question: public static byte [ ] asUnsignedByteArray ( int length , BigInteger value ) { byte [ ] bytes = value . toByteArray ( ) ; if ( bytes . length == length ) { return bytes ; } int start = bytes [ 0 ] == 0 ? 1 : 0 ; int count = bytes . length - start ; if ( count > length ) { throw new IllegalArgumentException ( "standard length exceeded for value" ) ; } byte [ ] tmp = new byte [ length ] ; System . arraycopy ( bytes , start , tmp , tmp . length - count , count ) ; return tmp ; }
target:  Return the passed in value as an unsigned byte array.