Public Key Encryption with Digital Signature Scheme
AssigneeResearch In Motion Limited
InventorHerb A. Little
Life of this patent
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Abstract
An improved encryption and digital signature system and method in accordance with the invention reuses an encryption ephemeral key pair from an encryption process in a digital signature process. The reuse of the encryption ephemeral key pair in the digital signature process advantageously results in reduced byte size of the digital signature and reduction of costly computation overhead. In a preferred embodiment, the invention is based on the El Gamal encryption scheme and the Nyberg-Rueppel signature scheme. The present invention is particularly useful for operation in conjunction with small communication devices having limited processing and storage, wherein such devices may communicate via bandwidth sensitive RF links.
Claims19
A public-key decryption process for ciphertext messages, comprising:
- receiving from a sender a public key of a key pair that is used for a single message, a ciphertext message that was encrypted using the key pair, and a second value s of a digital signature that was generated using the key pair and that comprises a first value r and the second value s;
- decrypting the ciphertext message into a plaintext message;
- calculating the first value r of the digital signature using the plaintext message and the public key;
- and
- validating the digital signature based on the calculated first value r and the received second value s.
A communication device, comprising:
- a computer-readably memory encoded with software instructions;
- and wherein:
- the communication device is configured to receive from a sender a public key X of a key pair that is used for a single message, a ciphertext message that was encrypted using the key pair, and a second value s of a digital signature that was generated using the key pair and that comprises a first value r and the second value s;
- the communication device is configured to decrypt the ciphertext message into a plaintext message;
- the communication device is configured to calculate the first value r of the digital signature using the plaintext message and the public key;
- and
- the communication device is configured to validate the digital signature based on the calculated first value r and the received second value s.
A wireless device for decrypting data, comprising:
- a data processor;
- a computer-readable memory encoded with instructions for commanding the data processor to execute steps including:
- receiving from a sender a public key X of a key pair that is used for a single message, a ciphertext message that was encrypted using the key pair, and a second value s of a digital signature that was generated using the key pair and that comprises a first value r and the second value s;
- decrypting the ciphertext message into a plaintext message;
- calculating the first value r of the digital signature using the plaintext message and the public key;
- and
- validating the digital signature based on the calculated first value r and the received second value s.
Dependencies are inferred from the claim text.