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54 votes

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

One example that immediately comes to mind is the attack on WEP, which is based on an unknown (to the designers at the time) related key attack on RC4 that lead to a key recovery. It needs to be a ...
poncho's user avatar
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29 votes

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

An example is GSM voice encryption using A5/1, used in Europe and USA on the voice channel of the radio link of cellphones before 3G. While with a good algorithm the 80-bit key size of A5/1 would be a ...
fgrieu's user avatar
  • 142k
28 votes

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

The DVD Content Scramble System. It needs to be a true cryptographic break, stemming from mathematical cryptanalysis Although the cipher is intrinsically weak, at only 40 bits, brute-forcing still ...
Mark's user avatar
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22 votes
Accepted

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

I'm no cryptographer, but I think the Flame malware matches your description. It's an extremely sophisticated tool for cyber espionage discovered in 2012. Experts believe it was developed by the US ...
Fabio says Reinstate Monica's user avatar
20 votes
Accepted

How many possible Enigma machine settings?

Depends on the exact model. Wikipedia is your friend: "Combining three rotors from a set of five, the rotor settings with 26 positions, and the plugboard with ten pairs of letters connected, the ...
kodlu's user avatar
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18 votes
Accepted

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

Are all encryption algorithms with fixed-point free permutations inherently flawed? Yes - when fixed points, or the lack of them, is knowable and detectable. This is a violation of multiple ...
Natanael's user avatar
  • 369
16 votes

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

Are all encryption algorithms with fixed-point free permutations inherently flawed? No, they are not inherently flawed. Consider the following cipher: Let $k_0$ be a key for AES-256, and let $k_1$...
Squeamish Ossifrage's user avatar
13 votes
Accepted

Under what conditions did a Bletchley bombe stop?

After a year I have managed to find a suitable solution to the problem. My understanding is based on the following picture that I created, based on a simplified version that I found online (at present ...
Geoff's user avatar
  • 351
9 votes
Accepted

Was the Enigma's double stepping mechanism intentional?

I suspect it was a semi-deliberate feature. That is, while it probably wasn't a design goal in and of itself, it neatly solved a mechanical issue that would otherwise have required a more complicated ...
Ilmari Karonen's user avatar
8 votes

How many possible Enigma machine settings?

The answer depends on the Enigma model, on the number of rotors among which the active rotors are chosen, on the number of wires used for the reflector, and on what one accounts for as part of a ...
fgrieu's user avatar
  • 142k
8 votes

When does the first rotor in Enigma machine rotate?

Having had the privilege of using one of the original machines, I can tell you the sequence is the following: set the plugs, and set the rotors. Once you push the key, you can feel the force of the ...
b degnan's user avatar
  • 4,830
8 votes

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

I didn't want to delete this question, but it seems like after pondering this for a week I finally understand right when I seek help online. When the ring setting and the rotor position all increase ...
Queso Pez's user avatar
  • 301
8 votes

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

The Dual EC DRBG Juniper Networks hack should qualify. It needs to be a true cryptographic break, stemming from mathematical cryptanalysis In 1997 Adam L. Young and Moti Yung presented a paper at ...
John Deters's user avatar
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8 votes

A modern rotor machine, could it be any safe?

No, modern standards for symmetric cryptography are heavily over-engineered and the power of chosen plaintext attacks/chosen ciphertext attacks can quickly uncover the structure of such a variant ...
Daniel S's user avatar
  • 23.9k
7 votes

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

Block ciphers operators from $\{0,1\}^n \to \{0,1\}^n$. Each key selects one permutation among all possible permutations $n!$ and this is very small one if you compare $2^{128}$ to $128^{128}$ For ...
kelalaka's user avatar
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6 votes
Accepted

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

It's wrong to treat a Hollywood historical movie as a documentary. It's also wrong to think of Enigma as a single problem with a single solution. There were many variants of the Enigma machine which ...
Daniel S's user avatar
  • 23.9k
5 votes

Modifying an Enigma machine to allow unchanged letters

There was at least one late Enigma derivative, the Russian M-125 Fialka, that did modify the reflector to allow a letter to encrypt to itself. Curiously, rather than simply making the cipher alphabet ...
Ilmari Karonen's user avatar
5 votes

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

This doesn't answer your question, but you may find clues in two wartime papers of Alan Turing which were formerly classified were declassified and published in the UK National Archives in 2015, and ...
Squeamish Ossifrage's user avatar
5 votes

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

There are three nice answers here, each supported with well thought out arguments. It seems to me that not only is it difficult to distinguish between fixed point free and non fixed point free ...
kodlu's user avatar
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5 votes
Accepted

Does machine cryptography only consist of rotor machines?

I would argue that a great many cryptographic designs lie between the mechanical designs of 2 and the micro-electronic designs of 3. These designs are electronic in nature, but without the universal ...
Daniel S's user avatar
  • 23.9k
4 votes

How does the ring settings of enigma change wiring tables?

Ok, here we go. Let's use Rotor I as an example. The wiring for this rotor looks like this: EKMFLGDQVZNTOWYHXUSPAIBRCJ On every rotor, there originally was a ...
b3nj4m1n's user avatar
  • 247
4 votes

Was the Enigma's double stepping mechanism intentional?

It was very likely not put in place deliberately, since it doesn't seems to make sense to have it or not have it in place deliberately. I assume it was just overlooked. Since double-stepping occured ...
AleksanderCH's user avatar
  • 6,462
4 votes
Accepted

Enigma message decode errors, and protocols to prevent them

On page 5 of the document you linked in the comment it says the following in section 22: Satzzeichen Es werden ausgedrückt: Punkt durch x, Doppelpunkt durch xx, Fragezeichen durch ud, ...
AleksanderCH's user avatar
  • 6,462
4 votes

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

Terms As stated on Wikipedia: Ring settings (Ringstellung) – the position of each alphabet ring relative to its rotor wiring. Starting position of the rotors (Grundstellung) – chosen by the operator, ...
AleksanderCH's user avatar
  • 6,462
4 votes
Accepted

Enigma - How many possibilities does the plugboard have?

out of 325 pairs to choose 10 pairs, there are 325C10 possibilities to connect pairs with 10 wires. This accounts for the fact that we can not choose a pair that has both letters identical to an ...
fgrieu's user avatar
  • 142k
3 votes

When does the first rotor in Enigma machine rotate?

When you press down a key the rightmost rotor turns first, when the key hits the bottom the electric circuit is made and one of the lamps lights up. At some positions turning the rightmost will turn ...
lpaseen's user avatar
  • 199
3 votes

Rotor machines: secrecy of the wiring

Off the top of my head, I see no obvious theoretical reason why a hypothetical Enigma-like rotor machine cipher with publicly known rotor wiring couldn't be secure, even by modern standards. It would ...
Ilmari Karonen's user avatar
3 votes

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

They may look equal but in fact each rotor defines a different letter substitution. A letter substitution is a function that converts each of the 26 letters into another letter. For example $a\...
Jackoson's user avatar
  • 133
3 votes

How does the ring settings of enigma change wiring tables?

The easiest way to understand the path of the current through the rotors is to make up six tables for the three wheels, three going forward and three going backwards plus a table for the reflector. ...
K ROSSER's user avatar
3 votes

Under what conditions did a Bletchley bombe stop?

Suppose it is an Army Enigma I. Choose reflector UKW-B or UKW-C. Choose three rotors from I, II, III, IV and V. For each of the 120 reflector/rotors permutations, there are 17,576 starting indicator ...
Chan Tai Man's user avatar

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