Transactions in Sidechain

Question

Suppose I have my own sidechain and have created a transaction of 100 BTCs from Bitcoin network to my Sidechain. To my understanding, this means 100 BTCs are now locked on Bitcoin Network and 100 pegged BTCs have been created in my sidechain.

Q1. What kind of address will hold these 100 pegged BTCs in my sidechain? Is it an address same as Bitocin wallet address?

Q2. Suppose Alice have 100 pegged BTCs in address A of sidechain, Alice made a transaction of 50 pegged BTCs to Bob which has another address (say address B). We now have 50 pegged BTCs in both address A and address B. How will Bob redeem pegged coins back to real BTCs in Bitcoin Network? Because if we see in Bitcoin's point of view, Alice is the authorized user to spend or redeem her 100 pegged BTCs back to real ones. Whereas Bob does not exist for Bitcoin Network who claims to possess 50 BTCs.

Answer 1

Q1: It depends on the sidechain. Every sidechain can implement their own rule to create and represent/encode adresses.

Q2: This is an active area of research. Some people propose implementing sidechains via Zero-Knowledge proofs or other ideas that either require Bitcoin rules to change or mining cooperation or both. Some sidechains already deployed, like RKS, propose there are a set of nodes you trust to hold custody of bitcoins transferred to the sidechain, much like a bank.