TY - JOUR
T1 - Tightly CCA-secure encryption scheme in a multi-user setting with corruptions
AU - Lee, Youngkyung
AU - Lee, Dong Hoon
AU - Park, Jong Hwan
N1 - Funding Information:
The study was funded by Institute for Information and communications Technology Promotion (Grant No. 2016-6-00600, A Study on Functional Encryption: Construction, Security Analysis, and Implementation).
Publisher Copyright:
© 2020, Springer Science+Business Media, LLC, part of Springer Nature.
PY - 2020/11/1
Y1 - 2020/11/1
N2 - The security of public-key encryption (PKE) schemes in a multi-user setting is aimed at capturing real-world scenarios in which an adversary could attack multiple users and multiple ciphertexts of its choice. However, the fact that a real-world adversary can also mount key-exposure attacks for a set of multiple public keys requires us to consider a more realistic notion of security in multi-user settings. In this study, we establish the security notion of PKE in a multi-user setting with corruptions, where an adversary is able to issue (adaptive) encryption, decryption, and corruption (i.e., private key) queries. We then propose the first practical PKE scheme whose security is proven in a multi-user setting with corruptions. The security of our scheme is based on the computational Diffie–Hellman (CDH) assumption and is proven to be tightly chosen-ciphertext secure in a random oracle model. Our scheme essentially follows the recently proposed modular approach of combining KEM and augmented DEM in a multi-user setting, but we show that this modular approach works well in a multi-user setting with corruptions.
AB - The security of public-key encryption (PKE) schemes in a multi-user setting is aimed at capturing real-world scenarios in which an adversary could attack multiple users and multiple ciphertexts of its choice. However, the fact that a real-world adversary can also mount key-exposure attacks for a set of multiple public keys requires us to consider a more realistic notion of security in multi-user settings. In this study, we establish the security notion of PKE in a multi-user setting with corruptions, where an adversary is able to issue (adaptive) encryption, decryption, and corruption (i.e., private key) queries. We then propose the first practical PKE scheme whose security is proven in a multi-user setting with corruptions. The security of our scheme is based on the computational Diffie–Hellman (CDH) assumption and is proven to be tightly chosen-ciphertext secure in a random oracle model. Our scheme essentially follows the recently proposed modular approach of combining KEM and augmented DEM in a multi-user setting, but we show that this modular approach works well in a multi-user setting with corruptions.
KW - CDH
KW - Multi-user setting with corruptions
KW - Public-key encryption
KW - Random oracle model
KW - Tight security
UR - http://www.scopus.com/inward/record.url?scp=85090241507&partnerID=8YFLogxK
U2 - 10.1007/s10623-020-00794-z
DO - 10.1007/s10623-020-00794-z
M3 - Article
AN - SCOPUS:85090241507
SN - 0925-1022
VL - 88
SP - 2433
EP - 2452
JO - Designs, Codes, and Cryptography
JF - Designs, Codes, and Cryptography
IS - 11
ER -