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Bits512 ​

In Sway, the b512 type is commonly used to handle public keys and signatures. This guide will explain how the b512 type is defined in Sway, how to visualize a b512 value using the SDK, and how to interact with a contract function that accepts a b512 parameter.

The b512 type in Sway is a wrapper around two b256 types, allowing for the representation of 64-byte values. It is defined as a struct:

rust
pub struct B512 {
  bytes: [b256; 2],
}
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b512 in the SDK ​

In the SDK, you can visualize a b512 value by examining a wallet's public key:

ts
import { Wallet } from 'fuels';

const wallet = Wallet.generate({
  provider,
});

console.log(walllet.publicKey);

// 0x97e3a666e4cd34b6b3cf778ef5ec617de4439b68f7a629245442a1fece7713094a1cb0aa7ad0ac253ca1ea47d4618f9090b2a881e829e091fb2c426763e94cca
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Example: Echoing a b512 Value in a Contract Function ​

Let's consider a contract function that accepts a b512 parameter and returns the same value:

rust
fn echo_b512(input: B512) -> B512 {
    input
}
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To call this function and validate the returned value, follow these steps:

ts
const b512 = wallet.publicKey;

const { value } = await contract.functions.echo_b512(b512).simulate();

expect(value).toEqual(b512);
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In this example, we generate a wallet, use its public key as the b512 input, call the echo_b512 contract function, and expect the returned value to match the original input.