(Perl) Verify JWT Using HS256, HS384, or HS512

Demonstrates how to verify a JWT that was signed using HS256, HS384, or HS512. (HS256 is JWT's acronym for HMAC-SHA256.)

This example verifies the 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.

Chilkat Perl Downloads Perl Module for Windows, MacOS, Linux, Alpine Linux, Solaris

use chilkat();

# Demonstrates how to verify an HMAC JWT using a shared secret (password).

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

$jwt = chilkat::CkJwt->new();

$token = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJodHRwOi8vZXhhbXBsZS5vcmciLCJzdWIiOiJKb2huIiwiYXVkIjoiaHR0cDovL2V4YW1wbGUuY29tIiwiaWF0IjoxNDYzNDMxODEyLCJuYmYiOjE0NjM0MzE4MTIsImV4cCI6MTQ2MzQzNTQxMn0.SHnMJ11qJH5pbp22YchT_9fL2HIx0koHiUHLG67_foU";

# First verify the signature.
# The password used to create this JWT was "secret".
$sigVerified = $jwt->VerifyJwt($token,"secret");
print "with correct password: " . $sigVerified . "\r\n";

# Now try with a different password:
$sigVerified = $jwt->VerifyJwt($token,"secret2");
print "with incorrect password " . $sigVerified . "\r\n";

# 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 = $jwt->IsTimeValid($token,$leeway);
print "time constraints valid: " . $bTimeValid . "\r\n";

# Now let's recover the original claims JSON (the payload).
$payload = $jwt->getPayload($token);
# The payload will likely be in compact form:
print $payload . "\r\n";

# We can format for human viewing by loading it into Chilkat's JSON object
# and emit.
$json = chilkat::CkJsonObject->new();
$success = $json->Load($payload);
$json->put_EmitCompact(0);
print $json->emit() . "\r\n";

# We can recover the original JOSE header in the same way:
$joseHeader = $jwt->getHeader($token);
# The payload will likely be in compact form:
print $joseHeader . "\r\n";

# We can format for human viewing by loading it into Chilkat's JSON object
# and emit.
$success = $json->Load($joseHeader);
$json->put_EmitCompact(0);
print $json->emit() . "\r\n";