Blockstream releases GDK 0.78.1: keys and seeds wiped from memory, sighash flags validated before signing

The release lists security-related changes: credentials, keys, seeds and other sensitive data are wiped from memory once no longer needed; user sighash flags are validated before signing with any signer, including hardware signers; in multisig, the PIN password returned by the server must be at least 36 characters, and the value and asset of explicit Liquid UTXOs are taken from the transaction rather than from the server. It also fixes a use-after-free when websocket clients are destroyed (Wamp), rounds up the RBF replacement fee as Bitcoin Core does, and reports out-of-range output indices as user errors. The source does not describe a vulnerability, exploitation or urgency.