-1
votes
0answers
12 views

Identifying ciphertext from noisy data

I am analyzing a series of urls that contain encryption of an unknown type which I would like to identify using various heuristics (e.g. ...
-2
votes
0answers
21 views

Hard drive security

I had a idea of making a secure hard drive https://en.wikipedia.org/wiki/Data_security. And add some new ways, so I wanted to ask does any body have a idea how to make a hard drive infect a forensic ...
1
vote
0answers
18 views

What does Set Membership actually prove?

While going through this paper, I came across the idea of Set Membership proofs. The proof allows a prover to prove that a value is contained in some set. The point where I am confused is, all the ...
0
votes
0answers
27 views

How can an email sender include his PGP key, so I can answer with an encrypted mail? [migrated]

Let's say I were to post my e-mail address and public PGP key to my website. When a client contacts me, they would have to include their PGP public key in the e-mail so that I can respond to them in ...
1
vote
1answer
21 views

Is MAC algorithm same at both sender and receiver end

The MAC algortihm which is used along with a secret key to generate a MAC tag on the sender end ,is it same at the receiver end also who again uses a MAC algorithm to generate a tag? If yes, then how ...
0
votes
0answers
12 views

Are symmetric and asymmetric keys both used in SSL/TLS

As far as what I have understood, both symmetric and asymmetric keys are used in SSL/TLS, is it right? The SSL/TLS uses Asymmetric Keys (Public key encryption) to generate a session key. The session ...
0
votes
1answer
35 views

How to make a document truly read only

How is it possibile to cryptographically make a document truly read only? As in read only I imply that the user can obviously view it which can be achieved by coding which pixels have which colors. ...
0
votes
1answer
22 views

FSB Hash Functions and Convetional hash Functions

I'm reading FSB cryptographic hash function and the authors say that security of this function depends on NP-Complete Problem: "Decoding Linear Code Unlike most other cryptographic hash functions in ...
-2
votes
1answer
42 views

How Proof all Subgroup point of prime order elliptic curve have prime order [#G=#E]?

anyone knows any reference that proof it ? Please Help .
1
vote
0answers
39 views

Privacy-Preserving relational databases: checking the existence of a record (or multiple records)

I would like to know if there exists a protocol which performs the following operation in a privacy-preserving fashion: User $U$ wants to know whether a record is stored in the database. The primary ...
1
vote
1answer
102 views

Is SHA related to AES or TLS in any way

I have been reading about SHA-2 family and I found a lot of in depth details, but I am confused about how it is related to TLS and AES. TLS encrypts data between server and client, but does it make ...
1
vote
3answers
136 views

How is the following different than RSA Signing of a document?

If the goal is to demonstrate that you are who you say you are, I think the following will work: Bob wants to know that you are Amy. Bob encrypts a number using Amy's public key and then asks her what ...
2
votes
1answer
32 views

Is multiple encryption using NaCL and TLS better?

In general, the idea of multiple encryption sounds interesting - for creating stronger cyphers (especially against implementation bugs), one could always get the configuration details wrong and mess ...
2
votes
1answer
50 views

Prevent MITM attack while encrypting data by using ElGamal ECC?

I am using ElGamal ECC to encrypt my plain text data. I want to ensure that my data is safe from a Man-In-The-Middle attack. What methodology I can adopt to achieve this goal? How can we prevent a ...
4
votes
1answer
36 views

CBC-MAC based on PRF

Why is the block cipher in the CBC-MAC taken to be a pseudo random permutation (PRP) and not a pseudo random function (PRF)? We don't need the bijective property of the PRP. So why go with it?
1
vote
0answers
59 views

Are partial hashes used in cryptographic protocols?

