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Verifying a Transfer

Prerequisites​

Before verifying a transfer, make sure you have:

  1. Initiated a Direct Transfer or Multi-sig Deploy Transfer
  2. The deploy_hash of the transfer you want to verify
  3. The public key hex for the source and target accounts

Query Transfer Details​

A transfer is a part of a deploy - in a Casper network, deploys can contain multiple transfers. Execution of the deploy includes writing information about each individual transfer to global state. A unique hash known as the transfer-address identifies each transfer. The transfer-address consists of a formatted string with a transfer- prefix.

First, we will use the deploy_hash to identify the corresponding transfer:

casper-client get-deploy \
--node-address http://<node-ip-address>:7777 \
[DEPLOY_HASH]

Important response fields:

  • "result"."execution_results"."result"."Success"."transfers" - List of transfers contained in a successful deploy.

After we have obtained the transfer-<hex> identifier, we can query transfer details.

casper-client query-global-state \
--id 8 \
--node-address http://<node-ip-address>:7777 \
--state-root-hash <state-root-hash> \
--key transfer-<hex>

Request fields:

  • id - Optional JSON-RPC identifier applied to the request and returned in the response. If not provided, a random integer will be assigned.
  • node-address - An IP address of a node on the network.
  • state-root-hash - The hex-encoded hash of the state root.
  • key - The base key for the query. This must be a properly formatted transfer address.
Explore the JSON-RPC request and response generated.

JSON-RPC Request:

{
    "id": 8,
    "jsonrpc": "2.0",
    "method": "state_get_item",
    "params": {
        "key": "transfer-8d81f4a1411d9481aed9c68cd700c39d870757b0236987bb6b7c2a7d72049c0e",
        "path": [],
        "state_root_hash": "cfdbf775b6671de3787cfb1f62f0c5319605a7c1711d6ece4660b37e57e81aa3"
    }
}

JSON-RPC Response:

{
    "id": 8,
    "jsonrpc": "2.0",
    "result": {
        "api_version": "1.0.0",
        "merkle_proof": "924 chars",
        "stored_value": {
            "Transfer": {
                "amount": "2500000000",
                "deploy_hash": "ec2d477a532e00b08cfa9447b7841a645a27d34ee12ec55318263617e5740713",
                "from": "account-hash-b0049301811f23aab30260da66927f96bfae7b99a66eb2727da23bf1427a38f5",
                "gas": "0",
                "id": null,
                "source": "uref-9e90f4bbd8f581816e305eb7ea2250ca84c96e43e8735e6aca133e7563c6f527-007",
                "target": "uref-6f4026262a505d5e1b0e03b1e3b7ab74a927f8f2868120cf1463813c19acb71e-004",
                "to": "account-hash-8ae68a6902ff3c029cea32bb67ae76b25d26329219e4c9ceb676745981fd3668"
            }
        }
    }
}

The query responds with more information about the transfer we conducted: its deploy hash, the account which executed the transfer, the source and target purses, and the target account. We can verify that our transfer processed successfully using this additional information.

The State Root Hash​

The state root hash is an identifier of the current network state. It gives a snapshot of the blockchain state at a moment in time. You can use the state root hash to query the network state after deployments.

casper-client get-state-root-hash --node-address [NODE_SERVER_ADDRESS]
Sample output of the get-state-root-hash command
{
    "id": -550641580167406055,
    "jsonrpc": "2.0",
    "result": {
        "api_version": "1.4.13",
        "state_root_hash": "a1f11692c5adc0e8b0a3f83e34d5831593a39ba03c8be73a0ebf7e9d9aadd76b"
    }
}
note

After any deploys to the network, you must get the new state root hash to see the new changes reflected. Otherwise, you will be looking at events in the past.

Query Account State​

Here, we will query for information about the Source account, using the state-root-hash of the block containing the transfer:

casper-client query-global-state \
--id 4 \
--node-address http://<node-ip-address>:7777 \
--state-root-hash <state-root-hash> \
--key <hex-encoded-source-account-public-key>

Request fields:

  • id - Optional JSON-RPC identifier applied to the request and returned in the response. If not provided, a random integer will be assigned
  • node-address - An IP address of a node on the network
  • state-root-hash - Hex-encoded hash of the network state
  • key - The base key for the query. This must be a properly formatted public key, account hash, contract address hash, URef, transfer hash, or deploy-info hash.

Important response fields:

  • "result"."stored_value"."Account"."main_purse" - the address of the main purse containing the sender's tokens. In this example, this purse is the source of the tokens transferred
Explore the JSON-RPC request and response generated.

