Perl Requires Chilkat v11.0.0+

Validate a JWS Using ECDSA P-256 SHA-256

See more JSON Web Signatures (JWS) Examples

Validates a JSON Web Signature (JWS) that uses ECDSA P-256 SHA-256 Chilkat2 Perl

use strict;
use warnings;
use Chilkat2;

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

# This example takes a JSON signature in compact serialization format,
# and uses an ECDSA public key to validate and recover the protected header and payload.

# We only need a public key for signature validation.  This is the ECDSA public key
# that is used:

#      {"kty":"EC",
#       "crv":"P-256",
#       "x":"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU",
#       "y":"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0"
#      }

my $sbPubKey = Chilkat2::StringBuilder->new;
$sbPubKey->Append('{"kty":"EC",');
$sbPubKey->Append('"crv":"P-256",');
$sbPubKey->Append('"x":"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU",');
$sbPubKey->Append('"y":"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0"');
$sbPubKey->Append('}');

my $pubKey = Chilkat2::PublicKey->new;
my $success = $pubKey->LoadFromString($sbPubKey->GetAsString());
if (!$success) {
    print $pubKey->LastErrorText, "\n";
    exit;
}

my $jws = Chilkat2::Jws->new;

# Set the ECC public key:
my $signatureIndex = 0;
$jws->SetPublicKey($signatureIndex, $pubKey);

# Load the JWS.
my $sbJws = Chilkat2::StringBuilder->new;
$sbJws->Append('eyJhbGciOiJFUzI1NiJ9');
$sbJws->Append('.');
$sbJws->Append('eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt');
$sbJws->Append('cGxlLmNvbS9pc19yb290Ijp0cnVlfQ');
$sbJws->Append('.');
$sbJws->Append('DtEhU3ljbEg8L38VWAfUAqOyKAM6-Xx-F4GawxaepmXFCgfTjDxw5djxLa8ISlSA');
$sbJws->Append('pmWQxfKTUJqPP3-Kg6NU1Q');

$success = $jws->LoadJwsSb($sbJws);
if (!$success) {
    print $jws->LastErrorText, "\n";
    exit;
}

# Validate the 1st (and only) signature at index 0..
my $v = $jws->Validate($signatureIndex);
if ($v < 0) {
    # Perhaps Chilkat was not unlocked or the trial expired..
    print "Method call failed for some other reason.\n";
    print $jws->LastErrorText, "\n";
    exit;
}

if ($v == 0) {
    print "Invalid signature.  The ECC key was incorrect, the JWS was invalid, or both.\n";
    exit;
}

# If we get here, the signature was validated..
print "Signature validated.\n";
print "--\n";

# Recover the original content:
print "Recovered content:\n";
print $jws->GetPayload('utf-8'), "\n";
print "--\n";

# Examine the protected header:

my $joseHeader = Chilkat2::JsonObject->new;
$success = $jws->GetProtectedH($signatureIndex, $joseHeader);
if (!$success) {
    print $jws->LastErrorText, "\n";
    exit;
}

$joseHeader->EmitCompact(0);

print "Protected (JOSE) header:\n";
print $joseHeader->Emit(), "\n";

# Output:

#     Signature validated.
#     --
#     Recovered content:
#     {"iss":"joe",
#      "exp":1300819380,
#      "http://example.com/is_root":true}
#     --
#     Protected (JOSE) header:
#     {
#       "alg": "ES256"
#     }