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name: golang-security description: Secure Go backend services against common vulnerabilities. Use when implementing input validation, crypto, or SQL injection prevention in Go. metadata: triggers: files: - 'crypto/rand' keywords: - argon2 - sanitize - jwt - bcrypt - validation - input validation - sql injection

Golang Security Standards

Priority: P0 (CRITICAL)

Implementation Guidelines

Input Validation

• Validation: Use go-playground/validator or google/go-cmp for struct validation.
• Sanitization: Sanitize user input before processing. Use bluemonday for HTML sanitization.

Cryptography

• Random: ALWAYS use crypto/rand, NEVER math/rand for security-sensitive operations (tokens, keys, IVs).
• Hashing: Use Argon2id for password hashing (golang.org/x/crypto/argon2). NOT use bcrypt (weaker) or MD5/SHA1 (insecure). Recommended params: time=1, memory=64MB, threads=4.
• Encryption: Use crypto/aes with GCM mode for authenticated encryption.

SQL Injection Prevention

• Parameterized Queries: ALWAYS use $1, $2 placeholders with database/sql or ORM (GORM, sqlx).
• No String Concatenation: Never build queries with fmt.Sprintf().

Authentication

• JWT: Use golang-jwt/jwt v5+. Enforce RS256 (preferred) or HS256. Reject none and symmetric algorithms for multi-service auth. Validate alg, iss, aud, exp claims.
• Sessions: Use secure, httpOnly cookies with gorilla/sessions.

Secret Management

• Environment Variables: Load secrets via godotenv or Kubernetes secrets.
• No Hardcoding: Never commit API keys, passwords, or tokens to Git.

Anti-Patterns

• No math/rand for Security: RNG predictable. Use crypto/rand.
• No fmt.Sprintf() for SQL: Causes SQL injection. Use placeholders.
• No bcrypt or MD5 for Passwords: Use argon2id exclusively.
• No Exposed Error Details: Don't leak stack traces to clients in production.

References

• Implementation Examples