Bentham's Gaze is the blog of University College London's information security research group, covering security failures, cryptography, and the law.
HN links it for analysis of the Post Office Horizon scandal and the English legal presumption that computers work correctly, plus UK cybersecurity policy.
Not in academic terms, no. tl;dr IBE refers to a specific process of mathematically using identifying data as a public key like a phone number or email.
As always with cryptography you have a key exchange/identity binding problem: if you receive my public key, how do you know it actually came from me? There are a few solutions to this problem:
1. Certificate authorities do an ID check (domain or extended validation). You know the cert is valid because (in theory) the CA doesn't sign unless it too is convinced and you trust them to do a good job (there's a whole history of CA issues and implementation problems I won't discuss further here - this is by and large the concept).
2. Web-of-Trust/Keybase - the valid key is signed by enough other people you trust / signs enough other public statements from accounts you trust you don't think MITM can happen.
3. Compare hashes (fingerprints) - OTR, OMEMO, Signal, WhatsApp, ZRTP et al. You have the right key because you trust the digest function.
4. Authenticated Key Exchange e.g. PAKE, SPAKE, NAXOS etc.
IBE solves the key exchange problem a different way - what if your public key was some identifiable piece of information (not necessarily biometric as others have suggested, but) e.g. an email address or telephone number? To realise this you need a key management server to go from these public keys to a private key, via a protected master secret and other global parameters, see https://crypto.stanford.edu/~dabo/papers/bfibe.pdf ,…
For some background. The legal presumption dates from 1997.
"Previously, section 69 of the Police and Criminal Evidence Act 1984 required anyone introducing computer-generated evidence to show the system was operating correctly and not being used improperly.
The change followed the Law Commission’s 1997 review of the law on hearsay evidence."[1]
from https://www.lawgazette.co.uk/law/it-experts-call-for-review-of-computer-is-always-right/5118414.article
[1] review https://cloud-platform-e218f50a4812967ba1215eaecede923f.s3.amazonaws.com/uploads/sites/30/2015/03/lc245_Legislating_the_Criminal_Code_Evidence_in_Criminal_Proceedings.pdf (page 197)
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Another interesting briefing note:
"The legal rule that computers are presumed to be operating correctly – unforeseen and unjust consequences": https://www.benthamsgaze.org/2022/06/30/the-legal-rule-that-computers-are-presumed-to-be-operating-correctly-unforeseen-and-unjust-consequences/
They suggest, when requested, that a party gets:
- records of known errors and bugs in the system, their effect, and the actions taken in response
- description of information security and other relevant standards and processes followed
- reports of audits performed on the system and how it is managed,
- evidence showing that reports of errors are managed properly and that changes to the system are properly controlled
- evidence confirming that the search for documents was performed adequately, and was done so by a person with…
I don't think you (or the sibling comment) got my point. No where am I "excusing" bugs. Civil engineering bugs are indeed a fact of life too, just check the god damn news.
What I'm saying, is that I think where PHK says "nobody sat down and documented precisely what went wrong", I think he is just wrong.
The guy in the Computerphile video, Steven Murdoch wrote this article:
https://www.benthamsgaze.org/2021/07/15/what-went-wrong-with-horizon-learning-from-the-post-office-trial/,
which has further details of the bugs, e.g.
"There is a window of time between a user printing and cutting-off a report. If another user was to perform a transaction during that window, that transaction may not show on the report."
which is from the long and very detailed judgment: https://www.benthamsgaze.org/wp-content/uploads/2021/07/Bates-and-Ors-v-the-Post-Office-Ltd-2019-EWHC-3408-QB.pdf
The problem that needs investigating here is the miscarriage of justice, apparently the post office was aware of the bugs at the same time as prosecuting people for falling victim to the bugs, in order to save face about their IT decision.
There is also a detailed description of the system in [1].
An interesting incidence/problem report is in [2] at 1h:03m:00s, where an replication error in their Riposte message store system is described. After a defect counter hardware was replaced, it will fill its empty store with messages from other counters.
[1] "Technical Appendix to Judgment (No.6) “Horizon Issues”", https://www.judiciary.uk/wp-content/uploads/2022/07/bates-v-post-office-appendix-1-1.pdf
[2] "Alvin Finch - Richard Coleman - Day 54 AM (17 May 2023) - Post Office Horizon IT Inquiry", https://www.youtube.com/watch?v=H0_-ebCVU5k&t=3780
[3] Steven Murdoch: "What went wrong with Horizon: learning from the Post Office Trial", https://www.benthamsgaze.org/2021/07/15/what-went-wrong-with-horizon-learning-from-the-post-office-trial/
Unfortunately, in England and Wales, courts consider computers, as a matter of law, to have been working correctly unless there is evidence to the contrary. Therefore, evidence produced by computers is treated as reliable unless other evidence suggests otherwise. This way of handling evidence is known as a ‘rebuttable presumption’. A court will treat a computer as if it is working perfectly unless someone can show why that is not the case.
(taken from https://www.benthamsgaze.org/2022/06/30/the-legal-rule-that-computers-are-presumed-to-be-operating-correctly-unforeseen-and-unjust-consequences/)
The sub post masters did not have access to the evidence required to show that the Horizon system was buggy and so were denied justice.
I did read a very technical report about this which obviously now I can't find :-( My takeaways were: (1) They didn't bother with double-entry bookkeeping. (2) It was a distributed system which no one fully understood and was not based on any normal distributed system principles. (3) Developers made ad hoc changes to the code and even database to temporarily patch things up, even going so far as to hard-code database ids into special cases throughout the code.
Edit: I think this one: https://www.judiciary.uk/wp-content/uploads/2019/12/bates-v-post-office-appendix-1.pdf Also related article: https://www.benthamsgaze.org/2021/07/15/what-went-wrong-with-horizon-learning-from-the-post-office-trial/