At least one proof transaction is received at a node of a blockchain network and comprises at least one Elliptic Curve Digital Signature Algorithm (ECDSA) signature and at least one zero-knowledge proof (ZKP) component. The node verifies the ECDSA signature of the at least one proof transaction based on a public key associated with the ECDSA signature and a signed part of the at least one proof transaction, and determined whether the ZKP component is correct for the ECDSA signature and a defined hash value and a defined hash function, in that it proves an ephemeral key counterpart to an r-part of the ECDSA signature to be a preimage of the defined hash value with respect to the defined hash function.