(Perl) Validate a JWS Using ECDSA P-256 SHA-256

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

Note: This example requires Chilkat v9.5.0.66 or greater.

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

use chilkat();

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

# Note: This example requires Chilkat v9.5.0.66 or greater.

# 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" 
#      } 

$sbPubKey = chilkat::CkStringBuilder->new();
$sbPubKey->Append("{\"kty\":\"EC\",");
$sbPubKey->Append("\"crv\":\"P-256\",");
$sbPubKey->Append("\"x\":\"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU\",");
$sbPubKey->Append("\"y\":\"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0\"");
$sbPubKey->Append("}");

$pubKey = chilkat::CkPublicKey->new();
$success = $pubKey->LoadFromString($sbPubKey->getAsString());
if ($success != 1) {
    print $pubKey->lastErrorText() . "\r\n";
    exit;
}

$jws = chilkat::CkJws->new();

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

# Load the JWS.
$sbJws = chilkat::CkStringBuilder->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 != 1) {
    print $jws->lastErrorText() . "\r\n";
    exit;
}

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

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

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

# Recover the original content:
print "Recovered content:" . "\r\n";
print $jws->getPayload("utf-8") . "\r\n";
print "--" . "\r\n";

# Examine the protected header:
# joseHeader is a JsonObject
$joseHeader = $jws->GetProtectedHeader($signatureIndex);
if ($jws->get_LastMethodSuccess() != 1) {
    print "No protected header found at the given index." . "\r\n";
    exit;
}

$joseHeader->put_EmitCompact(0);

print "Protected (JOSE) header:" . "\r\n";
print $joseHeader->emit() . "\r\n";

# Output:

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