Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange
Join us in building a kind, collaborative learning community via our updated Code of Conduct.

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 ...

5
votes
2answers
66 views

when does the first rotor in Enigma machine rotate?

I read a ton of articles aout Enigma machine. And the one thing that I can't get is when the first rotor stars rotating. Some articles says the rotor rotates after the first letter of message has been ...
1
vote
2answers
50 views

Using enigma and missing one word/sentence

After you set up all rotors, position and plugs in Enigma machine. If you don´t get the signal of one word or one sentence... your enigma settings are desynchronized. How you can recover from this ...
0
votes
0answers
89 views

Enigma decryption with known plaintext and plugboard?

I have an enigma encrypted message with no known plaintext and a message with known plaintext. I also know that I, II, and <...
4
votes
3answers
76 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 ...
2
votes
1answer
63 views

What is the difference in exchanging the Enigma rotors in their slots?

I have a question regarding the exchange of the rotors in a enigma machine. I know that there are 3 slots and that up to 8 rotors can be used in those slots. What I don't understand is, as all the ...
1
vote
1answer
66 views

Order of letters on 3-rd rotor: Enigma III

In the photo you can see the three Enigma's rotors. On the 1-st rotor (marked with number 50 on the photo) letters put on clockwise. On the 2-nd rotor letters put on counterclockwise. Question. ...
3
votes
1answer
102 views

Is it right that the Bomba can halt, but give you a different settings other than the one Germans really used for encryption using an Enigma?

Considering different groundsettings for these messages: AWE RDE AFR AFG HIU HKQ (where similar letters were known as (1,4) ,(2,5) females etc. I think the cipher clerk rotated the rotors based on ...
1
vote
0answers
30 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 $N$(...
3
votes
1answer
133 views

Why Rejewski advanced three position for the right rotor in the second set of rotors in the Cyclometer he devised?

In this article about decryption of Enigma(p.259), author says that the second set of rotors was stepped three positions beyond the groundsetting in the Cyclometer Rejewski devised. I would like ...
0
votes
0answers
99 views

Decrypting an enigma machine with custom rotors and no reflector

So for a homework assignment in our cryptography class we need to essentially write a script to decrypt given ciphertext from an Enigma machine with two given rotors, no reflector and a key. The ...
0
votes
2answers
96 views

Key vs Algorithm when applied to Enigma

I've just been reading the Why should I make my cipher public? question and answers on this site. I understand Kerckhoffs's principle, but I'm unsure exactly how this applies to Enigma - i.e. where ...
2
votes
2answers
223 views

A Modernized Enigma?

I've seen answers here and elsewhere discussing how well the WWII Enigma could hold up to modern cryptanalysis, however, those answers always seem to assume the WWII conditions where the Germans had a ...
5
votes
1answer
335 views

Does adding more characters to the Enigma rotors improve crypto strength?

This seems like an obvious question but I haven't been able to find it, so here goes: Enigma is based on an alphabet of A-Z (26 characters); obviously this directly affects message content (e.g. ...
7
votes
0answers
279 views

culling equivalent Enigma keys for short messages [closed]

The following for-loop iterates over all possible keys for an M3 Enigma for three selected rotors: ...
1
vote
0answers
43 views

Possible enigma settings? [duplicate]

I'm writing an assignment about the Enigma machine, and 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 ...
14
votes
3answers
374 views

Turing's (still?) classified inference engine algorithm?

Does anyone know the algorithm used by Turing's Colossus inference engine, so highly classified that the Brits kept it secret for decades after WW II? Indeed, it may still be classified. Several ...
8
votes
2answers
5k 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,...
8
votes
3answers
181 views

Would adding daily changing nulls in front of their messages have made the Engima harder to crack?

The British decrypted the German enigma because they knew that they would repeat the message key twice at the start of every message. Of course, technology to encrypt enigma without the repetition ...
4
votes
1answer
238 views

Would the rotors in Enigma machines always advance by one position? Or was there a way to set this?

Before encrypting a letter the first rotor advances by one, right? So there could be a way, once the first rotor turns 26 times, make the second rotor advance two positions instead of one. Or three. ...
0
votes
1answer
125 views

“Royal Flags Wave Kings Above” [closed]

I'm a starter to cryptanalysis and in fact to cryptology. Last night I was decrypting a message from a book that I would quite odd. It doesn't make sense. The decrypted message is "Royal Flags Waves ...
1
vote
0answers
473 views

Obtain Enigma key having a encrypted text and the plain text

I have an Enigma message and I know what the original message is (a repetition of the same letter). Is it possible obtain the enigma key? I only know what kind of Enigma machine is it, but I need to ...
2
votes
2answers
232 views

How exactly is an enigma simulation software supposed to encrypt alphabets?

EDIT: The model I'm trying to make is "Enigma 1". I learned initially about it from a book called "Code Book" and then looked at it in detail from its wikipedia page. The rotor wiring and other ...
6
votes
2answers
2k views

How does the ring settings of enigma change wiring tables?

EDIT: The model I'm trying to make is "Enigma 1". I learned initially about it from a book called "Code Book" and then looked at it in detail from its wikipedia page. The site wont allow me too add ...
7
votes
1answer
329 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 ...
5
votes
2answers
2k views

Why is this the inverse of a Enigma Machine rotor?

I am learning about how the Enigma Machine works and I found this example of one letter being encrypted by an Enigma Machine. It shows the letter "G" going through three rotors and then it goes into ...
0
votes
1answer
194 views

Which algorithm can be performed by humans?

Suppose I want my grandmother to perform encryption without any help from a computer, and she must encrypt the word 'HELLO' for me. I could ask her to instead of typing the real keys, that she always ...
1
vote
1answer
229 views

Engima machine decoding with PC and GPU

I saw this answer at this site about decoding a 3-rotor Engima machine's settings: How cryptographically secure was the original WW2 Enigma machine, from a modern viewpoint? And did some math for ...
2
votes
1answer
403 views

Security of permutation cipher

I would like to understand how secure the permutation cipher is. I would specifically like to understand the following concrete setup: If the alphabet is $L = \{0,1,\dots , 255\}$ and $\sigma_1, \...
5
votes
4answers
515 views

Get permutations from password

Are there any "good" ways to get a permutation from a password/pass-phrase? If one, for example, wanted to get a permutation of letters from a password, how might one do that in a smart way? I would ...
28
votes
3answers
19k 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 ...
14
votes
1answer
1k views

How to build an electro-mechanical public key cipher machine?

It is generally assumed that asymmetric encryption schemes were invented in 1973 at GCHQ in Britain and, independently, in 1976 at the MIT. Imagine, if the abstract idea of having a public key and a ...
4
votes
3answers
2k views

Could the Enigma algorithm be classified as a Feistel network?

The Enigma algorithm is a encryption method that was developed (I believe) by the Germans in WWII. It went a little something like this: When a letter was typed on the keyboard of the Enigma ...
7
votes
1answer
1k views

How to deduce enigma settings given a partial plaintext?

Assuming some large block of text is encrypted with an enigma machine and I only know a small subset of letters before and after encryption, how do I go about figuring out the enigma settings from ...
6
votes
3answers
1k views

Is the logic for how the enigma machine worked documented somewhere?

I know that there is a formula to calculate the result of any input but is the logic of how the machine actually worked documented? I have seen schematics for the circuitry and even a how to make ...
20
votes
6answers
2k 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 ...