The following terminology will be helpful in order to understand the complexity of cryptography.
- block cipher
- A symmetric cipher which operates on blocks of bits, typically of a fixed size.
- certificate
- A document used to prove the ownership of a public key. Certificates contain information about the owner of the public key and a digital signature which verifies the contents. A certificate can be used to authenticate a message.
- cipher
- A mathematical function used during encryption and decryption.
- ciphertext
- The result of encrypting a message.
- digest
- The output of a hashing algorithm.
- decryption
- A process of decoding a plaintext message from a ciphertext using the exact key which was used during encryption.
- encryption
- A process of encoding a plaintext message into a ciphertext using an encryption key.
- hash
- A hashing algorithm is a function which condenses an arbitrary amount of data to a fixed size. This result is known as a hash value or a hash digest. It can be easier, efficient, and more reliable to compute a hash and compare the values, than to compare the original data. In cryptography hashing is often used to verify a message or some data has not been tampered or compromised.
- secret key
- The type of key used in a symmetric encryption algorithm. Since the same key is used for encryption and decryption, the key must be kept secret and only provided to the authorized senders and recipients.
- message
- Another term for the input data to a hash or encryption function.
- plaintext
- Input to an encryption function. Also referred to as cleartext or a message.
- public key
- The part of a key in an asymmetric encryption system which is available to everyone.
- private key
- The part of a key in an asymmetric encryption system which is kept secret.
- symmetric encryption
- An encryption system where the same key is used for both encryption and decryption.
- asymmetric encryption
- An encryption system which uses a pair of keys, one public and one private. The encryption function uses the public key of the recipient. Decryption can only occur by using the private key. This ensures only the person receiving the ciphertext can decrypt the message.