feat(credentials): add new Credentials service and module

Introduce the Credentials service which is responsible for hashing and verifying passwords. Added appropriate methods within the service and provided it in a new Credentials module. The module exports the service to allow its use in other parts of the application.

src/credentials/credentials.module.ts

@@ -0,0 +1,10 @@
+import { Module } from "@nestjs/common";
+import { CredentialsService } from "./credentials.service";
+import { ConfigModule } from "@nestjs/config";
+
+@Module({
+	imports: [ConfigModule],
+	providers: [CredentialsService],
+	exports: [CredentialsService]
+})
+export class CredentialsModule {}

src/credentials/credentials.service.ts

@@ -0,0 +1,24 @@
+import { BadRequestException, Injectable } from "@nestjs/common";
+import * as argon from "argon2";
+// biome-ignore lint/style/useImportType: used by Next.js
+import { ConfigService } from "@nestjs/config";
+
+@Injectable()
+export class CredentialsService {
+
+	constructor(private configService: ConfigService) {
+	}
+
+	async hash(plaintextPassword: string) {
+		if (plaintextPassword.length < 6) throw new BadRequestException("Password is not strong enough !")
+		return argon.hash(Buffer.from(plaintextPassword), {
+			secret: this.configService.get("APP_HASH_SECRET"),
+		})
+	}
+
+	async check(plaintextPassword: string, hashedPassword: string) {
+		return argon.verify(hashedPassword, Buffer.from(plaintextPassword), {
+			secret: this.configService.get("APP_HASH_SECRET"),
+		})
+	}
+}