103 lines
3.1 KiB
TypeScript
103 lines
3.1 KiB
TypeScript
import { CACHE_MANAGER } from '@nestjs/cache-manager';
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import { Inject, Injectable, Logger } from '@nestjs/common';
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import { InjectMetric } from '@willsoto/nestjs-prometheus';
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import { Cache } from 'cache-manager';
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import { randomBytes, createHash } from 'crypto';
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@Injectable()
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export class PowService {
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private readonly logger = new Logger(PowService.name);
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private difficulty = 5;
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constructor(
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@Inject(CACHE_MANAGER) private cacheManager: Cache,
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@InjectMetric('pow_challenges_generated') private challengesGenerated: any,
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@InjectMetric('pow_challenges_completed') private challengesCompleted: any,
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@InjectMetric('pow_successful_verifies') private successfulVerifies: any,
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@InjectMetric('pow_failed_verifies') private failedVerifies: any,
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@InjectMetric('pow_difficulty') private powDifficulty: any,
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) {
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this.powDifficulty.set(this.difficulty);
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}
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/**
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* Generate a proof of work challenge, stored to redis for verification within
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* the next 60 seconds.
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*/
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async generateChallenge() {
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const challenge = this.generateRandom256BitString();
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this.logger.verbose(`Generated challenge: ${challenge}`);
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this.challengesGenerated.inc();
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await this.cacheManager.set(challenge, true, 60 * 1000);
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return challenge;
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}
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generateRandom256BitString() {
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const randomString = randomBytes(32).toString('hex');
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return randomString;
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}
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hashAndCheck(string: string) {
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return this.hashPassesDifficulty(this.hashString(string), this.difficulty);
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}
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hashPassesDifficulty(hash: string, difficulty: number) {
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return hash.startsWith('0'.repeat(difficulty));
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}
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/**
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* Verify that the proof of work submitted has a leading number of
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* zeroes equal to the challenge length and the challenge exists.
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*/
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async verifyChallenge(challenge: string, proof: string): Promise<boolean> {
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const expected = await this.cacheManager.get<boolean>(challenge);
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const success = expected ? this.hashAndCheck(proof + challenge) : false;
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if (success) {
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this.successfulVerifies.inc();
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} else {
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this.failedVerifies.inc();
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}
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return success;
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}
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async markChallengeAsComplete(challenge: string) {
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this.challengesCompleted.inc();
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await this.cacheManager.del(challenge);
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}
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/**
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* Perform a proof of work challenge to find a proof that hashes to a value
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*/
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async performChallenge(challenge: string) {
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let proof = this.generateRandom256BitString();
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let hash = this.hashString(proof + challenge);
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while (!this.hashPassesDifficulty(hash, this.difficulty)) {
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proof = this.generateRandom256BitString();
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hash = this.hashString(proof + challenge);
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}
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return { proof, hash };
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}
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/**
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* sha512 the provided string and return the result.
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*/
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hashString(input: string) {
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return createHash('sha512').update(input).digest('hex');
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}
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/**
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* Set the difficulty of the proof of work challenge.
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*/
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setDifficulty(difficulty: number) {
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this.difficulty = difficulty;
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this.powDifficulty.set(this.difficulty);
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}
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/**
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* Get the current difficulty of the proof of work challenge.
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*/
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getDifficulty() {
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return this.difficulty;
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}
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}
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