CustID is a mobile identity vault built on Nostr and the SISTR protocol.

It stores and manages multiple Nostr identities (keypairs) on a single
device, keeps private keys in hardware-backed secure storage (Android
Keystore), and exposes them only through controlled, auditable signing.

Identity vault: multiple identities, keys never leave the secure enclave.
Nostr signer (NIP-46 bunker): remote-sign for any NIP-46 compatible client.
NFC challenge-response: answer access-control challenges by tapping the
phone on an NFC reader (doors, gates, event ticketing, ...).
QR code support: scan or present signed proofs as an NFC fallback.
Zero-knowledge proofs: planned, for privacy-preserving identity claims.