VirtualTam's bookmarks

1. SHAttered 2017-02-24

   tags: attack, checksum, collision, cryptography/hash, security, sha1, source-code-management/git

   [ permalink ]

   • https://security.googleblog.com/2017/02/announcing-first-sha1-collision.html
   • https://arstechnica.com/security/2017/02/at-deaths-door-for-years-widely-used-sha1-function-is-now-dead/
   • https://news.ycombinator.com/item?id=13719368
   • https://github.com/peff/git/commits/jk/sha1dc
   • https://plus.google.com/+LinusTorvalds/posts/7tp2gYWQugL
2. Bash: test if a file needs to be downloaded 2014-04-09

   tags: curl, development, download, file, programming/shell, programming/shell/bash, programming/testing, web, wget

   [ permalink ]

    1#!/bin/bash
    2# Check if a file needs to be downloaded
    3# Useful iff there is no checksum available to check a local file
    4url=http://test-url.com
    5
    6dl=1
    7if [[ -f $file_path ]]; then
    8    local_size=$(ls -l $file_path | awk '{print $5}')
    9    remote_size=$(wget --spider $url 2>&1 | awk '/Length/ {print $2}')
   10
   11    if [[ $local_size -eq $remote_size ]]; then
   12        echo "The file was previously downloaded"
   13        dl=0
   14    else
   15        echo "Corrupted file found, re-downloading..."
   16        rm -f $file_path
   17    fi
   18else
   19    echo "Downloading file..."
   20fi
   21
   22[[ $dl -eq 1 ]] && wget $url -O $file_path