Blockchain as a CA: A Provably Secure Signcryption Scheme Leveraging Blockchains

Table 2

Comparisons between related signcryption schemes and the proposed scheme.

Schemes	PKI-/ID-/certificateless-based	Hardness assumption	High maintenance cost of CAs or a TTP	Seamless compliance with blockchains	Computational cost
					Signcryption	Unsigncryption	Total cost
Malone-Lee [5]	ID-based	BDH	Yes (TTP)	No			435.0
Karati et al. [4]	ID-based	BDH	Yes (TTP)	No	+	+  +	377.6
Zhou et al. [13]	Certificateless-based	BDH	Yes (TTP)	No	+	+	1254.0
Karati et al. [16]	Certificateless-based	BDH	Yes (TTP)	No		+  +	302.2
Rastegari et al. [17]	Certificateless-based	BDH	Yes (TTP)	No	+	+	996.0
ECDSA + ECC	PKI-based	ECDLP	Yes (CA)	No	( + ) + ( + )	( + ) + ( + )	243.2
The proposed scheme	Blockchain as a CA	ECDLP	No	Yes	+  +	+  +	214.2