Information Technology Reference
integrity and enabling the authentication of the interlocutors, so that only the
sender and the recipient can read and understand them.
Encryption algorithms try to protect, with a certain degree of security, high-
value information against possible attacks by criminals, competitors or anyone
who can use them to cause damage to someone else. This includes all aspects
of safety messages, authentication of the parties and integrity verification.
Cryptographic systems have been present in history for centuries, especially
for military reasons. Currently, encryption is no longer limited strictly to the
military field. Research is currently trying to take all of the advantages of
cryptography for creating a secure network available to the modern society.
To better familiarize with the concepts in cryptography we give some
Encryption is defined as the art or science of making secret messages.
Cryptographic analysis is the art of violating a cryptographic system and
Cryptology is the branch of mathematics that studies the mathematical
foundations of cryptography.
The clear message is called plaintext or clear text .
The encrypted message is called ciphertext . It looks like a random
sequence of symbols and it is incomprehensible.
Encryption and decryption are the transformations of a message from
plaintext to ciphertext back. They usually are generated though the use of
a string of characters, named ' key '. In that case, the decryption can be
done only if you know the key used in encryption.
Authentication is verifying the identity of individuals involved in a
Verifying the integrity is the test that certifies if the message has not been
altered during transmission.
The digital signature is a string derived from the encrypted message that
identifies the sender and verifies the integrity of the message.
A digital certificate is a document of identity that allows virtual entities to
identify the network.
3.2 Cryptography algorithms
Cryptography provides a set of algorithms and processes to make the
message unintelligible. Some of them are very powerful and have resisted to
several attacks; other are less safe, but equally important.