Questions tagged [reference-request]
A reference request is a request to be provided with a source from documentation, official papers, and specs related to one or more specific algorithms or cryptographic procedures. Open ended literature recommendation requests are off topic! Also: Crypto.SE is not an optimal replacement for a search engine. The reference-request tag is not something that provides a base to replace research efforts.
403
questions
53
votes
4
answers
52k
views
Is secp256r1 more secure than secp256k1?
Curves secp256r1 and secp256k1 are both examples of two elliptic curves used in various asymmetric cryptography.
Googling for these shows most of the top results are Bitcoin related. I've heard the ...
- 1,007
39
votes
1
answer
2k
views
Who first published the interest of more than two prime factors in RSA?
Multi-prime RSA is now a well known technique (described here): it uses $k>2$ distinct secret prime factors in the public RSA modulus, with the advantage that, using the CRT, we can gain a speed ...
- 134k
35
votes
4
answers
16k
views
Is there a string that's hash is equal to itself?
I was wondering if there's any string that has a hash equal to itself, so that – when using any (none specific) hash function – the hash would be equal to that string?
so that:
...
- 453
30
votes
2
answers
4k
views
When using Curve25519, why does the private key always have a fixed bit at 2^254?
When using Curve25519, the private key always seems to have a fixed bit set at position $2^{254}$.
Why is that? Is there any good reason to use a fixed positioned most-significant-bit in the private ...
- 684
28
votes
1
answer
5k
views
Examples of modern, widely used ciphers that suddenly fell?
RC4 and GOST are two major ciphers (defined as being widely used to encrypt large amounts of data) that fell to cryptanalysis (relatively) suddenly. The first becoming totally broken and the second ...
- 4,763
24
votes
5
answers
12k
views
Developing algorithm for detecting plain text via frequency analysis
I'm currently attempting the Matasano Crypto Challenges as a basic intro to cryptography. For solving some of the earlier challenges I utilised n-grams to determine which is going to be the most ...
- 243
24
votes
3
answers
2k
views
Selective format-compliant JPEG encryption?
I am working towards building a format-compliant encryption system for pictures. The aim of it is to be able to obscure specific areas of a picture (i.e. faces, car license numbers...) while keeping ...
- 349
20
votes
2
answers
32k
views
Does SHA-1024 hash exist?
Does SHA-1024 cryptographic hash function exist similarly to SHA-512? If not, what's the reason for that?
Links:
SHA-2 at Wikipedia
SHA-3 at Wikipedia
- 637
19
votes
2
answers
4k
views
What is "witness encryption"?
I recently skimmed over tho papers on time-lock encryption:
“Time-release Protocol from Bitcoin and Witness Encryption for SAT” by Liu, Garcia, and Ryan
“How to Build Time-Lock Encryption” by Jager
...
- 45.5k
19
votes
0
answers
423
views
Adding bit constants to the key schedule to reduce rounds?
Bit constants are often added to the key schedule to reduce slide attacks. I have reviewed David Wagner's work, where he showed that the increased rounds in a Feistel network do not help if you have ...
- 4,524
18
votes
3
answers
3k
views
Digital signature that is only verifiable by one specific person
I would like to digitally sign a message in such a way that the signature can only be verified by one specific person. Simply encrypting the signature will not work, because that person could then ...
- 281
18
votes
2
answers
2k
views
Is Bruce Schneier Applied Cryptography, Second ed. up to date?
I like Applied Cryptography, and I am returning to cryptography after a while. So I am wondering if that book is up to date or can be complemented with other references.
I am looking for a book, ...
- 191
18
votes
3
answers
5k
views
Webcam random number generator
I have a question about random number generators.
I have read from a real random number generator, based on a webcam ("randcam"). My problem is, that I do not really understand how the generation of ...
- 337
17
votes
2
answers
6k
views
Use case for extendable-output functions (XOF) such as SHAKE128/SHAKE256
FIPS 202 defines 2 functions, SHAKE128 and SHAKE256, as extendable-output functions (XOFs) that can have variable output length. But in Appendix A.2 marks:
it is possible to use an XOF as a hash ...
- 306
17
votes
2
answers
950
views
Status of Algebraic Eraser key exchange?
Algebraic Eraser™ is a relatively new asymmetric key agreement protocol (also designated the Colored Burau Key Agreement Protocol), based on a simultaneous conjugacy search problem in a braid ...
- 134k
17
votes
3
answers
1k
views
Is there a standardized tree hash?
SHA-1, SHA-2, and the standardized version of SHA-3 are all sequential. This is impractical for hashing very large files distributed across machines. Any sequential hash can be straightforwardly ...
