(C) JWE using RSAES-PKCS1-v1_5 and AES_128_CBC_HMAC_SHA_256

This example duplicates the example A.2 in RFC 7516 for JSON Web Encryption (JWE).

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

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#include <C_CkJsonObject.h>
#include <C_CkStringBuilder.h>
#include <C_CkPrivateKey.h>
#include <C_CkPublicKey.h>
#include <C_CkJwe.h>

void ChilkatSample(void)
    {
    BOOL success;
    const char *plaintext;
    HCkJsonObject jweProtHdr;
    HCkStringBuilder sbJwk;
    HCkPrivateKey rsaPrivKey;
    HCkPublicKey rsaPubKey;
    HCkJwe jwe;
    const char *strJwe;
    HCkJwe jwe2;
    const char *originalPlaintext;
    HCkStringBuilder sbJwe;

    // 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.

    plaintext = "Live long and prosper.";

    // First build the JWE Protected Header.
    // We want to build this: {"alg":"RSA1_5","enc":"A128CBC-HS256"}
    jweProtHdr = CkJsonObject_Create();
    CkJsonObject_AppendString(jweProtHdr,"alg","RSA1_5");
    CkJsonObject_AppendString(jweProtHdr,"enc","A128CBC-HS256");
    printf("JWE Protected Header: %s\n",CkJsonObject_emit(jweProtHdr));
    printf("--\n");

    // The specific RSA key used in the A.2 example is the following JWK:
    sbJwk = CkStringBuilder_Create();
    CkStringBuilder_Append(sbJwk,"{\"kty\":\"RSA\",");
    CkStringBuilder_Append(sbJwk,"\"n\":\"sXchDaQebHnPiGvyDOAT4saGEUetSyo9MKLOoWFsueri23bOdgWp4Dy1Wl");
    CkStringBuilder_Append(sbJwk,"UzewbgBHod5pcM9H95GQRV3JDXboIRROSBigeC5yjU1hGzHHyXss8UDpre");
    CkStringBuilder_Append(sbJwk,"cbAYxknTcQkhslANGRUZmdTOQ5qTRsLAt6BTYuyvVRdhS8exSZEy_c4gs_");
    CkStringBuilder_Append(sbJwk,"7svlJJQ4H9_NxsiIoLwAEk7-Q3UXERGYw_75IDrGA84-lA_-Ct4eTlXHBI");
    CkStringBuilder_Append(sbJwk,"Y2EaV7t7LjJaynVJCpkv4LKjTTAumiGUIuQhrNhZLuF_RJLqHpM2kgWFLU");
    CkStringBuilder_Append(sbJwk,"7-VTdL1VbC2tejvcI2BlMkEpk1BzBZI0KQB0GaDWFLN-aEAw3vRw\",");
    CkStringBuilder_Append(sbJwk,"\"e\":\"AQAB\",");
    CkStringBuilder_Append(sbJwk,"\"d\":\"VFCWOqXr8nvZNyaaJLXdnNPXZKRaWCjkU5Q2egQQpTBMwhprMzWzpR8Sxq");
    CkStringBuilder_Append(sbJwk,"1OPThh_J6MUD8Z35wky9b8eEO0pwNS8xlh1lOFRRBoNqDIKVOku0aZb-ry");
    CkStringBuilder_Append(sbJwk,"nq8cxjDTLZQ6Fz7jSjR1Klop-YKaUHc9GsEofQqYruPhzSA-QgajZGPbE_");
    CkStringBuilder_Append(sbJwk,"0ZaVDJHfyd7UUBUKunFMScbflYAAOYJqVIVwaYR5zWEEceUjNnTNo_CVSj");
    CkStringBuilder_Append(sbJwk,"-VvXLO5VZfCUAVLgW4dpf1SrtZjSt34YLsRarSb127reG_DUwg9Ch-Kyvj");
    CkStringBuilder_Append(sbJwk,"T1SkHgUWRVGcyly7uvVGRSDwsXypdrNinPA4jlhoNdizK2zF2CWQ\",");
    CkStringBuilder_Append(sbJwk,"\"p\":\"9gY2w6I6S6L0juEKsbeDAwpd9WMfgqFoeA9vEyEUuk4kLwBKcoe1x4HG68");
    CkStringBuilder_Append(sbJwk,"ik918hdDSE9vDQSccA3xXHOAFOPJ8R9EeIAbTi1VwBYnbTp87X-xcPWlEP");
    CkStringBuilder_Append(sbJwk,"krdoUKW60tgs1aNd_Nnc9LEVVPMS390zbFxt8TN_biaBgelNgbC95sM\",");
    CkStringBuilder_Append(sbJwk,"\"q\":\"uKlCKvKv_ZJMVcdIs5vVSU_6cPtYI1ljWytExV_skstvRSNi9r66jdd9-y");
    CkStringBuilder_Append(sbJwk,"BhVfuG4shsp2j7rGnIio901RBeHo6TPKWVVykPu1iYhQXw1jIABfw-MVsN");
    CkStringBuilder_Append(sbJwk,"-3bQ76WLdt2SDxsHs7q7zPyUyHXmps7ycZ5c72wGkUwNOjYelmkiNS0\",");
    CkStringBuilder_Append(sbJwk,"\"dp\":\"w0kZbV63cVRvVX6yk3C8cMxo2qCM4Y8nsq1lmMSYhG4EcL6FWbX5h9yuv");
    CkStringBuilder_Append(sbJwk,"ngs4iLEFk6eALoUS4vIWEwcL4txw9LsWH_zKI-hwoReoP77cOdSL4AVcra");
    CkStringBuilder_Append(sbJwk,"Hawlkpyd2TWjE5evgbhWtOxnZee3cXJBkAi64Ik6jZxbvk-RR3pEhnCs\",");
    CkStringBuilder_Append(sbJwk,"\"dq\":\"o_8V14SezckO6CNLKs_btPdFiO9_kC1DsuUTd2LAfIIVeMZ7jn1Gus_Ff");
    CkStringBuilder_Append(sbJwk,"7B7IVx3p5KuBGOVF8L-qifLb6nQnLysgHDh132NDioZkhH7mI7hPG-PYE_");
    CkStringBuilder_Append(sbJwk,"odApKdnqECHWw0J-F0JWnUd6D2B_1TvF9mXA2Qx-iGYn8OVV1Bsmp6qU\",");
    CkStringBuilder_Append(sbJwk,"\"qi\":\"eNho5yRBEBxhGBtQRww9QirZsB66TrfFReG_CcteI1aCneT0ELGhYlRlC");
    CkStringBuilder_Append(sbJwk,"tUkTRclIfuEPmNsNDPbLoLqqCVznFbvdB7x-Tl-m0l_eFTj2KiqwGqE9PZ");
    CkStringBuilder_Append(sbJwk,"B9nNTwMVvH3VRRSLWACvPnSiwP8N5Usy-WRXS-V7TbpxIhvepTfE0NNo\"");
    CkStringBuilder_Append(sbJwk,"}");

