Why does Kaspa use a different hash key for personal message signing?

Kaspa hashes personal messages with a separate blake2b key — called `PersonalMessageSigningHash` — that is distinct from the `TransactionSigningHash` key used when authorizing transactions. This separation is a security technique called domain separation: it ensures that a signature you produce for an arbitrary message (for example, to prove you own a wallet) can never be repurposed or mistaken for a valid transaction signature. The design also has a practical side benefit: it first reduces any message of arbitrary length down to a fixed-size hash before signing, which makes the signing operation consistent regardless of how long the original message is. For a beginner, this matters because it means signing a message in Kaspa is safe by design — the protocol itself prevents that signature from accidentally authorizing a spend.