EIP-191 wallet ownership proof. SumSub liveness uses POST /counterparty/wallet-verification/sumsub/initiate instead.

Cryptographic proof over message. EVM — EIP-191 hex; Bitcoin — compact base64 (65 bytes) or Electrum/Sparrow armor; Solana — Ed25519 base58.

Bitcoin message-signing format. Defaults to bip137 (Trezor, Ledger, Bitcoin Core). Use electrum for Electrum and Sparrow.

The exact UTF-8 string the wallet signed. After extracting the embedded date, the text must match character-for-character:

I am verifying ownership of the wallet address {signed_address} as {ownerId}. This message was signed on {DD/MM/YYYY} to confirm my control over this wallet.

{signed_address} is the same value as in this request body. {ownerId} is the same value as userId or businessId (whichever owner field you sent). {DD/MM/YYYY} is the calendar date in UTC and must be yesterday, today, or tomorrow relative to the server's current UTC date when the request is processed.