melwalletd: Themelio wallet daemon

As with other UTXO-based blockchains like Bitcoin that lacks an "account" abstraction, Themelio requires somewhat involved logic for wallets --- software that manages on-chain assets and provides an interface roughly similar to a bank account.

In Themelio, the "canonical" wallet software is melwalletd, a headless program that internally manages wallets and exposes a local REST API for operations on the wallets. Although you can use it directly as a Themelio wallet, melwalletd is intended more as a backend to wallet apps, such as melwallet-cli, the official CLI wallet.

---

Starting melwalletd

After installing melwalletd through cargo install --locked melwalletd, start it by giving it a directory in which wallets are stored and a network to which you want to connect:

$ melwalletd --wallet-dir ~/.themelio-wallets --network testnet
May 18 16:20:43.583  INFO melwalletd: opened wallet directory: []

If the directory doesn't exist it will be created. By default, melwalletd will start listening on localhost:11773.

---

Managing wallets

Creating a wallet

Endpoint PUT /wallets/[wallet name]

Body fields

• password: optional field; password with which to encrypt the private key. Warning: if not given, private key will be stored in cleartext!
• secret: optional field; secret key used to import an existing wallet

Response

• Nothing

Example

$ curl -s 'localhost:11773/wallets/alice' -X PUT --data '{"password": "password"}'

Listing all wallets

Endpoint GET /wallets

Response

• Hashtable mapping wallet names to a type WalletSummary with fields:
  • total_micromel: total µMEL balance of wallet
  • detailed_balance: a map connecting specific coin denomiations to amounts
  • staked_microsym: the amount of µSYM staked on the network
  • network: 1 for testnet, 255 for mainnet
  • address: address-encoded covenant hash
  • locked: boolean saying whether or not the wallet is locked.

Example

$ curl -s localhost:11773/wallets | jq
{
  "alice": {
    "total_micromel": 0,
    "network": 1,
    "address": "t607gqktd3njqewnjcvzxv2m4ta6epbcv1sdjkp0qkmztaq3wxn350",
    "detailed_balance": {
		"73": 9871,
        "6d": 32131,
        "64": 314159265
      },
    "staked_microsym": 2500000000,

    "locked": true
  },
  "labooyah": {
    "total_micromel": 0,
    "network": 255,
    "address": "t1jhtj4ex1n069xr8w6mbkgrt25jgzw0pam1a25redg9ykpsykbq70",
    "detailed_balance": {
		"6d": 202220,
    },
    "staked_microsym": 0,
    "locked": true
  },
  "testnet": {
    "total_micromel": 17322999920,
    "network": 1,
    "address": "t6zf5m662ge2hwax4hcs5kzqmr1a5214fa9sj2rbtassw04n6jffr0",
    "detailed_balance": {
		"64": 10111,
    },
    "staked_microsym": 0,
    "locked": true
  }
}

Dumping a wallet

Endpoint GET /wallets/[wallet name]

Response

• Hashtable mapping wallet names to type WalletSummary with fields:
  • total_micromel: total µMEL balance of wallet
  • detailed_balance: a map connecting specific coin denomiations to amounts
  • staked_microsym: the amount of µSYM staked on the network
  • network: 1 for testnet, 255 for mainnet
  • address: address-encoded covenant hash
  • locked: boolean saying whether or not the wallet is locked.

Example

$ curl -s localhost:11773/wallets/alice | jq
{
  "alice": {
    "total_micromel": 0,
    "network": 1,
    "address": "t607gqktd3njqewnjcvzxv2m4ta6epbcv1sdjkp0qkmztaq3wxn350",
    "detailed_balance": {
		"73": 9871,
        "6d": 32131,
        "64": 314159265
      },
    "staked_microsym": 2500000000,

    "locked": true
  }
}

---

Using a single wallet

Unlocking a wallet

Endpoint POST /wallets/[name]/unlock

Body fields

• password: password

Response

None

Locking a wallet

Endpoint POST /wallets/[name]/lock

Body fields

None

Response

None

Sending a faucet transaction

This verb sends a faucet transaction that adds a fixed sum of 1001 MEL to the wallet. Note: obviously, this only works with testnet wallets!

Endpoint POST /wallets/[name]/send-faucet

Body fields

None.

Response

Quoted hexadecimal transaction hash of the transaction being sent.

Example

$ curl -s localhost:11773/wallets/alice/send-faucet -X POST
"86588da7863b39152105e4f78c04e07a5d3f3ebf61d799f95293372dabdb06a1"

Listing all transactions

Endpoint GET /wallets/[name]/transactions/

Response

A JSON object containing a list with elements of type (TxHash, Option<BlockHeight>):

• TxHash: hash of a particular transaction associated with a given wallet
• Option<BlockHeight>: null if unconfirmed, otherwise the integer height of the block where the transaction was confirmed

Example

$ curl -s localhost:11773/wallets/bar/transactions | jq
[
  [
    "d23b4240f7e02a38e8deb8a111d0ec8650a8912df50d15ec43992e3085b4ca98",
    null
  ],


    [
      "5b4ca98d23b4240f7e02a38e8deb8a111d0ec8650a8912df50d15ec43992e308",
      48113
    ]

