Method and System for Secure Transmission of E-Mail
BACKGROUND OF THE INVENTION
THIS invention relates to a method of transmitting an e-mail message securely from a sender to a recipient, and to a system for implementing the method.
Conventional e-mail is notoriously insecure. Two security options are presently available. Firstly, the sender of an e-mail message can request a receipt notification. However, this can be cancelled by the recipient of the message, and even if a receipt notification is received, the sender cannot be certain that the message was received by the intended recipient. Secondly, the sender can digitally sign the e-mail using a public/private key system. This arrangement guarantees authenticity of the document and author, but does not prevent unauthorised viewing of the message.
Encryption systems requiring a unique key for decryption of a message, which must be sent to the recipient separately from the main, encrypted message, are cumbersome and inconvenient to use.
It is an object of the invention to provide an alternative method and system for transmitting e-mail messages securely.
SUMMARY OF THE INVENTION
According to the invention there is provided a method of transmitting an e- mail message securely from a sender to a recipient, the method comprising:
at a slave server, receiving an e-mail message from the sender, extracting message identification data therefrom, transmitting the message identification data securely to a master server, encrypting the message, and transmitting the encrypted message to the recipient;
at a master server, receiving and storing the message identification data from the slave server, receiving a key request transmitted securely by the recipient of the encrypted message, authenticating the recipient, and transmitting a key securely to the authenticated recipient to permit the recipient to decrypt the encrypted message.
The step of authenticating the recipient may include registering the recipient on a database associated with the master server.
The registration of the recipient preferably includes recording a password selected by the recipient for use by the recipient in the authentication process.
Preferably, secure transmissions of data between the slave server and the master server, and the recipient and the master server, utilise an existing secure communications technology, such as the secure sockets layer (SSL) in existing software.
Further to the invention there is provided an e-mail system for transmitting an e-mail message securely from a sender to a recipient, the system comprising:
a master server; and
at least one slave server,
the slave server being connectable securely to the master server and operable to receive an e-mail message from the sender, to extract message identification data therefrom, to transmit the message identification data securely to the master server, to encrypt the e-mail message, and to transmit the encrypted message to the recipient; the master server being contactable securely by the recipient of the encrypted message to receive authentication data from the recipient, to authenticate the recipient, and to transmit a key to the recipient to permit the encryption of the encrypted message.
The master server may be located at a site remote from both the sender and the recipient. Preferably, the slave server is located at the same site as the sender.
The slave server may be a dedicated secure mail server, or may comprise an existing mail server running suitable secure mail software.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a simplified schematic diagram showing a system for transmitting e-mail messages securely according to the invention; and
Figure 2 is a simplified flow diagram illustrating major steps in the method of the invention.
DESCRIPTION OF AN EMBODIMENT
Figure 1 shows an example of a system for sending e-mail messages securely from a sender 10 to a recipient 12. In most cases, but not necessarily, the sender and the recipient will be firms or companies each operating a network comprising a conventional mail server and several work stations.
At the premises of the sender 10, a conventional mail server 14 is provided, to which are connected a number of work stations 16, which will typically be conventional PC's or laptop/notebook computers. In addition to the conventional mail server 14, a secure slave mail server 18 of the invention is provided. The slave server 18 can communicate with the conventional mail server 14, as indicated by the connection 20, and also with any of the work stations 16 as indicated by the connection 22. Each work station, as usual, communicates with the conventional mail server 14 as indicated by the connections 24.
At the premises of the recipient 12 a similar system is provided, comprising a conventional non-secure mail server 114 and a number of work stations 116. Each of the work stations 116 can communicate with the mail server 114 via a respective connection 124.
Located remotely from both the sender and the recipient 12 is a secure master e-mail server 26, which can be accessed via the Internet and which typically comprises a server and associated database hosted on the Internet by an authorised service provider.
The slave server 18 functions as a secure SMTP (simple mail transport protocol) relay, which can be a stand-alone server, or which can effectively comprise software installed on an existing server at the customer's premises.
Conventionally, e-mail is sent by an SMTP server, which can either be at the user's premises, or be hosted by an Internet service provider (ISP) using a dial-up connection. E-mail software on the client's work stations is set up by creating a mail account in which the SMTP address of the relevant mail server is configured. When sending e-mail, this account is used and e-mail is directed from the work station to the selected SMTP server, which in turn dispatches the e-mail to the intended recipient.
