0
votes
0answers
3 views

Encrypting with CAPI and decrypting with .net RSACryptoServiceProvider

My question is specific to CAPI and RSACryptoServiceProvider in .net. I am using the CryptEncrypt function to encrypt a string. Then I store the result in a binary file and I decrypt the text in ...
1
vote
2answers
28 views

Is there any area where AES-CBC cannot be used ? If so, why ?

I would like to know the domains or specific applications where using AES-CBC is not advised due to any drawbacks like sequential encryption of AES-CBC ?
1
vote
1answer
27 views

Fully Homomorphic Encryption over the Integers - perform an operation on an encrypted data

In Fully Homomorphic Encryption scheme represented here Fully Homomorphic Encryption over the Integers In the Evaluate process (see section “3.1 The Construction” of the paper): $$Evaluate(pk, C, c1, ...
0
votes
0answers
11 views

Deprecation of RSA-SHA-1 in DKIM keys?

I recently noticed that OpenDKIM on my mail server is objecting to DKIM signatures from a client, saying their key is insecure. It may be that that's due to lack of secure DNS (confirmation anyone?) ...
-1
votes
0answers
12 views

Best password authentication process [on hold]

Which one do you think is the best password authentication process and why? Simply Text-based (e.g. upper-case, lower-case, numbers and special characters) Token-based (e.g. pin codes) ...
2
votes
1answer
169 views

What weaknesses in Hash_DRBG did NIST find and fix?

Matthew Green states in the Practical Kleptography presentation (video, at about 12:15) that Hash_DRBG (from SP800-90A) as originally proposed by NSA had potentially exploitable flaws or bugs and that ...
0
votes
0answers
20 views

Protocol for establishing physical ownership of a connected/IoT device?

If I'm connected to a device e.g. using BLE are there rules/protocols for establishing that I'm also in physical possession of that device (at least for the first time I connect to it)? Crypto is in ...
0
votes
1answer
17 views

Are there any relationship between ID-KEM and IBE?

In the $ID-KEM$, the master public key, the user's identity and along with the random number are used to encapsulate, then producing a pair $(C,K)$, it can be denoted as $$(C,K)\gets ...
2
votes
1answer
107 views

Understanding Pseudo Random Generators

I've been taking a crypto course online. I have a good idea how PRG's and Stream Ciphers work, but I'd love to get some input to help visualize what is actually happening. I understand a seed is used, ...
0
votes
2answers
58 views

cryptographic data structure wanted: sparse array without membership test

I would like a data structure supporting two operations: set(k,v), and get(k), with the following properties: k can be any number between 0 and something impressively large, like 2^256-1. If there ...
0
votes
1answer
48 views

Is it possible to find out whether a number is greater than another number without knowing the numbers?

Is it possible to construct a zero knowledge proof that one encrypted number is larger (or not) than another encrypted number without releasing the values of either numbers?
0
votes
0answers
19 views

What kind of encoding is used in these strings? [on hold]

I think this is the BASE64 encoding but decoding by BASE64 returns meaningless chars. Help me to decode this. The value must be 3-digit numbers. Thanks in advance. AAABBXCXMQAAAAAFCZcxAAAAAAA= ...
0
votes
2answers
61 views

Why haven't military-precision channel GPS receivers been hacked yet (like game consoles or Apple devices)?

I wonder what is the encryption scheme in these high-precision encrypted GPS streams (the so-called "P(Y) code". If there's a master key needed, then it has to be in every device. How come the key ...
1
vote
1answer
43 views

Generation of N bit prime numbers -> what is the actual range?

Short version: When generating a prime number of N bits, should I draw random numbers from the range $[0 , 2^n]$, or $[2^{(n-1)} , 2^n]$? Context: I'm trying to implement a toy-version of RSA as a ...
1
vote
1answer
68 views

Using modulus in one time pad?

I would like to know what is the real purpose of using a modulus in the equivalent of a Vernam cipher: Data $d$, large number $M$ Assume the key length is λ bits. Then M could be 2^λ. k is picked ...
3
votes
1answer
125 views

Is appending the hash of the plaintext to the end of an encrypted message sufficient to ensure integrity?

