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!

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2answers
249 views

Verifying Without Knowing Key

Say user Bob sends an encrypted message to a server. People can download the message from this server and later get the key directly from Bob. Is it possible for the server to somehow verify that ...
3
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0answers
25 views

Is there a sufficiently memory-hard asymmetric encryption available? [closed]

The Password Hashing Competition offers several memory-hard hashing algorithms that are aware of time memory trade-off and essentially try to make it hard for ASICs and FPGAs to brute-force hashes. ...
6
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0answers
308 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) $A \rightarrow B: r_A$ (...
0
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1answer
316 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 ...
6
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1answer
84 views

Efficiency of oblivious algorithms vs non-oblivious algorithms?

Recently, plenty of researchers are looking at designing efficient data-oblivious algorithms. Roughly speaking, an algorithm is said to be data-oblivious if its data access patterns are independednt ...
11
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0answers
267 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 ...
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0answers
28 views

Freely available softwares for simulating/implementing MPC protocols [closed]

I have been designing multiparty computation (MPC) protocols for functions that interest me. Although theoretically I am able to deduce the asymptotic complexity of the protocol, I wish to know as to ...
1
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1answer
140 views

CP-ABE for threshold cryptography

I would like to know if there is any research work using CP-ABE for threshold cryptography? I want to know also if applying CP-ABE for threshold cryptography would overcome other techniques.
3
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2answers
44 views

Are there some well-known crypto APIs that leak information?

Are there any well-known crypto APIs or libraries that leak or used to leak information (it can be the key or anything else)?
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0answers
125 views

Does anyone have a copy of the paper describing the HiSeC™ algorithm?

I'm trying to create a remote controller compatible with HiSec algorithm. It's so old that “National Semiconductor” (now “Texas Instruments”) discontinued NM95HS01/02 and docs are unavailable. Does ...
10
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1answer
150 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 ...
6
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1answer
1k 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 ...
5
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1answer
53 views

Binary format of encrypted PGP private key?

Short Version of the Question: I would like to remove any predictable information from an encrypted private keys binary representation. Does anyone have a hint where the binary format for encrypted ...
4
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1answer
125 views

ElGamal Signatures

I know various applications of RSA signatures. I wonder, is there any real-world applications of ElGamal signatures and encryption?
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0answers
86 views

Encrypted comms between devices on LAN

I'm trying to encrypt a protocol that shares data between devices on a local area network (i.e.no connection to the internet). I don't want to use predefined keys because they're too easy to read from ...
3
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0answers
96 views

What is the lightweight key exchange protocol of choice?

Assume I have to implement a secure channel protocol by myself. Assume further that for some obscure reasons (library restrictions?) I can't use any of the pre-made libraries for SSH, TLS and such. ...
2
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1answer
72 views

Where in FIPS documents stated that SHA-1 is not secure?

SHA-1 is not secured for a very long time, but I still can see it here: http://csrc.nist.gov/publications/fips/fips140-2/fips1402annexa.pdf Where in FIPS documents stated that SHA-1 is not secure?
4
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0answers
50 views

On a proposition in NTRU original paper: $\gamma_1 |f|_2 |g|_2 \leq |f \circledast g|_\infty \leq \gamma_2 |f|_2 |g|_2$

In the original paper of NTRU cryptosystem, we have the following proposition (that is said to be suggested by Don Coppersmith): For any $\epsilon > 0$, there are constants $\gamma_1,\gamma_2 &...
5
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1answer
196 views

Full encryption of IDs, partial decryption with customer specific key

I am looking for a "partial" encryption/decryption algorithm. Let's say I am encrypting the following List of IDs (long values) $[1,2,3,4]$ (with a secret key) to an encrypted string $e$, I would ...
3
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0answers
46 views

Election communication protocol

I'm not a cryptography expert, but this seems like it falls into this area. Imagine I want to design an election system (senate race for example) where I send the exact same ballot of 100 candidates ...
9
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1answer
187 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\...
6
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2answers
208 views

Finding the subgroup in isogeny-based cryptography

Isogeny-based cryptography is one of the newest post-quantum cryptography. Hardness of this system is based on finding isogeny between two elliptic curves. Also this is theorem: Elliptic curves ...
-1
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1answer
36 views

Documents about ZUC

ZUC is a function that converts a string to another string. However, unlike a Hash function, ZUC converts a certain-length string to a any-length string. Can someone point me to its documentation or ...
1
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1answer
196 views

Choosing primes in the Paillier cryptosystem

In the first step of key generation phase in Paillier cryptosystem given here. It's given that $$\operatorname{length}(p) = \operatorname{length}(q) ) \implies \operatorname{gcd}(pq,(p-1)(q-1))=1$$ ...
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0answers
61 views

How to normalize data of a generic HTTP request for the purpose of signing

I am working on PowerAuth 2.0, a solution for counter-based signing of HTTP requests (for the purpose of mobile banking). One of the tasks that I solved somehow but I am still not happy with the ...
3
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1answer
62 views

Block cipher mode of operation with beyond-birthday-bound security

I am looking for block cipher modes of operation that are secure even when the number of blocks encrypted exceeds the birthday bound.
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0answers
39 views

Does a password that's cracked someone's account increase the chances of cracking someone else's account?

