Perl Requires Chilkat v11.0.0+

Validate a Google ID Token

See more OAuth2 Examples

Demonstrates how to verify the signature of a Google id token. Chilkat2 Perl

use strict;
use warnings;
use Chilkat2;

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

my $http = Chilkat2::Http->new;

# First get the public key we'll be needing..
my $jwkStr = $http->QuickGetStr('https://www.googleapis.com/oauth2/v3/certs');
if (!$http->LastMethodSuccess) {
    print $http->LastErrorText, "\n";
    exit;
}

# We have the following:

#     {
#       "keys": [
#     {
#       "kid": "e8732db06287515556213b80acbcfd08cfb302a9",
#       "n": "4RIrO30287Wsq3gqXCMkUYMVAeI3H8...w2mbMNEBQ",
#       "kty": "RSA",
#       "e": "AQAB",
#       "alg": "RS256",
#       "use": "sig"
#     },
#     {
#       "kid": "8462a71da4f6d611fc0fecf0fc4ba9c37d65e6cd",
#       "e": "AQAB",
#       "n": "xT_ngLZNmT5GBtJZeTB...Ft4gK0eoFi0d3l8bcw",
#       "alg": "RS256",
#       "use": "sig",
#       "kty": "RSA"
#     }
#       ]
#     }

my $json = Chilkat2::JsonObject->new;
my $success = $json->Load($jwkStr);

# -------------------------------------------------

# Load the following..

#  {
#   "access_token": "ya29.a0...0f",
#   "expires_in": 3599,
#   "scope": "openid https://www.googleapis.com/auth/userinfo.email",
#   "token_type": "Bearer",
#   "id_token": "eyJhb...o5nQ"
# }

my $jsonToken = Chilkat2::JsonObject->new;
$success = $jsonToken->LoadFile('qa_data/tokens/google_sample_id_token.json');
if (!$success) {
    print "Failed to load the JSON file...\n";
    exit;
}

# Get the id_token;
my $sbIdToken = Chilkat2::StringBuilder->new;
$success = $sbIdToken->Append($jsonToken->StringOf('id_token'));

# Get the signature in base64url format.
# The header + payload remains in sbIdToken.
my $sig_b64Url = $sbIdToken->GetAfterFinal('.', 1);
my $headerPlusPayload = $sbIdToken->GetAsString();

print $sig_b64Url, "\n";
print $headerPlusPayload, "\n";

# ---------------------------------------------

# Try validating with each cert's public key.
# Hopefully one will be the key that verifies.

my $rsa = Chilkat2::Rsa->new;
$rsa->EncodingMode('base64url');

my $jsonKey = Chilkat2::JsonObject->new;
my $pubKey = Chilkat2::PublicKey->new;

my $numKeys = $json->SizeOfArray('keys');
my $i = 0;
while ($i < $numKeys) {
    $json->I($i);

    $json->ObjectOf2('keys[i]', $jsonKey);

    $success = $pubKey->LoadFromString($jsonKey->Emit());
    if (!$success) {
        print $pubKey->LastErrorText, "\n";
        exit;
    }

    print $i, "\n";
    print $pubKey->GetPem(1), "\n";

    $success = $rsa->UsePublicKey($pubKey);

    my $bVerified = $rsa->VerifyStringENC($headerPlusPayload, 'sha256', $sig_b64Url);
    print 'bVerified = ', ($bVerified ? 1 : 0), "\n";

    $i = $i + 1;
}

# The output is:

# 0
# -----BEGIN RSA PUBLIC KEY-----
# MIIBCgKCAQEA4RIrO30287Wsq3gqXCMkUYMVAeI3H8LVE6IXR1krdFeGnZLiGUPw
# cbkeVpXf3lmJdsStOg+jijces2DZCfPyIBiQuLYfxxmAZE6ErJ0QJFg1stwli2Pz
# 9ncYhFoqi8pXr7kEzEJBTzX4thuw56ydbGsshSEznPXoerCJOc7UI2+n0wFCWQ4Y
# LHbh/PrWt4vdadyUUUW/QpQHXQLdD8q/Qwqdj0O9zlJE7R6Elw2E9EqnHyIGu1hm
# LxhqrTru1M18SUhONYbVskV/BCEdVKs//X96849HorWQDCAgVMWfGsdMVq55FAdJ
# 680N5UmQDRynIZ4+PeNGN4S9iw2mbMNEBQIDAQAB
# -----END RSA PUBLIC KEY-----
#
# bVerified = True
# 1
# -----BEGIN RSA PUBLIC KEY-----
# MIIBCgKCAQEAxT/ngLZNmT5GBdkLtJZjNeTB+8B5yWgrq/e5eMZ1hrZhcmLK+dSn
# IkpOPV8/OekV67EnQ7I4II2rcNJnHGrGKZziXO3XN2gtUHE+mBJC99oULSbX/QwB
# Kz7gC/IBPq9EuxTt6Oq6fPkVQ9DbRIgWJSEGBF/KRaNl3kyAlIZfpY7XgHyJTTv8
# E7yAcYKPR+36gzdl+ps0sDLKzUuAtZNq8llK0u80z6AtAUIYwWdkEhM9upy6keKI
# TasIxcsO7M6kZPINUSbh6t5VAm8FuqRmxpgg+9c9/GQSGd89InVypoVzWLQ+wOGg
# 5G4H6JqIgtj0TRFt4gK0eoFi2U0d3l8bcwIDAQAB
# -----END RSA PUBLIC KEY-----
#
# bVerified = False