In my question (and answer) about a partial hash code used within a signature application I found out that partial hash codes are sometimes used within protocols with a relatively restricted security ...
2
votes
0answers
45 views

Managing data permissions/access through asymmetric cryptography

I want to manage authorization, as 3rd-party permissions, through asymmetric cryptography. I'm concerned about how is it possible to share access of encrypted data with N entities, and be able to ...
3
votes
3answers
128 views

Asymmetric algorithm for one time signing of small cleartext

I want to generate a key pair such that the private key can be used once to sign a small message (1024 bytes) at some indeterminate point in the future and the public key can be used to verify that ...
3
votes
1answer
78 views

Secure Deduplication and Encryption in a data store

Assume: We have a centralized data store that can store whatever we need Every user is online Function $f : File \to Key$ gets access to the store, and is the same for all users. $g : Key \to File$ ...
3
votes
1answer
43 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
vote
0answers
125 views

practically verifying block ciphers strength [on hold]

How do we verify practically the strength of a block ciphers? Most of the security analysis of block ciphers is usually around theoretical analysis and proofs in some random oracle model etc. For ...
0
votes
2answers
102 views

Homomorphic Encryption: how does the equality test on ciphertexts work?

Let's suppose we have a asymmetric crypto-system $H$ which is homomorphic with respect to some function $F$. Alice encrypts a message $m$ with her private key $e$ in the crypto-system $H$ and ...
2
votes
1answer
50 views

Question on Waters IBE

I'm reading “Efficient Identity-Based Encryption Without Random Oracles” by Brent Waters. In Page 9, I don't know how ...
0
votes
1answer
125 views

How should I treat a new cipher release like Spritz?

I have been looking at both the paper as well as the sourcecode of Spritz — a spongy RC4-like stream cipher and hash function by Ronald L. Rivest and Jacob Schuldt. The paper states We have also ...
4
votes
1answer
185 views

How does Random Oracle and Standard Model differ? [duplicate]

I am new to Crypto field. Many papers are boasting of not using Random Oracle model. Instead, those prove security in Standard Model. I am surprised how do these models differ. Can anyone please ...
3
votes
1answer
121 views

Repeatable crypto

Is there a safe way to do crypto that will always produce the same result for a given input? My use case is transferring deltas of huge files, to a backup server. The backup server has no knowledge ...
2
votes
1answer
118 views

Why are some key stretching methods better than others?

I'm trying to understand why some key stretching methods are better than others. The wikipedia article presents 3 different key stretching methods: A collision prone simple key stretching ...
5
votes
2answers
124 views

Choice of authenticated encryption mode for whole messages

There are several well-regarded block cipher modes for authenticated encryption which have made their way into standards and protocols: CCM, EAX, GCM, OCB, … If I am designing a new messaging or ...
5
votes
1answer
81 views

Understanding Genkin-Pipman-Tromer's ground potential, side channel attack on RSA

I'm pretty sure that by now folks might have come across this research from Genkin-Pipman-Tromer (GPT) on extracting the RSA key used by GnuPG (GPG) just by measuring the ground potential. I'm going ...
0
votes
0answers
55 views

Can Bitcoin HD public keys be used for symmetric encryption?

I asked this at bitcoin.stackexchange.com first, but it seems that this is more of a crypto-question anyway. I'm interested in using a Hierarchical Deterministic Bitcoin wallet branch as a "shared ...
0
votes
3answers
83 views

Security of very simple XOR with random? [duplicate]

I am currently trying to implement a very fast and simple encryption algorithm in Lua for the purpose of using it with ComputerCraft. The main problem is that bitwise operations in Lua (5.2 at least) ...
1
vote
1answer
184 views

RSA was rejected by which journal?

Is it true that first time RSA algorithm was rejected by a journal?
3
votes
1answer
55 views

Possible CPA or CCA attack when using AES-CBC mode under the following situation?

Both client and server know a shared key in advance. Both sides us EVP_BytesToKey() derive a pair of same key and same IV. Then, client and server start transferring data encrypted by AES-CBC mode ...
1
vote
1answer
134 views

What's the point of a Meet In The Middle attack using i.e. double AES with throw-away keys?

