package org.bouncycastle.crypto.util;

public abstract class Pack
{
    public static int bigEndianToInt(byte[] bs, int off)
    {
        int n = bs[off++] << 24;
        n |= (bs[off++] & 0xff) << 16;
        n |= (bs[off++] & 0xff) << 8;
        n |= (bs[off++] & 0xff);
        return n;
    }

    public static void intToBigEndian(int n, byte[] bs, int off)
    {
        bs[off++] = (byte)(n >>> 24);
        bs[off++] = (byte)(n >>> 16);
        bs[off++] = (byte)(n >>>  8);
        bs[off  ] = (byte)(n       );
    }
}

package org.bouncycastle.crypto.util;

public abstract class Pack
{
    public static int bigEndianToInt(byte[] bs, int off)
    {
        int n = bs[  off] << 24;
        n |= (bs[++off] & 0xff) << 16;
        n |= (bs[++off] & 0xff) << 8;
        n |= (bs[++off] & 0xff);
        return n;
    }

    public static void intToBigEndian(int n, byte[] bs, int off)
    {
        bs[  off] = (byte)(n >>> 24);
        bs[++off] = (byte)(n >>> 16);
        bs[++off] = (byte)(n >>>  8);
        bs[++off] = (byte)(n       );
    }

    public static long bigEndianToLong(byte[] bs, int off)
    {
        int hi = bigEndianToInt(bs, off);
        int lo = bigEndianToInt(bs, off + 4);
        return ((long)(hi & 0xffffffffL) << 32) | (long)(lo & 0xffffffffL);
    }

    public static void longToBigEndian(long n, byte[] bs, int off)
    {
        intToBigEndian((int)(n >>> 32), bs, off);
        intToBigEndian((int)(n & 0xffffffffL), bs, off + 4);
    }
}

Improve existing methods, add new ones for packing longs