(Objective-C) Verify JWT with EdDSA / Ed25519 Signature

Note: This example requires Chilkat v9.5.0.84 or greater.

Demonstrates how to verify a JWT that was signed using an Ed25519 private key.

This example verifies the EdDSA 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 data.

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#import <NSString.h>
#import <CkoPublicKey.h>
#import <CkoJwt.h>

// Demonstrates how to verify a JWT with an EdDSA/Ed25519 Signature
// *** Requires Chilkat v9.5.0.84 or greater.

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

// Use this Ed25519 public key for verification

NSString *jsonPubKey = @"{\"kty\": \"OKP\",\"alg\": \"EdDSA\",\"crv\": \"Ed25519\",\"x\": \"11qYAYKxCrfVS_7TyWQHOg7hcvPapiMlrwIaaPcHURo\"}";

CkoPublicKey *pubKey = [[CkoPublicKey alloc] init];
BOOL success = [pubKey LoadFromString: jsonPubKey];
if (success == NO) {
    NSLog(@"%@",pubKey.LastErrorText);
    return;
}

CkoJwt *jwt = [[CkoJwt alloc] init];
NSString *token = @"eyJhbGciOiJFZERTQSJ9.RXhhbXBsZSBvZiBFZDI1NTE5IHNpZ25pbmc.hgyY0il_MGCjP0JzlnLWG1PPOt7-09PGcvMg3AIbQR6dWbhijcNR4ki4iylGjg5BhVsPt9g7sVvpAr_MuM0KAg";

// First verify the signature.
BOOL sigVerified = [jwt VerifyJwtPk: token key: pubKey];
NSLog(@"%@%d",@"verified: ",sigVerified);

if (sigVerified == NO) {
    NSLog(@"%@",jwt.LastErrorText);
    return;
}

// 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.
int leeway = 60;
BOOL bTimeValid = [jwt IsTimeValid: token leeway: [NSNumber numberWithInt: leeway]];
NSLog(@"%@%d",@"time constraints valid: ",bTimeValid);

// Recover the original data (the payload).
NSString *payload = [jwt GetPayload: token];
NSLog(@"%@",payload);

// Recover the original JOSE header in the same way:
NSString *joseHeader = [jwt GetHeader: token];
NSLog(@"%@",joseHeader);