Popular:
 Building Resilient Systems on AWS: Learn how to design and implement a resilient, highly available, fault-tolerant infrastructure on AWS.

How to checksum

By  on  

Many of us see the term checksum and checksum outputs frequently but don't really take the time to run them -- oftentimes we simply trust the file we've downloaded is in working order and from the original source.  This past weekend when I was attempting to recover my Bitcoin Cash, however, I wasn't willing to chance it -- I wanted to ensure the app/file hadn't been compromised in any way.

For those who don't know what a checksum is, I think this definition from Lifewire is helpful:

A checksum is the outcome of running an algorithm, called a cryptographic hash function, on a piece of data, usually a single file. Comparing the checksum that you generate from your version of the file, with the one provided by the source of the file, helps ensure that your copy of the file is genuine and error free.

Armed with the file I wanted, and the verified checksum provided by the author, I ran a checksum on the file in question:

shasum 1 logo.png

# shasum: 1:
# e78c5ca49b926a15b3d4e5107f3b17b2cc6fd54b  logo.png

shasum is Mac's command line command for checking checkums.  The first argument represents which sha hash value you want to use (sha-1, sha-256, etc.) . The last argument is the file to check.

When it comes to financial and critical apps and files, it's probably worth your time to run a quick checksum to ensure what you've downloaded is what you really want!

Request Metrics real user monitoring
Request Metrics real user monitoring
Request Metrics real user monitoring
Request Metrics real user monitoring

Recent Features

  • By
    Create a CSS Cube

    CSS cubes really showcase what CSS has become over the years, evolving from simple color and dimension directives to a language capable of creating deep, creative visuals.  Add animation and you've got something really neat.  Unfortunately each CSS cube tutorial I've read is a bit...

  • By
    JavaScript Promise API

    While synchronous code is easier to follow and debug, async is generally better for performance and flexibility. Why "hold up the show" when you can trigger numerous requests at once and then handle them when each is ready?  Promises are becoming a big part of the JavaScript world...

Incredible Demos

  • By
    Custom Scrollbars in WebKit

    Before each of the browser vendors we like was providing unique CSS controls, Internet Explorer was setting the tone.  One such example is IE's early implementation of CSS filters. Internet Explorer was also the first browser that allowed developers to, for better or worse, customize...

  • By
    Making the Firefox Logo from HTML

    When each new t-shirt means staving off laundry for yet another day, swag quickly becomes the most coveted perk at any tech company. Mozilla WebDev had pretty much everything going for it: brilliant people, interesting problems, awesome office. Everything except a t-shirt. That had to change. The basic...

Discussion

  1. Marc Roussy

    Thanks for that. I hadn’t had to do it on the Mac side yet but on Windows the equivalent built-in utility is called CertUtil.

Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!