Attestation & Types

True Network supports a variety of on-chain attestation types and structures to enable flexible credential verification. This document outlines the core components and types used in the attestation system.

Core Types

Credential Types

The system supports the following primitive types for credential fields:

• Numeric Types:
  • Unsigned integers: U8, U16, U32, U64
  • Signed integers: I8, I16, I32, I64
  • Floating point: F32, F64
• Basic Types:
  • Char: Single character
  • Boolean: True/false value
  • Text: String data (up to 128 bytes)
  • Hash: 32-byte hash value

Address Types That Can Be Attested

Attestations can be issued to accounts on different blockchain networks using the AcquirerAddress enum:

• Substrate: Standard Substrate account (AccountId32)
• Ethereum: Ethereum address (H160)
• Solana: Solana public key (base58 encoded string)

Schema Structure

Schemas define the structure of attestations and are composed of:

• A sequence of field definitions, each containing:
  • Field name (as bytes)
  • Field type (CredType)
• Maximum limits:
  • Field count (MaxSchemaFields)
  • Field size (MaxSchemaFieldSize)

Size Constraints

Each credential type has specific size constraints in bytes:

• 1 byte: Char, U8, I8, Boolean
• 2 bytes: U16, I16
• 4 bytes: U32, I32, F32
• 8 bytes: U64, I64, F64
• 32 bytes: Hash
• 128 bytes: Text

Attestations

Attestations are stored on-chain and contain:

• Issuer hash: Reference to the attestation issuer
• Schema hash: Reference to the schema definition
• Recipient address: The AcquirerAddress receiving the attestation
• Attestation data: Vector of values conforming to the schema

Storage Structure

Attestations are stored in a nested map with the following keys:

1. Recipient address (AcquirerAddress)
2. Issuer hash
3. Schema hash

This structure allows efficient lookup of all attestations for a specific recipient from a particular issuer using a specific schema.

Operations

The system supports the following main operations:

Schema Creation

• Create new credential schemas
• Schemas are immutable once created
• Schema hash is derived from field names and types

Attestation Management

• Create new attestations
• Update existing attestations
• Validate attestation data against schema definitions

Address Validation

The system includes robust validation for:

• Substrate addresses (SS58 format)
• Ethereum addresses (20 bytes)
• Solana addresses (base58 encoded Ed25519 public keys)

Events

The system emits the following events:

• SchemaCreated: When a new schema is registered
• AttestationCreated: When a new attestation is issued
• AttestationUpdated: When an existing attestation is modified

Error Handling

Common error conditions include:

• SchemaNotFound: Referenced schema doesn't exist
• InvalidFormat: Attestation data doesn't match schema
• SchemaAlreadyExists: Attempt to create duplicate schema
• TooManySchemaFields: Schema exceeds field limit
• SchemaFieldTooLarge: Field size exceeds limit
• InvalidAddress: Invalid recipient address format
• AttestationNotFound: Referenced attestation doesn't exist
• InvalidAttestationIndex: Invalid index for attestation update