Checking the integrity and completeness of a file that you have transferred to your Android device that you might flash or restore to your phone is a very good idea. Have you ever downloaded a 100MB file and tried to flash or unpack it only to discover that the file was incomplete or corrupted? Checking a file's published checksum (usually an MD5 digest) against its calculated value can give you peace of mind and save you valuable time and rework. There are several options for doing this on your Android device: - AFV (Android File Verifier), which was developed by an AF member for the rooting community, can verify MD5 and SHA1 checksums and can verify Nandroid backups. Additionally, if you have a signed .jar type file (signed ROMs, .apk app files, update.zip files, etc.), AFV can also do a "jarsigner -v" type of verification even if you don't know/have a published MD5 checksum. - Astro File Manager (long-press filename, select Details, wait for checksum to be calculated) - several other apps in the Android Market If you need to check an MD5 checksum on your Windows machine, there are several utilities: - Download MD5 Checker 2.31 Free - A utility that can verify downloads with an MD5 checksum - Softpedia - Download the MD5summer - HashTab tool to quickly find file hash information To check the MD5 sum on a linux machine open a Terminal session and type "md5sum home/username/Desktop/filename.zip" To create the MD5 sum on a linux machine open a Terminal session and type "md5sum home/username/desktop/filename.zip > home/username/Desktop/filename.md5" When using either of these terminal commands be sure to change the path is specific to the file you wish to calculate the checksum for. You can also use the following program: - RHash | Free Development software downloads at SourceForge.net From a Apple Mac: open a Terminal session and type "openssl md5 <filename>"