Java Secure coding guidelines

Identify and apply Java secure coding practices to reduce vulnerabilities, protect sensitive data, and harden application behaviour against common attack vectors.

Prerequisites: Run ./mvnw compile or mvn compile before applying any changes. If compilation fails, stop immediately — do not proceed until the project is in a valid state.

Core areas: Input validation with type, length, format, and range checks; SQL/OS/LDAP injection defence via PreparedStatement and parameterized APIs; attack surface minimisation through least-privilege permissions and removal of unused features; strong cryptographic algorithms for hashing (passwords with BCrypt/Argon2), encryption (AES-GCM), and digital signatures while avoiding deprecated ciphers (MD5, SHA-1, DES); secure exception handling that logs diagnostic details internally while exposing only generic messages to clients; secrets management by loading credentials from environment variables or secret managers — never hardcoded; safe deserialization with strict allow-lists and preference for explicit DTOs over native Java serialization; output encoding to prevent XSS in rendered content.

Scope: The reference is organized by examples (with good/bad code patterns) for each core area. Apply recommendations based on applicable examples; validate compilation before changes and run ./mvnw clean verify or mvn clean verify after applying improvements.

Before applying changes: Read the reference for detailed good/bad examples, constraints, and safeguards for each secure coding pattern.

Reference

For detailed guidance, examples, and constraints, see references/124-java-secure-coding.md.