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Curve25519 library for Java

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package org.whispersystems.curve25519.java;

public class fe_isnonzero {

//CONVERT #include "fe.h"
//CONVERT #include "crypto_verify_32.crypto_verify_32.h"

    static final byte[] zero = new byte[32];

    /**
     * Checks that f is not zero const time
     * Preconditions:
     * |f| bounded by 1.1*2^26,1.1*2^25,1.1*2^26,1.1*2^25,etc.
     *
     * @param f
     * @return 0 if f == 0, any value between 1 and 255 if f != 0
     */
    public static int fe_isnonzero(int[] f) {
        byte[] s = new byte[32];
        fe_tobytes.fe_tobytes(s, f);
        return crypto_verify_32.crypto_verify_32(s, zero);
    }


}