E-mail firewall with stored key encryption/decryption

• US 7,162,738 B2
• Filed: 09/29/2001
• Issued: 01/09/2007
• Est. Priority Date: 07/23/1998
• Status: Expired

• Current Assignee: Tumbleweed Communications Corporation (Axway Software SA)
• Original Assignee: Tumbleweed Communications Corporation (Axway Software SA)
• Inventors: Dickinson, III, Robert D., Krishnamurthy, Sathvik
• Primary Examiner(s): Moise, Emmanuel L.
• Assistant Examiner(s): CALLAHAN, PAUL E
• Application Number:
  US09/967,117
• Publication Number:
  US 20040054886A1
• Time in Patent Office: 1,928 Days
• Field of Search: 380/282, 380/30, 713/151, 713/152, 713/153, 713/154, 713/156, 713/170, 713/201, 713/701, 726/14, 726/24, 726/17, 726/18, 726/11, 726/12, 726/13
• US Class Current: 726/14
• 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 filtering e-mail messages transmitted from an external site to an internal site associated with a first policy, comprising:

i. intercepting a plurality of data packets associated with an e-mail message having a sender address associated with an external site;

ii. assembling said data packets to an application level message;

iii. detecting whether the application level message includes a digital signature attachment;

iv. applying at least one policy condition to said application level e-mail message, said policy condition applied by reference to said attached digital signature, said applying providing a policy application result;

v. applying at least a second policy condition to said application level e-mail message in response to a predetermined condition of the attached digital signature, the second policy condition selected by reference to an identity associated with the valid digital signature;

vi. detecting that the digital signature is a valid digital signature; and

vii. processing said application level e-mail message in accordance with said applying at least a second policy condition.

2. A method for filtering e-mail messages transmitted from an external site to an internal site associated with a first policy, comprising:

i. intercepting a plurality of data packets associated with an e-mail message having a sender address associated with an external site;

ii. assembling said data packets to an application level message;

iii. detecting whether the application level message includes a digital signature attachment;

iv. applying at least one policy condition to said application level e-mail message, said policy condition applied by reference to said attached digital signature, said applying providing a policy application result;

v. applying a second policy for detecting whether the attached signature is associated with a domain which is included in a stored list of trusted domains; and

vi. processing said application level e-mail message in accordance with said applying at least a second policy condition.