E-mail firewall with stored key encryption/decryption

• US RE43,302 E1
• Filed: 05/29/2007
• Issued: 04/03/2012
• Est. Priority Date: 07/23/1998
• Status: Expired due to Fees

• Current Assignee: Axway Incorporated (Axway Software SA)
• Original Assignee: Axway Incorporated (Axway Software SA)
• Inventors: Dickinson, III, Robert D., Krishnamurthy, Sathvik
• Primary Examiner(s): Shiferaw, Eleni
• Assistant Examiner(s): CALLAHAN, PAUL E
• Application Number:
  US11/807,953
• Time in Patent Office: 1,771 Days
• Field of Search: 713/152, 713/154, 713/156, 713/170, 380/282, 380/30, 726/11, 726/14
• US Class Current: 726/14
• CPC Class Codes: H04L 2209/76 Proxy, i.e. using intermediary entity to perform cryptographic operations network architectures or network communication protocols using hop-by-hop encryption H04L63/0464
• CPC Class Codes: H04L 51/063 Content adaptation, e.g. replacement of unsuitable content
• CPC Class Codes: H04L 51/12 with filtering and selective blocking capabilities
• CPC Class Codes: H04L 51/24 with notification on incoming messages
• CPC Class Codes: H04L 63/0227 Filtering policies mail message filtering H04L51/212
• CPC Class Codes: H04L 63/0245 Filtering by information in the payload
• CPC Class Codes: H04L 63/0263 Rule management
• CPC Class Codes: H04L 63/0428 wherein the data content is protected, e.g. by encrypting or encapsulating the payload
• CPC Class Codes: H04L 63/0464 using hop-by-hop encryption, i.e. wherein an intermediate entity decrypts the information and re-encrypts it before forwarding it

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.

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

intercepting, at an SMTP relay implemented as programmed computer hardware separate and distinct from a packet inspection-type access firewall, a plurality of data packets associated with an e-mail message having a sender address associated with an external site;

assembling said data packets to an application level e-mail message;

detecting whether the application level e-mail message includes a digital signature attachment;

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

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;

detecting that the digital signature is a valid digital signature;

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

responsive to the interception at the SMTP relay, building a list of sender policies corresponding to the sender address of the application level e-mail message and building a list of recipient policies corresponding to one or more recipient addresses of the application level e-mail message;

the applied first and second policy conditions being respectively selected from one of the lists of sender and recipient policies for the application level e-mail message,

wherein different types of the sender and recipient policies are applied to the application level e-mail message in a predetermined priority order in which access management policies are applied after decryption policies and before remaining content control policies, formal conversion policies and security policies, wherein the security policies include at least client security usage, preserve encryption and plain text access policies.

4. The method of claim 3, further comprising:

decrypting said application level e-mail message prior to said applying at least a second policy condition.

5. The method of claim 3, further comprising:

at the SMTP relay, filtering said application level e-mail message in accord with an administrator selectable set of access control-type, content-type, virus-type and security-type policy conditions,

wherein the access control-type, content-type, virus-type and security-type policy conditions are specified as a collection of administrator selectable criteria, exceptions to said criteria, and actions.

6. The method of claim 3,

wherein the processing includes encrypting the application level e-mail message and forwarding the encrypted application level e-mail message to a recipient thereof.

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

intercepting at an SMTP relay implemented as programmed computer hardware separate and distinct from a packet inspection-type access firewall, a plurality of data packets associated with an e-mail message having a sender address associated with an external site;

assembling said data packets to an application level e-mail message;

detecting whether the application level e-mail message includes a digital signature attachment;

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

applying at least a second policy condition for detecting whether the attached signature is associated with a domain which is included in a stored list of trusted domains;

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

responsive to the interception at the SMTP relay, building a list of sender policies corresponding to the sender address of the application level e-mail message and building a list of recipient policies corresponding to one or more recipient addresses of the application level e-mail message;

the applied first and second policy conditions being respectively selected from one, of the lists of sender and recipient policies for the application level e-mail message,

wherein different types of the sender and recipient policies are applied to the application level e-mail message in a predetermined priority order in which access management policies are applied after decryption policies and before remaining content control policies, formal conversion policies and security policies, wherein the security policies include at least client security usage, preserve encryption and plain text access policies.

8. The method of claim 7, further comprising:

decrypting said application level e-mail message prior to applying at least a second policy condition.

9. The method of claim 7, further comprising:

at the SMTP relay, filtering said application level e-mail message in accord with an administrator selectable set of access control-type, content-type, virus-type and security-type policy conditions,

wherein the access control-type, content-type, virus-type and security-type policy conditions are specified as a collection of administrator selectable criteria, exceptions to said criteria, and actions.

10. The method of claim 7,

wherein the processing includes encrypting the application level e-mail message and forwarding the encrypted application level e-mail message to a recipient thereof.