title: How to sign a string with rsa-sha256 by using private key?
body: <p>I have to sign a string with <code>privateKey</code> generated by OpenSSL on each <code>API</code> call, the <code>privateKey</code> is received from a database and changes for each user.</p>
  <p>I've read that I should use <code>RSACryptoService</code> and add <code>privateKey</code> as parameter to achieve this. However I get error &quot;Invalid data&quot; in <code>ImportParameters</code></p>
  <p>This is the code:</p>
  <pre><code>string privateKey = &quot;-----BEGIN RSA PRIVATE KEY-----
      MIIJ.....&quot;
  
  RSAParameters rsap = new RSAParameters
  {
      Modulus = Encoding.ASCII.GetBytes(privateKey)
  };
  rsa.ImportParameters(rsap);
  byte[] encryptedData = rsa.Encrypt(Encoding.UTF8.GetBytes(StringToSign), false);
  string base64Encrypted = Convert.ToBase64String(encryptedData);
  </code></pre>
  <p>In the documentation of the service it is stated that it is required to sign the string with RSA-SHA256. Here is the code to sign that string in Node.JS:</p>
  <pre><code>const signature = crypto.createSign('RSA-SHA256').update(string).sign(privateKey, 'base64')
  </code></pre>
  <p>However, I wasn't able to find anything similar in c#.</p>