# U.S. Government's Right to an Encryption Scheme's Backdoor Keys **URL:** \ **Category:** Factual Questions\ **Created:** [July 28, 2007, 4:37pm UTC](https://boards.straightdope.com/t/u-s-governments-right-to-an-encryption-schemes-backdoor-keys/413497 "2007-07-28T16:37:44Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Nobody\_Special](https://avatars.discourse-cdn.com/v4/letter/n/bbce88/32.png) [@Nobody\_Special](https://boards.straightdope.com/u/Nobody_Special)\ **Post date:** [July 28, 2007, 4:37pm UTC](https://boards.straightdope.com/t/u-s-governments-right-to-an-encryption-schemes-backdoor-keys/413497/1 "2007-07-28T16:37:44Z")
Does U.S. law or regulation require producers of encryption technology products (hardware or software) to supply the US government with a backdoor key to enable security agencies to read messages using those products? ---
**Author:** ![psychonaut](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/psychonaut/32/4655_2.png) [@psychonaut](https://boards.straightdope.com/u/psychonaut)\ **Post date:** [July 28, 2007, 4:38pm UTC](https://boards.straightdope.com/t/u-s-governments-right-to-an-encryption-schemes-backdoor-keys/413497/2 "2007-07-28T16:38:49Z")
[QUOTE=Nobody Special] Does U.S. law or regulation require producers of encryption technology products (hardware or software) to supply the US government with a backdoor key to enable security agencies to read messages using those products? [/QUOTE] No. ---
**Author:** ![Rysto](https://avatars.discourse-cdn.com/v4/letter/r/ecccb3/32.png) [@Rysto](https://boards.straightdope.com/u/Rysto)\ **Post date:** [July 28, 2007, 4:41pm UTC](https://boards.straightdope.com/t/u-s-governments-right-to-an-encryption-schemes-backdoor-keys/413497/3 "2007-07-28T16:41:21Z")
No, and mathematicians don’t know how to do such a thing anyway. An encryption algorithm with such a backdoor would be equivalent to a public-key encryption algorithm, and new public key encryption algorithms don’t come around every day. ---
**Author:** ![Nobody\_Special](https://avatars.discourse-cdn.com/v4/letter/n/bbce88/32.png) [@Nobody\_Special](https://boards.straightdope.com/u/Nobody_Special)\ **Post date:** [July 28, 2007, 4:41pm UTC](https://boards.straightdope.com/t/u-s-governments-right-to-an-encryption-schemes-backdoor-keys/413497/4 "2007-07-28T16:41:36Z")
Could either of you provide a cite? Thanks. ---
**Author:** ![psychonaut](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/psychonaut/32/4655_2.png) [@psychonaut](https://boards.straightdope.com/u/psychonaut)\ **Post date:** [July 28, 2007, 4:45pm UTC](https://boards.straightdope.com/t/u-s-governments-right-to-an-encryption-schemes-backdoor-keys/413497/5 "2007-07-28T16:45:23Z")
[QUOTE=Nobody Special] Could either of you provide a cite? Thanks. [/QUOTE] No, we can’t. We can’t prove the absence of a law. If you are alleging that such a law exists, then you are the one who needs to provide a citation. ---
**Author:** ![Nobody\_Special](https://avatars.discourse-cdn.com/v4/letter/n/bbce88/32.png) [@Nobody\_Special](https://boards.straightdope.com/u/Nobody_Special)\ **Post date:** [July 28, 2007, 4:51pm UTC](https://boards.straightdope.com/t/u-s-governments-right-to-an-encryption-schemes-backdoor-keys/413497/6 "2007-07-28T16:51:40Z")
[QUOTE=psychonaut] No, we can’t. We can’t prove the absence of a law. If you are alleging that such a law exists, then you are the one who needs to provide a citation. [/QUOTE] Good point. I asked the question to settle a debate I’m having with someone. Is there a reliable source I could point to that would provide a reasonable amount of closure on the issue? Thanks for your quick replies. ---
