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After go1.16, go will use module mode by default, even when the repository is checked out under GOPATH or in a one-off directory. Add go.mod, go.sum to keep this repo buildable without opting out of the module mode. > go mod init github.com/mmcgrana/gobyexample > go mod tidy > go mod vendor In module mode, the 'vendor' directory is special and its contents will be actively maintained by the go command. pygments aren't the dependency the go will know about, so it will delete the contents from vendor directory. Move it to `third_party` directory now. And, vendor the blackfriday package. Note: the tutorial contents are not affected by the change in go1.16 because all the examples in this tutorial ask users to run the go command with the explicit list of files to be compiled (e.g. `go run hello-world.go` or `go build command-line-arguments.go`). When the source list is provided, the go command does not have to compute the build list and whether it's running in GOPATH mode or module mode becomes irrelevant.
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211 lines
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<!DOCTYPE html>
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<html>
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<head>
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<meta charset="utf-8">
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<title>Go by Example: SHA1 Hashes</title>
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<link rel=stylesheet href="site.css">
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</head>
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<script>
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onkeydown = (e) => {
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if (e.key == "ArrowLeft") {
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window.location.href = 'url-parsing';
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}
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if (e.key == "ArrowRight") {
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window.location.href = 'base64-encoding';
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}
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}
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</script>
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<body>
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<div class="example" id="sha1-hashes">
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<h2><a href="./">Go by Example</a>: SHA1 Hashes</h2>
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<table>
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<tr>
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<td class="docs">
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<p><a href="http://en.wikipedia.org/wiki/SHA-1"><em>SHA1 hashes</em></a> are
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frequently used to compute short identities for binary
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or text blobs. For example, the <a href="http://git-scm.com/">git revision control
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system</a> uses SHA1s extensively to
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identify versioned files and directories. Here’s how to
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compute SHA1 hashes in Go.</p>
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</td>
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<td class="code empty leading">
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</td>
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</tr>
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<tr>
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<td class="docs">
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</td>
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<td class="code leading">
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<a href="http://play.golang.org/p/XLftf8Gvj4y"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
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<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>Go implements several hash functions in various
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<code>crypto/*</code> packages.</p>
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</td>
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<td class="code leading">
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<div class="highlight"><pre><span class="kn">import</span> <span class="p">(</span>
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<span class="s">"crypto/sha1"</span>
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<span class="s">"fmt"</span>
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<span class="p">)</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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</td>
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<td class="code leading">
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<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
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<span class="nx">s</span> <span class="o">:=</span> <span class="s">"sha1 this string"</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>The pattern for generating a hash is <code>sha1.New()</code>,
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<code>sha1.Write(bytes)</code>, then <code>sha1.Sum([]byte{})</code>.
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Here we start with a new hash.</p>
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</td>
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<td class="code leading">
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<div class="highlight"><pre> <span class="nx">h</span> <span class="o">:=</span> <span class="nx">sha1</span><span class="p">.</span><span class="nx">New</span><span class="p">()</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p><code>Write</code> expects bytes. If you have a string <code>s</code>,
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use <code>[]byte(s)</code> to coerce it to bytes.</p>
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</td>
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<td class="code leading">
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<div class="highlight"><pre> <span class="nx">h</span><span class="p">.</span><span class="nx">Write</span><span class="p">([]</span><span class="nb">byte</span><span class="p">(</span><span class="nx">s</span><span class="p">))</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>This gets the finalized hash result as a byte
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slice. The argument to <code>Sum</code> can be used to append
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to an existing byte slice: it usually isn’t needed.</p>
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</td>
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<td class="code leading">
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<div class="highlight"><pre> <span class="nx">bs</span> <span class="o">:=</span> <span class="nx">h</span><span class="p">.</span><span class="nx">Sum</span><span class="p">(</span><span class="kc">nil</span><span class="p">)</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>SHA1 values are often printed in hex, for example
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in git commits. Use the <code>%x</code> format verb to convert
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a hash results to a hex string.</p>
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</td>
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<td class="code">
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<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">s</span><span class="p">)</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%x\n"</span><span class="p">,</span> <span class="nx">bs</span><span class="p">)</span>
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<span class="p">}</span>
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</pre></div>
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</td>
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</tr>
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</table>
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<table>
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<tr>
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<td class="docs">
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<p>Running the program computes the hash and prints it in
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a human-readable hex format.</p>
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</td>
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<td class="code leading">
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<div class="highlight"><pre><span class="gp">$</span> go run sha1-hashes.go
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<span class="go">sha1 this string</span>
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<span class="go">cf23df2207d99a74fbe169e3eba035e633b65d94</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>You can compute other hashes using a similar pattern to
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the one shown above. For example, to compute MD5 hashes
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import <code>crypto/md5</code> and use <code>md5.New()</code>.</p>
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</td>
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<td class="code empty leading">
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>Note that if you need cryptographically secure hashes,
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you should carefully research
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<a href="http://en.wikipedia.org/wiki/Cryptographic_hash_function">hash strength</a>!</p>
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</td>
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<td class="code empty">
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</td>
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</tr>
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</table>
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<p class="next">
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Next example: <a href="base64-encoding">Base64 Encoding</a>.
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</p>
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<p class="footer">
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by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/sha1-hashes">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
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</p>
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</div>
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<script>
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var codeLines = [];
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codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A \"crypto/sha1\"\u000A \"fmt\"\u000A)\u000A');codeLines.push('func main() {\u000A s :\u003D \"sha1 this string\"\u000A');codeLines.push(' h :\u003D sha1.New()\u000A');codeLines.push(' h.Write([]byte(s))\u000A');codeLines.push(' bs :\u003D h.Sum(nil)\u000A');codeLines.push(' fmt.Println(s)\u000A fmt.Printf(\"%x\\n\", bs)\u000A}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');
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</script>
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<script src="site.js" async></script>
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</body>
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</html>
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