Cryptography Concepts
Encryption: The process of converting data from plaintext to ciphertext.
Decryption: The process of converting data from ciphertext to plaintext.
Key: A parameter that controls the transformation of plaintext into ciphertext or vice-versa
Synchronous: When encryption or decryption occurs immediately.
Asynchronous: When encryption or decryption requests are processed from a queue.
Symmetric: When a single private key both encrypts and decrypts the data.
Symmetrical: same key for encrypting and decrypting.
Asymmetrical: When a key pair (one private and one public) performs encrypting and decrypting.
Digital Signature: Provides sender authentication and message integrity. The message acts as an input to a hash function, and the sender’s private key encrypts the hash value. A hash computation on the received message determines the validity of the message.
Hash: A one-way function that reduces a message to a hash value. A comparison of the sender’s hash value to the receiver’s hash value determines message integrity.
Digital Certificate: An electronic document that identifies the certificate holder.
Plaintext: A message in its original format.
Ciphertext: An altered form of a message that is unreadable without knowing the key and the encryption system used; also, referred to as a cryptogram
Cryptosystem: The components that make encryption possible, including the algorithm, key, and key management functions.
Cryptanalysis: The science of decrypting ciphertext without prior knowledge of the key or cryptosystem used.
Key Clustering: This occurs when different encryption keys generate the same plaintext message.
Keyspace: All the possible key values when using a particular algorithm or security measure.
Collision: An event that occurs when a hash function produces the same hash value on different messages.
Algorithm: A mathematical function that encrypts and decryypts data; also referred to as a cipher.
Cryptology: The science that studies encrypted communication and data.
Encoding: synonym of Encrypting
Decoding: synonym of Decrypting
Transposition: The process of shuffling or reordering the plaintext to hide the original message; also, referred to as permutation.
Substitution: The process of exchanging 1 byte in a message for another.
Confusion: The process of changing a key value during each round of encryption. Confusion is often carried out by substitution.
Diffusion: The process of changing the location of the plaintext within the ciphertext. Diffusion often uses transposition.
Avalanche effect: The condition in which any change in the key or plaintext, no matter how minor, will significantly change the ciphertext
Work factor: The amount of time and resources that would be needed to break the encryption.
One-way function: A mathematical function that can be more easily performed in one direction than in the other.
Trapdoor: A secret mechanism that allows the implementation of the reverse function in a one-way function.
Cryptographic Life Cycle:
- Implementation
- Maintenance
- Retirement or Replacement
