70 lines
2.4 KiB
JavaScript
70 lines
2.4 KiB
JavaScript
function decompressPublicKey(compressedKey) {
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// 获取压缩标志和X坐标
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var flag = compressedKey.slice(0, 2);
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var x = compressedKey.slice(2);
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// 定义常量
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var p = BigInt('0xFFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00000000FFFFFFFFFFFFFFFF', 16);
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var a = BigInt('0xFFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00000000FFFFFFFFFFFFFFFC', 16);
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var b = BigInt('0x28E9FA9E9D9F5E344D5A9E4BCF6509A7F39789F515AB8F92DDBCBD414D940E93', 16);
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// 计算Y坐标
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// y2 = x3 + ax + b
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var xBigInt = BigInt('0x' + x);
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var alpha = (xBigInt ** 3n) % p;
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var beta = (a * xBigInt + b) % p;
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var y2 = (alpha + beta) % p;
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var y = modularExponentiation(y2, (p + 1n) / 4n, p);
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// y2 的值开方有两个值，根据奇偶判定取哪一个
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if (flag === "02") {
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// 如果压缩标志为“02”，则Y坐标为偶数
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if (y % 2n === 0n) {
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return "04" + x + y.toString(16).padStart(64, '0');
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} else {
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y = p - y;
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return "04" + x + y.toString(16).padStart(64, '0');
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}
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} else if (flag === "03") {
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// 如果压缩标志为“03”，则Y坐标为奇数
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if (y % 2n === 1n) {
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return "04" + x + y.toString(16).padStart(64, '0');
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} else {
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y = p - y;
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return "04" + x + y.toString(16).padStart(64, '0');
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}
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} else {
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return null;
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}
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}
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function modularExponentiation(base, exponent, modulus) {
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var result = 1n;
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base = base % modulus;
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while (exponent > 0n) {
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if (exponent % 2n === 1n) {
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result = (result * base) % modulus;
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}
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base = (base * base) % modulus;
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exponent = exponent / 2n;
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}
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return result;
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}
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function hexToBase64(hex) {
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var bytes = [];
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for (var i = 0; i < hex.length-1; i += 2) {
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bytes.push(parseInt(hex.substr(i, 2), 16));
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}
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var byteArray = new Uint8Array(bytes);
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return btoa(String.fromCharCode.apply(null, byteArray));
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}
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function base64ToHex(base64) {
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var binaryString = atob(base64);
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var byteArray = new Uint8Array(binaryString.length);
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for (var i = 0; i < binaryString.length; i++) {
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byteArray[i] = binaryString.charCodeAt(i);
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}
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var hexArray = Array.prototype.map.call(byteArray, function(byte) {
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return ('0' + byte.toString(16)).slice(-2);
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});
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return hexArray.join('');
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} |