**Author:** ![SmackFu](https://avatars.discourse-cdn.com/v4/letter/s/53a042/32.png) [@SmackFu](https://boards.straightdope.com/u/SmackFu)\ **Post date:** [July 28, 2007, 4:59pm UTC](https://boards.straightdope.com/t/u-s-governments-right-to-an-encryption-schemes-backdoor-keys/413497/7 "2007-07-28T16:59:07Z")
I think this idea came around because of some events during the development of DES. > **[Data Encryption Standard |](https://en.wikipedia.org/wiki/Data_Encryption_Standard#NSA.27s_involvement_in_the_design)** > > On 17 March 1975, the proposed DES was published in the Federal Register. Public comments were requested, and in the following year two open workshops were held to discuss the proposed standard. There was criticism received from public-key cryptography pioneers Martin Hellman and Whitfield Diffie, citing a shortened key length and the mysterious "S-boxes" as evidence of improper interference from the NSA. The suspicion was that the algorithm had been covertly weakened by the intelligence agenc At the time, people thought the NSA reviewed the design and changed it, so people thought they added backdoors. But in fact they made it stronger against differential cryptanalysis, a crypto technique that was still a secret at the time. ---
**Author:** ![kellner](https://avatars.discourse-cdn.com/v4/letter/k/c2a13f/32.png) [@kellner](https://boards.straightdope.com/u/kellner)\ **Post date:** [July 28, 2007, 5:09pm UTC](https://boards.straightdope.com/t/u-s-governments-right-to-an-encryption-schemes-backdoor-keys/413497/8 "2007-07-28T17:09:42Z")
[QUOTE=SmackFu] I think this idea came around because of some events during the development of DES. [/QUOTE] And the [Clipper chip](http://en.wikipedia.org/wiki/Clipper_chip). Although it wasn’t mandatory and never caught on it was at least a limited attempt to establish backdoors. ---
**Author:** ![Rysto](https://avatars.discourse-cdn.com/v4/letter/r/ecccb3/32.png) [@Rysto](https://boards.straightdope.com/u/Rysto)\ **Post date:** [July 28, 2007, 5:15pm UTC](https://boards.straightdope.com/t/u-s-governments-right-to-an-encryption-schemes-backdoor-keys/413497/9 "2007-07-28T17:15:32Z")
[Here’s a cite for the mathematical improbability of it(Section 9, page 52)](http://www.schneier.com/paper-twofish-paper.html): > [@](#): > > The other possibility is that we have embedded a trap door into the Twofish magic constants and then transformed them by some means so that finding them would be a statistical impossibility(see [Har96 for some discussion of this possibility). The resulting construction wuld seem immune to current cryptanalytic techniques, but we as designers would know a secret transformation rule that we could apply to facilitate cryptanalysis. Again, we cannot prove this is not true. However, it has been show that this type of cipher, called a “master-key cryptosystem”, is equivalent to a public key cryptosystem [BFL96]. Again, as cryptographers we would achieve far greater recognition by publishing a public-key cryptosystem that is not dependent on factoring [RSA78] or the discrete logarithm problem[DH76, EIG85, NIST94]. And the resulting algorithm’s dual capabilities as both a symmetric and public-key algorithm would make it far more flexible than the AES competition. > > There is a large gab between a weakness that is exploitable in theory and one that is exploitable in practise. Even the best attack against DES (a linear-cryptanalysis-like attack combining quadratic approximations and a multiple-approximation method) requires just under 2^43 plaintext/ciphertext blocks[SK98], which is equivalent to about 64 terabytes of plaintext/ciphertext under a single key. A useful trap door would need to work with much less plaintext – a few thousand blocks – or it would have to reduce the effective keyspace to something on the order of 2^72. We believe that, given the quality of the public cryptanalytic research community, it would be impossible to put a weakness of this magnitude into a block cipher and have it remain undetected through the AES process. And we would be foolish to even try. ---