In order to use the system of the invention, the slave server (whether a stand-alone server or an existing server with suitable software installed on it) is configured with the current SMTP settings. On each client work station 16 a new, secure second mail account is created, pointing to the slave server as the SMTP server, with all other settings remaining the same as in the existing account. To send a secure e-mail, a user simply sends the e-mail via the newly created secure account and the e-mail is directed to the slave server, rather than to the existing non-secure mail server.
When such an e-mail is received by the slave server, it:
1. Detaches all attachments.
2. Saves the content of the e-mail body.
3. Merges and compresses of the above files into a single compressed file (similar to a "zip" file)
4. Creates a random 128 Character key and encrypts the files using Blowfish encryption.
5. Creates a new "secure e-mail" message with the encrypted file attached. The body of the e-mail message contains instructions on how to open the attached encrypted file and a link to the master server (for new users).
6. Sends a secure information packet to the master server containing the following information extracted from the original e-mail:
1. Sender e-mail address
2. Receiver e-mail address
3. E-mail Subject
4. Key generated in step 4
5. Unique e-mail ID
This information is stored in a database associated with the master server.
The secure e-mail is transmitted to the recipient in the same way as a non- secure e-mail, that is, from the mail server 14 of the sender to the mail server 114 of the recipient, via a connection indicated at 28, typically via the Internet. This encrypted, secure e-mail is received by the recipient's mail server 114 and sent on to the work station of the addressed recipient. The secure e-mail includes a component which contains instructions to the recipient for opening the secure portion of the e-mail, and a link to the master server to allow the recipient to register if the recipient is not already registered. The user double clicks on the secure e-mail attachment, launching a free viewer and prompting the recipient to provide an e-mail address and a password.
The recipient connects via his/her work station 116 to the master server 26 and, if necessary, performs a registration process, supplying personal identification details and a unique password. Assuming that the recipient is already registered on the database of the master server, the recipient provides his/her e-mail address and secret password. This process is carried out securely, for example, using the secure sockets layer (SSL) in Internet explorer or other Web browser software.
Having received the recipient's e-mail address and password, the master server authenticates the recipient by checking the supplied e-mail address
and password for validity. Additionally, the master server verifies, by comparing the message identification data with the supplied e-mail address, that the secure e-mail in question was intended for that recipient. If the authentication process is successful, the master server transmits a decryption key securely to the recipient at the relevant work station 116, allowing the secure e-mail to be opened and displayed by the viewer sent with the secure e-mail. The key is used automatically by the viewer and is not displayed to the recipient.
If the authentication process fails, the record for the secure e-mail in question is tagged. After three unsuccessful attempts at accessing the secure e-mail, it is destroyed. All steps of the above described process are logged and reported back to the sender via the slave server.
It is envisaged that the e-mail viewer provided with the secure e-mail message will contain one or more banners or other forms of advertising. It is proposed that recipients of the secure e-mail messages not be charged for the secure e-mail service, and it will be appreciated that only conventional software and equipment is required by the recipient in order to access the secure e-mail system of the invention.
The sender, at whose premises the slave server 18 is installed, will receive monthly detailed billing, with each billed item including the sender, receiver, e-mail subject, date/time sent and date/time received. It is envisaged that the sender would be billed according to the number of secure e-mail messages sent.
The simplified flow diagram of Figure 2 summarises the major steps of the above described method.
The database associated with the master server 26 will typically have the following structure:
Table: Transactions This table stores all transactions
Fields: Date_Sent Date e-mail was sent
Date_Actioned Date destroyed, timed out or received
Status e.g. received
Count number of tries used to view
Sender Sender's e-mail address
Reciever recipient's e-mail address e-maillD unique ID of e-mail
Subject Subject of original e-mail
Key unlock key
SlavelD unique ID of slave to determine customer
Billed indicator for billing action
Recipients This table stores all registered receivers
Fields: E-mail e-mail address
Password password min 8 char
Name name
Surname surname
Etc... additional customer information
Table: Slaves This table stores all master accounts
Fields: SlavelD unique ID of slave Status active or locked (for nonpayment)
Company name of registered company Etc... additional customer information...
It will be appreciated that the described method and system allow a company or individual wishing to transmit e-mail messages securely to do so without requiring the intended recipients of such messages to install special hardware or software at their own premises. The described system is relatively easy to install and users can easily select between the options of sending conventional, non-secure e-mails and secure e-mails using the system of the invention.
It will also be understood by those skilled in the art that the specific embodiment of the invention described above is purely exemplary, and that other encryption techniques and procedures could be used instead, within the ambit of the inventive concept.