Almost all encrypted data can be unencrypted without the password by the use of a very large amount of time on very powerful computers. Security is provided by making the encryption complex enough that no one would be likely to have enough computer power to break say a message about the merger next month in less than six months, at which time the message is no longer valuable. One of the most serious security attacks is one which gains the password to this account. As well as particularily stringent security for this account, the encryption systems mentioned above ensure that there is a second layer of protection against this type of attack. This also provides for a segmented internal security system, if such is necessary.
Email is particularly insecure.
Mail messages are simple ascii files that travel across the network where no password is necessary to get to them. Email is easily forged and can be altered. These systems have several functions including encrypting the message itself, verifying who sent the message and verifying that it was not tampered with. Audit trails are a means for the system administrators to find out if security has been breached and how much damage was done. Audit trails are records made by various pieces of software to log who logged into a system, from where and what files were accessed.