Enhancement of Digital Signature Algorithm in Bitcoin Blockchain Technology

Abstract

Bitcoin is a peer-to-peer electronic cash system largely used for online financial transactions. Its system is gained popularity due to its anonymity, privacy, and comparatively low transactions cost .Its wallet heavily relies on Elliptic Curve Digital Signature Algorithm (ECDSA). Weaknesses in such algorithms can significantly affect the safety and the security of bitcoin wallets. Thesis aims to improve the security of bitcoin wallet key management via enhancing the ECDSA. In this thesis, a secure key management wallet was designed. The proposed key management model consists of three main parts: (Cold, Hot, and Recover).On the Cold wallet, it has been applied new an encoding model with attaching new Arabic dictionary coupled with the proposed Image Steganography Passphrase Encryption algorithm (ISPE) is to increase the strength of master seed and Hybrid Deterministic Herirachy wallet (HDH) are to ensure high entropy of a set of determinist secrets keys. On the Hot wallet, the proposed key_ Gen algorithm is modifying to the key generation step of the ECDSA algorithm that it is to generate a fresh key pair at each transaction. The wallet address book and Markel root for HDH key are used as an additional seed to the key_Gen algorithm. The final part is the Recovery wallet model to ensure restoring all keys on both Hot and Cold wallets without daily backups in case of losing the wallet or its device not working. A simulated system has been implemented and simulation results have been obtained. The salt of the proposed Cold wallet model passed successfully the NIST and Zxcvbn tests, thus the cold wallet will be resisting against a dictionary attacks. The ISPE was overcoming the memorizing problem by using the stego image. The proposed hot wallet model acquires good anonymity and privacy for bitcoin users by eliminating transaction linkability without additional cost. The execution time for signing a transaction of the proposed schema is approximately 50 - 70 ms, which achieved the least signature time compared to other techniques. Finally, the need for daily backup is omitted thanks to proposed Recovery wallet model, which is then important in the bitcoin domain.