以下是JavaScript中实现SHA-256加密算法的详细代码：
```javascript
// 将字符串转成UTF-8编码的字节数组
function stringToUtf8ByteArray(str) {
const utf8 = unescape(encodeURIComponent(str));
const byteArray = [];
for (let i = 0; i < utf8.length; i++) {
byteArray.push(utf8.charCodeAt(i));
}
return byteArray;
}
// 将字节数组转成十六进制字符串
function byteArrayToHexString(byteArray) {
const hexString = [];
for (let i = 0; i < byteArray.length; i++) {
hexString.push(('0' + (byteArray[i] & 0xFF).toString(16)).slice(-2));
}
return hexString.join('');
}
// 右移位运算
function rotateRight(n, x) {
return (x >>> n) | (x << (32 - n));
}
// SHA-256加密算法
function sha256(str) {
const byteArray = stringToUtf8ByteArray(str);
const k = [
0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
];
const h = [
0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19
];
const paddedByteArray = [...byteArray];
paddedByteArray.push(0x80);
const messageLength = paddedByteArray.length * 8;
const paddingSize = (448 - (messageLength + 8) % 512 + 512) % 512;
for (let i = 0; i < paddingSize / 8; i++) {
paddedByteArray.push(0x00);
}
for (let i = 0; i < 8; i++) {
paddedByteArray.push((messageLength >>> (56 - i * 8)) & 0xFF);
}
const chunks = [];
for (let i = 0; i < paddedByteArray.length /
