Cryptography/Notes

Cryptography is a Greek word which means "Secret Writing"''Important Uses of Cryptography1. Protect confidentiality of message (Achieved with Encryption Algorithms) 2. Provide identity for authentication (Achieved with Asymmetric Encryption Algorithms, digital signature algorithms) 3. Verify information to check message integrity (Achieved with hash functions) To Validate information cryptographic function are used. Cryptographic functions are called as hash functionse.g. of Hash Functions1. MD5 (Message Digest 5) 2. SHA (Secure Hash Algorithm)Types of Cryptography1. Secret key cryptography (Both parties know the same secret key. Uses symmetric encryption) 2. Public key cryptography (Both parties have 2 different keys,Public key for encryption and Private key for decryption. Private key for signing, public key for signature verification.https://security.stackexchange.com/questions/69461/encrypt-with-private-and-decrypt-with-publichttps://stackoverflow.com/questions/30718174/encrypt-with-private-key-and-decrypt-with-public-key In Reversible public key algorithms, Data encrypted with private key can be decrypted with public key.Uses asymmetric encryption)March 2020 Encryption algorithms are called CiphersInformation in encrypted form is called Ciphertext2 Types of Ciphers1. Stream Ciphers (Process data byte at a time) 2. Block Ciphers (Process data in blocks 8 bytes at a time. Pad packets smaller than block)e.g. of Symmetric Encryption Algorithms1. DES (Data Encryption Standard - Block) 2. 3DES (Triple strength Data Encryption Standard - Block) 3. RC2 (Rivest Cipher 2 - Block) 4. RC4 (Rivest Cipher 4 - Stream)e.g. of Asymmetric Encryption Algorithms''' 1. RSA - Rivest Shamir Adleman 2. DSA - Digital Signature Algorithm - Can only be used for digital signatures.