70 lines
1.7 KiB
JavaScript
70 lines
1.7 KiB
JavaScript
var bignum = require('bignum');
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//x and y are both bignums
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var Point = function(x, y) {
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this.x = x;
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this.y = y;
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};
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var n = bignum.fromBuffer(new Buffer("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141", 'hex'), {
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size: 32
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});
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Point.getN = function() {
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return n;
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};
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var G;
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Point.getG = function() {
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// don't use Point in top scope, causes exception in browser
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// when Point is not loaded yet
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// use cached version if available
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G = G || new Point(bignum.fromBuffer(new Buffer("79BE667EF9DCBBAC55A06295CE870B07029BFCDB2DCE28D959F2815B16F81798", 'hex'), {
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size: 32
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}),
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bignum.fromBuffer(new Buffer("483ADA7726A3C4655DA4FBFC0E1108A8FD17B448A68554199C47D08FFB10D4B8", 'hex'), {
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size: 32
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}));
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return G;
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};
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//convert the public key of a Key into a Point
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Point.fromUncompressedPubKey = function(pubkey) {
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var point = new Point();
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point.x = bignum.fromBuffer(pubkey.slice(1, 33), {
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size: 32
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});
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point.y = bignum.fromBuffer(pubkey.slice(33, 65), {
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size: 32
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});
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return point;
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};
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//convert the Point into the Key containing a compressed public key
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Point.prototype.toUncompressedPubKey = function() {
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var xbuf = this.x.toBuffer({
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size: 32
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});
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var ybuf = this.y.toBuffer({
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size: 32
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});
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var prefix = new Buffer([0x04]);
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var pubkey = Buffer.concat([prefix, xbuf, ybuf]);
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return pubkey;
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};
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Point.prototype.toCompressedPubKey = function() {
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var xbuf = this.x.toBuffer({size: 32});
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var ybuf = this.y.toBuffer({size: 32});
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if (ybuf[ybuf.length-1] % 2) { //odd
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var pub = Buffer.concat([new Buffer([3]), xbuf]);
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}
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else { //even
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var pub = Buffer.concat([new Buffer([2]), xbuf]);
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}
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return pub;
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};
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module.exports = Point;
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