Question on Password Encryption, using stdlib or third party lib

[0xFFFFFFFF via Digitalmars-d-learn]

On a project I was asked to

a- Compute SHA-256 of a password
b- Do a BigInteger, convert to Hex String
c- Encrypt the key using a public key with the following 
parameters
  Entropy: I'm given some numbers
  Modulus: also given long numbers
[encrypt using RSA algorithm]

So far I'm familiar with a and b in Dlang.

how do I go about c) In Dlang ?

Thanks