How to Plausibly Deny Steganographic Secrets

Shahzad Ahmad, Stefan Rass

Abstract: We introduce the notion of oblivious secret sharing as an enhancement of (conventional) secret sharing with the added possibility of (plausibly) denying that some shares even exist. Secret sharing is a cryptographic technique that allows a distributed secure storage of information across multiple parties, such that no party or pre-defined coalition of parties can reconstruct the stored secret. Confidentiality, in this regard, does only apply to the secret, but not the the shares themselves. Oblivious secret sharing extends the secrecy also to the shares, thereby adding the additional possibility of denying the existence of shares in first place, or to reconstruct a different, harmless, secret upon force. We investigate a combination of steganography and secret sharing to enhance both primitives at the same time: secret sharing adds deniability to steganography and steganography adds extended confidentiality to secret sharing. Our construction is generic in its use of steganography, b