Sams Teach Yourself J2EE™ in 21 Days, Second Edition

Common Security Technology

Modern software architectures make use of several technologies for supporting system security. This section is a brief look at message digests, Secure Socket Layer (SSL) and digital certificates. To understand these you must first look at data encryption.

Data encryption means converting the data so that it can only be decrypted and read by authorized users. Encrypting data means applying a numerical algorithm that converts the data into another form that can, at a later time, be decrypted to recover the original data. Encryption algorithms typically use a variable component (such as a pass phrase) to “seed” the conversion; this variable component is known as the key. Symmetric encryption is so called because it uses ...