Why not just assign the function directly instead of having a separate function?  Something like this?

```
RSAKey.prototype.verify = function(text, signature, digestMethod) {
  var c = parseBigInt(signature, 16);
  var m = c.modPowInt(this.e, this.n);
  if (m == null) return null;
  var digest = pkcs1unpad2(m, (this.n.bitLength()+7)>>3);
  console.log("RSAVerify: message digest :- " + digest);
  return digest == digestMethod(text);
};
```

Same goes for the other function you created.