Paper 2019/1082

On the Security of Multikey Homomorphic Encryption

Hyang-Sook Lee and Jeongeun Park


Multikey fully homomorphic encryption (MFHE) scheme enables homomorphic computation on data encrypted under different keys. To decrypt a result ciphertext, all the involved secret keys are required. For multi decryptor setting, decryption is a protocol with minimal interaction among parties. However, all prior schemes supporting the protocol are not secure in public channel against a passive external adversary who can see any public information not joining the protocol. Furthermore, the possible adversaries have not been defined clearly. In this paper, we revisit the security of MFHE and present a secure one-round decryption protocol. We apply it to one of existing schemes and prove the scheme is secure against possible static adversaries. As an application, we construct a two round multiparty computation without common random string.

Available format(s)
Cryptographic protocols
Publication info
Published elsewhere. Minor revision.IMA CC 2019
security of MFHEMPC without CRSMultikey homomorphic encryption.
Contact author(s)
jungeun7430 @ naver com
2020-12-22: last of 2 revisions
2019-09-24: received
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      author = {Hyang-Sook Lee and Jeongeun Park},
      title = {On the Security of Multikey Homomorphic Encryption},
      howpublished = {Cryptology ePrint Archive, Paper 2019/1082},
      year = {2019},
      note = {\url{}},
      url = {}
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