Chaintope’s CTO Shigeyuki Azuchi explains how, by using ECDSA, multisignatures can be implemented without using a Bitcoin script.
Since using this technology does not use Bitcoin scripts, it is possible to implement high speed, secure 2-of-2 multisig between 2 parties.
This is an explanation of “Fast Secure Two-Party ECDSA Signing” by Yehuda Lindell

In this video, we will learn about:

• Multisig transactions using Bitcoin scripts
• Methods for generating and verifying standard ECDSA signatures
• 2-of-2 multisig with ECDSA
• How coins are locked with ECDSA multisig
• Calculating signature data with secret calculations
• The benefits of calculating signature data with secret calculations