**Author:** ![gazpacho](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@gazpacho](https://boards.straightdope.com/u/gazpacho)\ **Post date:** [July 28, 2007, 5:53pm UTC](https://boards.straightdope.com/t/u-s-governments-right-to-an-encryption-schemes-backdoor-keys/413497/10 "2007-07-28T17:53:02Z")
[QUOTE=Rysto] No, and mathematicians don’t know how to do such a thing anyway. An encryption algorithm with such a backdoor would be equivalent to a public-key encryption algorithm, and new public key encryption algorithms don’t come around every day. [/QUOTE] Sure they do. The PGP algorithm goes about 75% of the way there already. The PGP algorithm encrypt the main message with a standard symmetric cypher with a random key. This key is then encrypted using the recipients public key. If you send the message to more than one recipient then the symmetric key is encrypted with each recipients public key and place in the message. Conceivably a government public key could be used with every message. ---
**Author:** ![Rysto](https://avatars.discourse-cdn.com/v4/letter/r/ecccb3/32.png) [@Rysto](https://boards.straightdope.com/u/Rysto)\ **Post date:** [July 28, 2007, 5:56pm UTC](https://boards.straightdope.com/t/u-s-governments-right-to-an-encryption-schemes-backdoor-keys/413497/11 "2007-07-28T17:56:30Z")
I don’t see how the situations are at all analogous. The OP is asking whether encryption algorithms have “back-door” keys built into them to allow the government to covertly decrypt all traffic using that algorithm. This nothing to do with secure key exchange. ---
**Author:** ![Liberal](https://avatars.discourse-cdn.com/v4/letter/l/848f3c/32.png) [@Liberal](https://boards.straightdope.com/u/Liberal)\ **Post date:** [July 28, 2007, 6:49pm UTC](https://boards.straightdope.com/t/u-s-governments-right-to-an-encryption-schemes-backdoor-keys/413497/12 "2007-07-28T18:49:44Z")
Yeah, it seems to me that it’s really just a civics question. ---
**Author:** ![ChrisBooth12](https://avatars.discourse-cdn.com/v4/letter/c/e95f7d/32.png) [@ChrisBooth12](https://boards.straightdope.com/u/ChrisBooth12)\ **Post date:** [July 28, 2007, 6:51pm UTC](https://boards.straightdope.com/t/u-s-governments-right-to-an-encryption-schemes-backdoor-keys/413497/13 "2007-07-28T18:51:52Z")
No way, it would have been discovered already by differnt white/black hacker groups. ---
**Author:** ![Bear\_Nenno](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bear_nenno/32/3358_2.png) [@Bear\_Nenno](https://boards.straightdope.com/u/Bear_Nenno)\ **Post date:** [July 28, 2007, 7:21pm UTC](https://boards.straightdope.com/t/u-s-governments-right-to-an-encryption-schemes-backdoor-keys/413497/14 "2007-07-28T19:21:46Z")
[QUOTE=Nobody Special] Good point. I asked the question to settle a debate I’m having with someone. [/QUOTE] If that someone cannot provide you with a cite himself, then the debate is settled. He loses. What’s so hard about that concept? ---
**Author:** ![Nobody\_Special](https://avatars.discourse-cdn.com/v4/letter/n/bbce88/32.png) [@Nobody\_Special](https://boards.straightdope.com/u/Nobody_Special)\ **Post date:** [July 28, 2007, 7:44pm UTC](https://boards.straightdope.com/t/u-s-governments-right-to-an-encryption-schemes-backdoor-keys/413497/15 "2007-07-28T19:44:15Z")
[QUOTE=Liberal] Yeah, it seems to me that it’s really just a civics question. [/QUOTE] It is. The debate isn’t whether it’s possible, but whether it’s required by U.S. law. Thanks for all the answers. ---
**Author:** ![gazpacho](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@gazpacho](https://boards.straightdope.com/u/gazpacho)\ **Post date:** [July 29, 2007, 11:20pm UTC](https://boards.straightdope.com/t/u-s-governments-right-to-an-encryption-schemes-backdoor-keys/413497/16 "2007-07-29T23:20:39Z")
[QUOTE=Rysto] I don’t see how the situations are at all analogous. The OP is asking whether encryption algorithms have “back-door” keys built into them to allow the government to covertly decrypt all traffic using that algorithm. This nothing to do with secure key exchange. [/QUOTE] I disagree. I illustrated a method using current encryption technology that would allow encryption of messages between people that allowed for a back door for the government to read the messages. You previously said that there was not a way to make an algorithm that allowed for a back door. ---
