Reading about Gerard Huet's paper on the geometry of the Shri Yantra available in PDF format at this link http://pauillac.inria.fr/~huet/SKT/sanskrit.html.orig, I was prompted to try out the Postscript code he had in and Appendix in the paper. After typing the code into a .txt file, the file did not render using Evince or a PDF … Continue reading How to convert PostScript script to a .ps file for viewing in PDF viewer or to PNG
Tag: security
How to securely wipe a hard drive or USB drive in Linux using dd or scrub
Normally we'd use dd to clean wipe a hard drive as follows after opening a terminal window for a hard disk or USB drive accessible as /dev/sdb :$ sudo dd if=/dev/urandom of=/dev/sdb status=progress <enter> Another command to do a secure wipe of /dev/sdb is scrub that can be used as follows:$ sudo scrub -p dod … Continue reading How to securely wipe a hard drive or USB drive in Linux using dd or scrub
Email: [Firebase] Client access to your Cloud Firestore database expiring in X day(s)
The easiest way to overcome this expiry is to change the date in the rules after logging into the account:match /{document=**} {// from previous date 2020, 11, 11 to new date 2021, 12, 11allow read, write: if request.time < timestamp.date(2021, 12, 11);} However, do note that it is important to drop access using this method … Continue reading Email: [Firebase] Client access to your Cloud Firestore database expiring in X day(s)
How to check if user name or ID has been compromised in a data breach
When data breaches occur, there are various kinds of data that get compromised. The most critical data that can get compromised is the user name or ID or the password. All is not lost due to a great service hosted by Troy Hunt. Use https://haveibeenpwned.com/ to check if the User name or user ID appears … Continue reading How to check if user name or ID has been compromised in a data breach
Remember History in Firefox 75+ and private browser windows
Mozilla Firefox 75+ has made a change in the way it determines whether web sites open in a private window or not. This is now tied in with the "Remember History" option in Preferences -> Privacy and Security option. To enable Private Windows all the time, select "Never Remember History", but to disable private windows, … Continue reading Remember History in Firefox 75+ and private browser windows
How to validate a short URL
At times, short URLs starting with https://bit.ly or https://goo.gl or any other short and strange form are received via SMS or even email. It is difficult to authenticate and know where these URLs point to. If the source is trusted, then too, it is important to know and validate these URLs to ensure they do … Continue reading How to validate a short URL
Recover encrypted ecryptfs home folder from encrypted dm-crypt luks disk volume
Whew... saved by the skin of teeth. The grub2 bootloader of my computer got corrupt. I was not able to boot into the computer and all was lost. For security reasons, I set up LVM with full disk encryption. Thereafter, each user's home folder was further encrypted with ecryptfs (the default you get when you … Continue reading Recover encrypted ecryptfs home folder from encrypted dm-crypt luks disk volume
How to calculate MD5 or SHA256 sums in Linux and Android
Many of us use Linux Distributions like Ubuntu, Fedora, available for free on the Internet. To install these distributions on our computers, we need to down their ISO files. Recently, the Linux Mint ISO was hacked and malware inserted into some of it's files. It was then repacked and put up on an external website. … Continue reading How to calculate MD5 or SHA256 sums in Linux and Android
How to extend expiry date of Gnu Privacy Guard Keys (GPG/PGP) keys
When PGP/GPG keys expire, you have option to generate a sub key (if you think your key has been compromised), or you can extend the validity of the current key by extending it's expiry period. You can extend the key's expiry period since the keys are not compromised. To continue, Open a terminal window and … Continue reading How to extend expiry date of Gnu Privacy Guard Keys (GPG/PGP) keys
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