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Curve25519 library for Java

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package org.whispersystems.curve25519.java;

public class open {

//CONVERT #include 
//CONVERT #include "crypto_sign.h"
//CONVERT #include "crypto_hash_sha512.h"
//CONVERT #include "crypto_verify_32.h"
//CONVERT #include "ge.h"
//CONVERT #include "sc.h"

    public static int crypto_sign_open(
            Sha512 sha512provider,
            byte[] m, long mlen,
            byte[] sm, long smlen,
            byte[] pk
    ) {
        byte[] pkcopy = new byte[32];
        byte[] rcopy = new byte[32];
        byte[] scopy = new byte[32];
        byte[] h = new byte[64];
        byte[] rcheck = new byte[32];
        ge_p3 A = new ge_p3();
        ge_p2 R = new ge_p2();

        if (smlen < 64) return -1;
        if ((sm[63] & 224) != 0) return -1;
        if (ge_frombytes.ge_frombytes_negate_vartime(A, pk) != 0) return -1;

        byte[] pubkeyhash = new byte[64];
        sha512provider.calculateDigest(pubkeyhash, pk, 32);

        System.arraycopy(pk, 0, pkcopy, 0, 32);
        System.arraycopy(sm, 0, rcopy, 0, 32);
        System.arraycopy(sm, 32, scopy, 0, 32);

        System.arraycopy(sm, 0, m, 0, (int) smlen);
        System.arraycopy(pkcopy, 0, m, 32, 32);
        sha512provider.calculateDigest(h, m, smlen);
        sc_reduce.sc_reduce(h);

        ge_double_scalarmult.ge_double_scalarmult_vartime(R, h, A, scopy, null);
        ge_tobytes.ge_tobytes(rcheck, R);
        if (crypto_verify_32.crypto_verify_32(rcheck, rcopy) == 0) {
            System.arraycopy(m, 64, m, 0, (int) (smlen - 64));
            //memset(m + smlen - 64,0,64);
            return 0;
        }

//badsig:
        //memset(m,0,smlen);
        return -1;
    }


}