ecdsa-node-ts
Version:
TypeScript implementation of the Elliptic Curve Digital Signature Algorithm (ECDSA)
118 lines (117 loc) • 5.1 kB
JavaScript
;
// based on random-number-csprng: https://www.npmjs.com/package/random-number-csprng
var __createBinding = (this && this.__createBinding) || (Object.create ? (function(o, m, k, k2) {
if (k2 === undefined) k2 = k;
var desc = Object.getOwnPropertyDescriptor(m, k);
if (!desc || ("get" in desc ? !m.__esModule : desc.writable || desc.configurable)) {
desc = { enumerable: true, get: function() { return m[k]; } };
}
Object.defineProperty(o, k2, desc);
}) : (function(o, m, k, k2) {
if (k2 === undefined) k2 = k;
o[k2] = m[k];
}));
var __setModuleDefault = (this && this.__setModuleDefault) || (Object.create ? (function(o, v) {
Object.defineProperty(o, "default", { enumerable: true, value: v });
}) : function(o, v) {
o["default"] = v;
});
var __importStar = (this && this.__importStar) || (function () {
var ownKeys = function(o) {
ownKeys = Object.getOwnPropertyNames || function (o) {
var ar = [];
for (var k in o) if (Object.prototype.hasOwnProperty.call(o, k)) ar[ar.length] = k;
return ar;
};
return ownKeys(o);
};
return function (mod) {
if (mod && mod.__esModule) return mod;
var result = {};
if (mod != null) for (var k = ownKeys(mod), i = 0; i < k.length; i++) if (k[i] !== "default") __createBinding(result, mod, k[i]);
__setModuleDefault(result, mod);
return result;
};
})();
var __importDefault = (this && this.__importDefault) || function (mod) {
return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.modulo = modulo;
exports.between = between;
const big_integer_1 = __importDefault(require("big-integer"));
const crypto = __importStar(require("crypto"));
function modulo(x, n) {
let mod = x.divmod(n).remainder;
if (mod.lesser(0)) {
mod = mod.add(n);
}
return mod;
}
function calculateParameters(range) {
/* This does the equivalent of:
*
* bitsNeeded = Math.ceil(Math.log2(range));
* bytesNeeded = Math.ceil(bitsNeeded / 8);
* mask = Math.pow(2, bitsNeeded) - 1;
*
* ... however, it implements it as bitwise operations, to sidestep any
* possible implementation errors regarding floating point numbers in
* JavaScript runtimes. This is an easier solution than assessing each
* runtime and architecture individually.
*/
let bitsNeeded = 0;
let bytesNeeded = 0;
let mask = (0, big_integer_1.default)(1);
while (range.greater(0)) {
if (bitsNeeded % 8 === 0) {
bytesNeeded += 1;
}
bitsNeeded += 1;
mask = mask.shiftLeft(1).or(1); /* 0x00001111 -> 0x00011111 */
range = range.shiftRight(1); /* 0x01000000 -> 0x00100000 */
}
return { bitsNeeded, bytesNeeded, mask };
}
function between(minimum, maximum) {
if (!crypto || !crypto.randomBytes) {
throw new Error("No suitable random number generator available. Ensure that your runtime is linked against OpenSSL (or an equivalent) correctly.");
}
if (maximum.lesserOrEquals(minimum)) {
throw new Error("The maximum value must be higher than the minimum value.");
}
let range = maximum.minus(minimum);
let { bitsNeeded, bytesNeeded, mask } = calculateParameters(range);
let randomBytes = crypto.randomBytes(bytesNeeded);
let randomValue = (0, big_integer_1.default)(0);
/* Turn the random bytes into an integer, using bitwise operations. */
for (let i = (0, big_integer_1.default)(0); i.lesser(bytesNeeded); i = i.add(1)) {
randomValue = randomValue.or((0, big_integer_1.default)(randomBytes[i.toJSNumber()]).shiftLeft((0, big_integer_1.default)(8).multiply(i)));
}
/* We apply the mask to reduce the amount of attempts we might need
* to make to get a number that is in range. This is somewhat like
* the commonly used 'modulo trick', but without the bias:
*
* "Let's say you invoke secure_rand(0, 60). When the other code
* generates a random integer, you might get 243. If you take
* (243 & 63)-- noting that the mask is 63-- you get 51. Since
* 51 is less than 60, we can return this without bias. If we
* got 255, then 255 & 63 is 63. 63 > 60, so we try again.
*
* The purpose of the mask is to reduce the number of random
* numbers discarded for the sake of ensuring an unbiased
* distribution. In the example above, 243 would discard, but
* (243 & 63) is in the range of 0 and 60."
*
* (Source: Scott Arciszewski)
*/
randomValue = randomValue.and(mask);
if (randomValue.lesserOrEquals(range)) {
/* We've been working with 0 as a starting point, so we need to
* add the `minimum` here. */
return minimum.add(randomValue);
}
/* Outside of the acceptable range, throw it away and try again.
* We don't try any modulo tricks, as this would introduce bias. */
return between(minimum, maximum);
}