Cryptography
The science of securing information through mathematical techniques
Cryptography is the practice and study of techniques for secure communication in the presence of adversaries. It encompasses encryption, decryption, digital signatures, and other mathematical techniques used to protect information from unauthorized access or modification.
Core Objectives
- • Confidentiality: Keeping information secret
- • Integrity: Ensuring information hasn't been altered
- • Authentication: Verifying the identity of parties
- • Non-repudiation: Preventing denial of actions
Types of Cryptography
- • Symmetric encryption (shared key)
- • Asymmetric encryption (public/private keys)
- • Hash functions (one-way transformation)
- • Digital signatures
Cryptographic Principles
Modern cryptography is based on mathematical principles and computational hardness assumptions. These fundamental concepts ensure the security of cryptographic systems:
Kerckhoff's Principle
A cryptosystem should be secure even if everything about the system, except the key, is public knowledge.
Shannon's Maxim
"The enemy knows the system" - assume attackers have complete knowledge of the cryptographic algorithm.
Perfect Secrecy
A system has perfect secrecy if ciphertext provides no information about the plaintext without the key.
Computational Security
A system is computationally secure if breaking it requires more computational resources than are feasible.
AES
Advanced Encryption Standard
RSA
Rivest-Shamir-Adleman
SHA-256
Secure Hash Algorithm
ECC
Elliptic Curve Cryptography
ECDSA
Elliptic Curve Digital Signature Algorithm
Certified Security Fundamentals
Includes cryptography basics
Applied Cryptography Specialist
Advanced cryptography certification
This comprehensive guide introduces the fundamental concepts of cryptography, including encryption, decryption, keys, and cryptographic primitives.
Learn about Public Key Infrastructure (PKI), certificate authorities, and how digital certificates enable secure communications on the internet.
This hands-on guide explains how to properly implement cryptography in applications using standard libraries, with examples in multiple programming languages.