(PHP Extension) JWE using ECDH-ES+A256KW

See more JSON Web Encryption (JWE) Examples

{
    "kty": "EC",
    "d": "jZCffzVqJjryBH4EoaN0oD-TyLXrW2XHoDdIuPZnk8c",
    "use": "enc",
    "crv": "P-256",
    "kid": "evEK2thJMsWxBYRivXI8ykUf6n6zizLiLCGH3s58wKs",
    "x": "LOakgGvxWBsWbCPLY6Vq6OuBktIqG8POXFXe7ngQ2oM",
    "y": "voJvS6I-Mc4qqmEA_G2hLQqBck3a3vqaJbmzY7YPUD4",
    "alg": "ECDH-ES+A256KW"
}

Also shows how to decrypt.

Chilkat PHP Downloads PHP Extension for Windows, Linux, MacOS, Alpine Linux

<?php

include("chilkat.php");

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

// Create the following JSON:
// {
//     "kty": "EC",
//     "d": "jZCffzVqJjryBH4EoaN0oD-TyLXrW2XHoDdIuPZnk8c",
//     "use": "enc",
//     "crv": "P-256",
//     "kid": "evEK2thJMsWxBYRivXI8ykUf6n6zizLiLCGH3s58wKs",
//     "x": "LOakgGvxWBsWbCPLY6Vq6OuBktIqG8POXFXe7ngQ2oM",
//     "y": "voJvS6I-Mc4qqmEA_G2hLQqBck3a3vqaJbmzY7YPUD4",
//     "alg": "ECDH-ES+A256KW"
// }

$json = new CkJsonObject();
$json->UpdateString('kty','EC');
$json->UpdateString('d','jZCffzVqJjryBH4EoaN0oD-TyLXrW2XHoDdIuPZnk8c');
$json->UpdateString('use','enc');
$json->UpdateString('crv','P-256');
$json->UpdateString('kid','evEK2thJMsWxBYRivXI8ykUf6n6zizLiLCGH3s58wKs');
$json->UpdateString('x','LOakgGvxWBsWbCPLY6Vq6OuBktIqG8POXFXe7ngQ2oM');
$json->UpdateString('y','voJvS6I-Mc4qqmEA_G2hLQqBck3a3vqaJbmzY7YPUD4');
$json->UpdateString('alg','ECDH-ES+A256KW');

$pubkey = new CkPublicKey();

$success = $pubkey->LoadFromString($json->emit());
if ($success == false) {
    print $pubkey->lastErrorText() . "\n";
    exit;
}

// Build our protected header:

// 	{
// 	  "alg": "ECDH-ES+A256KW",
// 	  "enc": "A256GCM",
// 	  "exp": 1621957030,
// 	  "cty": "NJWT",
// 	  "epk": {
// 	    "kty": "EC",
// 	    "x": "QLpJ_LpFx-6yJhsb4OvHwU1khLnviiOwYOvmf5clK7w"
// 	    "y": "AJh7pJ3zZKDJkm8rbeG69GBooTosXJgSsvNFH0i3Vxnu"
// 	    "crv": "BP-256"
// 	  }
// 	}

// Use jwt only for getting the current date/time + 3600 seconds.
$jwt = new CkJwt();

$jweProtHdr = new CkJsonObject();
$jweProtHdr->UpdateString('alg','ECDH-ES+A256KW');
$jweProtHdr->UpdateString('enc','A256GCM');
$jweProtHdr->UpdateInt('exp',$jwt->GenNumericDate(3600));
$jweProtHdr->UpdateString('cty','NJWT');
$jweProtHdr->UpdateString('epk.kty','EC');
$jweProtHdr->UpdateString('epk.x','LOakgGvxWBsWbCPLY6Vq6OuBktIqG8POXFXe7ngQ2oM');
$jweProtHdr->UpdateString('epk.y','voJvS6I-Mc4qqmEA_G2hLQqBck3a3vqaJbmzY7YPUD4');
$jweProtHdr->UpdateString('epk.crv','P-256');

$jwe = new CkJwe();
$jwe->SetProtectedHeader($jweProtHdr);
$jwe->SetPublicKey(0,$pubkey);

$plainText = 'This is the text to be encrypted.';
$strJwe = $jwe->encrypt($plainText,'utf-8');
if ($jwe->get_LastMethodSuccess() != true) {
    print $jwe->lastErrorText() . "\n";
    exit;
}

print $strJwe . "\n";

// Let's decrypt...
$privkey = new CkPrivateKey();

$success = $privkey->LoadJwk($json->emit());
if ($success == false) {
    print $privkey->lastErrorText() . "\n";
    exit;
}

$jwe2 = new CkJwe();
$success = $jwe2->LoadJwe($strJwe);
if ($success == false) {
    print $jwe2->lastErrorText() . "\n";
    exit;
}

$jwe2->SetPrivateKey(0,$privkey);

//  Decrypt.
$decryptedText = $jwe2->decrypt(0,'utf-8');
if ($jwe2->get_LastMethodSuccess() != true) {
    print $jwe2->lastErrorText() . "\n";
    exit;
}

print $decryptedText . "\n";

?>