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Questions tagged [enigma]

The Enigma Machine was a piece of cryptographic hardware used by the German military during World War II; successful cryptanalysis was routinely applied against it and the scheme was considered broken. Questions relating to this machine should use this tag and you may also which to use the historic tag.

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How did the Bombe determine daily keys from Cribs?

I have a confusion regarding the functioning of the UK Bombe. If the message key's encoded using the Grundstellung (Ground Position) but the message itself used the chosen key, how can the crib ...
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0 answers
34 views

Enigma Implementation Question

How do rings affect encryption? My current understanding is that it is just an offset, but I am having difficulty understanding the output of a test case. ...
1 vote
1 answer
236 views

How do the notch and window positions on an Enigma machine correlate?

I am having difficulty visualizing the stepping process. The permutation of Wheel I of Enigma I is as follows: ...
1 vote
1 answer
36 views

Enigma machine Rejewski cataluge and ring settings

I'm trying to simulate Rejewski cyclometer and developed a code that run over all ~100k posibilities and generates for each setting an id that looks like that: 1313_111212_11221010 I run my code with ...
1 vote
0 answers
35 views

Fitness of Text Function, did I spot an error?

I am playing around with Enigma Encryption, and especially solving it piece-wise, like in https://www.youtube.com/watch?v=RzWB5jL5RX0 shown. The idea is, that the text gets clearer, if you get more ...
1 vote
2 answers
826 views

Enigma - How many possibilities does the plugboard have?

I try to relate my own calculation with the real result being about 150.738.274.937.250. The plugboard has 26 letters, and you have 10 wires to connect pairs of letters. My idea was to calculate first ...
-1 votes
4 answers
237 views

Enigma encryption

I know how an Enigma works and that the reflector means a current flow must return by a different route but my question is this. After returning from the reflector and through the rotors, it passes ...
3 votes
2 answers
278 views

Why isn't my Enigma simulator working?

I am attempting a to simulate an 'Enigma M3' machine. As I understand it, the M3 is internally wired as: Name ABCDEFGHIJKLMNOPQRSTUVWXYZ Notch I EKMFLGDQVZNTOWYHXUSPAIBRCJ Y II ...
0 votes
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114 views

Enigma - Bombe - Understanding the relative values of ring settings to key settings

For a project, I am writing Enigma and Bombe simulators in Python. I have coded up both and so far so good. My Enigma simulator gives the same results as the online simulator here: https://people....
3 votes
0 answers
111 views

Effective key length in Enigma encryption

Each Enigma machine setting induces a certain encryption in the sense of a function from the space of plain texts to the set of cipher texts. The number of different Enigma machine settings can be ...
33 votes
8 answers
12k views

Have any cryptographic breaks been executed in the real world since World War II?

Have there been any publicly known exploits of a cryptographic break in a widely used cryptographic system to actually read encrypted information (or falsely authenticate) since the Ultra program in ...
12 votes
2 answers
1k views

Under what conditions did a Bletchley bombe stop?

I am trying to understand the conditions necessary for one of the Bletchley Park bombes to stop. Let me give an example. I have been experimenting with Enigma machine and bombe simulators to try to ...
6 votes
1 answer
276 views

A modern rotor machine, could it be any safe?

I wonder if a rotor machine similar to enigma can be considered secure by today's standards under four conditions: A rotor machine which consists of 50 rotors picked out of a set of 100. A rotor ...
5 votes
1 answer
355 views

How to recover ring settings for the slow and the middle rotors on Enigma Checking Machine?

Summary: The operation of the Enigma Bombe is well documented. I manage to use it and a candidate checking machine to recover the plugboard pairs and the ring setting for the fast rotor. I struggle to ...
1 vote
2 answers
258 views

Problem with implementation of Enigma Machine

I'm having trouble making an implementation of Enigma Machine in VBA. My question is about implementing the rotors and their move. To be more precise, I will show below the way that I code my Enigma ...
6 votes
2 answers
468 views

What were Alan Turing and their team searching before doing KPA in the movie "The imitation game"?

I just watched the movie "The imitation game" (2014) which is based on Alan Turing's biography. At some point in the movie the machine built by Turing wasn't fast enough to decrypt the ...
3 votes
2 answers
228 views

Enigma machine rotor internal wiring question

I have a question regarding the internal wiring of the rotors of the Enigma machine. I'm trying to understand some details about the original Enigma machine. To the best of my understanding, each ...
2 votes
3 answers
329 views

How much would removing enigmas biggest flaw improve it?

