Key Terms

Symmetric algorithm Encryption method where the sender and receiver use an instance of the same key for encryption and decryption purposes.

Out-of-band method Sending data through an alternate communication channel.

Asymmetric algorithm Encryption method that uses two different key types, public and private. Also called public key cryptography.

Public key Value used in public key cryptography that is used for encryption and signature validation that can be known by all parties.

Private key Value used in public key cryptography that is used for decryption and signature creation and known to the only key owner.

Public key cryptography Asymmetric cryptography, which uses public and private key values for cryptographic functions.

Block cipher Symmetric algorithm type that encrypts chunks (blocks) of data at a time.

Diffusion Transposition processes used in encryption functions to increase randomness.

Confusion Substitution processes used in encryption functions to increase randomness.

Avalanche effect Algorithm design requirement so that slight changes in the input result in drastic changes to the output.

Stream cipher Algorithm type that generates a keystream (random values), which is XORd with plaintext for encryption purposes.

Keystream generator Component of a stream algorithm that creates random values for encryption purposes.

Initialization vectors (IVs) Values that are used with algorithms to increase randomness for cryptographic functions.

Triple DES (3DES)

Encrypting plaintext with one DES key and then encrypting it with a second DES key is no more secure than using a single DES key, therefore, Triple DES is used to obtain stronger encryption

DES-EDE2 2 keys are used. Encrypt with 1, decrypt with 2 and then encrypt with 1 again.

DES-EEE2 2 keys used. Encrypt with 1, encrypt with 2, encrypt with 1.

DES-EEE3 3 keys used. Encrypt with 1, encrypt with 2, encrypt with 3. Most secure, but requires 3 keys.

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