HTTP Basic Auth in Go

This is a template for using HTTP Basic Auth in a Go application.

Go has a built-in BasicAuth() method in the net/http module and I use that to authenticate the user. Because password hashing is so important, I’m using the bcrypt library for hasing in my template. Encryption is important with Basic Auth so we want to serve these requests over HTTPS. I’ve implemented TLS for this and you’ll need to generate a certificate. Here are a couple commands you can run to generate your certificate files.

openssl req -new -newkey rsa:2048 -nodes -keyout localhost.key -out localhost.csr
openssl x509 -req -days 365 -in localhost.csr -signkey localhost.key -out localhost.crt

I use a struct to store the application data. It will contain the server port, the web path, and the cert and key filenames. Normally you might load the username and password from a database but I’ve put them in this struct to keep the code simple. The username is admin and the password is 1234 for this example.

The auth() function authenticates a user. I use the bcrypt library for this because encryption is hard to get right. If the header is formatted correctly and the username is correct then we compare the hash with the password. For any requests that don’t authenticate, we respond indicating that the request was unauthorized and include a header that causes the browser to prompt the user for their username and password, which it will send back with the next request.

The fileHandler() function authenticates then serves static files stored in the ./www directory.

The helloHandler() function authenticates then outputs the traditional “Hello World” text to the user.

The hashHandler() function does not authenticate. If you pass it a ?pass=1234 parameter, it will print a bcrypt one-way hash for that password. You’ll get a different response each time because the password is properly salted by the bcrypt library. This is an example of how you might hash the password for storage in your user database. It’s also the tool I used to generate the hash that I stored in the struct.


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