Features

What the device does, and proof that it does it. Everything listed here is implemented and verified against real clients; nothing on this page is a promise. Every term is explained on the FAQ.

The device at a glance

FIDO2 / WebAuthn

• Passkeys (WebAuthn) over CTAP 2.1 — verified with Chrome, python-fido2 2.2.1, ykman and Yubico Authenticator
• 848 discoverable credentials (resident keys) — measured to refusal on hardware (8 slots of the original range are the Nostr reservation)
• Credential management: enumerate, rename, delete — via ykman or PicoForge
• Extensions: hmac-secret, credProtect, credBlob, largeBlobKey, minPinLength
• Large blobs (authenticatorLargeBlobs)
• User presence enforcement through the physical button; user verification with PIN
• ES256 (ECDSA over P-256) — the algorithm every client requests first, and the one the device path signs with
• Permissions enforced on every token: MC, GA, CM, ACFG, LBW
• Authenticator configuration; vendor configuration
• Seed backup: the vendor seed — the soft-lock key — exports once, as a 24-word phrase, and installs on any board; passkeys themselves are non-exportable by design — the procedure
• Enterprise attestation (enterpriseAttestation): a listed enterprise RP can request identifying attestation
• Signature counters: a persistent per-credential counter increments on every assertion
• Sealed store: credentials survive a reflash, and a flash dump alone is inert

OATH (YKOATH)

• TOTP and HOTP — 68 credentials reserved in the key store
• Access-code locking — until the correct access code is presented, the applet answers "locked"; it persists across power cycles (hardware-verified)
• Challenge-response generation, touch-gated
• Yubico Authenticator and ykman compatible

OTP

• YubiKey-slot OTP — the YubiKey one-time-password protocol over CCID
• Challenge-response generation, touch-gated challenge
• ykman otp compatible

OpenPGP 3.4

• OpenPGP card specification v3.4 — 3 key slots (Signature, Encryption, Authentication)
• RSA (2048, 3072, 4096), Ed25519, Curve25519, ECDSA (NIST P-256, P-384, P-521), secp256k1, Brainpool P-256r1
• Key generation on device; key import; public-key and certificate export
• PIN and Admin PIN protection; reset and unblock — via the admin PIN or a dedicated reset code
• Works with GnuPG, SSH and compatible tools over CCID

Nostr

• Up to 8 Nostr identities — BIP-340 (Schnorr) signing and NIP-44 v2 encryption, computed on the chip; the full tour is the applet page, the walk-through is the how-to
• NIP-07 window.nostr for web pages — getPublicKey, signEvent, nip44.encrypt/decrypt, listKeys — via the fapico2 Nostr extension over WebHID (Chrome 116+, usage page 0xFF00)
• Touch on every private-key operation — sign, encrypt, decrypt, generate, import, label, delete, export; only the public reads are touch-free, and no config bit changes that
• Keys sealed as AEAD records in the key store under the chip-unique OTP root — the same at-rest story as passkeys (why device-bound)
• The event is hashed in the browser; only the 32-byte sighash reaches the board, and the signature comes back with the npub that produced it

Platform

• Signed secure boot (opt-in, ./build-signed.sh): the bootrom refuses unsigned images
• Master key in OTP: the store key derives from a one-way-fused OTP row — nothing that seals the device lives in flash
• Rescue interface: reboot a running board into the mass-storage bootloader without auth or a button
• LED slot configuration via PicoForge

Capacity

For scale: a YubiKey 5 holds 100 resident passkeys.