javascript – 为什么我的crypto.sublte.digest实现会产生等长字符串的等效十六进制哈希值？

2019年8月6日 386次阅读

以下代码改编自这两个来源：

http://qnimate.com/hashing-using-web-cryptography-api/

https://developer.mozilla.org/en-US/docs/Web/API/SubtleCrypto/digest

(function () {
    "use strict";

    var crypto = window.crypto || window.msCrypto;

    if (typeof crypto.subtle === "undefined") {
        return;
    }

    function convertStringToArrayBuffer (str) {
        var strLength = str.length, buffer = new ArrayBuffer(strLength), i = 0;
        while (i < strLength) {
            buffer[i] = str.charCodeAt(i);
            i += 1;
        }
        return buffer;
    }

    function convertBufferToHex (buffer) {
        var data = new DataView(buffer), i = 0, 
            dataLength = data.byteLength, cData = null,
            hexValue = '';

        while (i < dataLength) {
            cData = data.getUint8(i).toString(16);
            if (cData.length < 2) {
                cData = '0' + cData;
            }

            hexValue += cData;
            i += 1;
        }
        return hexValue;
    }

    function digest (str) {
        var buf = convertStringToArrayBuffer(str);

        return crypto.subtle.digest("SHA-256", buf).then(function (hash) {
            return convertBufferToHex(hash);
        });
    }

    window.sha256 = {
        "convertStringToArrayBuffer": convertStringToArrayBuffer,
        "convertBufferToHex": convertBufferToHex,
        "digest": digest
    };
}());

使用sha256.digest(“this string”).then(function(x){console.log(x)});和sha256.digest(“那么强”).然后(function(x){console.log(x)});在Chrome或Firefox控制台中运行时生成相同的十六进制字符串.

实际上,具有相同长度的任何两个字符串将具有相同的十六进制表示.

我读过的所有内容都说有两个等效的哈希很少见.这意味着我在这里做错了什么.我不知道那是什么东西.

最佳答案 好的,我终于弄明白了.

根据MDN https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer,您无法直接将值分配给ArrayBuffer.

相反,你必须使用类似Uint8Array,Uint16Array,DataView等的东西来为ArrayBuffer赋值.

所以我改变了

function convertStringToArrayBuffer (str) {
    var strLength = str.length, buffer = new ArrayBuffer(strLength), i = 0;
    while (i < strLength) {
        buffer[i] = str.charCodeAt(i);
        i += 1;
    }
    return buffer;
}

至

function convertStringToArrayBuffer (str) {
    var strLength = str.length, buffer = new Uint8Array(strLength), i = 0;
    while (i < strLength) {
        buffer[i] = str.charCodeAt(i);
        i += 1;
    }
    return buffer;
}

瞧！ ：d

等长字符串不再具有匹配的哈希值.

点赞