Zig

Verify JWT Using an RSA Public Key (RS256, RS384, RS512)

See more JSON Web Token (JWT) Examples

Demonstrates how to verify a JWT that was signed using an RSA private key.

This example verifies the RSA signature. It also does the following:

• Checks to see if the time constraints ("nbf" and "exp") are valid.
• Recovers the original JOSE header.
• Recovers the original claims JSON.

Zig

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

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

    // Demonstrates how to verify an JWT using an RSA public key.

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

    const pub_key = try chilkat.PublicKey.init();
    defer pub_key.deinit();
    try pub_key.loadFromFile("qa_data/pem/rsa_public.pem");

    const jwt = try chilkat.Jwt.init();
    defer jwt.deinit();

    const token = "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJodHRwOi8vZXhhbXBsZS5vcmciLCJzdWIiOiJKb2huIiwiYXVkIjoiaHR0cDovL2V4YW1wbGUuY29tIiwiaWF0IjoxNDYzNDQ1MjM4LCJuYmYiOjE0NjM0NDUyMzgsImV4cCI6MTQ2MzQ0ODgzOH0.XRtqed6nuJ9lrp0wbNdDX3fCkSh_d9cHAniPbNcqm7G-5N3mtI5ntQvZBDP3pHtECVqufuDwW7XgUtzAi0ZXhyiRm1iZ3wMSN5lHWv52OQJmMHPA7VPd8Q1hDG-tx-QswzJKd75OEUHP7wIXq2Mg_YVElfDvJI6TGjGyS1y-RLHlz-ldlGsEwIBkO0PtzIYTVov97x8p9KCsPNhS4lZUIqKOYoTZUV5LpuAWARl-636DfMEB_A5_IEaw_W8leh2suP2ULVZxwE-Tk1kBC9tsSGrBrPTtg7sziaV4Lbb0JRANmh98uTRu5f8ji9CVOnpbMiAzjsJSy56kz_olweXSuA";

    // First verify the signature.
    const sig_verified = if (jwt.verifyJwtPk(token, pub_key)) true else |_| false;
    std.debug.print("verified: {}\n", .{sig_verified});

    // Let's see if the time constraints, if any, are valid.
    // The above JWT was created on the afternoon of 16-May-2016, with an expiration of 1 hour.
    // If the current system time is before the "nbf" time, or after the "exp" time,
    // then IsTimeValid will return false/0.
    // Also, we'll allow a leeway of 60 seconds to account for any clock skew.
    // Note: If the token has no "nbf" or "exp" claim fields, then IsTimeValid is always true.
    const leeway = 60;
    const b_time_valid = jwt.isTimeValid(token, leeway);
    std.debug.print("time constraints valid: {}\n", .{b_time_valid});

    // Now let's recover the original claims JSON (the payload).
    const payload = try jwt.getPayload(alloc, token);
    // The payload will likely be in compact form:
    std.debug.print("{s}\n", .{payload});

    // We can format for human viewing by loading it into Chilkat's JSON object
    // and emit.
    const json = try chilkat.JsonObject.init();
    defer json.deinit();
    try json.load(payload);
    json.setEmitCompact(false);
    std.debug.print("{s}\n", .{try json.emit(alloc)});

    // We can recover the original JOSE header in the same way:
    const jose_header = try jwt.getHeader(alloc, token);
    // The payload will likely be in compact form:
    std.debug.print("{s}\n", .{jose_header});

    // We can format for human viewing by loading it into Chilkat's JSON object
    // and emit.
    try json.load(jose_header);
    json.setEmitCompact(false);
    std.debug.print("{s}\n", .{try json.emit(alloc)});
}