What is Rubber-Hose Cryptanalysis?
A euphemism for extracting cryptographic keys through physical coercion or torture, highlighting that the weakest link in any encryption system is the human holding the key.
The term is a darkly humorous acknowledgment that no amount of mathematical security matters if someone can force you to reveal your password.
The Problem
- AES-256 is unbreakable by brute force
- But a human can be threatened, coerced, or legally compelled to reveal keys
- In some jurisdictions (UK), refusing to provide decryption keys is a crime
- Physical threats bypass all cryptographic protections
Technical Countermeasures
- Deniable encryption: Hidden volumes that reveal different data depending on the password given
- Shamir's Secret Sharing: Split the key so no single person can decrypt
- Dead man's switches: Automatic destruction of keys if not regularly authenticated
- Plausible deniability: Design systems so the existence of encrypted data can't be proven
Legal Landscape
- US: Fifth Amendment may protect against compelled decryption (case law is mixed)
- UK: Refusing to decrypt carries up to 5 years in prison (RIPA Part III)
- Australia: Compelled decryption law since 2018
- France: Refusing to decrypt carries up to 3 years in prison
Related Terms
Deniable Encryption
An encryption scheme where the existence of encrypted data cannot be proven, or where decryption can produce different plausible plaintexts.
Plausible Deniability
The ability to credibly deny knowledge of or responsibility for something, especially when encrypted data could be explained as random noise or when hidden volumes within encrypted containers cannot be proven to exist.
Shamir's Secret Sharing
A cryptographic method for splitting a secret into multiple parts so that a defined threshold of parts are needed to reconstruct it.
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