# Cronos Attestation Service (CAS)

### Overview

The Cronos Attestation Service (CAS) is a decentralized protocol on Cronos that enables users to create, verify, and revoke attestations (verifiable statements) on-chain. Attestations can represent credentials, endorsements, or any form of verifiable data. This document focuses on integrating with the core CAS contract methods: attest, multiAttest, revoke, and multiRevoke. These methods allow for creating and revoking single or multiple attestations efficiently.

### Prerequisites

#### Contract Address:

<table><thead><tr><th width="246.34765625"></th><th width="269.33203125">Testnet</th><th>Mainnet</th></tr></thead><tbody><tr><td><code>Schema Registry Address</code></td><td><a href="https://explorer.cronos.org/testnet/address/0x7630c9a763d530659ad94f8502163b669c573d2c">0x7630C9A763D530659ad94F8502163b669C573D2C</a></td><td><a href="https://explorer.cronos.org/address/0x21c793a65a23d0f019e91f3fb481e5a4166b570b">0x21c793A65A23d0f019E91F3FB481E5A4166B570b</a></td></tr><tr><td><code>CAS Address</code></td><td><a href="https://explorer.cronos.org/testnet/address/0x416bd35dccc6848c169b97795bf58faad1a20a10">0x416bD35dCCc6848c169B97795bF58faaD1A20A10</a></td><td><a href="https://explorer.cronos.org/address/0xf156ce895787218ced050efb2c069769a989d436">0xF156cE895787218CEd050eFb2c069769a989D436</a></td></tr></tbody></table>

#### Schema

<table><thead><tr><th width="216.45703125">Schema Value</th><th>Testnet Schema ID </th><th>Mainnet Schema ID</th></tr></thead><tbody><tr><td><code>bool isVerified</code></td><td>0x5bb8818557626dd 69c0003d405b7cabed1d6829b2b39835a30741c912c3dfa2f</td><td>0x5bb8818557626dd69c0003d405b7cabed1d6829b2b39835a30741c912c3dfa2f</td></tr></tbody></table>

