C

Verify JWT with EdDSA / Ed25519 Signature

See more JSON Web Token (JWT) Examples

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.

C

#include <C_CkPublicKey.h>
#include <C_CkJwt.h>

void ChilkatSample(void)
    {
    BOOL success;
    const char *jsonPubKey;
    HCkPublicKey pubKey;
    HCkJwt jwt;
    const char *token;
    BOOL sigVerified;
    int leeway;
    BOOL bTimeValid;
    const char *payload;
    const char *joseHeader;

    success = FALSE;

    // 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

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

    pubKey = CkPublicKey_Create();
    success = CkPublicKey_LoadFromString(pubKey,jsonPubKey);
    if (success == FALSE) {
        printf("%s\n",CkPublicKey_lastErrorText(pubKey));
        CkPublicKey_Dispose(pubKey);
        return;
    }

    jwt = CkJwt_Create();
    token = "eyJhbGciOiJFZERTQSJ9.RXhhbXBsZSBvZiBFZDI1NTE5IHNpZ25pbmc.hgyY0il_MGCjP0JzlnLWG1PPOt7-09PGcvMg3AIbQR6dWbhijcNR4ki4iylGjg5BhVsPt9g7sVvpAr_MuM0KAg";

    // First verify the signature.
    sigVerified = CkJwt_VerifyJwtPk(jwt,token,pubKey);
    printf("verified: %d\n",sigVerified);

    if (sigVerified == FALSE) {
        printf("%s\n",CkJwt_lastErrorText(jwt));
        CkPublicKey_Dispose(pubKey);
        CkJwt_Dispose(jwt);
        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.
    leeway = 60;
    bTimeValid = CkJwt_IsTimeValid(jwt,token,leeway);
    printf("time constraints valid: %d\n",bTimeValid);

    // Recover the original data (the payload).
    payload = CkJwt_getPayload(jwt,token);
    printf("%s\n",payload);

    // Recover the original JOSE header in the same way:
    joseHeader = CkJwt_getHeader(jwt,token);
    printf("%s\n",joseHeader);


    CkPublicKey_Dispose(pubKey);
    CkJwt_Dispose(jwt);

    }