How to encrypt a large file without loading the whole file into memory?

<p>I am new to Go so I am not sure if this is possible.</p> <p>I found an example <a href="https://astaxie.gitbooks.io/build-web-application-with-golang/en/09.6.html" rel="nofollow">here</a> for encrypting and decrypting a file, but as you can see, it requires the entire file to be loaded in memeory as a byte array. </p> <p>It is possible to encrypt a file reader stream so that the result can be pipe into a writer stream using io.Copy()?</p> <hr/>**评论：**<br/><br/>pcj2bs: <pre><p>There&#39;s an example in the docs that does that!</p> <p><a href="https://golang.org/pkg/crypto/cipher/#example_StreamWriter" rel="nofollow">https://golang.org/pkg/crypto/cipher/#example_StreamWriter</a></p></pre>elagergren: <pre><p>I really wouldn&#39;t recommend using it for anything serious because it hasn&#39;t been looked over by another set of eyes, but an interesting little package I wrote a while back was <a href="https://github.com/ericlagergren/boxer" rel="nofollow">https://github.com/ericlagergren/boxer</a>.</p> <p>It uses secretbox (NaCl) to encrypt chunks and puts the chunk number in the nonce. The idea is from <a href="https://www.imperialviolet.org/2014/06/27/streamingencryption.html" rel="nofollow">https://www.imperialviolet.org/2014/06/27/streamingencryption.html</a></p></pre>