Table 5.

Comparison of registration-based encryption primitives

Scheme	TTP-Less	Accumulator	Public Verifiability	Best practice	Extra
RBE [146]-2018	$✓$	Honest	$\times$	–	–Not efficient
RBE [148]-219	$✓$	Honest	$\times$	Cloud service	+Anonymity
VRBE [147]-2020	$✓$	Malicious	$✓$	Blockchain service	+Slightly efficient
ORBE [149]-2021	$✓$	Honest	$\times$	–	+Efficient