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"use strict";
/**
* @fileOverview
* Core operations on curve 25519 required for the higher level modules.
*/
/*
* Copyright (c) 2007, 2013, 2014 Michele Bini
* Copyright (c) 2014 Mega Limited
* under the MIT License.
*
* Authors: Guy K. Kloss, Michele Bini
*
* You should have received a copy of the license along with this program.
*/
var core = require('./core');
var utils = require('./utils');
/**
* @exports jodid25519/curve255
* Legacy compatibility module for Michele Bini's previous curve255.js.
*
* @description
* Legacy compatibility module for Michele Bini's previous curve255.js.
*
* <p>
* This code presents an API with all key formats as previously available
* from Michele Bini's curve255.js implementation.
* </p>
*/
var ns = {};
function curve25519_raw(f, c) {
var a, x_1, q;
x_1 = c;
a = core.dbl(x_1, core.ONE());
q = [x_1, core.ONE()];
var n = 255;
while (core.getbit(f, n) == 0) {
n--;
// For correct constant-time operation, bit 255 should always be
// set to 1 so the following 'while' loop is never entered.
if (n < 0) {
return core.ZERO();
}
}
n--;
var aq = [a, q];
while (n >= 0) {
var r, s;
var b = core.getbit(f, n);
r = core.sum(aq[0][0], aq[0][1], aq[1][0], aq[1][1], x_1);
s = core.dbl(aq[1 - b][0], aq[1 - b][1]);
aq[1 - b] = s;
aq[b] = r;
n--;
}
q = aq[1];
q[1] = core.invmodp(q[1]);
q[0] = core.mulmodp(q[0], q[1]);
core.reduce(q[0]);
return q[0];
}
function curve25519b32(a, b) {
return _base32encode(curve25519(_base32decode(a),
_base32decode(b)));
}
function curve25519(f, c) {
if (!c) {
c = core.BASE();
}
f[0] &= 0xFFF8;
f[15] = (f[15] & 0x7FFF) | 0x4000;
return curve25519_raw(f, c);
}
function _hexEncodeVector(k) {
var hexKey = utils.hexEncode(k);
// Pad with '0' at the front.
hexKey = new Array(64 + 1 - hexKey.length).join('0') + hexKey;
// Invert bytes.
return hexKey.split(/(..)/).reverse().join('');
}
function _hexDecodeVector(v) {
// assert(length(x) == 64);
// Invert bytes.
var hexKey = v.split(/(..)/).reverse().join('');
return utils.hexDecode(hexKey);
}
// Expose some functions to the outside through this name space.
/**
* Computes the scalar product of a point on the curve 25519.
*
* This function is used for the DH key-exchange protocol.
*
* Before multiplication, some bit operations are applied to the
* private key to ensure it is a valid Curve25519 secret key.
* It is the user's responsibility to make sure that the private
* key is a uniformly random, secret value.
*
* @function
* @param f {array}
* Private key.
* @param c {array}
* Public point on the curve. If not given, the curve's base point is used.
* @returns {array}
* Key point resulting from scalar product.
*/
ns.curve25519 = curve25519;
/**
* Computes the scalar product of a point on the curve 25519.
*
* This variant does not make sure that the private key is valid.
* The user has the responsibility to ensure the private key is
* valid or that this results in a safe protocol. Unless you know
* exactly what you are doing, you should not use this variant,
* please use 'curve25519' instead.
*
* @function
* @param f {array}
* Private key.
* @param c {array}
* Public point on the curve. If not given, the curve's base point is used.
* @returns {array}
* Key point resulting from scalar product.
*/
ns.curve25519_raw = curve25519_raw;
/**
* Encodes the internal representation of a key to a canonical hex
* representation.
*
* This is the format commonly used in other libraries and for
* test vectors, and is equivalent to the hex dump of the key in
* little-endian binary format.
*
* @function
* @param n {array}
* Array representation of key.
* @returns {string}
* Hexadecimal string representation of key.
*/
ns.hexEncodeVector = _hexEncodeVector;
/**
* Decodes a canonical hex representation of a key
* to an internally compatible array representation.
*
* @function
* @param n {string}
* Hexadecimal string representation of key.
* @returns {array}
* Array representation of key.
*/
ns.hexDecodeVector = _hexDecodeVector;
/**
* Encodes the internal representation of a key into a
* hexadecimal representation.
*
* This is a strict positional notation, most significant digit first.
*
* @function
* @param n {array}
* Array representation of key.
* @returns {string}
* Hexadecimal string representation of key.
*/
ns.hexencode = utils.hexEncode;
/**
* Decodes a hex representation of a key to an internally
* compatible array representation.
*
* @function
* @param n {string}
* Hexadecimal string representation of key.
* @returns {array}
* Array representation of key.
*/
ns.hexdecode = utils.hexDecode;
/**
* Encodes the internal representation of a key to a base32
* representation.
*
* @function
* @param n {array}
* Array representation of key.
* @returns {string}
* Base32 string representation of key.
*/
ns.base32encode = utils.base32encode;
/**
* Decodes a base32 representation of a key to an internally
* compatible array representation.
*
* @function
* @param n {string}
* Base32 string representation of key.
* @returns {array}
* Array representation of key.
*/
ns.base32decode = utils.base32decode;
module.exports = ns;
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