C

JWE with DEFLATE Compression

See more JSON Web Encryption (JWE) Examples

Demonstrates how to DEFLATE ("zip") compress the JWE payload prior to encryption.

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

C

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

void ChilkatSample(void)
    {
    BOOL success;
    HCkStringBuilder sbPlainText;
    BOOL bCrLf;
    const char *line;
    HCkJwe jwe;
    HCkJsonObject jweProtHdr;
    const char *aesWrappingKey;
    HCkStringBuilder sbJweCompressed;
    HCkStringBuilder sbJweUncompressed;
    HCkJwe jwe2;
    HCkStringBuilder sbOriginalText;

    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.

    // Create some plaintext to be encrypted.
    // This example will demonstrate with and without DEFLATE (zip) compression.
    sbPlainText = CkStringBuilder_Create();
    bCrLf = TRUE;
    line = "Live long and prosper.";
    CkStringBuilder_AppendLine(sbPlainText,line,bCrLf);
    CkStringBuilder_AppendLine(sbPlainText,line,bCrLf);
    CkStringBuilder_AppendLine(sbPlainText,line,bCrLf);
    CkStringBuilder_AppendLine(sbPlainText,line,bCrLf);

    // The text to be encrypted:
    printf("%s\n",CkStringBuilder_getAsString(sbPlainText));

    jwe = CkJwe_Create();

    // Build the JWE Protected Header: {"alg":"A128KW","enc":"A128CBC-HS256","zip":"DEF"}
    // The "zip":"DEF" parameter indicates that the plaintext payload should
    // be compressed prior to encryption.
    jweProtHdr = CkJsonObject_Create();
    CkJsonObject_AppendString(jweProtHdr,"alg","A128KW");
    CkJsonObject_AppendString(jweProtHdr,"enc","A128CBC-HS256");
    CkJsonObject_AppendString(jweProtHdr,"zip","DEF");
    CkJwe_SetProtectedHeader(jwe,jweProtHdr);

    // Set the AES key wrap key:
    aesWrappingKey = "GawgguFyGrWKav7AX4VKUg";
    CkJwe_SetWrappingKey(jwe,0,aesWrappingKey,"base64url");

    // Encrypt and return the JWE in sbJweCompressed:
    sbJweCompressed = CkStringBuilder_Create();
    success = CkJwe_EncryptSb(jwe,sbPlainText,"utf-8",sbJweCompressed);
    if (success != TRUE) {
        printf("%s\n",CkJwe_lastErrorText(jwe));
        CkStringBuilder_Dispose(sbPlainText);
        CkJwe_Dispose(jwe);
        CkJsonObject_Dispose(jweProtHdr);
        CkStringBuilder_Dispose(sbJweCompressed);
        return;
    }

    // Show the compressed JWE:
    printf("%s\n",CkStringBuilder_getAsString(sbJweCompressed));
    printf("size of compressed JWE: %d\n",CkStringBuilder_getLength(sbJweCompressed));

    // Now create a JWE without compression.
    CkJsonObject_Delete(jweProtHdr,"zip");
    // Make sure to update the shared protected header:
    CkJwe_SetProtectedHeader(jwe,jweProtHdr);

    sbJweUncompressed = CkStringBuilder_Create();
    success = CkJwe_EncryptSb(jwe,sbPlainText,"utf-8",sbJweUncompressed);
    if (success != TRUE) {
        printf("%s\n",CkJwe_lastErrorText(jwe));
        CkStringBuilder_Dispose(sbPlainText);
        CkJwe_Dispose(jwe);
        CkJsonObject_Dispose(jweProtHdr);
        CkStringBuilder_Dispose(sbJweCompressed);
        CkStringBuilder_Dispose(sbJweUncompressed);
        return;
    }

    // Show the uncompressed JWE:
    printf("%s\n",CkStringBuilder_getAsString(sbJweUncompressed));
    printf("size of uncompressed JWE: %d\n",CkStringBuilder_getLength(sbJweUncompressed));

    // Decrypting is the same whether compression is used or not.
    // The "zip" header in the JWE indicates that the payload should be 
    // automatically decompressed (inflated) after decrypting.
    jwe2 = CkJwe_Create();
    success = CkJwe_LoadJweSb(jwe2,sbJweCompressed);
    if (success != TRUE) {
        printf("%s\n",CkJwe_lastErrorText(jwe2));
        CkStringBuilder_Dispose(sbPlainText);
        CkJwe_Dispose(jwe);
        CkJsonObject_Dispose(jweProtHdr);
        CkStringBuilder_Dispose(sbJweCompressed);
        CkStringBuilder_Dispose(sbJweUncompressed);
        CkJwe_Dispose(jwe2);
        return;
    }