- 394
16
votes
6
answers
3k
views
How exactly is "true randomness" defined in the realms of cryptography?
Especially in relation to stream ciphers, I frequently read about (sometimes theoretical, sometimes practical) attacks that are able to "distinguish a ciphertext from a truly random stream".
What's ...
- 17.7k
16
votes
1
answer
3k
views
Difference between “ECDH with cofactor key” and “ECDH without cofactor key”?
I need to use “ECDH with a cofactor key” for generating symmetric key. I have a fair idea on how ECDH works, but I don’t understand the cofactor part.
What is the difference between ”ECDH with a co-...
- 191
16
votes
1
answer
3k
views
AMD's implementation of RDRAND instruction
The latest AMD programmer manuals, dated June 2015, include the RDRAND instruction in the instruction set. For completeness, it lacks ...
user10496
15
votes
2
answers
1k
views
How to do a literature search
How do I do a literature search of the research literature on cryptography? Assume there's some topic in cryptography I'd like to learn more about; how do I search the cryptographic research ...
- 36k
15
votes
3
answers
671
views
Turing's (still?) classified inference engine algorithm?
Does anyone know the algorithm used by Turing's Colossus inference engine, so highly classified that the Brits kept it secret for decades after WW II?
Indeed, it may still be classified. Several ...
- 261
14
votes
1
answer
2k
views
What was NIST’s reason to switch naming from MD… (Message Digest) to SHA… (Secure Hashing Algorithm)?
When NIST introduced SHA-0 in 1993, they – for the first time – switched their naming convention from MD-n to SHA-n. Since both point to similar constructions (read: hashing algorithms with the same ...
- 17.7k
14
votes
0
answers
216
views
Space complexity of quantum collision search?
Is there a known way to reduce the space complexity of quantum collision search (PDF) beyond what is offered by the built-in time-space tradeoff, while keeping the time complexity significantly below ...
user991
13
votes
2
answers
3k
views
Has threefish successfully been attacked (practically or theoretically)?
Reading Schneier's "The Doghouse: Crypteto" dated September 30, 2009, I noticed Bruce Schneier stating:
Threefish, the block cipher inside Skein, encrypts data at 7.6 clock cycles/byte with a 256-...
- 684
13
votes
1
answer
7k
views
Description of signatures with message recovery (as in ISO/IEC 9796-2 and EMV Signatures)
I'd like to get an overview of how the signatures with message recovery work, especially in case EMV and other smart card systems. Is there a nice overview available without being required to read the ...
- 443
12
votes
3
answers
2k
views
Does AES-NI offer better side-channel protection compared to AES in software?
Does AES-NI offer better side-channel protection compared to AES in software? Also, it would be great of you could provide according references in your answer.
- 167
12
votes
6
answers
8k
views
Which cryptography technique does not increase the size of the plain data?
I want to encrypt some data(text/voice/video) but it is essential that the size of the cipher data remains the same as the plain data.
Which techniques can I use, and how secure are these techniques ...
- 359
11
votes
1
answer
3k
views
How much entropy is lost via hashing when you add known or low entropy data?
(I updated the title, as I think there was some confusion as to the question)
Here's the question:
For example, if I have a bit stream that is 64K bytes long and there is about 16 *8 bits worth of ...
- 541
11
votes
1
answer
3k
views
Is every point on an elliptic curve of a prime order group a generator?
If the order of elliptic group is prime then every point is a generator of that group.
I tested the above statement on some elliptic curves and found it true.
Does that really work on all curves?
Is ...
- 121
11
votes
0
answers
203
views
How exactly does ASKE (Alpha Secure Key Establishment) in Zigbee work?
I am working on Zigbee security. For key establishment, some approaches are given in Zigbee. Some of them are:
ASKE (Alpha Secure Key Establishment),
ASAC (Alpha Secure Access Control), and
SKKE (...
10
votes
3
answers
7k
views
Is knowing the private key of RSA equivalent to the factorization of $N$?
Given the RSA modulus $N$ the fastest method to factor it is of sub-exponent order. But, now if I know the private key $d$ of RSA, does that mean I can factor $N$ efficiently?. It intuitively seems ...
- 1,272
10
votes
3
answers
907
views
Bitcoin Research
I have recently been assigned to advise a student on a senior thesis in math. She has taken linear algebra, introductory real analysis, basic cryptography, and abstract algebra. Her interest is in ...
- 227
10
votes
3
answers
3k
views
Is there an encryption format that preserves length and only outputs alphanumerics?
I'm trying to design a promo code system for a server app I'm designing. Basically, I generate a promo code for a certain item and give the code out to someone, who then types it into the server.
...