What's the point of a Meet In The Middle attack while using, for example, a double AES encryption and using one time keys? You can recover the keys for a secret message already known and you can't use ...
1
vote
1answer
40 views

Comparing Difference Distribution Tables

I have been studying the Diff. Cryptanalysis and finding it hard to do a problem. The problem is I have calculated the tables programmatically and found that the second table has a max value of 6 ...
2
votes
1answer
49 views

PBKDF2-SHA256+SHA256 for password storage

I recently came across an interesting paper detailing the use of hardened session cookies. Each cookie includes a preimage of the password hash, and the preimage is hashed once more and compared to ...
4
votes
2answers
85 views

Are variable-length crypto hash functions still susceptible to collisions?

I just recently learned that the SHA-3 finalist Keccak allows for variable length output. As the only answer to this question states, "[it] need to have an output length at least equal to the input ...
3
votes
1answer
67 views

PBKDF2 Salt and Password Ordering

I am currently reading about PBKDF2, and understand that the salt is used only once, while the password is used multiple times in the computation of the final key (see this question). How would the ...
1
vote
0answers
47 views

How to distribute symmetric key between $n$ entities?

If there are $n$ servers for broadcasting a symmetric key in such a manner that following holds: No server alone can find the key $K$ alone. Any two servers can pass $k_i$ and $k_j$ such that ...
3
votes
1answer
64 views

Partial hash code protocol for security tokens providing signatures

I've read the following two sentences within a beta protocol specification, which references ISO/IEC 7816-8 for PSO:HASH which already contains notions of a "partial hash". The off-card entity is ...
1
vote
0answers
44 views

Type G Bilinear Pairings

I was reading PBC and its implementations for finding pairing parameters. I am particularly interested in implementing a BLS signature scheme with 20-byte (160-bit) signatures ("short signatures"). ...
-1
votes
0answers
34 views

What c++ crypto library might I use for XTS mode? [closed]

Ideally, I would like to use crypto++ for it's simplistic and straightforward API. This has so far worked very well in a domain where data needs to be read from / written to at random seek locations: ...
-1
votes
0answers
76 views

why should one use lattice-based systems in travel documents in post- quantum computers era? [closed]

What are the attack algos and complexities to break lattice based systems What is the motivation for using lattice crypto? How does shor's algorithm work exactly? why it has not been used extensively? ...
1
vote
1answer
45 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 ...
0
votes
1answer
127 views
+50

Proof for composed signatures

Assumes that we have 3 signature algorithms, $S^A$ with key pair $(sk^A,pk^A)$, $S^B$ with key pair $(sk^B,pk^B)$,$S^C$ with key pair $(sk^C,pk^C)$. We denote by $\epsilon$, $\epsilon'$ and ...
4
votes
1answer
59 views

OCB and GCM security

Is OCB as secure as GCM or CCM ? Since OCB design is quite different from GCM and CCM, I was wondering if the security properties of these latters are satisfied by OCB, as well. Thank you.
-2
votes
0answers
54 views

Why is composite order bilinear group used for scenarios needing highly secure systems?

Why composite order bilinear group is used for scenarios that need highly secure system compare to prime order bilinear group that used for efficiency? We know that composite order bilinear group are ...
3
votes
1answer
103 views

Proving Non-Existence of ECC Backdoors

In light of the NIST Dual EC DRBG scandal, I was intrigued by a NIST slide (slide 9) that said the two points P and Q can be chosen so that the chooser can prove they don't have a backdoor. This ...
4
votes
1answer
131 views

Is hashing a list of hashes safe?

I have an arbitrary long list of hashes (e.g. git tree hashes), and I'm wondering by how much I am increasing the risk of hash collisions by condensing them into a single hash, like so: ...
-5
votes
4answers
242 views

Found a way to crack AES-128, what now?

I have just found a way to crack AES-128 in a reasonable time (1-2 days). How do I publish and prove this? I remember reading about lots of people who cracked DES and other ciphers but how did they ...

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