crypto - Imapenguin

Making and breaking Ciphers on the Commodore 64 Part 11 - One time pads on a Commodore 64, probably a bad idea

A while ago, I explained in detail how to generate one time pad sheets and use them to encrypt and decrypt messages. It turned out to be doable, only requiring a pencil and a way to create random numbers, but it's slow, error prone and tedious. WhyThe one time pad

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Making and breaking Ciphers on the Commodore 64 Part 10 - Finding hash collisions with a type in game from 1984

HashesWe did an implementation of a once popular hashing function in Part 8 on RC4 without really going into why. A hash function is any function that is used to map data of an arbitrary size (input) to a fixed size output. An algorithm is applied to the input and

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Making and Breaking Ciphers with Commodore 64 Part 9 - Finding Smallish Primes

RecapSo far we've Reversed a stringShifted bits left and right (mostly right)Brute forced a known simple cipherChanneled our inner John Connor by cracking ATM machinesSearched through a large number looking for matchesLearned how to use XOR to recover dataCreated a Linear Feedback Shift Register to generate better random numbersImplemented

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Making and breaking Ciphers on the Commodore 64 Part 8 - RC4

RecapSo far in this 8 part series on doing weird things with Ciphers on old computers we've: Reversed a stringShifted bits left and right (mostly right)Brute forced a known simple cipherChanneled our inner John Connor by cracking ATM machinesSearched through a large number looking for matchesLearned how to use

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Making and breaking Ciphers on the Commodore 64 Part 7 - Pseudo Random with Linear Congruential Generators

So far in this 7 part (shocked I've made it through 7!) series on doing weird things with Ciphers on old computers we've: Reversed a stringShifted bits left and right (mostly right)Brute forced a known simple cipherChanneled our inner John Connor by cracking ATM machinesSearched through a large number

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Making and Breaking Ciphers with a Commodore 64 - Part 6: XOR is Magical - Data recovery

ReviewSo far we've: Reversed a stringShifted bits left and right (mostly right)Brute forced a known simple cipherFaked it, but then looking for a 4 digit known pinSearched through a large number looking for matchesWe now have most of the basic skills in Assembly to start doing some real work.

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Quick post: Determining length in Commodore Assembly

A common task in our code is to determine the length of something. In this example, let's check the length of a string like "are you keeping up?" In Python, this is crazy easy. #!/usr/bin/env python message = "are you keeping up?" len(message) Python 3In 6510 Assembly, this

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Making and Breaking Ciphers with a Commodore 64 - Part 4: The PIN Program from Terminator 2

A few minutes into Terminator 2, the young John Connor takes his Atari Portfolio out of his bag and inserts a foil covered card into an ATM machine and proceeds to crack a pin number and steal some cash from an unsuspecting account. This is a movie prop and doesn't

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Making and Breaking Ciphers with a Commodore 64 - Part 3: The Caesar Cipher

Well here we are at part three and it's a lot to pack into one page. Let's build upon what I called the Shift Cipher and implement what is often referred to as the Caesar Cipher, although there is much debate on when this was really first done. The idea

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Making and Breaking Ciphers with Python, er Commodore- Part 2: The Shift Cipher

In Part 1 we did a simple reverse of a string. While simple, these software steps will help build the skills we need going forward in Assembly without feeling like I skipped right to a 300 line after doing a short one. One foot in front of the other and

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Making and Breaking Ciphers with Python, er, a Commodore- Part 1: The Reverse Cipher

Sometime during my weeklong exploration of SHA-256 on a Commodore realized that there was a whole world of exploration that could be explored. Just because a Computer system is old, doesn't mean it's not interesting or useful. I had expected it to take months to figure out the SHA-256 implementation,

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Simple, 'unbreakable' encryption with a pencil

Last week, at this bat-time on this bat-channel, I talked about checking off one of my 35 year old bucket list items by learning Commodore assembly language. (shut up, you're old too.) Coincidentally, I picked this up at the time I was re-reading Cryptonomicon by Neal Stephenson for the ump-teenth