E-mail firewall with stored key encryption/decryption

• US 20040054886A1
• Filed: 09/29/2001
• Published: 03/18/2004
• Est. Priority Date: 11/03/1998
• Status: Active Grant

• Current Assignee: Robert D. Dickinson III, Sathvik Krishnamurthy
• Original Assignee: Robert D. Dickinson III, Sathvik Krishnamurthy
• Inventors: Dickinson, Robert D. III, Krishnamurthy, Sathvik
• Granted Patent: US 7,162,738 B2
• Time in Patent Office: Days
• US Class Current: 713/153
• CPC Class Codes: H04L 51/212 using filtering or selective blocking
• CPC Class Codes: H04L 63/02 for separating internal from external traffic, e.g. firewalls
• CPC Class Codes: H04L 63/0428 wherein the data content is protected, e.g. by encrypting or encapsulating the payload
• CPC Class Codes: H04L 63/0823 using certificates cryptographic mechanisms or cryptographic arrangements for entity authentication involving certificates H04L9/3263
• CPC Class Codes: H04L 63/12 Applying verification of the received information cryptographic mechanisms or cryptographic arrangements for data integrity or data verification H04L9/32

Abstract

An e-mail firewall (105) applies policies to e-mail messages (204) between a first site and a plurality of second sites in accordance with a plurality of administrator selectable policies (216). The firewall comprises a simple mail transfer protocol (SMTP) relay (202) for causing the e-mail messages (204) to be transmitted between the first site and selected ones of the second sites. A plurality of policy managers (216) enforce administrator selectable policies. The policies, such as encryption and decryption policies, comprise at least a first source/destination policy (218), at least a first content policy (202) and at least a first virus policy (224). The policies are characterized by a plurality of administrator selectable criteria (310), a plurality of administrator selectable exceptions (312) to the criteria and a plurality of administrator selectable actions (314, 316, 322) associated with the criteria and exceptions. The policy managers comprise an access manager (218) for restricting transmission of e-mail messages (204) between the first site and the second sites in accordance with the source/destination policy (218). The policy managers (216) further comprise a content manager (220) for restricting transmission of e-mail messages (204) between the first site and the second sites in accordance with the content policy (220), and a virus manager (224) for restriction transmission of e-mail messages (204) between the first site and the second sites in accordance with the virus policy (224).

Claims

1. A method for transmitting a message between a sender associated with a first e-mail firewall and a recipient associated with a second e-mail firewall, the method comprising:

intercepting a message from the sender intended for the recipient;

searching an encryption directory for an entry associated with the recipient;

retrieving an encryption key associated with a second firewall, the second firewall associated with the recipient;

encoding the message with the encryption key of the second e-mail firewall to provide an encrypted message; and

allowing the message to proceed through the firewall.

2. The method of claim 1, wherein said encoding the message is by employing an encryption key that is stored locally by the first e-mail firewall.

3. The method of claim 1, wherein said encoding the message is by employing an encryption key that is retrieved from an external server.

4. The method of claim 3, wherein retrieving the key from an external server is over a secure communication link.

5. The method of claim 4, wherein the secure communication link is by employing a locally stored encryption key associated with the external server.

6. A method for receiving a message from a sender associated with a first e-mail firewall, the first e-mail firewall encoding the message by using an encryption key of the second e-mail firewall, comprising:

intercepting the message by the second e-mail firewall;

decoding the message with a private key of the second e-mail firewall; and

allowing the message to proceed through the firewall to the recipient.

7. A method for controlling e-mail message transmission across an e-mail firewall, the e-mail firewall interposed between an internal network and external networks, the method comprising:

intercepting a message from a sender associated with the internal network to a recipient associated with an external network;

filtering the message by examining content associated with the message by employing user defined content filter conditions of the e-mail firewall; and

restricting the transmission of the message in accordance with the results of said filtering.

8. The method of claim 7, wherein said filtering is by parsing the text of the message in accordance with said filter conditions.

9. The method of claim 8, wherein said parsing of text is by searching for keywords in the text.

10. The method of claim 8, wherein said parsing of text is by searching for word patterns in the text.

11. The method of claim 10, wherein said filter conditions employ Boolean expressions.

12. The method of claim 7, wherein said filtering conditions include rejecting all executable attachments.

13. The method of claim 7, wherein said filtering conditions include requiring executable attachments to include digital signatures.

14. The methof claim 13, further comprising filtering executable attachments by reference to a directory of trusted signatures.

15. The method of claim 7, wherein said restricting the transmission includes routing the message in accordance with user defined routing policies.