We"re reaching the end of the performance đánh giá season, and everybody at work is a bit on edge waiting for their rating. Tuesdaywas when my manager was supposed lớn tell me mine. When we met, he refused lớn disclose though, but asked me to lớn wait for one more day. Previously, he asked for my address, và said he"s sending me a package. He was obviously upbeating, so I thought it"d be a good news.
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This morning a FedEx man handed me a package containing a wooden box & a cryptogram.
The wooden box is a lovely mini Enigma! It works like a charm, and can simulate all well-known Enigma machines that have 26 keys.
It looks lượt thích I have to lớn use this Enigma to lớn crack the cryptogram, which I reckon contains the result of my perf review.
The simulator is well-crafted & super sophisticated. It has tons of options. I have to admit that before today I"d never paid much attention lớn Enigma. I felt stupid because I didn"t know where to lớn start. Here I am a technical lead responsible for the correct use of crypto, và consider myself a history buff, yet I knew next to lớn nothing about the most famous broken encryption device in history. I had a good laugh at this thought. It always feels good when I am reminded not lớn take myself so seriously.
After playing with the Enigma for half an hour without making any progress, I pretended that I had more important work lớn do, & put it aside. Wednesday is my meeting day. I spent a couple of hours in various 1:1s, and a couple more helping a teammate debug a weird issue in Tink"s experimental post-quantum crypto module. BTW we just released Tink 1.5.0 last week, kiểm tra it out!
We were implementing HRSS, one of the finalists of the NIST PQC competition. HRSS is a lattice-based public key encapsulation method. It provides two functions: encap & decap. The former allows a sender to lớn transport a secret to a recipient using the recipient"s public key. The latter allows the recipient lớn recover the secret using the private key.
The issue was that the decap function returned a wrong result. This function takes an encapsulated secret and a private key. Either our code was wrong or the input đầu vào were corrupted. A lot of printfs later, I found that the private key was malformed. But how? In the failed unit thử nghiệm we just copied the private key pointer from one place to lớn another.
At this point I"d spent 2-3 hours on this issue, already run out of places to lớn printf. Time lớn take a break. I wanted to lớn distract myself with another problem, and the Enigma cryptogram was just a perfect choice.
I thought, well, it is a serious machine, if I want khổng lồ crack it I have khổng lồ understand how it works first. I read the manual, và digested the Enigma pages on Wikipedia. The cryptanalysis is fascinating, but I"m afraid it won"t help me because all I got is a single ciphertext. The manager hinted that I only had to guess the encryption key. I wasn"t sure if I should trust him, but I didn"t have any better idea.
Several different Enigma models were produced, each has many settings, và this simulator replicates them all. It provides a long thực đơn that allows lớn choose the machine model, và configure the initial state. The machine state, including the position of the rotors, how they interact with each other, is the encryption key. That is, if I want to decrypt, I need lớn find the state when the messages was being encrypted.
The state space is too huge to lớn brute force. I reckoned that my manager probably used the default settings, meaning many bits of the state are already correct. The most obvious place for him to change is the initial position of the rotors. There are 4 rotors, each has 26 positions, meaning the key is a 4-char word và totally there are 26^4 possibilities. I thought well if I can"t guess it a brute-force search wouldn"t be a bad idea.
It was obvious that the key is my name THAI. It didn"t work. My next brilliant idea was GOOG. No luck. Hmm, maybe I misconfigured the machine? I read the manual one more time, and also performed a few trial encryption/decryption with random keys. I didn"t make any mistake, it seems that bầu really wasn"t the key.
Dinner time came, và together M. And I were eating & guessing the encryption key. Have you tried SNOW? Oh my god, it must be SNOW! He loves skiing, & he knows you also love it! M. Was so excited, but SNOW wasn"t it. It must be 2020 then, have you tried that? I said Enigma doesn"t allow khổng lồ enter numbers. Stupid machine, M. Protested! Funtimes.
Eventually I found the key, & the message decrypts lớn this:
It looks lượt thích I was promoted :-). It took me 5 years. At this rate I"ll be CEO in about 300 years. There"s a high chance that I might need another life.
While pondering what I should write in my first reorg announcement as the CEO, I composed an encrypted response. When the manager saw it, he thought I decrypted his original message incorrectly, & gave me more hints! It hurt my ego, I said no no, I cracked it, & that"s my reply for you. The bastard was still trying to lớn decrypt it while I was writing this. He asked for a hint, but I"m not sure why I should help him, given that I"m already promoted.
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Riding high on the adrenaline rush, I went back to lớn the HRSS issue, and found the problematic lines of code within a few minutes. It"s still unclear what exactly went wrong, but at least we now know the origin of the problem. There"s something wrong with the way we were copying the private key pointer. I shared the finding with my teammate, and thought he will be very happy when he sees this tomorrow -- he had been wrestling with this bug for days.
They say, vì what you love và you don"t have to lớn work another day in your life. I say bullshit, most jobs including mine suck in one way or another, và that"s okay. Today was another day, however, I indeed did what I love, và didn"t feel lượt thích working at all. Thank you boss & everyone!