Key disclosure laws, also known as mandatory key disclosure, is legislation that requires individuals to surrender cryptographic keys to law enforcement. The purpose is to allow access to material for confiscation or digital forensics purposes and use it either as evidence in a court of law or to enforce national security interests. Similarly, mandatory decryption laws force owners of encrypted data to supply decrypted data to law enforcement. Nations vary widely in the specifics of how they implement key disclosure laws. Some, such as Australia, give law enforcement wide-ranging power to compel assistance in decrypting data from any party. Some, such as Belgium, concerned with self-incrimination, only allow law enforcement to compel assistance from non-suspects. Some require only specific third parties such as telecommunications carriers, certification providers, or maintainers of encryption services to provide assistance with decryption. In all cases, a warrant is generally required.
Theory and countermeasures Mandatory decryption is technically a weaker requirement than key disclosure, since it is possible in some cryptosystems to prove that a message has been decrypted correctly without revealing the key. For example, using RSA public-key encryption, one can verify given the message (plaintext), the encrypted message (ciphertext), and the public key of the recipient that the message is correct by merely re-encrypting it and comparing the result to the encrypted message. Such a scheme is called undeniable, since once the government has validated the message they cannot deny that it is the correct decrypted message. As a countermeasure to key disclosure laws, some personal privacy products such as BestCrypt, FreeOTFE, and TrueCrypt have begun incorporating deniable encryption technology, which enable a single piece of encrypted data to be decrypted in two or more different ways, creating plausible deniability. Another alternative is steganography, which hides encrypted data inside of benign data so that it is more difficult to identify in the first place. A problematic aspect of key disclosure is that it leads to a total compromise of all data encrypted using that key in the past or future; time-limited encryption schemes such as those of Desmedt et al. allow decryption only for a limited time period.
Criticism and alternatives Critics of key disclosure laws view them as compromising information privacy, by revealing personal information that may not be pertinent to the crime under investigation, as well as violating the right against self-incrimination and more generally the right to silence, in nations which respect these rights. In some cases, it may be impossible to decrypt the data because the key has been lost, forgotten or revoked, or because the data is actually random data which cannot be effectively distinguished from encrypted data. A proactive alternative to key disclosure law is key escrow law, where the government holds in escrow a copy of all cryptographic keys in use, but is only permitted to use them if an appropriate warrant is issued. Key escrow systems face difficult technical issues and are subject to many of the same criticisms as key disclosure law; they avoid some issues like lost keys, while introducing new issues such as the risk of accidental disclosure of large numbers of keys, theft of the keys by hackers or abuse of power by government employees with access to the keys. It would also be nearly impossible to prevent the government from secretly using the key database to aid mass surveillance efforts such as those exposed by Edward Snowden. The ambiguous term key recovery is applied to both types of systems.
Legislation by nation This list shows only nations where laws or cases are known about this topic.
Antigua and Barbuda The Computer Misuse Bill, 2006, Article 21(5)(c), if enacted, would allow police with a warrant to demand and use decryption keys. Failure to comply may incur "a fine of fifteen thousand [East Caribbean] dollars" and/or "imprisonment for two years."
Australia The Cybercrime Act 2001 No. 161, Items 12 and 28 grant police with a magistrate's order the wide-ranging power to require "a specified person to provide any information or assistance that is reasonable and necessary to allow the officer to "access computer data that is "evidential material"; this is understood to include mandatory decryption. Failing to comply carries a penalty of 6 months' imprisonment. Electronic Frontiers Australia calls the provision "alarming" and "contrary to the common law privilege against self-incrimination." The Crimes Act 1914, 3LA(5) "A person commits an offence if the person fails to comply with the order. Penalty for contravention of this subsection: Imprisonment for 2 years."
Belgium The Loi du 28 novembre 2000 relative à la criminalité informatique (Law on computer crime of 28 November 2000), Article 9 allows a judge to order the authorities to search the computer systems and telecommunications providers to provide assistance to law enforcement, including mandatory decryption, and to keep their assistance secret; but this action cannot be taken against suspects or their families. Failure to comply is punishable by 6 months to 1 year in jail and/or a fine of 130 to 100,000 euros.
Cambodia Cambodia promulgated its Law on Electronic Commerce on 2 November 2019, after passage through legislature and receiving consent from the monarch, becoming the last among ASEAN states to adopt a domestic law governing electronic commerce. Article 43 of the statute prohibits any encryption of evidence in the form of data that could lead to an indictment, or any evidence in an electronic system that relates to an offense. This statutory obligation may imply that authorities could order decryption of any data implicated in an investigation. While remaining untested in courts, this obligation actively contradicts an accused person's procedural right against self-incrimination as provided under Article 143 of the Code of Criminal Procedure.
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