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<HTML><HEAD><TITLE>Diffie-Hellman</TITLE></HEAD><BODY>
<script>
  SUBROSA = {};
</script>
<script src="BigInteger.js"></script>
<script src="nacl.js"></script>
<script>
// Dependencies:
// https://raw.githubusercontent.com/peterolson/BigInteger.js/master/BigInteger.js
// https://raw.githubusercontent.com/dchest/tweetnacl-js/master/nacl.js

function array_to_uint8_array(min_length, array){
  var length = Math.max(array.length, min_length);
  var result = new Uint8Array(length);
  for (var i=0; i<length; i++){
    result[length - i - 1] = i >= array.length ? 0 : array[array.length - i - 1];
  }
  return result;
}

function X25519_scalar_to_bigint(array){
  var hex = byte_array_to_hex_string(array);
  var big = bigInt(hex, 16);
  return big;
}

function bigint_to_X25519_scalar(big){
  return array_to_uint8_array(32, big.toArray(256).value);
}

function test_nacl(){
  var prime_big = bigInt(2).pow(255).minus( 19 );
  var one_big = bigInt(1);
  var one = bigint_to_X25519_scalar( one_big );
  console.log("one: ", one);


  var p = nacl.scalarMult.base(one);
  console.log("p: ", p); // should be 9 ?

  var s_big = bigInt(3);
  var s = bigint_to_X25519_scalar(s_big);
  console.log("s: ", s);

  var p2 = nacl.scalarMult(s, p)
  console.log("p2: ", p2);

  var s_inv = bigint_to_X25519_scalar(s_big.modInv(prime_big));
  console.log("s_inv: ", s_inv);

  var p3 = nacl.scalarMult(s_inv, p2)
  console.log("p3: ", p3);
}

test_nacl();
</script>
</BODY></HTML>