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

    // Decrypt (also automatically decompresses).
    sbOriginalText = CkStringBuilder_Create();
    success = CkJwe_DecryptSb(jwe2,0,"utf-8",sbOriginalText);
    if (success != TRUE) {
        printf("%s\n",CkJwe_lastErrorText(jwe2));
        CkStringBuilder_Dispose(sbPlainText);
        CkJwe_Dispose(jwe);
        CkJsonObject_Dispose(jweProtHdr);
        CkStringBuilder_Dispose(sbJweCompressed);
        CkStringBuilder_Dispose(sbJweUncompressed);
        CkJwe_Dispose(jwe2);
        CkStringBuilder_Dispose(sbOriginalText);
        return;
    }

    printf("original text from compressed JWE: \n");
    printf("%s\n",CkStringBuilder_getAsString(sbOriginalText));

    // -----------------------------------------------------------
    // Do the same with the uncompressed JWE

    success = CkJwe_LoadJweSb(jwe2,sbJweUncompressed);
    if (success != TRUE) {
        printf("%s\n",CkJwe_lastErrorText(jwe2));
        CkStringBuilder_Dispose(sbPlainText);
        CkJwe_Dispose(jwe);
        CkJsonObject_Dispose(jweProtHdr);
        CkStringBuilder_Dispose(sbJweCompressed);
        CkStringBuilder_Dispose(sbJweUncompressed);
        CkJwe_Dispose(jwe2);
        CkStringBuilder_Dispose(sbOriginalText);
        return;
    }

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

    // Decrypt.
    CkStringBuilder_Clear(sbOriginalText);
    success = CkJwe_DecryptSb(jwe2,0,"utf-8",sbOriginalText);
    if (success != TRUE) {
        printf("%s\n",CkJwe_lastErrorText(jwe2));
        CkStringBuilder_Dispose(sbPlainText);
        CkJwe_Dispose(jwe);
        CkJsonObject_Dispose(jweProtHdr);
        CkStringBuilder_Dispose(sbJweCompressed);
        CkStringBuilder_Dispose(sbJweUncompressed);
        CkJwe_Dispose(jwe2);
        CkStringBuilder_Dispose(sbOriginalText);
        return;
    }

    printf("original text from uncompressed JWE: \n");
    printf("%s\n",CkStringBuilder_getAsString(sbOriginalText));

    // ------------------------------------------------
    // The output of this example is:
    // (Note: Your output data will be different because the content encryption key is randomly generated.)

    // eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2IiwiemlwIjoiREVGIn0.xuW-pEAIdEUFnk10m8ocursvktO8Of9ByCCAt6LgKkkOtCWCUn1kQw.zpGj-9WVni3cQxyOuZbcGA.0hzP1myua3oYpUHwCIY_3edBUREbUpLaX6wYuJduOdI.Ppc6aEO3y3B8BJ1FKMPjlA
    // size of compressed JWE: 212
    // eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.N4KeyC7nnSFkieJOyE24_zKeuV_m7v5UKoJb1TgV4Yc_r2RzUPNvyA.6AEdyXSCKx-iMmUJyypSLg.QpixfyrwhGpmwUDp623viik4smPav7vwPLiC2r-V-jwnSfEH3mxWu6DbrIz3mixaqATwynmEBzVPxvS9jTXpSAGCnniib4_0WoPl3r_wF5tlsKOEe--jpNso-DKd1Tp8jJxj3JkFWt3IRnUUKGj17g.sBfDwFc5fzpaI-UW8-SW4g
    // size of uncompressed JWE: 303
    // original text from compressed JWE: 
    // Live long and prosper.
    // Live long and prosper.
    // Live long and prosper.
    // Live long and prosper.
    // 
    // original text from uncompressed JWE: 
    // Live long and prosper.
    // Live long and prosper.
    // Live long and prosper.
    // Live long and prosper.
    // 


    CkStringBuilder_Dispose(sbPlainText);
    CkJwe_Dispose(jwe);
    CkJsonObject_Dispose(jweProtHdr);
    CkStringBuilder_Dispose(sbJweCompressed);
    CkStringBuilder_Dispose(sbJweUncompressed);
    CkJwe_Dispose(jwe2);
    CkStringBuilder_Dispose(sbOriginalText);

    }