Enigma's biggest flaw was that a letter could never be encrypted as itself. How much would enigma's security increase if it were possible that a letter could be encrypted as itself? I know that would ...
3 votes
1 answer
95 views

Why the permutation of the right hand rotor given in Rejewski's paper is $PNP^{-1}$?

I would like to know why the permutation of the right hand rotor given in Rejewski's paper is $PNP^{-1}$. First of all I can't get how he added an $P$(alphabetic permutation) at the front of $N$(...
1 vote
1 answer
161 views

Enigma Machine rotors math

I have been doing a study about the enigma machine for the past weeks. I managed to get ahold of the formulae used in "Cryptography, Information theory and error-correction" book for the ...
1 vote
1 answer
133 views

Enigma Questions: Eliminating the can't encode to itself flaw? Maybe not a flaw

I am currently writing a paper in my old age for the fun of it. I feel that the enigma machine had gotten a bad wrap for some of its flaws. I decided to write a machine simulation to see if I can ...
3 votes
0 answers
134 views

Enigma rotor settings and the notch

According to https://www.reddit.com/r/cryptography/comments/v0sw2r/enigma_ring_settings_question/ While the rotor is in the machine, the ring+notch+rotor all rotate in sync. While the rotor is pulled ...
30 votes
4 answers
24k views

How cryptographically secure was the original WW2 Enigma machine, from a modern viewpoint?

If cryptanalysts today were to crack the original Enigma machine, “how fast” or “how easily” could they do it? What methods would they use? The original cracking was significantly helped by operator ...
1 vote
0 answers
241 views

Determining the initial positions of Engima's rotors

We want to perform a known plaintext attack on the enigma M3, the goal is to reach the initial settings of the 3 rotors. I tried to bruteforce those values since I know the plaintext, ciphertext, ...
5 votes
2 answers
192 views

Does machine cryptography only consist of rotor machines?

For the chronological categorisation of cryptography, I have proceeded as follows: Cryptography by hand (e.g. Caesar, Vigenére, etc., till around 1900/1920) Cryptography using machines (e.g. Enigma, ...
1 vote
1 answer
267 views

Why did the germans encrypted twice a random three alphabet word in enigma?

I have read that the Germans used to encipher a random three alphabet word chosen by the operator twice and put that before the enciphered message. What purpose did that have and what key they were ...
0 votes
1 answer
154 views

Question about Enigma's rotors turnover

I've been trying to make an algorithm work like the real Enigma machine, fully customizable. I use two online emulators to check that my encoded message is correct : https://cryptii.com/pipes/enigma-...
2 votes
2 answers
355 views

Is a long Enigma message vulnerable to the index of coincidence?

Let's say we have a ciphertext of length 1000. We try to decipher it with an Enigma machine with random rotors and initial positions but no plugboard (so only $5 * 4 * 3 * 26^3 \approx 2^{20}$ ...
0 votes
2 answers
724 views

How to calculate the key size of a redesign of Enigma

I have a 'for fun' project, which is a pure software based redesign of the Enigma I. I'd like to compute the key length of my design, but I need some help with that. I have a write-up here (see ...
3 votes
3 answers
511 views

Rotor machines: secrecy of the wiring

During the heyday of rotor machines, the internal rotor wiring was always a closely guarded secret. Even fully cleared repair staff was not allowed to do anything that could reveal it. As the wiring ...
2 votes
1 answer
531 views

Explanation of Enigma rotor movement

I found this explanation of Enigma rotor movement on this website, but can't quite understand the methodology: Enigma rotation example A ⤑ B → D ⤑ C (rotor III in position B) C ⤑ C → D ⤑ D (rotor II ...
4 votes
4 answers
1k views

Modifying an Enigma machine to allow unchanged letters

One of the biggest flaws of Enigma was that a letter couldn’t represent itself because the route through the machine was one-way. I was thinking a quick fix could be to introduce a rotor position that ...
19 votes
4 answers
3k views

Are encryption algorithms with fixed-point free permutations inherently flawed?

