Mrs J.Sri Maha Lakshmi, P.Yaswanth kumar, S.Abhinash, S.Haripriya,T.Gowri Santhoshi 03 03 Modern distributed computing environments require secure authentication across organizational boundaries without exposing sensitive identity credentials Existing crossdomain authentication solutions rely on centralized trusted third parties creating single points of failure and privacy vulnerabilities This paper proposes a BlockchainBased Privacy Preserving Cross Domain Authentication Scheme BPCDAS combining zeroknowledge proof ZKP protocols for privacypreserving credential verification Ethereum smart contracts for trustless authentication management and decentralized identifiers DIDs The scheme eliminates centralized certificate authorities by distributing trust across a permissioned blockchain consortium Security analysis demonstrates resistance to impersonation replay and maninthemiddle attacks Performance evaluation shows average authentication latency of 18 seconds with throughput of 180 authentications per minute suitable for enterprise federated identity management Copyright (c) Journal of Science Engineering Technology and Management Science. All rights reserved 2026