README.md

JSON Web Tokens (JWT) library

This library implement signing and verification of JSON Web Tokens, or JWTs, based on RFC 7159.

The library is implemented in the zig language and only uses the standard libraries.

Features

• Sign
• Verify
• iss check
• sub check
• aud check
• exp check
• nbf check
• iat check
• jti check
• typ check

Encryption algorithms:

• HS256
• HS384
• HS512
• PS256
• PS384

Create Token

fn createToken(alg: zjwt.Algorithm, signatureOptions: zjwt.SignatureOptions, buffer: *std.ArrayList(u8), allocator: Allocator) !void {
    var j = zjwt.ZJwt.init(allocator);

    var token = zjwt.Token.init(allocator);
    defer token.deinit();

    // Builds the header as follows { "typ": "JWT", "alg": "HS256" }
    try token.createDefaultHeader(alg);

    // Builds the payload as follows { "iss": "zjwt", "sub": "username", "iat": 1690702984, "exp": 1690706584 }
    try token.addIssuer(issuer);
    try token.addSubject("username");
    try token.addIssuedAt();
    try token.addExpiresAt(3600);

    // Encodes the header and the token to base64 and creates the signature using the chosen algorithm
    try buffer.appendSlice(try j.encode(alg, signatureOptions, &token));
}

Validate Token

fn vlidateToken(alg: zjwt.Algorithm, signatureOptions: zjwt.SignatureOptions, tokenBase64: []const u8, allocator: Allocator) !void {
    var j = zjwt.ZJwt.init(allocator);
    var token = zjwt.Token.init(allocator);
    defer token.deinit();

    // The default header validator checks the algorithm and the type
    var headerValidator = try zjwt.validator.createDefaultHeaderValidator(allocator, alg.phrase());
    defer headerValidator.deinit();

    // The default payload validator checks the issuer and the expiration time
    var payloadValidator = try zjwt.validator.createDefaultPayloadValidator(allocator, issuer);

    try j.decode(alg, signatureOptions, .{
        .saveHeader = false, // Do not save the header
        .savePayload = true, // Save the payload 
        .headerValidator = headerValidator, // Validate the header
        .payloadValidator = payloadValidator, // Validate the payload
    }, tokenBase64, &token);

    std.debug.print("Token validated for subject: {s}\n", .{token.payload.get(zjwt.Claims.SUBJECT).?.string});
}

Here the whole example github.com/rolfscherer/zjwt/blob/master/example/src/main.zig