Zig

JWE with Binary Data

See more JSON Web Encryption (JWE) Examples

Demonstrates how to create a JWE that contains a binary payload (such as a JPG image).

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

Zig

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

    var success: bool = 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.

    // Load a JPG file that will be the JWE payload.
    const jpg_bytes = try chilkat.BinData.init();
    defer jpg_bytes.deinit();
    success = if (jpg_bytes.loadFile("qa_data/jpg/starfish.jpg")) true else |_| false;
    // Make sure your app checks the success/failure of the call to LoadFile..
    std.debug.print("Original JPG size = {d}\n", .{jpg_bytes.getNumBytes()});

    const jwe = try chilkat.Jwe.init();
    defer jwe.deinit();

    const jwe_prot_hdr = try chilkat.JsonObject.init();
    defer jwe_prot_hdr.deinit();
    jwe_prot_hdr.appendString("alg", "A128KW") catch {};
    jwe_prot_hdr.appendString("enc", "A128CBC-HS256") catch {};
    jwe.setProtectedHeader(jwe_prot_hdr) catch {};

    const aes_wrapping_key = "GawgguFyGrWKav7AX4VKUg";
    jwe.setWrappingKey(0, aes_wrapping_key, "base64url") catch {};

    // Encrypt and return the JWE in sbJwe:
    const sb_jwe = try chilkat.StringBuilder.init();
    defer sb_jwe.deinit();
    success = if (jwe.encryptBd(jpg_bytes, sb_jwe)) true else |_| false;
    if (!success) {
        std.debug.print("{s}\n", .{try jwe.getLastErrorText(alloc)});
        return;
    }

    // Show the JWE:
    std.debug.print("{s}\n", .{try sb_jwe.getAsString(alloc)});
    std.debug.print("size of JWE: {d}\n", .{sb_jwe.getLength()});

    // ---------------------------------------------------------
    // Decrypt to get the original JPG file..

    const jwe2 = try chilkat.Jwe.init();
    defer jwe2.deinit();
    success = if (jwe2.loadJweSb(sb_jwe)) true else |_| false;
    if (!success) {
        std.debug.print("{s}\n", .{try jwe2.getLastErrorText(alloc)});
        return;
    }

    // Set the AES wrap key.
    jwe2.setWrappingKey(0, aes_wrapping_key, "base64url") catch {};

    // Decrypt.
    const jpg_original = try chilkat.BinData.init();
    defer jpg_original.deinit();
    success = if (jwe2.decryptBd(0, jpg_original)) true else |_| false;
    if (!success) {
        std.debug.print("{s}\n", .{try jwe2.getLastErrorText(alloc)});
        return;
    }

    std.debug.print("Decrypted JPG size = {d}\n", .{jpg_original.getNumBytes()});

    // Save the decrypted JPG to a file.
    success = if (jpg_original.writeFile("qa_output/jwe_decrypted_starfish.jpg")) true else |_| false;

    std.debug.print("success = {}\n", .{success});

    // The output of this program, when tested, was:
    // Original JPG size = 6229
    // eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.9YFz_wteV ... 7Et3hKhpxnKEXw
    // size of JWE: 8473
    // Decrypted JPG size = 6229
    // success = True
}