matheusportela / enigma-machine Goto Github PK

This is the best simulator I found so far, showing the encoding path step by step: http://www.enigmaco.de/enigma/enigma.swf. Let's use it to benchmark my Enigma simulator implementation.

Hello,

Using the dcode to verify with rotor types III, II, I, ground settings A, E, W and ring setting A, A, A, I input AAA and the output is EZI while the expected output is IBM.

Using ground setting A, D, V, when inputting AAAA the output is QEZI while the expected output is QIBM.

Extracted from Technical Details on the Enigma Machine

Remember that, when depressing a key, the rotors advance before the electrical signal runs through the rotors. Therefore, to examine the current flow through the rightmost rotor in A position, the rotor must be set in the Z position before depressing the key (this also counts for the other rotors if they are due to step). In the examples above, no plugs are set on the plugboard and the signal runs directly from the A key, through the entry rotor, to rotor I.

Currently, stepping is applied after running the letter encoding

It would be nice to encode all settings in a single binary (base64 perhaps) variable representing all possible combinations.
in that way, hashing a string and producing a setting would work as a key.

Issue #6 was due to a mistakenly configured plugboard. Should I had done some assertions, such as checking whether each plugboard configuration has exactly two letters, this would have been avoided.

Use keydown instead of keyup

After adding the inner ring position, the code is messy. Let's enhance it.

Output only updates if I change the input.

Extracted from Technical Details on the Enigma Machine:

The rotors appear to work as a normal odometer, with the right-most rotor always stepping on each key stroke and the other rotors stepping after a complete cycle of the previous rotor, but there is an important difference due to the system of pawls and teeth. The middle rotor will advance on the next step of the first rotor a second time in a row, if the middle rotor is in its own turnover position. This is called the double-step. Below and example of such a sequence when the rotors III – II - I are used:

KDO KDP, KDQ, KER, LFS, LFT, LFU…

As you can observe, stepping from Q to R advances the middle rotor, and on the next step that middle rotor steps again, advancing the third rotor also. This is caused by the mechanical design of pawls and ratchets. There are three pawls that are all three activated on every key stroke. Each pawl is half positioned on the index ring (carrying a notch) of the rotor on its right, and half positioned above the 26 teeth of the rotor on its left (viewed from the point of the operator). A rotor’s ring prevents the pawl from pushing into the teeth of the next-left rotor. When a notch occurs in a ring, the pawl can drop into that notch and push into the teeth of the next-left rotor. Since the right-most pawl is not above an index ring it will continuously advance the right-most rotor.

Once the right-most rotor has stepped and the middle (spring-loaded) pawl can drop down in the right rotor's notch, it will engage the middle rotor's teeth, pushing the middle rotor one step. An identical event will take place when the middle rotor's notch enables the third pawl to drive the teeth of the left-most rotor. A rotor will not only advance if its teeth are catched, but also when a pawl pushes into its notch. This situation creates a double-step of the middle rotor: the right rotor steps and the middle pawl takes the middle rotor one step further. If the middle rotor has moved by this step into its own notch position, then, on the next step, the left-most pawl catches the teeth of the left-most rotor, but the same pawl also pushes in the middle rotor's notch, moving it a second time in a row. Note that a double notched rotor in the middle position will also have two double steps.

Quoting http://enigma.louisedade.co.uk/howitworks.html:

There are five possible rotors that can be used in any order for the three rotor positions: right, middle, left. Each rotor has an inner ring of contacts and an outer ring of contacts and their purpose is to scramble the signal. The outer ring contacts connect each rotor to the next rotor (or the static rotor / reflector) as well as its own inner ring. The inner ring contacts can be rotated relative to the outer ring which results in even more possible connections (and therefore, letter substitutions). The whole rotor itself can be rotated relative to the static rotor, so that the static rotor 'A' output is not connected to 'A' input on the rotating rotor.

Currently, the rotors don't have a configurable inner ring to allow scrambling even further the input/output rings. We can consider it as if the inner setting was fixed, i.e., the output A is always considered to be connected to the A position of its inner ring.

The simulator at http://enigma.louisedade.co.uk/enigma.html can be used to provide output messages for testing purposes.

I saw you are using Object.assign on test_enigma.js, just be aware that this is a ES2015 feature and may not be compatible in some browsers or NodeJS versions.

More info: https://developer.mozilla.org/pt-BR/docs/Web/JavaScript/Reference/Global_Objects/Object/assign#Browser_compatibility