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Nov
13
awarded  Popular Question
Jun
19
awarded  Supporter
Jun
19
awarded  Scholar
Jun
19
accepted efficient 16 bit hash
Jun
19
comment efficient 16 bit hash
Yes I'm sure I need that, and incrementing an int is not enough because I need two hashes of the same value, produced at different times, to produce the same result. Thanks for your answer. Where can I find or how to generate the table used in the algorithm ?
Jun
19
awarded  Editor
Jun
19
awarded  Commentator
Jun
19
comment efficient 16 bit hash
No it's not. I asked the two questions, they're different. In here, I want a ID, not a checksum. And the data length is not the same, in one case it's a hundred bits, in another it's up to tens of thousands.
Jun
19
asked efficient 16 bit hash
Apr
13
comment Is there a crypto system which detects decryption somewhere between sender and receiver?
Maybe there can be a mechanism to prevent that ? What if, as mentioned in my comment to logicalscope's post, the function used to decrypt the message would not work after the message has been sent ? Maybe this idea is not that far from the already existing ideas regarding PFS or defense against replay attacks ?
Apr
13
comment Is there a crypto system which detects decryption somewhere between sender and receiver?
Regarding my first solution, let me develop my thoughts a little (it's not easy with 600 chars only): maybe a message M would have to be applied to f1() to pass it on, and f2() to decrypt part of it and pass it on, where f1() is made in such a way that it modifies f2(), making it unusable, so that both functions can't be used for the same message (either pass it on without reading, or read it and pass it on).
Apr
13
comment Is there a crypto system which detects decryption somewhere between sender and receiver?
Alternatively, I also thought of another scheme: for every read, the user has to ask permission to a authoritative person (such as the sender or receiver, perhaps), which would then be able to grant access and to give him keys so that he can decrypt the message. The authority would then have a log of read (and possibly another one for write) accesses. The user who asks the read permission would have to be authenticated so that only he can read it. The drawback in that scheme is that it's not very efficient, it requires a lot of back and forth, but maybe we could do it just once per flow.
Apr
13
comment Is there a crypto system which detects decryption somewhere between sender and receiver?
Thank you, your explanation is pretty clear. What I had in mind was a mysterious mathematical function or cryptographic scheme that had to be applied by a user (and him only, because only him would have the correct keys for that), in order to decrypt it, but that would have the side effect of changing the information (or the meta data) in such a way that it could be traced back to the user. The user would have to be regular (not admin) and unable to copy the information in order to apply the function once, and return the message unmodified. Is that not possible ?
Apr
12
comment Is there a crypto system which detects decryption somewhere between sender and receiver?
This is an interesting answer, however I don't think quantum cryptography is available at usage level just yet, and I'm not looking for solutions involving science fiction, I would like a solution that I could deploy. As for the 'asymmetric encryption' you talked about, I don't want middle nodes to be unable to access the data, I just want to be able to know if they did. Maybe that's just not possible, in today's world ?
Apr
12
asked Is there a crypto system which detects decryption somewhere between sender and receiver?
Apr
11
comment network improvements over ipsec
In other words, I would like a solution that performs as well as ipsec as far as security is concerned, without impairing the enhancements of the TCP protocol made by the routers. Is that possible ?
Apr
11
comment network improvements over ipsec
What kind of detail do you need ? I don't know how much more specific I can be, without giving the whole protocol, which would be quite long, and I'm allowed to anyway. Let me just add an example: tcp considers any untransmitted packet to be caused by congestion. In my environment, many packets fail to reach their destination for other reasons. I hence needed to slightly modify the protocol stack so that the throughput would not be cut in half when the lost of a packet is not due to a congestion issue. This requires accessing and modifying the tcp window in some cases.
Apr
6
comment network improvements over ipsec
Do you mean 'endpoint solution' as explained in is.gd/EX5GoL ? From what I understand, and although I'm not a security expert, this kind of security is about securing the host from unwanted access. What I want is to protect the information being transfered from unwanted eavesdroppers and unwanted modification, at the tcp level, regardless of the application using it. I don't know of any solutions besides ipsec providing this.
Apr
5
awarded  Student
Apr
5
asked network improvements over ipsec