title: to use RSA_PKCS1_OAEP_PADDING for RSA signature
body: <p>Previously I was using rsa signature with no padding ,but now I was asked to add PKCS1_OAEP padding ,Initially I tried simple adding this flag "RSA_PKCS1_OAEP_PADDING", but it is giving error code while running like this</p>
  
  <pre><code>error:04066076:rsa routines:RSA_EAY_PRIVATE_ENCRYPT:unknown padding type
  </code></pre>
  
  <p>Further I googled about the rsa signature with PKCS1_OAEP padding but didn't get anything except it is said that for implementing RSA_PKCS1_OAEP padding you have to use this one </p>
  
  <pre><code>int RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen,
             unsigned char *f, int fl, unsigned char *p, int pl);
  </code></pre>
  
  <p>and then do private_encrypt with RSA_NO_padding but still having confusion as they have not explained clearly how to use this padding_add function explictly .can anyone provide help .would really appreciate that .</p>
  
  <p>thanks in advance</p>