- 203
10
votes
2
answers
2k
views
Why cannot I assume that cryptography published in venues/journals handled by the same publishers as prestigious journals is serious?
I do not know if it is allowed to ask this question.
I have been told that "most of the papers on chaos-based cryptography are appearing in fee/generalist journals, whose focus is not security&...
- 407
10
votes
1
answer
567
views
Who is the inventor of the OFB block cipher mode of operation?
Handbook of Applied Cryptography gives two resources for the OFB mode
1980 FIPS 81. This doesn't give any references, unlike NIST.
1983 ANSI X3.106, unfortunately pay-walled.
Who is the inventor of ...
- 46k
10
votes
2
answers
14k
views
Digital Signature using symmetric key cryptography
Generally digital signature is a public key cryptography concept.But it needs high overhead.
So is there any publication or link available where 'digital signature using symmetric key' has been ...
- 201
10
votes
1
answer
212
views
A general definition for cryptocurrencies
I am trying to find the definitions to several terms related to digital currencies. Unfortunately, I am always ending up on Bitcoin-oriented pages and websites which only take Bitcoin itself into ...
- 605
9
votes
3
answers
3k
views
Elliptic Curves of different forms
Looking at http://safecurves.cr.yp.to/ to find a safe curve, I find that most curves described here are of a different form from that generally used.
In Bouncy Castle, for example, ...
- 223
9
votes
4
answers
7k
views
Security proofs for CBC mode
I'm looking for different approaches to proofs for the security of CBC mode encryption. What are the best sources of information about this subject?
- 2,817
9
votes
1
answer
229
views
What was the NSA's reasoning for making their bitwise combination functions in SHA-1 the way they did?
I know that these functions are there to actually make the program work. What I want to know is why they made the functions one way but not another.
For example, why did they pick
F1(B, C, D) = (B &...
- 101
9
votes
2
answers
519
views
What is the official, generally accepted definition of "lightweight crypto"?
I frequently stumble upon the term "lightweight crypto". It tends to be used is a for special algorithms that use less resources, for constrained systems. Yet, it's somewhat unclear to me ...
- 17.7k
9
votes
2
answers
810
views
Standard parameters for Boneh–Lynn–Shacham signature?
The Boneh–Lynn–Shacham signature is (as far as I know) unrivaled in compactness, promising $b$-bit security for $2b$-bit signature (perhaps: asymptotically).
Are there standard parameters for BLS ...
- 134k
9
votes
1
answer
1k
views
Adi Shamir's secret database of all primes
I was going through these presentation slides (PDF) on Crypto 2013.
It summarizes the paper, Factoring RSA keys from certified smart cards: Coppersmith in the wild.
In the last slide, it was ...
- 469
9
votes
2
answers
709
views
What current authenticated key exchange standards exist?
If neither of the 'big two' of TLS Handshake and IKE are appropriate in a given situation, what alternative Authenticated Key Exchange (AKE) standards exist and are recommended?
Many protocols have ...
- 1,489
9
votes
1
answer
566
views
Are there any long term RC4 bias based exploits?
The RC4 cipher possibly exhibits low level bias in it's long run PRNG keystream. I'm specifically excluding short term bias attacks which I'm defining as outputs < 1024 bytes. Are there any real ...
- 14.6k
9
votes
1
answer
1k
views
Families of public/private keys in elliptic curve cryptography
I'm looking for a related key scheme for elliptic curve cryptography. The basic idea would be that there would be a master public key and a master private key. From the master public key, you could ...
- 4,709
9
votes
1
answer
297
views
Is there any general description language for block ciphers?
In page 9 (16 in the PDF) of Final report of European project IST-1999-12324 (NESSIE), it is mentioned that:
The NESSIE project is also developing a new generic tool to analyze block
ciphers with ...
- 3,972
9
votes
1
answer
2k
views
What is the original SKID3 protocol?
While searching for a mutual authentication protocol I often stumbled upon SKID3. However I encountered different variations of it.
The basic structure is the following:
(1) $A \rightarrow B: r_A$
(...
- 161
9
votes
1
answer
637
views
Are there any security issues when replacing the SHA-256 initialisation values?
As RFC 4634 describes in section 6.1, SHA-256 is initialized using eight 32-bit words.
These were obtained by taking the first 32 bits of the fractional parts of the square roots of the first eight ...
- 17.7k
9
votes
1
answer
423
views
State recovery of Micalli-Schnorr random number generator modulo a prime
Let $p$ be a public prime of $n$ bits. Define the sequence $x_i=z_{i-1}^e \bmod p$, where $z_i$ is the $k$ high-order bits of $x_i$, and $r_i$ the remaining $n-k$ bits of $x_i$ (thus $z_i=\Big\lfloor\...
- 818