]

Checking on a transaction

Endpoint GET /wallets/[name]/transactions/[txhash]

Response

A JSON of a type TransactionStatus with fields:

• raw: the actual transaction in JSON format
• confirmed_height: null if not confirmed, otherwise the height at which the transaction was confirmed.
• outputs: an array of AnnCoinID objects like:
  • coin_data: a CoinData object
  • is_change: is this a change output that goes to myself?
  • coin_id: a string-represented CoinID (txhash-index)

Example

$ curl -s localhost:11773/wallets/alice/transactions/
442bdc353b773b8949c59cee8061545a9a89e27a2e6638fcc1d065583bb170b8  | jq
{
  "raw": {
    "kind": 255,
    "inputs": [],
    "outputs": [
      {
        "covhash": "t4xn73csvjxp0dvh0gs6ehpgfq0ht0akr9g6tkxywv7xvfp09cy6x0",
        "value": 1001000000,
        "denom": "MEL",
        "additional_data": ""
      }
    ],
    "fee": 1001000000,
    "covenants": [],
    "data": "72a1aba97ada3d1958932244836b0c72aaedeef7f6b032c1877c83ae05e28469",
    "sigs": []
  },
  "confirmed_height": 42633,
  "outputs": [
    {
      "coin_data": {
        "covhash": "t4xn73csvjxp0dvh0gs6ehpgfq0ht0akr9g6tkxywv7xvfp09cy6x0",
        "value": 1001000000,
        "denom": "MEL",
        "additional_data": ""
      },
      "is_change": true,
      "coin_id": "442bdc353b773b8949c59cee8061545a9a89e27a2e6638fcc1d065583bb170b8-0"
    }
  ]
}

Preparing a transaction

Note: This prepares a transaction to be sent from a wallet, creating a filled-in, valid transaction, but without changing the wallet state. If the you actually want to send the transaction, the send-tx call must be used.

Keep in mind, this endpoint is not useful for more advanced covenant deployment. Check send-tx

Endpoint POST /wallets/[name]/prepare-tx

Body fields

• outputs: an array of CoinDatas, representing the desired outputs of the transaction. Any change outputs that are added are guaranteed to be added after these outputs.

• kind: optional TxKind of the transaction (defaults to Normal)

• inputs: optional an array of CoinIDs, representing inputs that must be spent by this transaction. This is useful for building covenant chains and such.

• data: optional additional data of the transaction (defaults to empty)

• covenants:

• nobalance: optional vector of Denoms on which balancing --- checking that exactly the same number of coins are produce by a transaction as those consumed by it --- should not be done. Normally, this is used to exempt ERG balance from being checked when preparing a DOSC-minting transaction.

• signing_key: optional an ed25519 signing key that corresponds to the wallet's covenant. WARNING: Only for advanced usecases, this can cause loss of funds if not used properly

Response

• JSON-encoded Transaction

Example

$ curl -s localhost:11773/wallets/alice/prepare-tx -X POST --data '{
    "outputs": [
        {
            "covhash": "57df1dd5b067f77a177127cbe4d69aa10fe8fcac3b2f9718cb8263d5a6216ab0",
            "value": 1000,
            "denom": "6d",
            "additional_data": ""
        }
    ],
    "signing_key": "4239e79eab9b39c49de990363197a64e1a54f0f9a0d12a936e85e69ea7fb05b006425dfe7967003e2a5362e36231730f2faaa6068979afc52784f916466e05b6"
}'


{
    "kind": 0,
    "inputs": [
        {
            "txhash": "4950f3af9da569e1a99a7e738026a581d6e96caaf02d94b02efcd645540a2d2f",
            "index": 0
        }
    ],
    "outputs": [
        {
            "covhash": "57df1dd5b067f77a177127cbe4d69aa10fe8fcac3b2f9718cb8263d5a6216ab0",
            "value": 1000,
            "denom": "6d",
            "additional_data": ""
        },
        {
            "covhash": "41d04b65a010aaa3404e1a109c53e3190a393d7ff920fa5644969a879547d0aa",
            "value": 1000998977,
            "denom": "6d",
            "additional_data": ""
        }
    ],
    "fee": 23,
    "scripts": [
        "420009f100000000000000000000000000000000000000000000000000000000000000064200005050f02006425dfe7967003e2a5362e36231730f2faaa6068979afc52784f916466e05b6420001320020"
    ],
    "data": "",
    "sigs": [
        "df3cc2795d3c9576b85c4c960501af3e44bbc490c9dc51c8422f18a3a0fa1150c2f745440206748c8205971ba0cff32b87c9797a4d1098ce3bd677db62e8560c"
    ]
}

Sending a transaction

Note: This endpoint will reject any transactions that are malformed or don't belong to the wallet. For personal use recommend using [melwallet-cli]({{< ref my-first-tx.md>}}) instead. If you must use this endpoint, consider using /prepare-tx to prepare the body of this transaction

Endpoint POST /wallets/[name]/send-tx

Body

JSON-encoded Transaction with fields:

• kind: TXKind of this transaction
• inputs: an array of CoinIDs
• outputs: an array of CoinDatas
• fee: CoinValue

Response

• Quoted transaction hash