Abstract: The present disclosure a method for a lattice-based homomorphic proxy re-encryption scheme. Conventional methods are attribute based and the attribute-based encryption schemes employ very expensive operations and generate long ciphertexts and secret keys (whose sizes also increase linearly with the size of the access policy), which makes them hard to implement in real-life applications. The present disclosure provides a unidirectional, single-hop HPRE scheme from the Learning With Errors (LWE) assumption which is Chosen Plaintext Attack (CPA) secure. Further, the present disclosure is based on the widely accepted BGV algorithm that supports both levelled FHE operations as well as arbitrary number of ciphertexts with unique and secure re-encryption key generation. Further, the present disclosure provides batch evaluation of ciphertexts, in order to enable re-encryption and evaluation of multiple ciphertexts.

Abstract: This disclosure relates to field of cryptography and digital signatures. The constant theft of cryptocurrencies is due to compromise of the secret signing key inherently stored in a single location. Also, one of challenges in the existing ECDSA signature is single point failure, wherein the signing key (private key) is prone to theft. The disclosed technique overcomes the challenging in the existing techniques by party distributed signature that ensures the safety of the private key. The disclosed techniques slits the key in two parts and saves at two different locations/machines. Further based on a ECDSA based technique, the digital signature is obtained securely using several steps that includes generation of first two parts of digital signature at one party, generation of the second two parts of digital signature at second party, finally decrypting a complete digital signature at the first party.