Encryption types Symmetric encryption Asymmetric encryption Same key for encryption and decryption Fast Easy to setup Does not provide authentication Different key for encryption and decryption Slower Requires safe key exchange Provides authentication
Algorithms DES first „standardized“ algorithm, 64-bit blocks 56-bit keys very succeptible to brute-force attacks 3DES addresses issues with DES key shortness encyption-decryption-encryption with 3 56-bit keys for an effective 168-bit AES 128-bit basic blocks keys of 128, 192 and 256-bit lengths faster and more secure than 3DES free and public
Authentication proof of message source and author contents have not been altered delivery in correct sequence MITM attack protection
MAC MATCH? MAC algorithm MAC algorithm
Hash functions Properties: produces constant length output easy to compute it is almost impossible to find inverse value it is almost impossible to find collisions small input change produces large output change Common algorithms: MD5, SHA-1, SHA-256 Used to compute HMAC.
Asymmetric encryption Public-key encryption
Asymmetric encryption encryption decryption authors private key authors public key
Properties ciphertext encrypted with private key may only be decrypted by corresponding public key ciphertext encrypted with public key may only be decrypted by corresponding private key provides confidentiality and authentication still requires secure key exchange