we just created:
    strOut.append(strJwe);
    strOut.append("\r\n");

    // Decrypt the JWE that was just produced.
    // 1) Load the JWE.
    // 2) Set the AES wrapping key.
    // 3) Decrypt.
    CkJwe jwe2;
    success = jwe2.LoadJwe(strJwe);
    if (success != true) {
        strOut.append(jwe2.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Set the AES wrap key.  Important to use "ascii"
    jwe2.SetWrappingKey(0,aesWrappingKey,"ascii");

    // Decrypt.
    const char *originalPlaintext = jwe2.decrypt(0,"utf-8");
    if (jwe2.get_LastMethodSuccess() != true) {
        strOut.append(jwe2.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    strOut.append("original text: ");
    strOut.append("\r\n");
    strOut.append(originalPlaintext);
    strOut.append("\r\n");


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }