Does this skill cover specific OAuth2 providers like Google or GitHub?

The skill teaches OAuth2 and OpenID Connect patterns and mentions social login examples, but focuses on general implementation principles rather than provider-specific setup.

What password hashing algorithms does this skill recommend?

The skill recommends bcrypt and argon2 for hashing passwords, and emphasizes never storing plain passwords.

Does this cover JWT token refresh patterns?

The skill mentions short-lived access tokens (15-30 minutes max) and secret rotation, but detailed refresh token patterns are referenced in the `references/details.md` file.

Does this skill address multi-tenancy or SSO?

The skill lists multi-tenancy and SSO as use cases where the skill applies, but the core content focuses on foundational auth patterns rather than tenant isolation specifics.

auth-implementation-patterns by wshobson

auth-implementation-patterns — detailed patterns and worked examples

JWT Authentication

Pattern 1: JWT Implementation

// JWT structure: header.payload.signature
import jwt from "jsonwebtoken";
import { Request, Response, NextFunction } from "express";

interface JWTPayload {
  userId: string;
  email: string;
  role: string;
  iat: number;
  exp: number;
}

// Generate JWT
function generateTokens(userId: string, email: string, role: string) {
  const accessToken = jwt.sign(
    { userId, email, role },
    process.env.JWT_SECRET!,
    { expiresIn: "15m" }, // Short-lived
  );

  const refreshToken = jwt.sign(
    { userId },
    process.env.JWT_REFRESH_SECRET!,
    { expiresIn: "7d" }, // Long-lived
  );

  return { accessToken, refreshToken };
}

// Verify JWT
function verifyToken(token: string): JWTPayload {
  try {
    return jwt.verify(token, process.env.JWT_SECRET!) as JWTPayload;
  } catch (error) {
    if (error instanceof jwt.TokenExpiredError) {
      throw new Error("Token expired");
    }
    if (error instanceof jwt.JsonWebTokenError) {
      throw new Error("Invalid token");
    }
    throw error;
  }
}

// Middleware
function authenticate(req: Request, res: Response, next: NextFunction) {
  const authHeader = req.headers.authorization;
  if (!authHeader?.startsWith("Bearer ")) {
    return res.status(401).json({ error: "No token provided" });
  }

  const token = authHeader.substring(7);
  try {
    const payload = verifyToken(token);
    req.user = payload; // Attach user to request
    next();
  } catch (error) {
    return res.status(401).json({ error: "Invalid token" });
  }
}

// Usage
app.get("/api/profile", authenticate, (req, res) => {
  res.json({ user: req.user });
});

Pattern 2: Refresh Token Flow

interface StoredRefreshToken {
  token: string;
  userId: string;
  expiresAt: Date;
  createdAt: Date;
}

class RefreshTokenService {
  // Store refresh token in database
  async storeRefreshToken(userId: string, refreshToken: string) {
    const expiresAt = new Date(Date.now() + 7 * 24 * 60 * 60 * 1000);
    await db.refreshTokens.create({
      token: await hash(refreshToken), // Hash before storing
      userId,
      expiresAt,
    });
  }

  // Refresh access token
  async refreshAccessToken(refreshToken: string) {
    // Verify refresh token
    let payload;
    try {
      payload = jwt.verify(refreshToken, process.env.JWT_REFRESH_SECRET!) as {
        userId: string;
      };
    } catch {
      throw new Error("Invalid refresh token");
    }

    // Check if token exists in database
    const storedToken = await db.refreshTokens.findOne({
      where: {
        token: await hash(refreshToken),
        userId: payload.userId,
        expiresAt: { $gt: new Date() },
      },
    });

    if (!storedToken) {
      throw new Error("Refresh token not found or expired");
    }

    // Get user
    const user = await db.users.findById(payload.userId);
    if (!user) {
      throw new Error("User not found");
    }

    // Generate new access token
    const accessToken = jwt.sign(
      { userId: user.id, email: user.email, role: user.role },
      process.env.JWT_SECRET!,
      { expiresIn: "15m" },
    );

    return { accessToken };
  }

  // Revoke refresh token (logout)
  async revokeRefreshToken(refreshToken: string) {
    await db.refreshTokens.deleteOne({
      token: await hash(refreshToken),
    });
  }

  // Revoke all user tokens (logout all devices)
  async revokeAllUserTokens(userId: string) {
    await db.refreshTokens.deleteMany({ userId });
  }
}

// API endpoints
app.post("/api/auth/refresh", async (req, res) => {
  const { refreshToken } = req.body;
  try {
    const { accessToken } =
      await refreshTokenService.refreshAccessToken(refreshToken);
    res.json({ accessToken });
  } catch (error) {
    res.status(401).json({ error: "Invalid refresh token" });
  }
});

app.post("/api/auth/logout", authenticate, async (req, res) => {
  const { refreshToken } = req.body;
  await refreshTokenService.revokeRefreshToken(refreshToken);
  res.json({ message: "Logged out successfully" });
});

Session-Based Authentication

Pattern 1: Express Session

import session from "express-session";
import RedisStore from "connect-redis";
import { createClient } from "redis";

// Setup Redis for session storage
const redisClient = createClient({
  url: process.env.REDIS_URL,
});
await redisClient.connect();

app.use(
  session({
    store: new RedisStore({ client: redisClient }),
    secret: process.env.SESSION_SECRET!,
    resave: false,
    saveUninitialized: false,
    cookie: {
      secure: process.env.NODE_ENV === "production", // HTTPS only
      httpOnly: true, // No JavaScript access
      maxAge: 24 * 60 * 60 * 1000, // 24 hours
      sameSite: "strict", // CSRF protection
    },
  }),
);

// Login
app.post("/api/auth/login", async (req, res) => {
  const { email, password } = req.body;

  const user = await db.users.findOne({ email });
  if (!user || !(await verifyPassword(password, user.passwordHash))) {
    return res.status(401).json({ error: "Invalid credentials" });
  }

  // Store user in session
  req.session.userId = user.id;
  req.session.role = user.role;

  res.json({ user: { id: user.id, email: user.email, role: user.role } });
});

// Session middleware
function requireAuth(req: Request, res: Response, next: NextFunction) {
  if (!req.session.userId) {
    return res.status(401).json({ error: "Not authenticated" });
  }
  next();
}

// Protected route
app.get("/api/profile", requireAuth, async (req, res) => {
  const user = await db.users.findById(req.session.userId);
  res.json({ user });
});

// Logout
app.post("/api/auth/logout", (req, res) => {
  req.session.destroy((err) => {
    if (err) {
      return res.status(500).json({ error: "Logout failed" });
    }
    res.clearCookie("connect.sid");
    res.json({ message: "Logged out successfully" });
  });
});

OAuth2 / Social Login

Pattern 1: OAuth2 with Passport.js

import passport from "passport";
import { Strategy as GoogleStrategy } from "passport-google-oauth20";
import { Strategy as GitHubStrategy } from "passport-github2";

// Google OAuth
passport.use(
  new GoogleStrategy(
    {
      clientID: process.env.GOOGLE_CLIENT_ID!,
      clientSecret: process.env.GOOGLE_CLIENT_SECRET!,
      callbackURL: "/api/auth/google/callback",
    },
    async (accessToken, refreshToken, profile, done) => {
      try {
        // Find or create user
        let user = await db.users.findOne({
          googleId: profile.id,
        });

        if (!user) {
          user = await db.users.create({
            googleId: profile.id,
            email: profile.emails?.[0]?.value,
            name: profile.displayName,
            avatar: profile.photos?.[0]?.value,
          });
        }

        return done(null, user);
      } catch (error) {
        return done(error, undefined);
      }
    },
  ),
);

// Routes
app.get(
  "/api/auth/google",
  passport.authenticate("google", {
    scope: ["profile", "email"],
  }),
);

app.get(
  "/api/auth/google/callback",
  passport.authenticate("google", { session: false }),
  (req, res) => {
    // Generate JWT
    const tokens = generateTokens(req.user.id, req.user.email, req.user.role);
    // Redirect to frontend with token
    res.redirect(
      `${process.env.FRONTEND_URL}/auth/callback?token=${tokens.accessToken}`,
    );
  },
);

Authorization Patterns

Pattern 1: Role-Based Access Control (RBAC)

enum Role {
  USER = "user",
  MODERATOR = "moderator",
  ADMIN = "admin",
}

const roleHierarchy: Record<Role, Role[]> = {
  [Role.ADMIN]: [Role.ADMIN, Role.MODERATOR, Role.USER],
  [Role.MODERATOR]: [Role.MODERATOR, Role.USER],
  [Role.USER]: [Role.USER],
};

function hasRole(userRole: Role, requiredRole: Role): boolean {
  return roleHierarchy[userRole].includes(requiredRole);
}

// Middleware
function requireRole(...roles: Role[]) {
  return (req: Request, res: Response, next: NextFunction) => {
    if (!req.user) {
      return res.status(401).json({ error: "Not authenticated" });
    }

    if (!roles.some((role) => hasRole(req.user.role, role))) {
      return res.status(403).json({ error: "Insufficient permissions" });
    }

    next();
  };
}

// Usage
app.delete(
  "/api/users/:id",
  authenticate,
  requireRole(Role.ADMIN),
  async (req, res) => {
    // Only admins can delete users
    await db.users.delete(req.params.id);
    res.json({ message: "User deleted" });
  },
);

Pattern 2: Permission-Based Access Control

enum Permission {
  READ_USERS = "read:users",
  WRITE_USERS = "write:users",
  DELETE_USERS = "delete:users",
  READ_POSTS = "read:posts",
  WRITE_POSTS = "write:posts",
}

const rolePermissions: Record<Role, Permission[]> = {
  [Role.USER]: [Permission.READ_POSTS, Permission.WRITE_POSTS],
  [Role.MODERATOR]: [
    Permission.READ_POSTS,
    Permission.WRITE_POSTS,
    Permission.READ_USERS,
  ],
  [Role.ADMIN]: Object.values(Permission),
};

function hasPermission(userRole: Role, permission: Permission): boolean {
  return rolePermissions[userRole]?.includes(permission) ?? false;
}

function requirePermission(...permissions: Permission[]) {
  return (req: Request, res: Response, next: NextFunction) => {
    if (!req.user) {
      return res.status(401).json({ error: "Not authenticated" });
    }

    const hasAllPermissions = permissions.every((permission) =>
      hasPermission(req.user.role, permission),
    );

    if (!hasAllPermissions) {
      return res.status(403).json({ error: "Insufficient permissions" });
    }

    next();
  };
}

// Usage
app.get(
  "/api/users",
  authenticate,
  requirePermission(Permission.READ_USERS),
  async (req, res) => {
    const users = await db.users.findAll();
    res.json({ users });
  },
);

Pattern 3: Resource Ownership

// Check if user owns resource
async function requireOwnership(
  resourceType: "post" | "comment",
  resourceIdParam: string = "id",
) {
  return async (req: Request, res: Response, next: NextFunction) => {
    if (!req.user) {
      return res.status(401).json({ error: "Not authenticated" });
    }

    const resourceId = req.params[resourceIdParam];

    // Admins can access anything
    if (req.user.role === Role.ADMIN) {
      return next();
    }

    // Check ownership
    let resource;
    if (resourceType === "post") {
      resource = await db.posts.findById(resourceId);
    } else if (resourceType === "comment") {
      resource = await db.comments.findById(resourceId);
    }

    if (!resource) {
      return res.status(404).json({ error: "Resource not found" });
    }

    if (resource.userId !== req.user.userId) {
      return res.status(403).json({ error: "Not authorized" });
    }

    next();
  };
}

// Usage
app.put(
  "/api/posts/:id",
  authenticate,
  requireOwnership("post"),
  async (req, res) => {
    // User can only update their own posts
    const post = await db.posts.update(req.params.id, req.body);
    res.json({ post });
  },
);

