# Cryptography Glossary

From TheAlmightyGuru

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

Term | Definition |
---|---|

Asymmetric Key Algorithms | Those ciphers that require one key to encrypt and a different key to decrypt. |

Attack | Any process of trying to bypass encryption in a way unwanted by the creator. |

Brute Force Attack | An attack which attempts every possible password combination. They guarantee a correct answer, but usually take too long to be feasible. Also known as an exhaustive search. |

Cipher | Any algorithm that converts plaintext into ciphertext. Examples include the Caesar Cipher, One-Time Pad, and many others. |

Ciphertext | Ciphertext is information that has been encrypted through a cipher and is no longer readable. Before it has been encrypted, it is called plaintext. |

Crack | The process of deciphering information without needing the key or by guessing 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. |

Man In the Middle Attack | An attack where someone intercepts an encrypted message, and replaces it with a different message. |

Nonce | A one-time random salt used to prevent a attacks like 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. |

Private Key | A key that must only be known to the sender and recipient in order for the encryption to be secure. Most traditional ciphers use a private key. |

Pseudorandom | Something that appears random, but isn't. Most values generated by computers are actually pseudorandom rather than random. |

Public Key | A key that is made public, and can be used to encrypt plaintext into ciphertext that can only be decrypted with a private key. |

Public Key Encryption | A form of encryption where a public key is generated from a private key. The public key is made freely available, and when plaintext is encrypted, it should only be able to be decrypted with the private key. |

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. |

Symmetric Key Algorithms | Those ciphers that can be encrypted and decrypted with the same key. Most traditional ciphers use a symmetric key algorithm. |

Trapdoor Function | A mathematical function that is easy to compute one-way, but difficult to compute in reverse. Trapdoor functions are found in asymmetric key algorithms for public key encryption. |