2.1.2 Cryptography Facts
Cryptography is the science of converting data into a secret code to hide the meaning of the message during transmission. Cryptographic systems provide the following security services:
• Confidentiality, by ensuring that only authorized parties can access data.
• Integrity, by verifying that data has not been altered in transit.
• Authentication, by proving the identity of the sender or receiver.
• Non-repudiation, by validating that communications have come from a particular sender at a particular time.
The following terms are related to cryptography:
Term Definition
Plaintext Plaintext is a readable message.
Cipher text Cipher text is the message in a form that makes it unreadable to all but those for whom the message was intended.
Cryptographer A cryptographer is a person who develops ways of converting plaintext to cipher text.
Cryptanalysis Cryptanalysis is the method of recovering original data that has been encrypted without having access to the key used in the encryption process. This can be done to measure and validate the strength of a cryptosystem. It can also be done to violate the confidentiality and/or integrity of a cryptosystem.
Cryptosystem A cryptosystem is the associated items of cryptography that are used as a unit to provide a single means of encryption and decryption.
Cryptology Cryptology is the study of cryptography and cryptanalysis.
Key A key is a variable in a cipher used to encrypt or decrypt a message. The key should be kept secret.
The key space is the range of the possible values that can be used to construct a key. Generally speaking, the longer the key space, the stronger the cryptosystem.
Algorithm A cipher or algorithm is the process or formula used to convert a message or otherwise hide its meaning. Examples of algorithms include:
• A transposition cipher (also called an anagram) changes the position of characters in the plaintext message.
• A substitution cipher replaces one set of characters with symbols or
• Confidentiality, by ensuring that only authorized parties can access data.
• Integrity, by verifying that data has not been altered in transit.
• Authentication, by proving the identity of the sender or receiver.
• Non-repudiation, by validating that communications have come from a particular sender at a particular time.
The following terms are related to cryptography:
Term Definition
Plaintext Plaintext is a readable message.
Cipher text Cipher text is the message in a form that makes it unreadable to all but those for whom the message was intended.
Cryptographer A cryptographer is a person who develops ways of converting plaintext to cipher text.
Cryptanalysis Cryptanalysis is the method of recovering original data that has been encrypted without having access to the key used in the encryption process. This can be done to measure and validate the strength of a cryptosystem. It can also be done to violate the confidentiality and/or integrity of a cryptosystem.
Cryptosystem A cryptosystem is the associated items of cryptography that are used as a unit to provide a single means of encryption and decryption.
Cryptology Cryptology is the study of cryptography and cryptanalysis.
Key A key is a variable in a cipher used to encrypt or decrypt a message. The key should be kept secret.
The key space is the range of the possible values that can be used to construct a key. Generally speaking, the longer the key space, the stronger the cryptosystem.
Algorithm A cipher or algorithm is the process or formula used to convert a message or otherwise hide its meaning. Examples of algorithms include:
• A transposition cipher (also called an anagram) changes the position of characters in the plaintext message.
• A substitution cipher replaces one set of characters with symbols or