Simon Willison’s Weblog

URLsafe base64 encoding/decoding in two lines. A much better solution than my base65 hack—if you understand how base64 padding works (I didn’t) you can use it to generate URL-safe compressed hashes. Performance should be significantly better than my version.

# 28th August 2008, 9:57 am / base64, base65, python, urlsafe

Django snippets: Sign a string using SHA1, then shrink it using url-safe base65. I needed a way to create tamper-proof URLs and cookies by signing them, but didn’t want the overhead of a full 40 character SHA1 hash. After some experimentation, it turns out you can knock a 40 char hash down to 27 characters by encoding it using a custom base65 encoding which only uses URL-safe characters.

# 27th August 2008, 10:18 pm / base65, cookies, cryptography, django, django-snippets, hashes, python, security, sha1, signedcookies, urls