Systems and methods for identity-based encryption and related cryptographic techniques

• US 9,356,779 B2
• Filed: 02/08/2012
• Issued: 05/31/2016
• Est. Priority Date: 08/13/2001
• Status: Expired due to Fees

• Current Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford University)
• Original Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford University), Regents of the University of California (University of California)
• Inventors: Boneh, Dan, Franklin, Matthew
• Primary Examiner(s): Nalven, Andrew
• Assistant Examiner(s): FIELDS, COURTNEY D
• Application Number:
  US13/369,165
• Publication Number:
  US 20120159188A1
• Time in Patent Office: 1,574 Days
• Field of Search: 713/189, 380/28, 380/30, 380/277, 380/278
• US Class Current: 1/1
• CPC Class Codes: H04L 2209/04 Masking or blinding
• CPC Class Codes: H04L 9/0847 involving identity based encryption [IBE] schemes
• CPC Class Codes: H04L 9/3073 involving pairings, e.g. identity based encryption [IBE], bilinear mappings or bilinear pairings, e.g. Weil or Tate pairing

Abstract

A method and system for encrypting a first piece of information M to be sent by a sender [100] to a receiver [110] allows both sender and receiver to compute a secret message key using identity-based information and a bilinear map. The sender uses a bilinear map to encrypt a message M, producing ciphertext V to be sent from the sender [100] to the receiver [110]. The receiver [110] uses the bilinear map to decrypt V and recover the original message M. According to one embodiment, the bilinear map is based on a Weil pairing or a Tate pairing defined on a subgroup of an elliptic curve. Also described are several applications of the techniques, including key revocation, credential management, and return receipt notification.

Claims

1. A method, comprising:

with computing equipment, encrypting data using a public key that is formed using an identity, wherein encrypting the data comprises encrypting the data using cryptographic system parameters and a bilinear map, wherein the cryptographic system parameters include an element P of an algebraic group and a computed value sP, wherein s represents a secret master key, and wherein encrypting the data using the cryptographic system parameters and the bilinear map comprises;

with the computing equipment, obtaining the cryptographic system parameters P and sP;

with the computing equipment, selecting a random secret r; and

with the computing equipment, encrypting the data using r, sP, the public key that is formed using the identity, and the bilinear map.

6. The method defined in claim 1 wherein the identity comprises a user identity.

7. The method defined in claim 6 wherein the user identity comprises an email address.

2. A method, comprising:

with computing equipment, decrypting encrypted data using a private key d that corresponds to an identity, wherein decrypting the data comprises decrypting the data using cryptographic system parameters and a bilinear map, wherein the cryptographic system parameters comprise an element P of an algebraic group, and wherein decrypting the data using the cryptographic system parameters and the bilinear map comprises;

with the computing equipment, obtaining a computed value sQ, wherein s represents a secret master key and Q represents a public key associated with the identity.

3. The method defined in claim 2 wherein the identity comprises a user identity.

4. The method defined in claim 3 wherein the user identity comprises an email address.

5. The method defined in claim 2 wherein decrypting the data using the cryptographic system parameters and the bilinear map comprises:

with the computing equipment, obtaining a computed value rP, wherein r is a random secret number; and

with the computing equipment, decrypting the encrypted data using rP, sQ, and the bilinear map.