Cryptography glossary

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This is a list of common cryptographic terms and their meanings.

Word Definition
Attack Any process of trying to read encrypted information that is unwanted by the creator.
Cipher Any algorithm that converts plaintext into ciphertext. Examples include the One-Time Pad, Caesar Cipher, and many others.
Ciphertext Ciphertext is information that has been encrypted and is no longer readable. Before it has been encrypted, it is called plaintext.
Crack The process of deciphering information without needing the key. In cryptography, the goal is to make ciphers that are uncrackable.
Decrypt The act of deciphering information to its original plainly readable form through the use of a key.
Defeat The act of circumventing a system to get secret information. This can include cracking a cipher, obtaining keys through theft or subterfuge, or any other manner.
Encrypt The act of enciphering information so that it cannot be plainly read without first decrypting it using a key.
Hash The result of putting information through a hash function.
Hash Function A algorithm that converts an arbitrary amount of information into a fixed-length of information called a hash. Hash functions are one-way so the original information cannot be recovered from the hash.
Key The information necessary to decrypt information that has been encrypted. This is different than a password which is an easily-remembered piece of information that is usually converted into a key.
Lookup Attack An attack which uses a premade list to defeat a cipher, examples include a Dictionary Attack and a Rainbow Attack. Lookup attacks are often defeated by using a salt.
Nonce A one-time salt, usually random, used to prevent a Replay Attack.
Password A password is a piece of information that can be remembered which is used to generate a key to decrypt ciphertext.
Plaintext Plaintext refers to readable information before it has been encrypted. Once plaintext has been encrypted, it becomes ciphertext.
Pseudorandom Something that appears random, but isn't. Most values generated by computers are actually pseudorandom rather than random.
Random A produced value that cannot be predicted. Random values are extremely difficult to produce, and are usually pseudorandom.
Salt Information added to plaintext before being hashed or encrypted to help prevent lookup attacks.