SECURE MESSAGE DELIVERY USING A TRUST BROKER

• US 20140245000A1
• Filed: 05/06/2014
• Published: 08/28/2014
• Est. Priority Date: 06/23/2008
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Byrum, Frank, Mehta, Mayank, Jain, Chandresh, Conceicao, Ladislau, Kress, Brian, Gourevitch, Greg, Nelte, Michael, Barnes, Chris
• Granted Patent: US 9,917,828 B2
• Time in Patent Office: Days
• US Class Current: 713/156
• CPC Class Codes: H04L 51/00 User-to-user messaging in packet-switching networks, transmitted according to store-and-forward or real-time protocols, e.g. e-mail
• CPC Class Codes: H04L 63/0428 wherein the data content is protected, e.g. by encrypting or encapsulating the payload
• CPC Class Codes: H04L 63/0435 wherein the sending and receiving network entities apply symmetric encryption, i.e. same key used for encryption and decryption cryptographic mechanisms or cryptographic arrangements for symmetric key encryption H04L9/06
• CPC Class Codes: H04L 63/0807 using tickets, e.g. Kerberos cryptographic mechanisms or cryptographic arrangements for entity authentication using tickets or tokens H04L9/3213

Abstract

An email security system is described that allows users within different organizations to securely send email to one another. The email security system provides a federation server on the Internet or other unsecured network accessible by each of the organizations. Each organization provides identity information to the federation server. When a sender in one organization sends a message to a recipient in another organization, the federation server provides the sender'"'"'s email server with a secure token for encrypting the message to provide secure delivery over the unsecured network.

Claims

1. A computer-implemented method comprising:

receiving, by a federation server, a request from a server of a first organization, wherein;

the federation server is configured to act as a trust broker between the first organization and a second organization, and

the request identifies the server of the first organization and requests a token for securely sending a message to a server of the second organization; and

sending, by the federation server to the server of the first organization, a response to the request, wherein;

the response includes a symmetric key and an encrypted token containing the symmetric key, and

the encrypted token is encrypted with a public key of the second organization.

2. The computer-implemented method of claim 1, wherein:

the server of the first organization is configured to secure the message by encrypting the message with the symmetric key, and

the server of the second organization is configured to obtain the symmetric key from the encrypted token and decrypt the message using the symmetric key.

3. The computer-implemented method of claim 1, wherein:

the server of the first organization is configured to secure the message by encrypting the message with a separate encryption key and encrypting the separate encryption key with the symmetric key, and

the server of the second organization is configured to obtain the symmetric key from the encrypted token, decrypt the separate encryption key using the symmetric key, and decrypt the message using the separate encryption key.

4. The computer-implemented method of claim 1, further comprising:

receiving, by the federation server from the server of the first organization, a request for each domain identified in the message when the message is addressed to multiple recipients at different domains.

5. The computer-implemented method of claim 1, wherein the request identifies the server of the first organization using identity information that matches identity information previously provided by the first organization to the federation server.

6. The computer-implemented method of claim 1, wherein the request further identifies a purpose for which the token is requested.

7. The computer-implemented method of claim 1, wherein the symmetric key is a proof of possession key.

8. A computer-readable storage device that does not consist of a signal, the computer-readable storage device storing computer-executable instructions that, when executed by a processor of a federation server, cause the federation server to perform a method comprising:

receiving a request from a server of a first organization, wherein;

the federation server is configured to act as a trust broker between the first organization and a second organization, and

the request identifies the server of the first organization and requests a token for securely sending a message to a server of the second organization; and

sending a response to the request to the server of the first organization, wherein;

the response includes a symmetric key and an encrypted token containing the symmetric key, and

the encrypted token is encrypted with a public key of the second organization.

9. The computer-readable storage device of claim 8, wherein:

the server of the first organization is configured to secure the message by encrypting the message with the symmetric key, and

the server of the second organization is configured to obtain the symmetric key from the encrypted token and decrypt the message using the symmetric key.

10. The computer-readable storage device of claim 8, wherein:

the server of the first organization is configured to secure the message by encrypting the message with a separate encryption key and encrypting the separate encryption key with the symmetric key, and

the server of the second organization is configured to obtain the symmetric key from the encrypted token, decrypt the separate encryption key using the symmetric key, and decrypt the message using the separate encryption key.

11. The computer-readable storage device of claim 8, wherein the federation server receives a request for each domain identified in the message when the message is addressed to multiple recipients at different domains.

12. The computer-readable storage device of claim 8, wherein the request identifies the server of the first organization using identity information that matches identity information previously provided by the first organization to the federation server.

13. The computer-readable storage device of claim 8, wherein the request further identifies a purpose for which the token is requested.

14. The computer-readable storage device of claim 8, wherein the symmetric key is a proof of possession key.

15. A federation server comprising:

a processor configured to execute computer-executable instructions; and

memory storing computer-executable instructions that, when executed by the processor, cause the federation server to perform a method comprising;

receiving a request from a server of a first organization, wherein;

the federation server is configured to act as a trust broker between the first organization and a second organization, and

the request identifies the server of the first organization and requests a token for securely sending a message to a server of the second organization; and

sending a response to the request to the server of the first organization, wherein;

the response includes a symmetric key and an encrypted token containing the symmetric key, and

the encrypted token is encrypted with a public key of the second organization.

16. The federation server of claim 15, wherein:

the server of the first organization is configured to secure the message by encrypting the message with the symmetric key, and

the server of the second organization is configured to obtain the symmetric key from the encrypted token and decrypt the message using the symmetric key.

17. The federation server of claim 15, wherein:

the server of the first organization is configured to secure the message by encrypting the message with a separate encryption key and encrypting the separate encryption key with the symmetric key, and

the server of the second organization is configured to obtain the symmetric key from the encrypted token, decrypt the separate encryption key using the symmetric key, and decrypt the message using the separate encryption key.

18. The federation server of claim 15, wherein the federation server receives a request for each domain identified in the message when the message is addressed to multiple recipients at different domains.

19. The federation server of claim 15, wherein the request identifies the server of the first organization using identity information that matches identity information previously provided by the first organization to the federation server.

20. The federation server of claim 15, wherein the request further identifies a purpose for which the token is requested.