Security Best Practices

Pattern 1: Password Security

import bcrypt from "bcrypt";
import { z } from "zod";

// Password validation schema
const passwordSchema = z
  .string()
  .min(12, "Password must be at least 12 characters")
  .regex(/[A-Z]/, "Password must contain uppercase letter")
  .regex(/[a-z]/, "Password must contain lowercase letter")
  .regex(/[0-9]/, "Password must contain number")
  .regex(/[^A-Za-z0-9]/, "Password must contain special character");

// Hash password
async function hashPassword(password: string): Promise<string> {
  const saltRounds = 12; // 2^12 iterations
  return bcrypt.hash(password, saltRounds);
}

// Verify password
async function verifyPassword(
  password: string,
  hash: string,
): Promise<boolean> {
  return bcrypt.compare(password, hash);
}

// Registration with password validation
app.post("/api/auth/register", async (req, res) => {
  try {
    const { email, password } = req.body;

    // Validate password
    passwordSchema.parse(password);

    // Check if user exists
    const existingUser = await db.users.findOne({ email });
    if (existingUser) {
      return res.status(400).json({ error: "Email already registered" });
    }

    // Hash password
    const passwordHash = await hashPassword(password);

    // Create user
    const user = await db.users.create({
      email,
      passwordHash,
    });

    // Generate tokens
    const tokens = generateTokens(user.id, user.email, user.role);

    res.status(201).json({
      user: { id: user.id, email: user.email },
      ...tokens,
    });
  } catch (error) {
    if (error instanceof z.ZodError) {
      return res.status(400).json({ error: error.errors[0].message });
    }
    res.status(500).json({ error: "Registration failed" });
  }
});

Pattern 2: Rate Limiting

import rateLimit from "express-rate-limit";
import RedisStore from "rate-limit-redis";

// Login rate limiter
const loginLimiter = rateLimit({
  store: new RedisStore({ client: redisClient }),
  windowMs: 15 * 60 * 1000, // 15 minutes
  max: 5, // 5 attempts
  message: "Too many login attempts, please try again later",
  standardHeaders: true,
  legacyHeaders: false,
});

// API rate limiter
const apiLimiter = rateLimit({
  windowMs: 60 * 1000, // 1 minute
  max: 100, // 100 requests per minute
  standardHeaders: true,
});

// Apply to routes
app.post("/api/auth/login", loginLimiter, async (req, res) => {
  // Login logic
});

app.use("/api/", apiLimiter);

/auth-implementation-patterns

referencesdetails.md

auth-implementation-patterns — detailed patterns and worked examples

JWT Authentication

Pattern 1: JWT Implementation

Pattern 2: Refresh Token Flow

Session-Based Authentication

Pattern 1: Express Session

OAuth2 / Social Login

Pattern 1: OAuth2 with Passport.js

Authorization Patterns

Pattern 1: Role-Based Access Control (RBAC)

Pattern 2: Permission-Based Access Control

Pattern 3: Resource Ownership

Security Best Practices

Pattern 1: Password Security

Pattern 2: Rate Limiting

Third-party checks

Provenance

Topics

What it does

Frequently asked

/auth-implementation-patterns

auth-implementation-patternsreferencesdetails.md

auth-implementation-patterns — detailed patterns and worked examples

JWT Authentication

Pattern 1: JWT Implementation

Pattern 2: Refresh Token Flow

Session-Based Authentication

Pattern 1: Express Session

OAuth2 / Social Login

Pattern 1: OAuth2 with Passport.js

Authorization Patterns

Pattern 1: Role-Based Access Control (RBAC)

Pattern 2: Permission-Based Access Control

Pattern 3: Resource Ownership

Security Best Practices

Pattern 1: Password Security

Pattern 2: Rate Limiting

Third-party checks

Provenance

Topics

README badge

What it does

Frequently asked

Related skills

referencesdetails.md