Each attribute has:

• name – machine-readable key (age, residency.country)
• type – scalar, range, enum, set, boolean, reference
• issuer – self-asserted, gov, institution, protocol
• value – stored encrypted in the Vault
• valid_from / valid_until – temporal bounds
• attestation_proof – optional proof from external issuer

Attributes live in a Merkle Attribute Tree inside the Vault:

attributes_root = MerkleRoot([
    leaf(attribute_1),
    leaf(attribute_2),
    ...
])

Attribute Leaf Encoding

Attribute {
descriptor_id    // e.g. "residency_country"
value_commitment // commitment to the real value
issuer_id        // who asserted it
valid_from
valid_until
attestation_ref? // external attestation link
}

Attribute Tree (recap)

attribute_leaf = H(
  descriptor_id,
  value_commitment,
  issuer_id,
  valid_from,
  valid_until,
  attestation_ref?
)

attributes_root = MerkleRoot(
  sorted_by(descriptor_id, [attribute_leaf_1, attribute_leaf_2, ...])
)

The real values live encrypted in the Vault; the Identity Layer only sees commitments and metadata.

• value_commitment can be a Pedersen / hash commitment to the real value.
• The raw value lives encrypted in the Vault; the tree only sees the commitment + metadata.
• Sorting leaves by descriptor_id before building the tree keeps it deterministic.

The Vault stores the raw values, encrypted.

The attribute tree only stores commitments and metadata, so Verifiers never see personal data, only committed facts.