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[QUOTE="jargoman, post: 3723, member: 9018"]
Well, I came up with the fllowing code. I decided to throw an exception for negative values and hope the code doesn't require the retrieval of big endian negative values.

[CODE]
public static byte[] bigIntegerToBytes (BigInteger biToConvert, int nbBytesToReturn)
        {
            byte[] twosComplement = BigInteger.ToByteArray ();
            byte[] bytesToReturn = new byte[nbBytesToReturn];
            //TODO two's compliments
            //if ((biToConvert.

if (biToConvert.Sign < 0) {
                // not sure about this one
                throw new NotImplementedException ("bigIntegerToBytes does not implement the retrieval of negative values");
            }

// not sure about this either
            if (twosComplement [twosComplement.Length - 1] == 0) {
                // there's an empty byte at the end (little endian) to denote a positive number
                byte[] twosComplementWithoutSign = new byte[twosComplement.Length - 1];
                System.Array.Copy (twosComplement, twosComplementWithoutSign, twosComplementWithoutSign.Length);
                twosComplement = twosComplementWithoutSign;
            }

int nbBytesOfPaddingRequired = nbBytesToReturn - twosComplement.Length;

if (nbBytesOfPaddingRequired < 0) {
                throw new IndexOutOfRangeException("nbBytesToReturn "+nbBytesToReturn+" is too small");
            }

// big endian
            //System.Array.Copy(twosComplement, 0, bytesToReturn, nbBytesOfPaddingRequired, twosComplement.Length);

// little endian
            System.Array.Copy(twosComplement, bytesToReturn, twosComplement.Length);

return bytesToReturn;

}
[/CODE]
[/QUOTE]

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