A reference request is a request to be provided with (links to) documentation, official papers, and specs related to one or more specific algorithms or cryptographic procedures, to provide a trusted base for what's being said or written.

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2
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2answers
159 views

P10 to P8 in S-DES

I am new to cryptography. During my learning I am facing a problem with S-DES. I am confused where P10 to P8 come from, and I’m ...
1
vote
0answers
37 views

Commitment scheme to share money

I have such problem: party $X$ has an amount of money $M$, which it needs to share with $n$ other parties. Every week the amount of money is different. Let say not, that I am a party A, which is one ...
1
vote
0answers
19 views

System of linear congruence, not relatively prime [migrated]

Consider we have the following set of congruences $$x\equiv b_i \pmod {m_i}$$ for all $1\leq i\leq d$. $m_i$'s doesn't have to be relatively prime, so the Chinese remainder theorem doesn't work here. ...
6
votes
1answer
445 views

Keccak padding implementation, and bit ordering

I am trying to implement Keccak in Java for my school work. And I am getting stuck in two places: On the summary page the padding is shown as P = M || 0x01 || 0x00 || … || 0x00 P = P xor ...
0
votes
0answers
26 views

Does “identity-based dynamic threshold signature” exist and could such scheme contain a “Signature Combination” algorithm?

I came across [1] and I'm very puzzled by this paper. They use a building block which they call "identity-based dynamic threshold (IBDT) signature", citing paper [2]. First of all [2] does use this ...
1
vote
1answer
55 views

What is the “Walsh Function” about?

I'm currently dealing on the so called “Walsh Function” (WF) that is written like: $$f^W(a)=\sum_{x\in{F^n_2}}(-1)^{f(x)+(a,x)}$$ What I know is that this function is used to approximate an arbitrary ...
0
votes
2answers
161 views

Cryptosystems used to generate public key certificate

Where can we find the cryptosystems used to generate public key certificate? Are the cryptosystems under the signature algorithm and signature hash algorithm? Do I need to analyze the packets ...
2
votes
1answer
38 views

Use of Lamport's Signature as a primitive

Is Lamport's One Time Signature used as a primitive to construct any other cryptographic protocols?
4
votes
2answers
157 views

Use cases for “online” authenticated encryption?

What is the the point of an "online" mode for an authenticated cipher? I understand what "online" means in this context. However, I have trouble coming up with applications that would benefit from ...
6
votes
4answers
683 views

Is the logic for how the enigma machine worked documented somewhere?

I know that there is a formula to calculate the result of any input but is the logic of how the machine actually worked documented? I have seen schematics for the circuitry and even a how to make ...
1
vote
3answers
106 views

Salsa20-GCM composition secure?

AES-GCM seems to be used by everyone but I never seen even one post about Salsa20-GCM. Is it secure? Wikipedia mentions that GCM ...
2
votes
3answers
176 views

If a cipher has key length shorter than plaintext, then it is not perfectly secure

I am trying to verify the statement above. So far I only know that a One-Time-Pad is the only “perfectly secure” cipher. It has a key length which is exactly the same as the plaintext. I think the ...
4
votes
1answer
1k views

What is “Implicit Authentication”?

What is “Implicit Authentication” in the context of authentication methods? I searched the Web but could not find any article that describes this. If anyone can describe it, that would be a great ...
10
votes
7answers
1k 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 ...
3
votes
1answer
176 views

“Practical” operations supported by functional encryption?

I'm curious about what operations have been developed into functional encryption schemes. What I mean by that is: what operations can be performed over encrypted ciphertexts? Obviously homomorphic ...
1
vote
0answers
86 views

Existence of encryption schemes where $F_{k}^{-1} \big( F_{k}(A) + R \big) = A + O(R)$

Is there a encryption scheme in literature, where I can do something like $$F_{k_1}^{-1} \big( F_{k_2}(A) + R \big) = A + O(R)$$ where, $A$ is a $m \times n$ real matrix, $R$ is a $m \times n$ real ...
10
votes
0answers
473 views

Who first published the interest of more than two prime factors in RSA?

Multi-prime RSA is now a well known technique: 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 boost in ...
2
votes
0answers
233 views

Elliptic Curve based blind signature implementation

I want to use Elliptic Curve based blind signature scheme for my research. There is no proper implementation of ECC-based blind signatures. Can someone describe to me which things I need to follow ...
2
votes
1answer
391 views

Feistel cipher vs Substitution-permutation network - number of rounds

So I have been doing for the last couple of days comparison between Feistel cipher and Substitution-permutation network. Now I can say I know a lot about them and their similarities and differences ...
7
votes
2answers
541 views

Implement deniable encryption with AES/RSA

I'm on a crypto app using OpenSSL (I'm more an implementer/cryptographer than a cryptologist), mainly as a hobby, for now. My app will be able to encrypt a file (not a container) with symmetric or ...
1
vote
0answers
50 views

What is the fixed point attribute of DES (when used with weak-keys)

I've heard in some lecture that the weak keys in DES implies the existence of $2^{32}$ fixed points in the algorithm, i.e. that $DES_k(x)=x$ for $2^{32}$ such $x$'s. I couldn't find anything about ...
0
votes
0answers
48 views

PRG variant as a commitment scheme

I would like to use a PRG in order to achieve the commitment properties (i.e. Hiding and Binding), however, if we look at a general PRG we cannot state that it has the Binding property. First I show ...
2
votes
3answers
259 views

Difference between Symmetric and Asymmetric. Is this answer correct, based on a written test?

