Zig

JWE using A256GCMKW

See more JSON Web Encryption (JWE) Examples

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

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

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

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

    const plaintext = "My text to enrypt";

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

    // First build the JWE Protected Header:

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

    const jwe_prot_hdr = try chilkat.JsonObject.init();
    defer jwe_prot_hdr.deinit();
    jwe_prot_hdr.appendString("alg", "A256GCMKW") catch {};
    // kid is optional
    jwe_prot_hdr.appendString("kid", "18ec08e1-bfa9-4d95-b205-2b4dd1d4321d") catch {};
    // tag is optional
    jwe_prot_hdr.appendString("tag", "kfPduVQ3T3H6vnewt--ksw") catch {};
    jwe_prot_hdr.appendString("enc", "A256GCM") catch {};
    // the iv should be 16 random chars.
    const prng = try chilkat.Prng.init();
    defer prng.deinit();
    jwe_prot_hdr.appendString("iv", try prng.randomString(alloc, 16, true, true, true)) catch {};
    jwe.setProtectedHeader(jwe_prot_hdr) catch {};

    std.debug.print("JWE Protected Header: {s}\n", .{try jwe_prot_hdr.emit(alloc)});
    std.debug.print("--\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 aes_wrapping_key = "2baf4f730f5e4542b428593ef9cceb0e";
    jwe.setWrappingKey(0, aes_wrapping_key, "ascii") catch {};

    // Encrypt and return the JWE:
    const str_jwe = jwe.encrypt(alloc, plaintext, "utf-8") catch {
        std.debug.print("{s}\n", .{try jwe.getLastErrorText(alloc)});
        return;
    };

    // Show the JWE we just created:
    std.debug.print("{s}\n", .{str_jwe});

    // Decrypt the JWE that was just produced.
    // 1) Load the JWE.
    // 2) Set the AES wrapping key.
    // 3) Decrypt.
    const jwe2 = try chilkat.Jwe.init();
    defer jwe2.deinit();
    jwe2.loadJwe(str_jwe) catch {
        std.debug.print("{s}\n", .{try jwe2.getLastErrorText(alloc)});
        return;
    };

    // Set the AES wrap key.  Important to use "ascii"
    jwe2.setWrappingKey(0, aes_wrapping_key, "ascii") catch {};

    // Decrypt.
    const original_plaintext = jwe2.decrypt(alloc, 0, "utf-8") catch {
        std.debug.print("{s}\n", .{try jwe2.getLastErrorText(alloc)});
        return;
    };

    std.debug.print("original text: \n", .{});
    std.debug.print("{s}\n", .{original_plaintext});
}