Security firm Steganos has launched a secure email service that encrypts communications to ensure that the contents can be read only by the intended recipient.

Users of the Secure E-Mail service are provided with free guest access in order to pick up encrypted emails sent by other Steganos users, and can reply with encrypted emails themselves.

The service is based on a technique called 'asymmetrical encryption' which uses public and private encryption keys instead of 'classic' passwords. The public gate key is used for encryption, and the private key is used for decryption.

The keys are linked to each other, and any data encrypted with one key can only be decrypted by its counterpart, and vice versa. The public key can be distributed, but only the owner possesses the private key.

Aston Fallen, chief executive at Steganos, said: "Billions of unencrypted emails are sent every day. As technology use becomes more widespread, people increasingly send confidential information over email.

"They do this without thinking of the repercussions of those emails being intercepted, copied, forwarded or even changed, which can be done with a surprisingly low level of technical knowledge."

Access to the Secure E-Mail service costs £3.95 for one month, £19.95 for one year and £29.95 for two years.