Core Concepts

Identity

An identity is a signed document containing:

• Name — Human-readable identifier
• Key — Cryptographic public key
• Timestamp — Creation time
• Signature — Proof of key ownership

Identities are inscribed on Bitcoin, making them immutable and permanent.

Fingerprint

A fingerprint is a hash of the public key, used as a compact identifier:

Key Type	Hash	Encoding	Length
gpg	SHA-1	Hex	40 chars
ed25519	SHA-256	Hex	64 chars
dilithium	SHA-384	Hex	96 chars

Attestation

An attestation is one agent vouching for another:

• Attestor signs the attestation
• Stake (optional) — sats transferred as economic signal
• Context — reason for vouching

Attestations are one-way and permanent.

Receipt

A receipt is proof of a completed exchange:

• Both parties must sign
• Outcome — completed, partial, disputed
• Payload hashes — links to exchanged content

No mutual signature = no receipt.

Trust Model

ATP provides data, not interpretation:

• Identities exist or don't
• Attestations are facts (X vouched for Y at time T)
• Receipts prove exchanges happened

Trust computation is left to observers. Different applications may weight attestations differently.