A randomized analog of Chaum — van Antwerpen undeniable signature

We suggest an elliptic curve modification of the undeniable signature introduced by D. Chaum and H. van-Antwerpen. The signature generation algorithm is supplemented with a preliminary stage of randomization. For signature verification and disavowal protocols, two options are offered. Theorems showing that these protocols meet their purpose have been proven. A method for converting an undeniable signature into a regular digital signature is described, illustrated by the Schnorr electronic signature scheme as an example.