Is appending the hash of the plaintext to the end of an encrypted message sufficient to ensure integrity? My reasoning is that the attacker doesn't know all the plaintext, so by having a hash, the ...
1
vote
0answers
38 views

Forward pseudorandom permutation [on hold]

Please consider the following scenario: The user A and B use their keys, K1 and K2 respectively. Each client have a vector of elements. Each client separately permutes his vector using his key and ...
0
votes
1answer
54 views

Is it possible to hand-negotiate an SSL/TLS session?

I'm interested in trying to hand-negotiate an SSL/TLS session. Similar to how one would use telnet to port 80 and type GET / HTTP/1.1. I know there's a lot of steps ...
0
votes
1answer
50 views

AES Affine Transformation in $GF(2^4)$

in $GF(2^8)$ the AES affine transformation is defined as \begin{equation*} b( x ) = ( x^7 + x^6 + x^2 + x ) + a ( x )( x^7 + x^6 + x^5 + x^4 + 1) mod (x^8 + 1) \end{equation*} where the polynom $( x^7 ...
1
vote
2answers
60 views

Random vs. Fixed Paddings

Is there any consensus (i.e. are there any research results) on the benefits and drawbacks of various padding schemes? Generally there seem to be two kinds of them: random paddings, like ISO10126 ...
-1
votes
0answers
24 views

How to get PrivateKey from byte[] [on hold]

I have a PrivateKey in byte[] format. (Which is internally read from .key file) Now I am trying to get PrivateKey from the byte[] using "EC" algorithm My code snippet: ...
0
votes
1answer
63 views

DES cipher breaking bruteforce method

I was reading upon Biham and shamir's paper and a fact has been presented over there - if $ P1 = \overline P2$ and I choose a key $K1 = \overline K2$ then in that case $$T1 = DES(P1, K1)$$ $$T2 = ...
-1
votes
1answer
29 views

Bouncy Castle elliptic curve from explicit parameters (E-521)

I'd like to use a curve that's not included in the Bouncy Castle EC named curves spec, specifically E-521. According to the BC javadocs, you need a few values in order to do this: q, a, and b for the ...
0
votes
1answer
24 views

For calculating the index of coincidence for each sequence

I was learning about the finding the key length reading the following web site... http://practicalcryptography.com/cryptanalysis/stochastic-searching/cryptanalysis-vigenere-cipher/ and I really don't ...
0
votes
0answers
23 views

Perform general computation using a crypto algorithm as a building block

I have a somewhat special question. In our software we use a existing dongle which got cracked by our customers. The protection offered by the dongle isn't very sophisticated. For the moment I can't ...
0
votes
1answer
36 views

Checking the share membership in secret sharing schemes

I was thinking of this since yesterday. Imagine, a secret is split into its respective shares (using any secret sharing scheme) with threshold $t$ and total $n$. Can we find out given any random ...
1
vote
1answer
57 views

DES Encryption Algorithm all 64 bits for key instead of 56 bits

Would a DES algorithm that uses all 64 bits for the key instead of just the 56 bits be more secure? I have been thinking about it but those 8 bits used for parity are very useful and but including ...
-1
votes
0answers
33 views

https://bitcointalk.org/index.php?topic=790883.0 [on hold]

Can you please do a peer review from a mathematical standpoint of the following thread at the bitcoin forum: https://bitcointalk.org/index.php?topic=790883.0
1
vote
1answer
45 views

How do disk encryption programs solve the “IV problem”?

I was reading a paper on the "elephant diffuser" used in BitLocker and it got me wondering how other systems (e.g. TrueCrypt before it shutdown) solved the problem the elephant diffuser was meant to ...
0
votes
1answer
42 views

Is elliptic curve point multiplication semantically secure?

Is elliptic curve point multiplication semantically secure? I'd like to know if there are some sets of elliptic curve parameters (e.g. NIST curves) that are proved to be semantically secure or that ...
8
votes
1answer
742 views

Why do the elliptic curves recommended by NIST use 521 bits rather than 512?

