> ## Documentation Index
> Fetch the complete documentation index at: https://circle-devdocs-test-ai-codegen-component.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Create a challenge to sign message

> Generates a challenge for signing a message from a specified user-controlled wallet. This endpoint supports Ethereum-based blockchains (using EIP-191), Solana and Aptos (using Ed25519 signatures). Note that Smart Contract Accounts (SCA) are specific to Ethereum and EVM-compatible chains. The difference between Ethereum's EOA and SCA can be found in the [account types guide](/wallets/account-types). You can also check the list of Ethereum Dapps that support SCA: https://eip1271.io/.