    // Load this JWK into a Chilkat private key object.
    rsaPrivKey = CkPrivateKey_Create();
    success = CkPrivateKey_LoadJwk(rsaPrivKey,CkStringBuilder_getAsString(sbJwk));
    if (success != TRUE) {
        printf("%s\n",CkPrivateKey_lastErrorText(rsaPrivKey));
        CkJsonObject_Dispose(jweProtHdr);
        CkStringBuilder_Dispose(sbJwk);
        CkPrivateKey_Dispose(rsaPrivKey);
        return;
    }

    // The public key is used to encrypt (i.e. create the JWE), 
    // and the private key is used to decrypt.
    // The RSA public key is simply a subset of the private key.  The RSA public key
    // is composed of the "n" and "e" members shown above.  These are also known as the
    // modulus and exponent.
    // We can simply get the public key object from the private key object
    rsaPubKey = CkPrivateKey_GetPublicKey(rsaPrivKey);

    // Create the JWE...
    jwe = CkJwe_Create();
    CkJwe_SetProtectedHeader(jwe,jweProtHdr);
    CkJwe_SetPublicKey(jwe,0,rsaPubKey);
    CkPublicKey_Dispose(rsaPubKey);

    strJwe = CkJwe_encrypt(jwe,plaintext,"utf-8");
    if (CkJwe_getLastMethodSuccess(jwe) != TRUE) {
        printf("%s\n",CkJwe_lastErrorText(jwe));
        CkJsonObject_Dispose(jweProtHdr);
        CkStringBuilder_Dispose(sbJwk);
        CkPrivateKey_Dispose(rsaPrivKey);
        CkJwe_Dispose(jwe);
        return;
    }

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

    // Note: The RSA PKCS1_V1_5 padding uses random value, and the results
    // will be different each time.  However, each result should be successfully
    // decrypting if using the correct RSA private key.