#### ABI:

CASABI.json

```json
[
  {
    "inputs": [],
    "stateMutability": "nonpayable",
    "type": "constructor"
  },
  {
    "inputs": [],
    "name": "AlreadyAttested",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "AlreadyRevoked",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "InvalidAttestation",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "InvalidAttestations",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "InvalidDefaultAdmin",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "InvalidExpirationTime",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "InvalidLength",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "InvalidRegistry",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "InvalidSchema",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "Irrevocable",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "NotFound",
    "type": "error"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "address",
        "name": "recipient",
        "type": "address"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "attester",
        "type": "address"
      },
      {
        "indexed": false,
        "internalType": "bytes32",
        "name": "uid",
        "type": "bytes32"
      },
      {
        "indexed": true,
        "internalType": "bytes32",
        "name": "schemaUID",
        "type": "bytes32"
      }
    ],
    "name": "Attested",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": false,
        "internalType": "uint8",
        "name": "version",
        "type": "uint8"
      }
    ],
    "name": "Initialized",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "address",
        "name": "recipient",
        "type": "address"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "attester",
        "type": "address"
      },
      {
        "indexed": false,
        "internalType": "bytes32",
        "name": "uid",
        "type": "bytes32"
      },
      {
        "indexed": true,
        "internalType": "bytes32",
        "name": "schemaUID",
        "type": "bytes32"
      }
    ],
    "name": "Revoked",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "bytes32",
        "name": "role",
        "type": "bytes32"
      },
      {
        "indexed": true,
        "internalType": "bytes32",
        "name": "previousAdminRole",
        "type": "bytes32"
      },
      {
        "indexed": true,
        "internalType": "bytes32",
        "name": "newAdminRole",
        "type": "bytes32"
      }
    ],
    "name": "RoleAdminChanged",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "bytes32",
        "name": "role",
        "type": "bytes32"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "account",
        "type": "address"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "sender",
        "type": "address"
      }
    ],
    "name": "RoleGranted",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "bytes32",
        "name": "role",
        "type": "bytes32"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "account",
        "type": "address"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "sender",
        "type": "address"
      }
    ],
    "name": "RoleRevoked",
    "type": "event"
  },
  {
    "inputs": [],
    "name": "ATTESTER_ROLE",
    "outputs": [
      {
        "internalType": "bytes32",
        "name": "",
        "type": "bytes32"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "DEFAULT_ADMIN_ROLE",
    "outputs": [
      {
        "internalType": "bytes32",
        "name": "",
        "type": "bytes32"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "components": [
          {
            "internalType": "bytes32",
            "name": "schema",
            "type": "bytes32"
          },
          {
            "components": [
              {
                "internalType": "address",
                "name": "recipient",
                "type": "address"
              },
              {
                "internalType": "uint64",
                "name": "expirationTime",
                "type": "uint64"
              },
              {
                "internalType": "bool",
                "name": "revocable",
                "type": "bool"
              },
              {
                "internalType": "bytes",
                "name": "data",
                "type": "bytes"
              }
            ],
            "internalType": "struct AttestationRequestData",
            "name": "data",
            "type": "tuple"
          }
        ],
        "internalType": "struct AttestationRequest",
        "name": "request",
        "type": "tuple"
      }
    ],
    "name": "attest",
    "outputs": [
      {
        "internalType": "bytes32",
        "name": "",
        "type": "bytes32"
      }
    ],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "bytes32",
        "name": "uid",
        "type": "bytes32"
      }
    ],
    "name": "getAttestation",
    "outputs": [
      {
        "components": [
          {
            "internalType": "bytes32",
            "name": "uid",
            "type": "bytes32"
          },
          {
            "internalType": "bytes32",
            "name": "schema",
            "type": "bytes32"
          },
          {
            "internalType": "uint64",
            "name": "time",
            "type": "uint64"
          },
          {
            "internalType": "uint64",
            "name": "expirationTime",
            "type": "uint64"
          },
          {
            "internalType": "uint64",
            "name": "revocationTime",
            "type": "uint64"
          },
          {
            "internalType": "address",
            "name": "recipient",
            "type": "address"
          },
          {
            "internalType": "address",
            "name": "attester",
            "type": "address"
          },
          {
            "internalType": "bool",
            "name": "revocable",
            "type": "bool"
          },
          {
            "internalType": "bytes",
            "name": "data",
            "type": "bytes"
          }
        ],
        "internalType": "struct Attestation",
        "name": "",
        "type": "tuple"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "recipient",
        "type": "address"
      },
      {
        "internalType": "bytes32",
        "name": "schemaUid",
        "type": "bytes32"
      }
    ],
    "name": "getAttestationUid",
    "outputs": [
      {
        "internalType": "bytes32",
        "name": "",
        "type": "bytes32"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "bytes32",
        "name": "role",
        "type": "bytes32"
      }
    ],
    "name": "getRoleAdmin",
    "outputs": [
      {
        "internalType": "bytes32",
        "name": "",
        "type": "bytes32"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "getSchemaRegistry",
    "outputs": [
      {
        "internalType": "contract ISchemaRegistry",
        "name": "",
        "type": "address"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "bytes32",
        "name": "role",
        "type": "bytes32"
      },
      {
        "internalType": "address",
        "name": "account",
        "type": "address"
      }
    ],
    "name": "grantRole",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "bytes32",
        "name": "role",
        "type": "bytes32"
      },
      {
        "internalType": "address",
        "name": "account",
        "type": "address"
      }
    ],
    "name": "hasRole",
    "outputs": [
      {
        "internalType": "bool",
        "name": "",
        "type": "bool"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "defaultAdmin",
        "type": "address"
      },
      {
        "internalType": "contract ISchemaRegistry",
        "name": "registry",
        "type": "address"
      }
    ],
    "name": "initialize",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "bytes32",
        "name": "uid",
        "type": "bytes32"
      }
    ],
    "name": "isAttestationValid",
    "outputs": [
      {
        "internalType": "bool",
        "name": "",
        "type": "bool"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "components": [
          {
            "internalType": "bytes32",
            "name": "schema",
            "type": "bytes32"
          },
          {
            "components": [
              {
                "internalType": "address",
                "name": "recipient",
                "type": "address"
              },
              {
                "internalType": "uint64",
                "name": "expirationTime",
                "type": "uint64"
              },
              {
                "internalType": "bool",
                "name": "revocable",
                "type": "bool"
              },
              {
                "internalType": "bytes",
                "name": "data",
                "type": "bytes"
              }
            ],
            "internalType": "struct AttestationRequestData[]",
            "name": "data",
            "type": "tuple[]"
          }
        ],
        "internalType": "struct MultiAttestationRequest[]",
        "name": "multiRequests",
        "type": "tuple[]"
      }
    ],
    "name": "multiAttest",
    "outputs": [
      {
        "internalType": "bytes32[]",
        "name": "",
        "type": "bytes32[]"
      }
    ],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "components": [
          {
            "internalType": "bytes32",
            "name": "schema",
            "type": "bytes32"
          },
          {
            "components": [
              {
                "internalType": "bytes32",
                "name": "uid",
                "type": "bytes32"
              }
            ],
            "internalType": "struct RevocationRequestData[]",
            "name": "data",
            "type": "tuple[]"
          }
        ],
        "internalType": "struct MultiRevocationRequest[]",
        "name": "multiRequests",
        "type": "tuple[]"
      }
    ],
    "name": "multiRevoke",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "bytes32",
        "name": "role",
        "type": "bytes32"
      },
      {
        "internalType": "address",
        "name": "account",
        "type": "address"
      }
    ],
    "name": "renounceRole",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "components": [
          {
            "internalType": "bytes32",
            "name": "schema",
            "type": "bytes32"
          },
          {
            "components": [
              {
                "internalType": "bytes32",
                "name": "uid",
                "type": "bytes32"
              }
            ],
            "internalType": "struct RevocationRequestData",
            "name": "data",
            "type": "tuple"
          }
        ],
        "internalType": "struct RevocationRequest",
        "name": "request",
        "type": "tuple"
      }
    ],
    "name": "revoke",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "bytes32",
        "name": "role",
        "type": "bytes32"
      },
      {
        "internalType": "address",
        "name": "account",
        "type": "address"
      }
    ],
    "name": "revokeRole",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "bytes4",
        "name": "interfaceId",
        "type": "bytes4"
      }
    ],
    "name": "supportsInterface",
    "outputs": [
      {
        "internalType": "bool",
        "name": "",
        "type": "bool"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "version",
    "outputs": [
      {
        "internalType": "uint8",
        "name": "",
        "type": "uint8"
      }
    ],
    "stateMutability": "pure",
    "type": "function"
  }
]
```

