Data Backups Security
Email integrity and access controls are a vital component when considering offsite backup storage. It must be ensured that message contents are intact and that only authorized parties can access messages stored in the backup system.
Protecting message contents from being viewed by unauthorized parties is accomplished via encryption with the AES-128 (Rijndael-128) algorithm. AES-128 encryption is recognized by the U.S. federal government as acceptable for government documents considered "Secret" level. As a further protection, each mailbox is assigned a unique, secret key used for the encryption of that mailbox's data.
After the message has been encrypted, the well-known MD5 algorithm is used to generate a signature. When the message is accepted by the backup system, the MD5 process is again completed and the two signatures are compared. If the message has changed during its transport to the backup system, the system simultaneously starts a new transfer to get the data moved to the backup system and lets system engineers know about the event. In this way, message contents are assured to be stored unchanged.
Finally, to prevent the possibility of email address harvesting from the backup system, the IDs associated with the encrypted mail stores are long-digit random numbers. Only by using protected data at separate facilities can individual users be associated with a given backup email store. In combination with individual encryption keys, this creates a "silo" for each user's email data, distinct and protected from other users' information.