Honey Encryption: Security Beyond the Brute-Force Bound

We introduce

honey encryption

(HE), a simple, general approach to encrypting messages using low min-entropy keys such as passwords. HE is designed to produce a ciphertext which, when decrypted with any of a number of

incorrect

keys, yields plausible-looking but bogus plaintexts called

honey messages

. A key benefit of HE is that it provides security in cases where too little entropy is available to withstand brute-force attacks that try every key; in this sense, HE provides security beyond conventional brute-force bounds. HE can also provide a hedge against partial disclosure of high min-entropy keys.

HE significantly improves security in a number of practical settings. To showcase this improvement, we build concrete HE schemes for password-based encryption of RSA secret keys and credit card numbers. The key challenges are development of appropriate instances of a new type of randomized message encoding scheme called a

distribution-transforming encoder

(DTE), and analyses of the expected maximum loading of bins in various kinds of balls-and-bins games.