JSON-RPC Request:

{
    "id": 4,
    "jsonrpc": "2.0",
    "method": "state_get_item",
    "params": {
        "key": "account-hash-b0049301811f23aab30260da66927f96bfae7b99a66eb2727da23bf1427a38f5",
        "path": [],
        "state_root_hash": "cfdbf775b6671de3787cfb1f62f0c5319605a7c1711d6ece4660b37e57e81aa3"
    }
}

JSON-RPC Response:

{
    "id": 4,
    "jsonrpc": "2.0",
    "result": {
        "api_version": "1.0.0",
        "merkle_proof": "2228 chars",
        "stored_value": {
            "Account": {
                "account_hash": "account-hash-b0049301811f23aab30260da66927f96bfae7b99a66eb2727da23bf1427a38f5",
                "action_thresholds": {
                    "deployment": 1,
                    "key_management": 1
                },
                "associated_keys": [
                    {
                        "account_hash": "account-hash-b0049301811f23aab30260da66927f96bfae7b99a66eb2727da23bf1427a38f5",
                        "weight": 1
                    }
                ],
                "main_purse": "uref-9e90f4bbd8f581816e305eb7ea2250ca84c96e43e8735e6aca133e7563c6f527-007",
                "named_keys": []
            }
        }
    }
}

We can repeat the same step to query information about the Target account:

casper-client query-global-state \
--id 5 \
--node-address http://<node-ip-address>:7777 \
--state-root-hash <state-root-hash> \
--key <hex-encoded-target-account-public-key>
Explore the JSON-RPC request and response generated.

JSON-RPC Request:

{
    "id": 5,
    "jsonrpc": "2.0",
    "method": "state_get_item",
    "params": {
        "key": "account-hash-8ae68a6902ff3c029cea32bb67ae76b25d26329219e4c9ceb676745981fd3668",
        "path": [],
        "state_root_hash": "cfdbf775b6671de3787cfb1f62f0c5319605a7c1711d6ece4660b37e57e81aa3"
    }
}

JSON-RPC Response:

{
    "id": 5,
    "jsonrpc": "2.0",
    "result": {
        "api_version": "1.0.0",
        "merkle_proof": "2228 chars",
        "stored_value": {
            "Account": {
                "account_hash": "account-hash-8ae68a6902ff3c029cea32bb67ae76b25d26329219e4c9ceb676745981fd3668",
                "action_thresholds": {
                    "deployment": 1,
                    "key_management": 1
                },
                "associated_keys": [
                    {
                        "account_hash": "account-hash-8ae68a6902ff3c029cea32bb67ae76b25d26329219e4c9ceb676745981fd3668",
                        "weight": 1
                    }
                ],
                "main_purse": "uref-6f4026262a505d5e1b0e03b1e3b7ab74a927f8f2868120cf1463813c19acb71e-007",
                "named_keys": []
            }
        }
    }
}

Get Purse Balance​

All accounts on a Casper network have a purse associated with the Casper system mint, which we call the main purse. The balance associated with a given purse is recorded in global state, and the value can be queried using the URef associated with the purse.

Now that we have the source purse address, we can verify its balance using the get-balance command:

casper-client get-balance \
--id 6 \
--node-address http://<node-ip-address>:7777 \
--state-root-hash <state-root-hash> \
--purse-uref <source-account-purse-uref>

Request fields:

  • id - Optional JSON-RPC identifier applied to the request and returned in the response. If not provided, a random integer will be assigned
  • node-address - An IP address of a node on the network
  • state-root-hash - Hex-encoded hash of the state root
  • purse-uref - The URef under which the purse is stored, following the format "uref-<hex_value>".
Explore the JSON-RPC request and response generated.

JSON-RPC Request:

{
    "id": 6,
    "jsonrpc": "2.0",
    "method": "state_get_balance",
    "params": {
        "purse_uref": "uref-6f4026262a505d5e1b0e03b1e3b7ab74a927f8f2868120cf1463813c19acb71e-007",
        "state_root_hash": "cfdbf775b6671de3787cfb1f62f0c5319605a7c1711d6ece4660b37e57e81aa3"
    }
}

JSON-RPC Response:

{
    "id": 6,
    "jsonrpc": "2.0",
    "result": {
        "api_version": "1.0.0",
        "balance_value": "5000000000",
        "merkle_proof": "2502 chars"
    }
}

Similarly, we have the address of the target purse, so we can get its balance.

casper-client get-balance \
--id 7 \
--node-address http://<node-ip-address>:7777 \
--state-root-hash <state-root-hash> \
--purse-uref <target-account-purse-uref>
Explore the JSON-RPC request and response generated.

JSON-RPC Request:

{
    "id": 7,
    "jsonrpc": "2.0",
    "method": "state_get_balance",
    "params": {
        "purse_uref": "uref-6f4026262a505d5e1b0e03b1e3b7ab74a927f8f2868120cf1463813c19acb71e-007",
        "state_root_hash": "cfdbf775b6671de3787cfb1f62f0c5319605a7c1711d6ece4660b37e57e81aa3"
    }
}

JSON-RPC Response:

{
    "id": 7,
    "jsonrpc": "2.0",
    "result": {
        "api_version": "1.0.0",
        "balance_value": "5000000000",
        "merkle_proof": "2502 chars"
    }
}

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