Flaw in Enigma One of the Enigma machine's flaw was the derangement (fixed-point free permutation) of the produced ciphertext, or simply put: No plaintext-letter can be enciphered to itself. See this ...
3 votes
1 answer
620 views

Enigma machine Encryption steps

I am trying to build a simulated enigma machine.I am basing it off of this one https://www.101computing.net/enigma-machine-emulator/ I have setup the 3 rotors and I am having trouble understanding the ...
3 votes
1 answer
1k views

What was the key length of the Enigma? [closed]

When I type in any plaintext to an Enigma machine (Enigma machine emulator) the substitution does not seem to follow any pattern. In other words, there is no cycle in the use of enciphering alphabets (...
0 votes
1 answer
273 views

Is my Enigma inspired cipher any good?

I am working is a project that would implement a cipher that would output ciphertext that would be easy to transmit through morse code, just like they did in the days of Enigma. Use of AES or the ...
2 votes
1 answer
966 views

Enigma ring settings - is the relative location of the turnover all that matters?

I understand that the ring setting of an Enigma rotor changes the alignment between the internal wiring and the letters on the ring. For example, in the diagram below, rotor I has ring setting 2 (B), ...
2 votes
0 answers
327 views

Why are there only 10 plugboard pairs in the enigma?

The plugboard provides a new layer of security for the enigma but why can we only swap at most 10 letters? I only found things like "10 was the most common." but why stop there? Isn't adding ...
23 votes
6 answers
3k views

Can an Enigma-style cipher of sufficient complexity be considered secure today?

Regarding the German Enigma machines, if I recall correctly, the reason they were defeated was because the Allies were able to generate a massive database of possible rotor settings, and because the ...
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0 answers
28 views

Looking for books and non-paywalled websites about Enigma "rapid analytic machinery"

I am by now perfectly aware that "Bletchley Park had much more available to them than 'Bombes,'" but I'm finding it difficult to find on-line explanations of their many other types of "...
4 votes
1 answer
105 views

Why are the indicator drums of a Bombe machine labelled from A to Z clockwise?

I am researching the Bombe Machine, having just completed a project on the Enigma Machine. I visited The Rutherford Journal - The Turing Bombe, and it claimed that The scales on the three ...
7 votes
1 answer
593 views

Why does the Bombe not consider the Ringstellung when determining stecker pairs?

I am doing research on the Bombe Machine, and I read that when the Bombe tries to find the stecker (plugboard) partners of letters, it only needs to use the rotor types and arrangement and also the "...
11 votes
2 answers
25k views

How many possible Enigma machine settings?

I'm trying to calculate the amount of settings the enigma machine has. I have found several sites regarding this topic, but it seems like there are two answers to my question. The first answer is 158,...
1 vote
1 answer
191 views

Secure enigma machine?

The enigma machine had a serious flaw: the letters could not be encrypted as themselves. Is there an online enigma simulator I can try that does not have this flaw, which would likely make it secure?
2 votes
0 answers
72 views

How does a ring affect an inverse rotor?

Rotor I with ring A would look like this: ABCDEFGHIJKLMNOPQRSTUVWXYZ ↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓ EKMFLGDQVZNTOWYHXUSPAIBRCJ Inverse rotor I with ring A would look ...
0 votes
0 answers
192 views

What is the best way to attack enigma without any a priori knowledge about the plaintext?

I know in great (great great great) detail about how they cracked enigma during the second world war. Looking into it, I decided to have a crack at breaking it. I've come apon a single problem with my ...
3 votes
1 answer
179 views

Theory Question with Enigma

I have been reading a bit about how the Enigma machine was cracked in WW2. There was also this wonderful post which highlighted a lot of useful information. Let's assume I know everything about how ...
2 votes
1 answer
1k views

What's different between ground setting and ring set in the Enigma machine?

I am writing a python program for the Enigma machine. I know what the ground setting (Grundstellung) is but I don't know the difference between ground setting and ring setting. What's different ...
2 votes
3 answers
207 views

Was Enigma really that hard to crack, given that you had access to hundreds of messages per network per day?

Well, I guess that I have always been a little bit suspicious ... so to speak ... of the "official stories" about the difficulty of recovering Enigma message texts during WW2, because it seems to me ...
0 votes
1 answer
46 views

Question about Enigmas involutional property and its reduction of possible ciphers

I'm currently learning cryptography at a university. I can't wrap my mind around how the involutional property of Engima reduces its possible ciphers while being poly-alphabetic. Can someone please ...