curl --request POST \
--url https://api.privy.io/v1/wallets/{wallet_id}/rpc \
--header 'Authorization: Basic <encoded-value>' \
--header 'Content-Type: application/json' \
--header 'privy-app-id: <privy-app-id>' \
--data '{
"method": "secp256k1_sign",
"params": {
"hash": "0x12345678",
}
}'