SchemaRegistryABI.json

```json
[
  {
    "inputs": [],
    "stateMutability": "nonpayable",
    "type": "constructor"
  },
  {
    "inputs": [],
    "name": "AlreadyExists",
    "type": "error"
  },
  {
    "inputs": [],
    "name": "InvalidDefaultAdmin",
    "type": "error"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": false,
        "internalType": "uint8",
        "name": "version",
        "type": "uint8"
      }
    ],
    "name": "Initialized",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "bytes32",
        "name": "uid",
        "type": "bytes32"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "registerer",
        "type": "address"
      },
      {
        "components": [
          {
            "internalType": "bytes32",
            "name": "uid",
            "type": "bytes32"
          },
          {
            "internalType": "bool",
            "name": "revocable",
            "type": "bool"
          },
          {
            "internalType": "string",
            "name": "schema",
            "type": "string"
          }
        ],
        "indexed": false,
        "internalType": "struct SchemaRecord",
        "name": "schema",
        "type": "tuple"
      }
    ],
    "name": "Registered",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "bytes32",
        "name": "role",
        "type": "bytes32"
      },
      {
        "indexed": true,
        "internalType": "bytes32",
        "name": "previousAdminRole",
        "type": "bytes32"
      },
      {
        "indexed": true,
        "internalType": "bytes32",
        "name": "newAdminRole",
        "type": "bytes32"
      }
    ],
    "name": "RoleAdminChanged",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "bytes32",
        "name": "role",
        "type": "bytes32"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "account",
        "type": "address"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "sender",
        "type": "address"
      }
    ],
    "name": "RoleGranted",
    "type": "event"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "bytes32",
        "name": "role",
        "type": "bytes32"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "account",
        "type": "address"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "sender",
        "type": "address"
      }
    ],
    "name": "RoleRevoked",
    "type": "event"
  },
  {
    "inputs": [],
    "name": "DEFAULT_ADMIN_ROLE",
    "outputs": [
      {
        "internalType": "bytes32",
        "name": "",
        "type": "bytes32"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "bytes32",
        "name": "role",
        "type": "bytes32"
      }
    ],
    "name": "getRoleAdmin",
    "outputs": [
      {
        "internalType": "bytes32",
        "name": "",
        "type": "bytes32"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "bytes32",
        "name": "uid",
        "type": "bytes32"
      }
    ],
    "name": "getSchema",
    "outputs": [
      {
        "components": [
          {
            "internalType": "bytes32",
            "name": "uid",
            "type": "bytes32"
          },
          {
            "internalType": "bool",
            "name": "revocable",
            "type": "bool"
          },
          {
            "internalType": "string",
            "name": "schema",
            "type": "string"
          }
        ],
        "internalType": "struct SchemaRecord",
        "name": "",
        "type": "tuple"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "bytes32",
        "name": "role",
        "type": "bytes32"
      },
      {
        "internalType": "address",
        "name": "account",
        "type": "address"
      }
    ],
    "name": "grantRole",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "bytes32",
        "name": "role",
        "type": "bytes32"
      },
      {
        "internalType": "address",
        "name": "account",
        "type": "address"
      }
    ],
    "name": "hasRole",
    "outputs": [
      {
        "internalType": "bool",
        "name": "",
        "type": "bool"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "defaultAdmin",
        "type": "address"
      }
    ],
    "name": "initialize",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "string",
        "name": "schema",
        "type": "string"
      },
      {
        "internalType": "bool",
        "name": "revocable",
        "type": "bool"
      }
    ],
    "name": "register",
    "outputs": [
      {
        "internalType": "bytes32",
        "name": "",
        "type": "bytes32"
      }
    ],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "bytes32",
        "name": "role",
        "type": "bytes32"
      },
      {
        "internalType": "address",
        "name": "account",
        "type": "address"
      }
    ],
    "name": "renounceRole",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "bytes32",
        "name": "role",
        "type": "bytes32"
      },
      {
        "internalType": "address",
        "name": "account",
        "type": "address"
      }
    ],
    "name": "revokeRole",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "bytes4",
        "name": "interfaceId",
        "type": "bytes4"
      }
    ],
    "name": "supportsInterface",
    "outputs": [
      {
        "internalType": "bool",
        "name": "",
        "type": "bool"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "version",
    "outputs": [
      {
        "internalType": "uint8",
        "name": "",
        "type": "uint8"
      }
    ],
    "stateMutability": "pure",
    "type": "function"
  }
]
```