Encryption and Cryptography

Encryption is as old as communication. Early written languages were a form of encryption: Only those who knew the language could read the messages. Throughout history, encryption has taken a wide variety of forms; for example, the Navajo language was used as a form of encryption during World War II. Cryptography is the science of digital security, and a branch of mathematics. Historically, it has been limited to encryption—the creation of secret messages—but since the mid-1970s it has been expanded to include other security-related techniques, such as digital signatures.

The increasing usage of electronic-data communications systems in banking and business has generated a need to ensure data security, as it is fairly easy to intercept communication traffic between two computers. Consumers who use credit cards, electronic mail, electronic cash, electronic purses, and home banking in transmitting electronic information demand advanced applications that provide enhanced security for the data sent. For instance, a customer of home banking can use a home computer to instruct the bank to pay bills by transferring funds from her account to another (i.e., to the payee). Security concerns include ensuring that the electronic message sent was not intercepted by a third party, who then might change the identity of the payee, and/or that the message was not recorded by the third party and sent again and again. Cryptographic systems operate with an encryption algorithm and key, which convert an original message (plain text) into a coded message (cipher text). In turn, in order to decode the cipher text, a decryption algorithm and key are needed.

An encryption program scrambles a file, using a user-selected password. When encrypted, the file turns into a hodgepodge of unreadable letters, numbers, or symbols. The text is restored using the decryption program with the same password. There are several methods used to scramble data. Some techniques involve simply substituting one character with another, while others employ several stages of encryption, with a different character each time.

Cryptography provides safety measures to address common security threats to electronic data transmission. According to Antony Watts, most common security threats include: • Interception, which resembles passive eavesdropping;

• Replay, in which genuine messages are recorded and repeatedly resent;
• Masquerade, the receipt of a message from a source other than the source indicated in the message;
• Repudiation, the receipt of a message that the sender denies sending;
• Manipulation, the interception and modification of messages for fraud or sabotage.

Watts also notes the following safety features, which are provided by most cryptographic systems to protect against the above-mentioned threats:

• Secrecy, which protects message privacy from anyone without an appropriate key;
• Integrity, which allows for the detection of alterations made to a message;
• Signature, which establishes sender identity, proving that an individual sent the message.