What best describes the reason why private keys are considered secure against brute force attacks? The huge number of possible combinations makes guessing impractical The blockchain automatically detects brute force attacks and blocks access Private keys are secret and not shared Brute force is only used for public keysWhat best describes the reason why private keys are considered secure against brute force attacks? The huge number of possible combinations makes guessing impractical The blockchain automatically detects brute force attacks and blocks access Private keys are secret and not shared Brute force is only used for public keys