I asked the following question on a final exam: Symmetric Ciphers (e.g. AES, DES, Blowfish) use up to 256 bit on the best case, which are considered strong against brute-force attacks. On ...
0
votes
1answer
47 views

Is there (this) a case in which salting is dispensable?

tl;dr this is not a duplicate of "what is a salt/why use salt?" question. Instead it is specificly asking when salt may not be necessary for hashing securly? (i.e. when the data being hashed is ...
1
vote
1answer
47 views

What is the functional role of CKY-I and CKY-R in ISAKMP (IKEv1)?

According to RFC 2409: CKY-I and CKY-R are the Initiator's cookie and the Responder's cookie, respectively, from the ISAKMP header. Each CKY is a 64 bit value that is included in each ISAKMP ...
1
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0answers
116 views

Bilinear pairing

I am working on Efficient Construction of Pairings which are being realized by Miller's algorithm. In this algorithm the basic steps are point doubling and line function computation point addition ...
0
votes
1answer
68 views

Understanding Cryptography practically [closed]

I have just undergone a one semester course in cryptography. I was introduced to multiple theoretical aspects, the way several algorithms work, the methods and their stability and so on. Due to time ...
1
vote
1answer
161 views

How to encrypt letters less than block n using Hill Cipher

I am learning about Hill Cipher and know that it is a block cipher where each block of n letters (considered as an $n$-component vector) is multiplied by an invertible $n \times n$ matrix, again ...
0
votes
1answer
96 views

A one way Function provably reversible at N applications with the same seed?

I'm looking for a function that is generally one way from some secret $F(s, A) \rightarrow Y$, where $A$ is known, $Y$ is produced (also known), and $s$ is kept secret. But whose repeated application ...
1
vote
2answers
402 views

Is .NET DESCryptoServiceProvider secure in this case?

I have the following piece of .NET code (see below). I know that DES is not quite secure, I saw that MSDN does not recommend using DES, only for compatibility with legacy programs. I also saw that ...
6
votes
3answers
377 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: ...
2
votes
3answers
422 views

Does AES CTR mode store header information in encrypted files?

According to the movable-type.co.uk website, In the ‘counter mode’ used in this implementation, a counter which changes with each block is first encrypted, and the result is bitwise xor’d with the ...
3
votes
1answer
231 views

What is the difference between “secp…” and “sect…”?

The National Institute of Standards and Technology (NIST) recommended elliptic curve domain parameters to have names such as “secp…” and “sect…”. For example: “secp224k1” and “sect571k1”. What is ...
1
vote
1answer
133 views

RC4 key schedule and algorithm design

I've looked up RC4 algorithm and it's seems easy enough but some parts of it seem random to me. In the key schedule part take for example the following part : ...
4
votes
1answer
144 views

Is SRP post-quantum secure?

Is SRP-6a post-quantum secure? If it is not post-quantum secure, do any post-quantum secure alternatives similar to SRP-6a exist?
4
votes
1answer
262 views

reducing false positives in searchable encryption

Practical techniques for searchable encryption proposed by Song et al. [1] have a false positive rate of $l/2^m$ where $l$ is left half of encrypted bits and $m$ is right half and $l+m=n$ where $n$ is ...
1
vote
0answers
35 views

Plaintext-aware encryption for symmetric schemes?

The notion of plaintext-awareness is well-known for asymmetric encryption, but the notion seems to make sense for symmetric encryption as well. Is this a known concept?
5
votes
3answers
479 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?
3
votes
1answer
118 views

What is the technical name for a public key container in DER format?

I have a public key in the following (format-neutral; the type is specified by the DER bytes) format: ...
2
votes
2answers
333 views

SHA512withRSA - Looking for details about the Signature Algorithm

I am trying to find information about the Signature Algorithm SHA512withRSA and have been unsuccessful so far. In the current state, the signature is too long, so I would like to check the code for ...
3
votes
1answer
120 views

Which public key encryption scheme is re-randomizable? How can I re-randomize an encryption scheme?

Which public key encryption scheme is re-randomizable? Is there any library for re-randomizable encryption scheme? If not, how can I re-randomize a given public key encryption scheme? I cannot find ...
4
votes
1answer
529 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 ...
6
votes
2answers
2k views

Is secp256r1 more secure than secp256k1?

Curves secp256r1 and secp256k1 are both examples of two eliptic curves used in various asymmetric cryptography. Googling for these shows most of the top results are Bitcoin related. I've heard the ...
10
votes
3answers
643 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 ...
3
votes
1answer
83 views

Implementing the Mceliece Encryption - making the Generator Matrix

I am working on an implementation of the Mceliece Encryption system (MCE) and the Niederreiter encryption system. I have been through the basics of finite fields, polynomial arithmetic and some coding ...
-1
votes
1answer
130 views

What's the best packet cipher mode for use with UDP for example? Advantages or disadvantages of any alternatives?

Cipher modes typically assume data is streamed or read from a reliable channel with guaranteed ordering. However, many communication transports, such as UDP, are not reliable and don't guarantee order ...
1
vote
1answer
126 views

EAX: OMAC and CMAC

OMAC is specified as the underlying algorithm to provide authentication within the EAX authenticated encryption (with associated data). Would that be OMAC1 or OMAC2? If it is OMAC1, does that mean it ...
2
votes
1answer
103 views

Is it possible to track down copies of WW2-era codebooks?

I've got an academic curiosity regarding some of the old Japanese naval codes used during World War II specifically… but I was just wondering if any of the codebooks from this era had been made ...
2
votes
1answer
92 views

Construct block cipher from a smaller one with mixing function

I read about the AEZ encryption scheme as presented at the CAESAR competition. To me it seems like a construction of an arbitrary length block cipher from a smaller one. The key component is the ...
0
votes
0answers
148 views

RSA and ECDSA Certificate Sizes

Is there a table (or a whitepaper from official sources) that compares the size of X509 certificates generated with RSA (starting from 1024 bits) and ECDSA (starting from 160 bits) ? Thanks for the ...