Code review request: 7197245: Eliminate sun.security.ssl.JsseJce dependency on sun.security.ec

[Michael StJohns]

At 06:31 AM 9/12/2012, Vincent Ryan wrote:


>>Also, instead of the function trimZeroes, how about instead a
>>"static byte getMagnitude (BigInteger val, int magSize)" method which is really what you're trying to do.  Still throw the RuntimeError, but do it inside that method.  This is a method I really wish were part of BigInteger.
>
>Returns a byte[] I guess. What value is passed in magSize?
>

Here's a version that covers all the possibilities for getting the magnitude from a BigInteger.  It has the property that 

orig.equals (new BigInteger (orig.signum(), getMagnitude(orig, magSize)))

for any value of magSize >= ((orig.bitLength() +7 ) >> 3)

Mike


>    static byte[] getMagnitude (BigInteger value, int magSize) {
>        
>        if (BigInteger.ZERO.equals(value))
>            return new byte[1];
>        BigInteger val = value;
>        if (value.signum() == -1)
>            val = value.negate();
>        int repLength = (val.bitLength()+7) >> 3;
>
>        if (magSize < repLength) 
>            throw new RuntimeException ("Magnitude size invalid");
>        byte[] data = val.toByteArray();
>        if (magSize == data.length)
>            return data;
>
>        byte[] result = new byte[magSize];
>        if (data.length > result.length) { // leading zeros
>            System.arraycopy (data, data.length-magSize,
>                              result, 0, magSize);
>        } else { // needs padding
>            System.arraycopy (data, 0, 
>                              result, magSize-data.length, 
>                              data.length);
>        }
>                              
>
>        return result;
>    }