> For the complete documentation index, see [llms.txt](https://circular-protocol.gitbook.io/standard-apis/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://circular-protocol.gitbook.io/standard-apis/api-docs/typescript/signmessage.md).

# SignMessage

This helper function takes care of signing a transaction using the elliptic curve Secp256k1, which is the default cryptographic method used on Circular. The function is used as follows:

```typescript
var Signature = Circular.SignMessage(PrivateKey, Message);
```

This function is used to obtain transaction signatures before submission. It requires the use of a wallet's private key to sign the message.