Encryption is a fundamental security control that protects data from unauthorized access, whether stored on disk, transmitted over networks, or processed in memory.
Why it matters
- Protects sensitive data even if storage or transmission is compromised.
- Required by virtually all compliance frameworks (HIPAA, PCI-DSS, GDPR).
- Enables secure communication over untrusted networks.
- Provides non-repudiation through digital signatures.
Types of encryption
- Symmetric: Same key encrypts and decrypts (AES, ChaCha20). Fast, used for bulk data.
- Asymmetric: Public key encrypts, private key decrypts (RSA, ECC). Used for key exchange and signatures.
- Hashing: One-way transformation for integrity verification (SHA-256). Not encryption but related.
Encryption contexts
- Data at rest: Encrypting stored data (disk encryption, database encryption).
- Data in transit: Protecting network communications (TLS, VPNs).
- Data in use: Emerging techniques like homomorphic encryption, secure enclaves.
Common algorithms
- AES-256: Industry standard symmetric encryption, considered quantum-resistant.
- RSA-2048/4096: Widely used asymmetric encryption, being phased out for ECC.
- ECC (Elliptic Curve): Smaller keys, same security as larger RSA keys.
- ChaCha20-Poly1305: Modern alternative to AES, faster on devices without AES hardware.
Key management
- Keys must be protected as carefully as the data they encrypt.
- Use Hardware Security Modules (HSMs) for key storage.
- Implement key rotation policies.
- Separate key management from encrypted data.
- Plan for key recovery and escrow scenarios.
Common mistakes
- Using weak or deprecated algorithms (DES, MD5, SHA-1).
- Hardcoding encryption keys in source code.
- Improper initialization vector (IV) handling.
- Not encrypting all copies of sensitive data (backups, logs).
- Confusing encoding (Base64) with encryption.
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A simple substitution cipher that shifts letters by a fixed number of positions in the alphabet.
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A mathematical procedure for encrypting and decrypting data to protect confidentiality.
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A one-way mathematical algorithm that converts data into a fixed-size string, used for integrity verification and password storage.
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A measure of randomness or unpredictability in data, critical for generating secure cryptographic keys, passwords, and tokens that resist guessing attacks.
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A security protocol where both client and server authenticate each other using X.509 certificates, providing bidirectional identity verification beyond standard TLS.
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