Wikipedia says in reference to the elliptic curves officially recommended by NIST in FIPS 186-3: Five prime fields for certain primes p of sizes 192, 224, 256, 384, and 521 bits. For each of the ...
2
votes
1answer
23 views

Committing Bilinear equation in Groth-Sahai framework

Groth-Sahai framework enables us to commit to QE, MSME, PP equations. Now, is the equation below committable in GS framework? A bilinear map $e: G_1 \times G_2 \rightarrow G_T$. $g_1 \in G_1$ and ...
0
votes
1answer
24 views

Security properties and Cryptography objectives applied in algorithms

We all know there are five properties of Security. They are: Confidentiality Availability Authorization Integrity and Provenance As Security and Cryptography are co-related these properties ...
2
votes
1answer
39 views

Calculate the security of a cascade cipher

I’m reading “The Security of Multiple Encryption in the Ideal Cipher Model” and I’m having a hard time understanding something. How do I calculate the bounds of cascade cipher from the following ...
1
vote
0answers
39 views

exchanging private key between service and iPhone app - digital signing

I need to do digital signing of my request data which will be sent to the server. My server sends distinct private keys to her clients after authentication and expects all responses to be digitally ...
1
vote
1answer
60 views

AES-128 with weak key

Doing malware research (simple crypto locker) I found out that it uses AES-128 with weak key - every one of the sixteen bytes is represented by (a-z,A-Z,0-9). Thus simple brute-force attack should ...
0
votes
0answers
15 views

Plain cascade and Xor cascade

I have seen in few places (mostly papers) talking about plain cascade and XOR cascade. I know what is cascade cipher is but I am not clear about what these are. Can anyone help to understand using ...
1
vote
0answers
26 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?
0
votes
1answer
73 views

In today's world where is AES-CBC used? [on hold]

I am curious and wanted to know that is there any application to AES-CBC (along with other sub-modes to it like AES-CBC-MAC etc)
7
votes
2answers
936 views

Why is the P-521 elliptic curve not in Suite B if AES-256 is?

In the NSA's document, "The Case for Elliptic Curve Cryptography", we have ...
1
vote
1answer
66 views

Modes of operation for Public Key Encryption schemes

Symmetric key encryption schemes have well defined modes of operations for achieving deterministic (ECB) or Randomized (CBC, OFB, CTR ) etc. and other applications of the same. But are they defined ...
3
votes
3answers
159 views

Ways to make a “doomsday” cryptocurrency which becomes untradable

As a social experiment (not a money-making scheme), I'm interested in developing a crazy cryptocurrency which, by its very design, will become worthless and untradable after a certain point. Ideally, ...
2
votes
1answer
118 views

Why is 224 bit ecdsa faster than 192 bit ecdsa?

I ran several benchmarks using openssl on 2 different computers and I got a surprising result. for the Nist 192 bit curve the benchmark result is ...
-2
votes
0answers
23 views

what is the difference between existential forgery by know message attack and existential forgery by chosen message attack in digital signature?

existential forgery is the attack must create a valid signature on at least one message ,so can i know what is the differences between when they apply on chosen message and known message attack ? I ...
0
votes
1answer
41 views

How can i calculate prime of Elliptic Curve?

In many articles i have found directly the calculation of prime elliptic curve. How can i calculate this prime $p$ ? For example if I consider NIST P-256, $ p = 2^{256}-2^{224}+2^{192}+2^{96}-1$. Why ...
1
vote
0answers
37 views

Does Ciphertext policy ABE support search operation on encrypted data

Basically CP-ABE (or attribute based encryption) allows end-users to encrypt the data with desired access control structure. I was investigating the how to do keyword-search on encrypted data given ...
-3
votes
0answers
32 views

Help me find a relevance in this data [on hold]

I have been given a cryto to solve and my head hearts now so asking for help. Please can someone help me find a link between these the ids of 54189266E4A00760E1008000143C444F etc. MATCH 1 1. ...
4
votes
3answers
347 views

Diffie-Hellman and man-in-the-middle attacks

See here for the man-in-the-middle attack on Diffie-Hellman that I'm concerned about: What is Diffie-Hellman? How do we combat this? I have two questions: Is one solution for both Alice and Bob ...
1
vote
0answers
78 views

Is it feasible to use combination of ABE schemes for encrypting the data?

I have a peculiar requirement for preserving the shared log files. For example I have 1000 records which belong to different organizations as listed below and all the logs are present in a single CSV ...
3
votes
0answers
127 views

reducing false positives in searchable encryption

Practical techniques for searchable encryption proposed by Song et all 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 ...

15 30 50 per page