1. Advanced Encryption Standard (AES)
1.1. fixed to 128 bits; three different key sizes (AES-128, AES-192, AES-256)
1.2. encryption by substitution bytes, shifting rows, mixing column, add round keys
1.3. decryption by applying inverse function of round operations
2. Hashing
2.1. type of cryptographic algorithm that has some specific characteristics
2.2. fixed-length output
2.3. collision occur if same hashing produce same output
2.4. MD5
2.4.1. 128-bit hash
2.5. SHA
2.5.1. SHA-1
2.5.1.1. no longer considered secure
2.5.1.2. 160-bit hash function
2.5.2. SHA-2
2.5.2.1. two similar hash functions; different block size
2.5.2.2. SHA-256 uses 32-byte (256 bits) words
2.5.2.3. SHA-512 uses 64-byte (512 bits) words
2.5.3. SHA-3
2.5.3.1. latest version in October 2012
3. Digital Signature
3.1. not ensure confidentiality
3.2. nonrepudation = proving who the sender
3.3. reverse asymmetric encryption
4. Steganography
4.1. art and science of writing hidden message
4.2. form security through obscurity
4.3. advantage is message not attract attention to themselves
4.4. hide additional data without altering original file
5. key elements
5.1. encryption algorithm
5.1.1. mathematical function/calculation
5.2. encryption key
5.2.1. information similar to password
5.3. key length
5.3.1. predetermined length for key
6. key systems
6.1. symmetric (private)
6.1.1. single, secret, bidirectional keys
6.1.2. encrypt = plaintext -> ciphertext decrypt = ciphertext -> plaintext
6.1.3. Data Encryption Standard (DES)
6.1.3.1. block cipher uses 64 bits
6.1.3.2. replaced with AES
6.1.4. advantage
6.1.4.1. remember/know one key
6.1.4.2. suitable for bulk data encryption
6.1.5. disadvantage
6.1.5.1. difficulty distributing keys
6.1.5.2. limitations of shared secret
6.2. asymmetric (public)
6.2.1. pairs of unidirectional, complementary keys
6.2.2. one key to encrypt and one key to decrypt
6.2.3. used for short messages