Encryption ensures that all data stored on a system or sent by one system to another cannot be 'read' by anyone else. There are two main types of encryption:

• Symmetric encryption: is the application of a mathematical process at the originating end, and a reverse process at the receiving end. The processes at each end use the same 'key' to encrypt and decrypt the data.

• Asymmetric encryption: uses different keys for encryption and decryption. A common usage is a certificate authority's private and public key.

Most message data encryption is symmetric. The data sent may be optionally encrypted using a number of well known algorithms:

Algorithm	Effective key size (bits)	Use
DES-40	40	Not supported – insufficient strength
DES-56	56	Not supported – insufficient strength
3DES	112 (AKA two key DES)	Not supported – insufficient strength
3DES	168 (AKA three key DES)	'Low' security.
RC4-128	128	'Low' security.
AES-128	128	'Medium' security.
AES-256	256	'Strong' security.

In general the larger the key size, the more secure the encryption. However, smaller key sizes usually incur less processing.

IP Office supports encryption using:

• Transport Layer Security (TLS v1.2 with v1.0 and v1.1 for legacy)

• Secure Shell (SSH v2)

• Secure RTP (SRTP)