Certificateless Sanitizable Signature With Designated Verifier

As a new type of digital signature, sanitizable signature enables a semi-trusted entity to alter a signed document and re-create a signature of the altered document in the name of original signer. This approach offers an effective solution to sanitize sensitive information in signed documents while ensuring the authenticity of sanitized documents. Most of current sanitizable signature schemes have the complex certificate management issue or the key escrow limitation. Recently, two certificateless sanitizable signature schemes have been proposed to address the above issues. However, they both rely on costly bilinear pairings, which incur high computation costs to create signature, make sanitization and perform verification. In the work, we design a pairing-free certificateless sanitizable signature scheme with a designated verifier. The proposed scheme achieves signature verification through a designated verifier, thereby preventing malicious propagation and illegal abuse of signatures. By eliminating the need for pairing operations, the scheme offers substantial improvements in computational efficiency. Security proofs demonstrate that it satisfies existential unforgeability and immutability against adaptive chosen message attacks. In addition, simulation experiments indicate that our approach reduces the computation costs of signature generation, sanitization, and verification by approximately 88.15%/88.48%, 99.98%/99.01%, and 71.22%/78.64%, respectively, when compared to the most recent two certificateless sanitizable signature schemes.