    // Let's decrypt the JWE that was just produced.
    // Do the following to decrypt a JWE:
    // 1) Load the JWE.
    // 2) Set the private key for decryption.
    // 3) Decrypt.
    jwe2 = CkJwe_Create();
    success = CkJwe_LoadJwe(jwe2,strJwe);
    if (success != TRUE) {
        printf("%s\n",CkJwe_lastErrorText(jwe2));
        CkJsonObject_Dispose(jweProtHdr);
        CkStringBuilder_Dispose(sbJwk);
        CkPrivateKey_Dispose(rsaPrivKey);
        CkJwe_Dispose(jwe);
        CkJwe_Dispose(jwe2);
        return;
    }

    // Provide the RSA private key for decryption.
    // (The JWE was encrypted for a single recipient at index 0.)
    CkJwe_SetPrivateKey(jwe2,0,rsaPrivKey);

    // Decrypt.
    originalPlaintext = CkJwe_decrypt(jwe2,0,"utf-8");
    if (CkJwe_getLastMethodSuccess(jwe2) != TRUE) {
        printf("%s\n",CkJwe_lastErrorText(jwe2));
        CkJsonObject_Dispose(jweProtHdr);
        CkStringBuilder_Dispose(sbJwk);
        CkPrivateKey_Dispose(rsaPrivKey);
        CkJwe_Dispose(jwe);
        CkJwe_Dispose(jwe2);
        return;
    }

    printf("original text: \n");
    printf("%s\n",originalPlaintext);

    // ---------------------------------------------------------------------------------
    // It should also be possible to decrypt the JWE as shown in RFC 7516, Appendix A.2.7
    // because it was produced using the same RSA key.

    sbJwe = CkStringBuilder_Create();
    CkStringBuilder_Append(sbJwe,"eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.");
    CkStringBuilder_Append(sbJwe,"UGhIOguC7IuEvf_NPVaXsGMoLOmwvc1GyqlIKOK1nN94nHPoltGRhWhw7Zx0-kFm");
    CkStringBuilder_Append(sbJwe,"1NJn8LE9XShH59_i8J0PH5ZZyNfGy2xGdULU7sHNF6Gp2vPLgNZ__deLKxGHZ7Pc");
    CkStringBuilder_Append(sbJwe,"HALUzoOegEI-8E66jX2E4zyJKx-YxzZIItRzC5hlRirb6Y5Cl_p-ko3YvkkysZIF");
    CkStringBuilder_Append(sbJwe,"NPccxRU7qve1WYPxqbb2Yw8kZqa2rMWI5ng8OtvzlV7elprCbuPhcCdZ6XDP0_F8");
    CkStringBuilder_Append(sbJwe,"rkXds2vE4X-ncOIM8hAYHHi29NX0mcKiRaD0-D-ljQTP-cFPgwCp6X-nZZd9OHBv");
    CkStringBuilder_Append(sbJwe,"-B3oWh2TbqmScqXMR4gp_A.");
    CkStringBuilder_Append(sbJwe,"AxY8DCtDaGlsbGljb3RoZQ.");
    CkStringBuilder_Append(sbJwe,"KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY.");
    CkStringBuilder_Append(sbJwe,"9hH0vgRfYgPnAHOd8stkvw");

    success = CkJwe_LoadJweSb(jwe2,sbJwe);
    if (success != TRUE) {
        printf("%s\n",CkJwe_lastErrorText(jwe2));
        CkJsonObject_Dispose(jweProtHdr);
        CkStringBuilder_Dispose(sbJwk);
        CkPrivateKey_Dispose(rsaPrivKey);
        CkJwe_Dispose(jwe);
        CkJwe_Dispose(jwe2);
        CkStringBuilder_Dispose(sbJwe);
        return;
    }

    // Provide the RSA private key for decryption.
    CkJwe_SetPrivateKey(jwe2,0,rsaPrivKey);

    // Decrypt.
    originalPlaintext = CkJwe_decrypt(jwe2,0,"utf-8");
    if (CkJwe_getLastMethodSuccess(jwe2) != TRUE) {
        printf("%s\n",CkJwe_lastErrorText(jwe2));
        CkJsonObject_Dispose(jweProtHdr);
        CkStringBuilder_Dispose(sbJwk);
        CkPrivateKey_Dispose(rsaPrivKey);
        CkJwe_Dispose(jwe);
        CkJwe_Dispose(jwe2);
        CkStringBuilder_Dispose(sbJwe);
        return;
    }

    printf("%s\n",originalPlaintext);


    CkJsonObject_Dispose(jweProtHdr);
    CkStringBuilder_Dispose(sbJwk);
    CkPrivateKey_Dispose(rsaPrivKey);
    CkJwe_Dispose(jwe);
    CkJwe_Dispose(jwe2);
    CkStringBuilder_Dispose(sbJwe);

    }