Verifiable Backup

Create an encrypted backup of the server's keyshare using a verifiable encryption scheme. The mobile client can verify the backup is correct without decrypting it, so the keyshare stays protected while the backup is checked. Key aspects include:

• Encryption of the server's secret share for secure storage
• Public verifiability of the backup's correctness without decryption
• Assurance that the backed-up share corresponds to the active MPC wallet

Use a verifiable backup to recover the server keyshare after a server failure or data loss.