Cryptography
23 articles
Cybersecurity guides, tutorials, and insights about cryptography from Pwnsy.
Cloud Key Management: KMS, Envelope Encryption, HSMs
How cloud KMS works: envelope encryption with data keys and key-encryption keys, key policies and separation of duties, rotation, BYOK and external key stores, and what encryption at rest actually protects against.
Code Signing: Certificates, Timestamping and Key Custody
How code signing actually runs: the signing pipeline, RFC 3161 timestamping, HSM key custody, stolen signing keys in real incidents, and platform rules.
mTLS vs TLS: What Mutual Authentication Actually Adds
Standard TLS authenticates the server to the client. mTLS adds a client certificate so both sides prove identity. What that buys, what it costs in certificate lifecycle, and when it is the wrong tool.
Block vs Stream Ciphers: Differences, Modes & Use Cases
How block and stream ciphers differ, what modes of operation do, and where each fits. A plain guide to the two families of symmetric encryption.
End-to-End Encryption
What end-to-end encryption means in plain terms, what it protects, why metadata still leaks, and how apps like Signal and WhatsApp use it.
Homomorphic Encryption
How homomorphic encryption lets you compute on encrypted data without decrypting it, the levels of the technology, and where it is practical today.
How AES Works: The Block Cipher Behind Modern Encryption
A plain guide to AES: rounds, the substitution-permutation network, key sizes, and why GCM beats CBC for real-world encryption.
How Diffie-Hellman Works: Key Exchange Over an Open Channel
Diffie-Hellman lets two parties agree a shared secret over a channel anyone can read. How the math works, ephemeral DH, and forward secrecy.
How Digital Signatures Work: Signing & Verifying
Digital signatures prove who sent a message and that it is unchanged. How hash-then-sign works, why signing differs from encryption, and verifying.
How Elliptic Curve Cryptography Works
A plain guide to ECC: why a 256-bit curve matches 3072-bit RSA, the discrete log trapdoor, and how ECDH and ECDSA are used.
How Hashing Works: Cryptographic Hash Functions
A plain guide to cryptographic hash functions: one-way and collision resistance, SHA-2 and SHA-3, and why hashing is not encryption.
How RSA Works: Public Keys, Trapdoors, and Factoring
A plain guide to RSA: how a public/private keypair works, the factoring trapdoor, key sizes, and why it is used for key exchange and signatures.
How the TLS 1.3 Handshake Works
A plain walkthrough of the TLS 1.3 handshake: key exchange, certificates, and how a browser and server agree on session keys in one round trip.
Key Derivation Functions
What key derivation functions do, how PBKDF2, HKDF, and Argon2 differ, and when to stretch a password versus derive keys from a strong secret.
Password Hashing: bcrypt, scrypt and Argon2
Why password hashing has to be slow, how work factors and memory-hardness stop cracking, and how to choose Argon2id for new systems.
Perfect Forward Secrecy
Why ephemeral keys keep past encrypted traffic safe even if a long-term private key later leaks, and how forward secrecy works in TLS.
Post-Quantum Cryptography
How quantum computers threaten RSA and ECC, what the NIST post-quantum standards replace them with, and why harvest-now-decrypt-later matters today.
Salting and Peppering: Safer Password Storage
How salts and peppers protect stored passwords, why they defeat rainbow tables, and where each belongs. A plain guide to password hashing hygiene.
Secure Random Number Generation
Why cryptography needs CSPRNGs, how they differ from ordinary random functions, what entropy is, and how weak randomness breaks otherwise strong crypto.
Steganography: Hiding Data Inside Files
How steganography hides data inside images and other files, how it differs from encryption, how defenders detect it, and how malware abuses it.
Symmetric vs Asymmetric Encryption: The Two Families
A plain guide to the two encryption families, when each is used, and how hybrid encryption combines them to secure the modern web.
HMAC: Keyed-Hash Message Authentication
HMAC proves a message is intact and from who you expect. How keyed hashing works, why a plain hash is not enough, and where HMAC fits.
Zero-Knowledge Proofs
How to prove you know a secret without revealing it, the properties every ZK proof needs, and its uses in privacy and blockchains.