RSA is an asymmetric (public-key) algorithm that uses a mathematically related key pair (public and private) for encryption/decryption or signing/verification. AES, 3DES, and RC4 are symmetric algorithms that use a single shared secret key.

A security policy is an important document to develop while designing an information system. The security policy begins with the organization's basic commitment to information security formulated as a general policy statement. The policy is then applied to all aspects of the system design or security solution. The policy identifies security goals (e.g., confidentiality, integrity, availability, accountability, and assurance) the system should support, and these goals guide the procedures, standards and controls used in the IT security architecture design. The policy also should require definition of critical assets, the perceived threat, and security-related roles and responsibilities. Source: STONEBURNER, Gary & al, National Institute of Standards and Technology (NIST), NIST Special Publication 800-27, Engineering Principles for Information Technology Security (A Baseline for Achieving Security), June 2001 (page 6).

Section: Software Development Security

Tripwire is an integrity checking product, triggering alarms when important files (e.g.
system or configuration files) are modified.
This is a tool that is not likely to be used by hackers, other than for studying its workings in order to
circumvent it.
Other programs are password-cracking programs and are likely to be used by security
administrators as well as by hackers. More info regarding Tripwire available on the Tripwire, Inc.
Web Site.
NOTE:
The biggest competitor to the commercial version of Tripwire is the freeware version of Tripwire.
You can get the Open Source version of Tripwire at the following URL: http://sourceforge.net/projects/tripwire/