# Swisstronik & Ethereum calls

Calls in the blockchain context are read-only interactions with the blockchain, retrieving information from the blockchain without altering, deleting, or adding data.

### Ethereum Calls

We can use ethers.js to execute calls to the Ethereum blockchain. specifically for smart contracts, we can use `provider.call({to, data})` to retrieve values from smart contracts

```javascript
provider.call({
  to: "0x4976fb03C32e5B8cfe2b6cCB31c09Ba78EBaBa41",
  // Function selector for `function getMessage(uint256)` + encoded argument `1`
  data: "0xa5f3c4f600000000000000000000000000000000000000000000000000000000000000001"
});
```

In this code example, the function `call` is made to the `to` smart contract address, executing the `view returns` function `getMessage(uint256)` while providing the argument `1`. This process will return a message from the smart contract.

#### Swisstronik Calls

For Swisstronik calls, we need to make sure the `data` field of the `call` is encrypted using SwisstronikJS.

```javascript
provider.call({
  to: "0x4976fb03C32e5B8cfe2b6cCB31c09Ba78EBaBa41",
  //The `data` field must be an encrypted value, otherwise, the call will not work
  data: "0xf53a7d4fcf3116b8476ac3f986542794f0df2516070c555580ae29049c0ec91b8a2d82d2bf06694fea0c485fa48cb34b596a9f496a19f2ecb3c1da0540544cffb03f1dee14d7887fea1de6d982a46edfaab773"
});
```

This example shows that when making Swisstronik calls, **the data field needs to be filled with an encrypted value using SwisstronikJS**. Otherwise, the call won't work. Let's now explore how to encrypt this data for successful calls on the Swisstronik blockchain.


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