PHP ActiveX Requires Chilkat v11.0.0+

Azure Key Vault Sign with a Certificate's Private Key

See more Azure Key Vault Examples

Signs a hash using the private key of a certificate previously imported to an Azure Key Vault. PHP ActiveX

<?php

$success = 0;

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

//  See Azure Key Vault Get Certificates for a more detailed explanation
//  for how Chilkat is automatically getting the OAuth2 access token for your application.

//  Provide information needed for Chilkat to automatically get an OAuth2 access token as needed.
$json = new COM("Chilkat.JsonObject");
$json->UpdateString('client_id','APP_ID');
$json->UpdateString('client_secret','APP_PASSWORD');
$json->UpdateString('resource','https://vault.azure.net');
$json->UpdateString('token_endpoint','https://login.microsoftonline.com/TENANT_ID/oauth2/token');

//  In this example, we'll sign the SHA256 hash of the string "This is a test"
$sb = new COM("Chilkat.StringBuilder");
$signedString = 'This is a test';
$sb->Append($signedString);
$hash_base64url = $sb->getHash('sha256','base64url','utf-8');

//  We're going to send a POST to the following URL:
//  POST {vaultBaseUrl}/keys/{key-or-cert-name}/{key-or-cert-version}/sign?api-version=7.4

//  For example:

//  POST https://VAULT_NAME.vault.azure.net/keys/CERT_NAME/CERT_VERSION/sign?api-version=7.4
//  
//  {
//    "alg": "RS512",
//    "value": "RUE3Nzg4NTQ4QjQ5RjFFN0U2NzAyQzhDNEMwMkJDOTA1MTYyOTUzNjI5NDhBNzZDQTlFOTM1NDA2M0ZGMjk2Mg"
//  }

//  The alg can be one of the following
//  ES256  ECDSA using P-256 and SHA-256
//  ES256K ECDSA using P-256K and SHA-256
//  ES384  ECDSA using P-384 and SHA-384
//  ES512  ECDSA using P-521 and SHA-512
//  PS256  RSASSA-PSS using SHA-256 and MGF1 with SHA-256
//  PS384  RSASSA-PSS using SHA-384 and MGF1 with SHA-384
//  PS512  RSASSA-PSS using SHA-512 and MGF1 with SHA-512
//  RS256  RSASSA-PKCS1-v1_5 using SHA-256
//  RS384  RSASSA-PKCS1-v1_5 using SHA-384
//  RS512  RSASSA-PKCS1-v1_5 using SHA-512

//  The sample POST above uses SHA512.  We'll instead sign a SHA256 hash..

$jsonBody = new COM("Chilkat.JsonObject");
$jsonBody->UpdateString('alg','RS256');
$jsonBody->UpdateString('value',$hash_base64url);

$http = new COM("Chilkat.Http");

//  Instead of providing an actual access token, we give Chilkat the information that allows it to 
//  automatically fetch the access token using the OAuth2 client credentials flow.
$http->AuthToken = $json->emit();

$http->SetUrlVar('certName','importCert01');
$http->SetUrlVar('certVersion','7140c8755ed14839b5d86a9f7e7f0497');
//  Note: Replace "VAULT_NAME" with the name of your Azure key vault.
$url = 'https://VAULT_NAME.vault.azure.net/keys/{$certName}/{$certVersion}/sign?api-version=7.4';
$resp = new COM("Chilkat.HttpResponse");
$success = $http->HttpJson('POST',$url,$jsonBody,'application/json',$resp);
if ($success == 0) {
    print $http->LastErrorText . "\n";
    exit;
}

$statusCode = $resp->StatusCode;

$jsonResp = new COM("Chilkat.JsonObject");
$resp->GetBodyJson($jsonResp);

$jsonResp->EmitCompact = 0;
print $jsonResp->emit() . "\n";

if ($statusCode != 200) {
    print 'Failed.' . "\n";
    exit;
}

//  A successful response body contains JSON like this:
//  Note: Azure's documentation is not very clear, but base64url is the encoding, not "base64".
//  {
//    "kid": "https://kvchilkat.vault.azure.net/keys/importCert01/7140c8755ed14839b5d86a9f7e7f0497",
//    "value": "JzWd2YF21gjtW ... Em37hKOQ"
//  }

//  Let's validate the signature using the cert's public key.
//  This example will load the corresponding certificate from a local file and will verify the signature against the original data.
//  
$cert = new COM("Chilkat.Cert");
$success = $cert->LoadFromFile('qa_data/certs/chilkat_code_signing_2024.cer');
if ($success == 0) {
    print $cert->LastErrorText . "\n";
    exit;
}

$rsa = new COM("Chilkat.Rsa");
//  Tell the RSA object to use the cert's public key.
$success = $rsa->SetX509Cert($cert,0);
if ($success == 0) {
    print $rsa->LastErrorText . "\n";
    exit;
}

//  Verify the signature using the cert's public key against the original string.
$rsa->EncodingMode = 'base64url';
$valid = $rsa->VerifyStringENC($signedString,'sha-256',$jsonResp->stringOf('value'));
print 'signature valid = ' . $valid . "\n";

?>