**Author:** ![Rysto](https://avatars.discourse-cdn.com/v4/letter/r/ecccb3/32.png) [@Rysto](https://boards.straightdope.com/u/Rysto)\ **Post date:** [July 30, 2007, 1:17am UTC](https://boards.straightdope.com/t/u-s-governments-right-to-an-encryption-schemes-backdoor-keys/413497/17 "2007-07-30T01:17:54Z")
That wasn’t what the OP asked. The OP asked if there’s some Master Key built into encryption algorithms to allow a government to read anything encrypted with it. ---
**Author:** ![What\_the](https://avatars.discourse-cdn.com/v4/letter/w/f4b2a3/32.png) [@What\_the](https://boards.straightdope.com/u/What_the)\ **Post date:** [December 17, 2013, 3:04pm UTC](https://boards.straightdope.com/t/u-s-governments-right-to-an-encryption-schemes-backdoor-keys/413497/18 "2013-12-17T15:04:44Z")
Seven year old thread… what’s the latest? ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [December 17, 2013, 4:29pm UTC](https://boards.straightdope.com/t/u-s-governments-right-to-an-encryption-schemes-backdoor-keys/413497/19 "2013-12-17T16:29:43Z")
> [@What\_the](#): > > Seven year old thread… what’s the latest? Still no law requiring backdoors, even if they were possible. ---
**Author:** ![Walton\_Firm](https://avatars.discourse-cdn.com/v4/letter/w/45deac/32.png) [@Walton\_Firm](https://boards.straightdope.com/u/Walton_Firm)\ **Post date:** [December 17, 2013, 6:16pm UTC](https://boards.straightdope.com/t/u-s-governments-right-to-an-encryption-schemes-backdoor-keys/413497/20 "2013-12-17T18:16:46Z")
Well, there is this: > **[Dual\_EC\_DRBG](https://en.wikipedia.org/wiki/Dual_EC_DRBG)** > > Dual\_EC\_DRBG (Dual Elliptic Curve Deterministic Random Bit Generator) is an algorithm that was presented as a cryptographically secure pseudorandom number generator (CSPRNG) using methods in elliptic curve cryptography. Despite wide public criticism, including the public identification of a backdoor, it was for seven years one of four CSPRNGs standardized in NIST SP 800-90A as originally published circa June 2006, until it was withdrawn in 2014. > Weaknesses in the cryptographic security of the ... Summary: it’s a random-number generator, intended to be suitable for cryptographic use, which was adopted as an official NIST standard thanks to the NSA heavily leaning on the standardization committee. Not long after its publication, some cryptographers pointed out that a set of numeric constants which was part of the standard, could very easily hide a back-door which would allow the party which generated those constants (the NSA) to predict all future output of the RNG after seeing just the first 32 bytes. This would allow them to easily break any system which relied on the unpredictability of that RNG for its security. And because it’s an official government standard, quite a lot of security products contain this RNG, and some notable ones even use it as their default RNG. In one of the documents released by Snowden, there is a reference to a 2006 NIST standard containing a backdoor. This is almost certainly a reference to dual-ec-drbg. This is not tin-foil-hat stuff; the evidence is strong enough that Occam’s Razor actually supports the conspiracy theory in this case. Once you know what to look for, the backdoor is actually quite blatant. NIST has issued a recommendation against future use of this standard, and the RSA company had recalled one of their popular crypto libraries because it was using that RNG as the default. [Next page](https://boards.straightdope.com/t/u-s-governments-right-to-an-encryption-schemes-backdoor-keys/413497.md?page=2)