SECURE MESSAGING WITH READ-UNDENIABILITY AND DELETION-VERIFIABILITY

• US 20120198235A1
• Filed: 02/01/2011
• Published: 08/02/2012
• Est. Priority Date: 02/01/2011
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Kotla, Ramakrishna R., Wester, Benjamin J.
• Granted Patent: US 8,527,769 B2
• Time in Patent Office: Days
• US Class Current: 713/171
• CPC Class Codes: H04L 63/0428 wherein the data content is protected, e.g. by encrypting or encapsulating the payload
• CPC Class Codes: H04L 63/126 the source of the received data
• CPC Class Codes: H04L 9/0861 Generation of secret information including derivation or calculation of cryptographic keys or passwords
• CPC Class Codes: H04L 9/3236 using cryptographic hash functions
• CPC Class Codes: H04L 9/3263 involving certificates, e.g. public key certificate [PKC] or attribute certificate [AC]; Public key infrastructure [PKI] arrangements network architectures or network communication protocols for supporting authentication of entities using certificates in a packet data network H04L63/0823

Abstract

A cryptographically-secure component is used to provide read-undeniability and deletion-verifiability for messaging applications. When a messaging application of a sending node desires to send a message to a messaging application of a receiving node, the sending node requests an encryption key from the receiving node. The cryptographically-secure component of the receiving node generates an encryption key that is bound to a state of the receiving node. The messaging application of the sending node encrypts the message using the encryption key and sends the encrypted message to the messaging application of the receiving node. Because the encryption key used to encrypt the message is bound to the state associated with reading the message by the cryptographically-secure component, if the receiving node desires to decrypt and read the encrypted message, the receiving node may advance its state to the bound state to retrieve the decryption key.

Claims

1. A method comprising:

generating a message at a sending computing device;

sending a request for an encryption key from the sending computing device to a receiving computing device through a network, wherein the request includes an identifier of the message;

receiving an encryption key by the sending computing device through the network, wherein the encryption key is bound to a state associated with reading the identified message;

verifying that the state that the encryption key is bound to is the state associated with reading the identified message by the sending computing device; and

if the state that the encryption key is bound to is the state associated with reading the identified message;

encrypting the message using the encryption key by the sending computing device; and

sending the encrypted message to the receiving computing device by the sending computing device through the network.

2. The method of claim 1, further comprising:

if the state that the encryption key is bound to is not the state associated with reading the identified message, generating an error.

3. The method of claim 1, wherein the encryption key is associated with a proof-of-attestation, and verifying that the state that the encryption key is bound to is the state associated with reading the identified message comprises verifying that the state that the encryption key is bound to is the state associated with reading the identified message using the proof-of-attestation, wherein the proof-of-attestation was generated by a cryptographically-secure component of the receiving computing device.

4. The method of claim 1, further comprising:

requesting a proof that the message was read by the receiving computing device; and

receiving the proof that the message was read from the receiving computing device, wherein the proof that the message was read was generated by a cryptographically-secure component of the receiving computing device.

5. The method of claim 4, wherein the proof the message was read comprises a state digest.

6. The method of claim 1, further comprising:

requesting a proof that the message was deleted by the receiving computing device; and

receiving the proof that the message was deleted from the receiving computing device, wherein the proof that the message was deleted was generated by a cryptographically-secure component of the receiving computing device.

7. The method of claim 6, wherein the cryptographically-secure component comprises a trusted platform module.

8. A method comprising:

receiving a request for an encryption key from a sending computing device by a receiving computing device through a network, wherein the request includes an identifier of a message;

generating an encryption key by the receiving computing device, wherein the encryption key is generated by a cryptographically-secure component of the receiving computing device and is bound to a state associated with reading the identified message;

sending the generated encryption key to the sending computing device by the receiving computing device; and

receiving an encrypted message by the receiving computing device from the sending computing device, wherein the encrypted message was encrypted by the sending computing device using the encryption key.

9. The method of claim 8, further comprising:

determining to read the encrypted message by the receiving computing device;

in response to the determining, updating a state digest by the receiving computing device to the state associated with reading the identified message, wherein the state digest is stored in the cryptographically-secure component of the receiving computing device;

in response to the updating, receiving access to a decryption key by the receiving computing device from the cryptographically-secure component;

decrypting the encrypted message by the receiving computing device using the decryption key; and

reading the decrypted message by the receiving computing device.

10. The method of claim 9, further comprising:

receiving a request for proof that the receiving computing device read the message;

retrieving the state digest from the cryptographically-secure component; and

sending the state digest as proof that the receiving computing device read the message.

11. The method of claim 8, further comprising:

determining not to read the encrypted message by the receiving computing device; and

in response to the determining, updating a state digest by the receiving computing device to a deletion state associated with deleting the message, wherein the state digest is stored in the cryptographically-secure component of the receiving computing device.

12. The method of claim 11, further comprising:

receiving a request for proof that the receiving computing device deleted the message;

retrieving the state digest from the cryptographically-secure component; and

sending the state digest as proof that the receiving computing device deleted the message.

13. The method of claim 11, wherein the cryptographically-secure component comprises a trusted platform module.

14. The method of claim 13, wherein the state digest is stored in a secure register of the cryptographically-secure component.

15. A system comprising:

at least one computing device;

a cryptographically-secure component; and

a messaging application adapted to;

receive a request for an encryption key, wherein the request includes an identifier of a message;

generate an encryption key using the cryptographically-secure component, wherein the encryption key is bound to a state associated with reading the identified message;

send the generated encryption key; and

receive an encrypted message, wherein the encrypted message was encrypted using the encryption key.

16. The system of claim 15, wherein the messaging application is further adapted to:

determine to read the encrypted message;

in response to the determination, instruct the cryptographically-secure component to update a state digest to the state associated with reading the identified message;

in response to the update, receive access to a decryption key by the cryptographically-secure component;

decrypt the encrypted message using the decryption key; and

read the decrypted message.

17. The system of claim 16, wherein the messaging application is further adapted to:

receive a request for proof that the message was read;

retrieve the state digest from the cryptographically-secure component; and

send the state digest as proof that message was read.

18. The system of claim 15, wherein the messaging application is further adapted to:

determine not to read the encrypted message; and

in response to the determining, instruct the cryptographically-secure component to update a state digest to a deletion state associated with deleting the message.

19. The system of claim 18, wherein the messaging application is further adapted to:

receive a request for proof that the message was deleted;

retrieve the state digest from the cryptographically-secure component; and

sending the state digest as proof that the message was deleted.

20. The system of claim 15, wherein the cryptographically-secure component is a trusted platform module.