181 lines
4.0 KiB
Markdown
181 lines
4.0 KiB
Markdown
---
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id: 5eb3e4b5f629b9a07429a5d2
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title: SHA-1
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challengeType: 5
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forumTopicId: 385326
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dashedName: sha-1
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---
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# --description--
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**SHA-1** 或稱 **SHA1** 是一種單向散列函數，它產生數據的 160 位摘要信息。
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SHA-1 經常出現在安全協議中；例如，許多 HTTPS 網站使用 SHA-1 來保護他們的連接。
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BitTorrent 使用 SHA-1 來驗證下載內容。
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Git 和 Mercurial 使用 SHA-1 摘要來覈驗提交內容。
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美國政府標準 [FIPS 180-1](https://rosettacode.org/wiki/SHA-1/FIPS-180-1) 了定義 SHA-1。
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# --instructions--
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寫一個函數返回給定字符串的 SHA-1 消息摘要。
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# --hints--
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`SHA1` 應該是一個函數。
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```js
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assert(typeof SHA1 === 'function');
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```
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`SHA1("abc")` 應該返回一個字符串。
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```js
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assert(typeof SHA1('abc') === 'string');
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```
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`SHA1("abc")` 應該返回 `"a9993e364706816aba3e25717850c26c9cd0d89d"`
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```js
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assert.equal(SHA1('abc'), 'a9993e364706816aba3e25717850c26c9cd0d89d');
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```
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`SHA1("Rosetta Code")` 應該返回 `"48c98f7e5a6e736d790ab740dfc3f51a61abe2b5"`
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```js
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assert.equal(SHA1('Rosetta Code'), '48c98f7e5a6e736d790ab740dfc3f51a61abe2b5');
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```
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`SHA1("Hello world")` 應該返回 `"7b502c3a1f48c8609ae212cdfb639dee39673f5e"`
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```js
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assert.equal(SHA1('Hello world'), '7b502c3a1f48c8609ae212cdfb639dee39673f5e');
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```
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`SHA1("Programming")` 應該返回 `"d1a946bf8b2f2a7292c250063ee28989d742cd4b"`
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```js
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assert.equal(SHA1('Programming'), 'd1a946bf8b2f2a7292c250063ee28989d742cd4b');
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```
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`SHA1("is Awesome")` 應該返回 `"6537205da59c72b57ed3881843c2d24103d683a3"`
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```js
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assert.equal(SHA1('is Awesome'), '6537205da59c72b57ed3881843c2d24103d683a3');
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```
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# --seed--
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## --seed-contents--
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```js
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function SHA1(input) {
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}
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```
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# --solutions--
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```js
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function SHA1(input) {
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var hexcase = 0;
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var b64pad = '';
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var chrsz = 8;
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function hex_sha1(s) {
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return binb2hex(core_sha1(str2binb(s), s.length * chrsz));
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}
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function core_sha1(x, len) {
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x[len >> 5] |= 0x80 << (24 - (len % 32));
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x[(((len + 64) >> 9) << 4) + 15] = len;
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var w = Array(80);
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var a = 1732584193;
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var b = -271733879;
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var c = -1732584194;
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var d = 271733878;
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var e = -1009589776;
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for (var i = 0; i < x.length; i += 16) {
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var olda = a;
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var oldb = b;
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var oldc = c;
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var oldd = d;
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var olde = e;
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for (var j = 0; j < 80; j++) {
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if (j < 16) w[j] = x[i + j];
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else w[j] = rol(w[j - 3] ^ w[j - 8] ^ w[j - 14] ^ w[j - 16], 1);
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var t = safe_add(
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safe_add(rol(a, 5), sha1_ft(j, b, c, d)),
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safe_add(safe_add(e, w[j]), sha1_kt(j))
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);
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e = d;
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d = c;
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c = rol(b, 30);
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b = a;
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a = t;
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}
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a = safe_add(a, olda);
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b = safe_add(b, oldb);
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c = safe_add(c, oldc);
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d = safe_add(d, oldd);
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e = safe_add(e, olde);
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}
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return Array(a, b, c, d, e);
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}
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function sha1_ft(t, b, c, d) {
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if (t < 20) return (b & c) | (~b & d);
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if (t < 40) return b ^ c ^ d;
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if (t < 60) return (b & c) | (b & d) | (c & d);
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return b ^ c ^ d;
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}
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function sha1_kt(t) {
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return t < 20
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? 1518500249
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: t < 40
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? 1859775393
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: t < 60
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? -1894007588
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: -899497514;
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}
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function safe_add(x, y) {
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var lsw = (x & 0xffff) + (y & 0xffff);
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var msw = (x >> 16) + (y >> 16) + (lsw >> 16);
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return (msw << 16) | (lsw & 0xffff);
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}
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function rol(num, cnt) {
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return (num << cnt) | (num >>> (32 - cnt));
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}
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function str2binb(str) {
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var bin = Array();
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var mask = (1 << chrsz) - 1;
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for (var i = 0; i < str.length * chrsz; i += chrsz)
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bin[i >> 5] |= (str.charCodeAt(i / chrsz) & mask) << (24 - (i % 32));
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return bin;
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}
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function binb2hex(binarray) {
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var hex_tab = hexcase ? '0123456789ABCDEF' : '0123456789abcdef';
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var str = '';
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for (var i = 0; i < binarray.length * 4; i++) {
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str +=
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hex_tab.charAt((binarray[i >> 2] >> ((3 - (i % 4)) * 8 + 4)) & 0xf) +
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hex_tab.charAt((binarray[i >> 2] >> ((3 - (i % 4)) * 8)) & 0xf);
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}
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return str;
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}
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return hex_sha1(input);
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}
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```
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