Delphi 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. Delphi ActiveX

var
success: Integer;
json: TChilkatJsonObject;
sb: TChilkatStringBuilder;
signedString: WideString;
hash_base64url: WideString;
jsonBody: TChilkatJsonObject;
http: TChilkatHttp;
url: WideString;
resp: TChilkatHttpResponse;
statusCode: Integer;
jsonResp: TChilkatJsonObject;
cert: TChilkatCert;
rsa: TChilkatRsa;
valid: Integer;

begin
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 := TChilkatJsonObject.Create(Self);
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 := TChilkatStringBuilder.Create(Self);
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 := TChilkatJsonObject.Create(Self);
jsonBody.UpdateString('alg','RS256');
jsonBody.UpdateString('value',hash_base64url);

http := TChilkatHttp.Create(Self);

//  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 := TChilkatHttpResponse.Create(Self);
success := http.HttpJson('POST',url,jsonBody.ControlInterface,'application/json',resp.ControlInterface);
if (success = 0) then
  begin
    Memo1.Lines.Add(http.LastErrorText);
    Exit;
  end;

statusCode := resp.StatusCode;

jsonResp := TChilkatJsonObject.Create(Self);
resp.GetBodyJson(jsonResp.ControlInterface);

jsonResp.EmitCompact := 0;
Memo1.Lines.Add(jsonResp.Emit());

if (statusCode <> 200) then
  begin
    Memo1.Lines.Add('Failed.');
    Exit;
  end;

//  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 := TChilkatCert.Create(Self);
success := cert.LoadFromFile('qa_data/certs/chilkat_code_signing_2024.cer');
if (success = 0) then
  begin
    Memo1.Lines.Add(cert.LastErrorText);
    Exit;
  end;

rsa := TChilkatRsa.Create(Self);
//  Tell the RSA object to use the cert's public key.
success := rsa.SetX509Cert(cert.ControlInterface,0);
if (success = 0) then
  begin
    Memo1.Lines.Add(rsa.LastErrorText);
    Exit;
  end;

//  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'));
Memo1.Lines.Add('signature valid = ' + IntToStr(Ord(valid)));