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1500 questions
11
votes
1 answer
Alice trusts Bob only when Bob trusts Alice
some story first: Alice and Bob both have public/private key pairs. Now Bob wants Alice to sign his public key id. Alice agrees but only when Bob signs the public key id of her.
Is this something that can be achieved? at the end, the signatures…
esskar
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11
votes
2 answers
What do NM-CPA and NM-CCA mean?
When I've been researching authenticated encryption, the following terms keep showing up:
NM-CPA
NM-CCA
....without any definition as to what they mean. I've tried searching the web for their definitions, but I'm not getting very far. Could…
starbeamrainbowlabs
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11
votes
2 answers
What is a rank-1 constraint system?
Why not rank-2 constraint system or rank-3 constraint system?
How do rank-1 constraint systems link to circuits?
WeCanBeFriends
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11
votes
1 answer
CAESAR finalists: Lightweight case (Ascon vs ACORN)
The Ascon cipher has been selected as the first choice in lightweight case and ACORN as the second. However according to Face-off between the CAESAR Lightweight Finalists: ACORN vs. Ascon paper, the winner of the face-off is ACORN.
They mentioned…
hardyrama
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11
votes
1 answer
how does BearSSL's GCM modular reduction work?
BearSSL (in src/hash/ghash_ctmul.c) seems to be doing a modular reduction that I don't completely understand. Here's the code:
/*
* GHASH specification has the bits "reversed" (most
* significant is in fact least significant), which does
* not…
neubert
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11
votes
3 answers
Homomorphic encryption - Why does addition not imply multiplication?
As far as I know:
There are some partially homomorphic encryption (PHE) systems that support either addition or multiplication.
A fully homomorphic encryption (FHE) system can do addition as well as multiplication and thus supports arbitrary…
AleksanderCH
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11
votes
1 answer
Point halving on elliptic curves of even order
I am trying to understand how point halving on elliptic curves of even order works. Specifically: suppose $g$ is an elliptic curve, and $G$ is a generator point on this curve. The order of group generated by $G$ is even and equal to $q$. Suppose…
irakliy
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11
votes
5 answers
How do I construct a 256-bit hash function from 128-bit AES?
I would like to generate a 256-bit hash on a microcontroller that has a 128-bit (only) AES engine. How can I construct a 256-bit hash function from a 128-bit cipher?
joeforker
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11
votes
1 answer
Should the secret key of Shamir's secret-sharing algorithm be interpreted byte by byte?
Should the secret message of Shamir's secret-sharing algorithm be interpreted and processed byte by byte?
Interpreting it byte by byte makes it easier to process, but in case one of the shareholders decides to tamper with some of the bytes in his…
Penn
- 153
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11
votes
4 answers
Why is SHA-512 limited to an input of $2^{128}$ bits?
Both SHA-384 and SHA-512 are limited to an input size of less than $2^{128}$ bits. Considering SHA-512 has a higher output size, couldn't it include more input data?
w0f
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11
votes
1 answer
How does the process of creating a new secure Elliptic Curve look like?
I'm especially curious about the technique djb would have used to come up with his Curve 25519. Say I have already written down my goals, such as - Twist Secure, Speed, Side Channel resistance, etc. In this case, how do I go about creating new…
Cookies
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11
votes
3 answers
Is signing a hash instead of the full data considered secure?
I reference object in some of my code in hashes. The signature is itself is another object separate from the one I am signing (for obvious reason). I consider simpler to simply sign the reference to my object (its hash), but I wonder if it is…
Gopoi
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11
votes
3 answers
What is different below two Ciphersuites?
I have two questions;
I need an explanation for the differences of below two cipher suites.
How do they work with SSL/TLS protocol? (my main concern first one doesn't have 'ecdhe_rsa' part…
uma
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11
votes
2 answers
Can quantum computers put computer security in jeopardy?
There are many articles about quantum computers describing how powerful they are in computing and that they can solve very complicated equations in a short time.
One of the biggest security measures that provide safety for computer security is that…
R1w
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11
votes
5 answers
How to best obtain bit sequences from throwing normal dice?
Throwing normal dice, one can get sequences of digits in [0,5]. In practice, which is the best procedure to transform such sequences into a desired number of bit sequences?
Mok-Kong Shen
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