For every find in password that cracks someone's account, does that particular password have a higher probability of cracking someone else's account more than a brute force dictionary choice? How ...
28
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1answer
4k 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 ...
6
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1answer
103 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 ...
3
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1answer
54 views

How are the IVs of SHA512/256 and SHA512/224 calculated?

This seems odd to me, because there are a lot of resources out there saying that the initializer values of SHA512 and SHA384 are the first 64 bits of the fractional parts of the square roots of prime ...
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0answers
62 views

What functional encryption scheme can be used to compute a linear function?

I am looking for a functional encryption scheme that can compute a linear function. I do not need to work with attributes. All I want is to compute the result of a function $y = a*x+b$, where $x$ is ...
9
votes
5answers
367 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 ...
0
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2answers
233 views

DES hardware implementation of substitution lookup table [ ReWorked ]

I'm a crypto enthusiastic and student of cryptography. I'm developing a project with other students titled "A hardware implementation of a DES cryptography for educational purposes", our idea was to ...
14
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3answers
2k 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 ...
1
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0answers
131 views

Example describing Baek and Zheng’s threshold identity-based decryption scheme

I am trying to work through an example of Baek and Zheng’s “threshold identity-based decryption scheme” and I tried a lot to solve this, but somewhere I’m doing something wrong. I hope someone can ...
7
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3answers
301 views

What was the first MD5 collision ever constructed?

We all know that MD5's collision resistance is severly broken. But when thinking of "random" strings with great cryptographic importance I've come up with NIST's curve seeds and MD5 collisions. But ...
1
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0answers
59 views

Does using a verifiable secret sharing scheme ensure robustness of a protocol if it is secure under the semi-honest adversarial model

Consider a protocol $\pi$ which uses a linear secret sharing scheme like that of Shamir secret sharing. Further assume that the protocol $\pi$ has been proven to be secure (correctness and privacy) ...
1
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1answer
43 views

Attacks on schemes based on elliptic curves when the transmitted points are not on the curve

Some elliptic curve schemes require to send a curve point during the normal execution of the protocol. For example, ElGamal encryption and ElGamal signature require this. On the other hand, ECDSA does ...
5
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4answers
1k 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?
4
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2answers
103 views

Are there simpler FHE methods than Craig Gentry's original paper?

Craig Gentry's 2010 paper on FHE is very cool, and I'm planning on implementing a basic proof of concept FHE. I was wondering though, are there any simpler methods that have been discovered since ...
4
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2answers
607 views

Update to “Cryptographic Right Answers”

I'm a big fan of Colin Percival's "Cryptographic Right Answers" post. This was written in 2009, which is a long time ago in Internet years. Is the advice still valid or, if not, can someone point me ...
21
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1answer
1k views

Proof for the SHA3 claim that 256 bit security is “post-quantum sufficient”?

On page 14 of "Keccak and the SHA-3 Standardization" (February 6, 2013) it says: Instantiation of a sponge function the permutation KECCAK-f 7 permutations: b → {25,50,100,200,400,800,...
4
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1answer
58 views

VIC cipher author known?

Does anybody know if the design of VIC cipher is attributed to anybody? I've tried Google and found nothing. There are quite a few sites describing the method in detail, a few implementing it ...
3
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1answer
50 views

What are fixed points and length extension attack in hash functions?

I was recently reading about hash functions, and I came across fixed points (one or more fixed points, interested in both) and length extensions, but I didn't exactly understand how these work. If ...
4
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1answer
43 views

Generate a random number $r \in \{1,2, \dots , k\}$, where $k$ is not public and is distributedly held

A set of parties can securely generate a random number $r \in \{1,2,3,\dots, k\}$ when $k$ is publicly known. However, can we generate the random number $r$ if $k$ is not publicly known and is held by ...
4
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1answer
207 views

Discrete logarithm problem is easy in a cyclic group of order a power of two

Let $G=\langle g\rangle$ be a cyclic group of order $2^{k}$ and let $h\in G$. I have read that it is easy to find $\log _{g} h$, but I haven't been able to figure out how. Do you know why this can be ...
2
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0answers
37 views

RC6-like key schedule with 16-bit S-boxes

I am trying to figure out an encryption algorithm whose key schedule function seems to be similar to RC6. However, it seems to be creating S-Boxes using 16-bit integers instead of 32-bit ones. I have ...
3
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0answers
31 views

What is the current encryption method used on GSM currently?

I am currently doing a mini project which sniffs GSM packets using gr-gsm and wireshark. I was wondering if anyone knows what is the name of the current encryption algorithm method used on GSM?
3
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1answer
50 views

Identity-based proxy re-encryption using different system parameters

I am wondering if there is an identity based proxy re-encryption scheme (such as the Green-Ateniese scheme https://eprint.iacr.org/2006/473.pdf) that converts an encryption computed with ID1, system ...
5
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2answers
110 views

Where did Martin Hellman acknowledge Ralph Merkle's contribution to public-key cryptography?

I am trying to find the article to reference when discussing the Diffie-Hellman key exchange. According to Wikipedia Hellman said that The system...has since become known as Diffie–Hellman key ...