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Merged
samdaw13 merged 1 commit into from
Mar 9, 2026
Merged

refactor: extract codebreaking into standalone module #102

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181 changes: 4 additions & 177 deletions src/utils/codebreaking.test.tsx → src/codebreaking/crib-analysis.test.tsx
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Original file line number Diff line number Diff line change
@@ -1,75 +1,19 @@
import { initialReflectorState } from '../features/reflector';
import { initialRotorState } from '../features/rotors/features';
import type {
PlugboardCable,
ReflectorState,
RotorState,
} from '../types/interfaces';
import type { CribSearchResult, MenuEdge } from './codebreaking';
import type { ReflectorState, RotorState } from '../types/interfaces';
import { encryptLetter, stepRotors } from '../utils/enigma';
import type { MenuEdge } from './crib-analysis';
import {
buildMenuEdges,
cribSearchAsync,
encryptString,
findCribPositions,
propagateMenuConstraints,
} from './codebreaking';
import { encryptLetter, stepRotors } from './enigma';
} from './crib-analysis';

const rotorI: RotorState = initialRotorState.available[1]!;
const rotorII: RotorState = initialRotorState.available[2]!;
const rotorIII: RotorState = initialRotorState.available[3]!;

const reflectorB: ReflectorState = initialReflectorState.reflectors[2]!;
const emptyPlugboard: PlugboardCable = {};

describe('encryptString', () => {
it('encrypts a string through the full signal path', () => {
const rotors = [rotorIII, rotorII, rotorI];
const result = encryptString('AAA', rotors, emptyPlugboard, reflectorB);
expect(result).toHaveLength(3);
expect(result).toMatch(/^[A-Z]+$/);
});

it('produces consistent output for same config', () => {
const rotors = [rotorIII, rotorII, rotorI];
const result1 = encryptString('HELLO', rotors, emptyPlugboard, reflectorB);
const result2 = encryptString('HELLO', rotors, emptyPlugboard, reflectorB);
expect(result1).toBe(result2);
});

it('decrypts back to original (Enigma symmetry)', () => {
const rotors = [rotorIII, rotorII, rotorI];
const encrypted = encryptString(
'HELLO',
rotors,
emptyPlugboard,
reflectorB,
);
const decrypted = encryptString(
encrypted,
rotors,
emptyPlugboard,
reflectorB,
);
expect(decrypted).toBe('HELLO');
});

it('no letter encrypts to itself', () => {
const rotors = [rotorIII, rotorII, rotorI];
const plaintext = 'AAAAAAAAAA';
const result = encryptString(plaintext, rotors, emptyPlugboard, reflectorB);
for (let i = 0; i < plaintext.length; i++) {
expect(result[i]).not.toBe(plaintext[i]);
}
});
});

// Limit rotors to III, II, I for faster crib search tests (6 perms vs 60)
const limitedRotors = {
1: initialRotorState.available[1]!,
2: initialRotorState.available[2]!,
3: initialRotorState.available[3]!,
};

const buildScramblerTableAt = (
rotors: RotorState[],
Expand Down Expand Up @@ -222,123 +166,6 @@ describe('propagateMenuConstraints', () => {
});
});

describe('cribSearchAsync', () => {
it('finds a matching result with derived plugboard when crib is present', async () => {
jest.useRealTimers();
const plaintext = 'WITHTION';
const crib = 'WITH';
const rotors = [
{ ...rotorIII, config: { ...rotorIII.config, currentIndex: 0 } },
{ ...rotorII, config: { ...rotorII.config, currentIndex: 0 } },
{ ...rotorI, config: { ...rotorI.config, currentIndex: 0 } },
];
const ciphertext = encryptString(
plaintext,
rotors,
emptyPlugboard,
reflectorB,
);
const segment = ciphertext.slice(0, crib.length);

const results: CribSearchResult[] = await cribSearchAsync(
ciphertext,
crib,
limitedRotors,
{ 2: initialReflectorState.reflectors[2]! },
() => {},
);

expect(results.length).toBeGreaterThan(0);
expect(results[0]!.derivedPlugboard).toBeDefined();
expect(results[0]!.cribPosition).toBeGreaterThanOrEqual(0);
expect(results[0]!.nlpScore).toBeGreaterThanOrEqual(0);
expect(results[0]!.nlpScore).toBeLessThanOrEqual(100);

// Verify the correct config is self-consistent: with an empty plugboard every
// stecker value must map to itself (verified via the exported lower-level API).
const tablesAtPos0 = Array.from({ length: crib.length }, (_, i) =>
buildScramblerTableAt(rotors, i + 1),
);
const edges = buildMenuEdges(crib, segment, tablesAtPos0, 0);
const stecker = propagateMenuConstraints(edges, crib[0]!, crib[0]!);
expect(stecker).not.toBeNull();
for (const [key, value] of stecker!.entries()) {
expect(key).toBe(value);
}
}, 60000);

it('includes derivedPlugboard in every result', async () => {
jest.useRealTimers();
const rotors = [
{ ...rotorIII, config: { ...rotorIII.config, currentIndex: 0 } },
{ ...rotorII, config: { ...rotorII.config, currentIndex: 0 } },
{ ...rotorI, config: { ...rotorI.config, currentIndex: 0 } },
];
const ciphertext = encryptString(
'WITHTION',
rotors,
emptyPlugboard,
reflectorB,
);

const results = await cribSearchAsync(
ciphertext,
'WITH',
limitedRotors,
{ 2: initialReflectorState.reflectors[2]! },
() => {},
);

for (const result of results) {
expect(result.derivedPlugboard).toBeDefined();
expect(typeof result.derivedPlugboard).toBe('object');
}
}, 60000);

it('returns empty array when crib is longer than ciphertext', async () => {
jest.useRealTimers();
const progressValues: number[] = [];

const results = await cribSearchAsync(
'ABC',
'HELLO',
limitedRotors,
{ 2: initialReflectorState.reflectors[2]! },
(p) => progressValues.push(p),
);

expect(results).toEqual([]);
expect(progressValues[progressValues.length - 1]).toBe(1);
});

it('calls onProgress from 0 to 1', async () => {
jest.useRealTimers();
const rotors = [
{ ...rotorIII, config: { ...rotorIII.config, currentIndex: 0 } },
{ ...rotorII, config: { ...rotorII.config, currentIndex: 0 } },
{ ...rotorI, config: { ...rotorI.config, currentIndex: 0 } },
];
const ciphertext = encryptString(
'WITHTION',
rotors,
emptyPlugboard,
reflectorB,
);
const progressValues: number[] = [];

await cribSearchAsync(
ciphertext,
'WITH',
limitedRotors,
{ 2: initialReflectorState.reflectors[2]! },
(p) => progressValues.push(p),
);

expect(progressValues.length).toBeGreaterThan(0);
expect(progressValues[progressValues.length - 1]).toBe(1);
}, 60000);
});

describe('findCribPositions', () => {
it('eliminates positions where crib letter matches ciphertext letter', () => {
const ciphertext = 'ABCDEF';
Expand Down
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