Ethereum converting string & random string to private key

Question

I am receiving as input a private key string and a random string. Goal is to get public key and address.

1. When I am receiving the string I do:

   var hash = Crypto.util.hexToBytes(privStr);

   this.priv = new BigInteger(hash);

2. A random string:

   var hash = keccak256.array(suppliedKey);

   this.priv = new BigInteger(hash);

On both randomly work, am I doing it correctly?

UPDATE 1. In first case my issue was I was not appending "0x" as prefix of the string.

Answer 1

1. In first case my issue was I was not appending "0x" as prefix of the string.

2. My error was using keccak256.array(suppliedKey). The correct way was using:

   var privStr = keccak256(suppliedKey);

   var hash = Crypto.util.hexToBytes(privStr);

   this.priv = new BigInteger(hash);