POST returns a payloadToSign, and the signed retry returns the encrypted seed.
Generate a fresh P-256 client key pair specifically for the export. Send its clientPublicKey on both export requests, then decrypt encryptedWalletCredentials with the matching private key after the signed retry succeeds.
1
First call — receive the challenge
2
Client signs the payload
Sign
payloadToSign with an active session signing key on the account. Keep the export private key on the client; Grid will use the matching clientPublicKey from step 1 to seal the wallet credentials.3
Signed retry — receive the encrypted seed
4
Decrypt on the client
encryptedWalletCredentials uses the same base58check/HPKE format as encryptedSessionSigningKey. Decrypt with the export private key that matches the clientPublicKey you sent on both export requests — see decrypt the session signing key for code.The plaintext is a BIP-39 mnemonic (the wallet’s master seed).