# All Questions

18 views

### Blinding value of particular form

I'm working with an implementation that creates a blinding value for RW signatures with the following C++ code: ...
58 views

### Is the inverse of a point on an elliptic curve over $\mathbb{Z}_p$ always in the group?

I'm working on a zero knowledge proof system that uses ECC over $\mathbb{Z}_p$ (currently using NIST P-256 since mbed TLS doesn't support group operations on Curve25519, but the problem should be ...
44 views

### Converting ECC Code from python to Java. Extended Euclidean Algorithm not working. [closed]

I'm in the process of converting a Python program I found for calculating ECDSA public keypairs from a given private key. In this particular case it's on the Bitcoin curve. ...
50 views

### Cryptanalysis of Marvin32

So I am curious about the security analysis of Marvin32, the randomized hash algorithm used in .NET (to prevent hash-table DoS). I found the source code here: ...
174 views

...
43 views

### Are there security issues with adding plaintext length to TLS packets?

I have quite a big problem, because of a software implementation of TLS I had to adapt I had to create something which is now biting me. It all comes down to this: I need to know the length of the ...
66 views

### Sending the next one-time pad key in this one-time pad message? [duplicate]

I am doing a research project on cryptography next year, and I'm really new to cryptography. This isn't some really advanced thing or anything, and I'm just trying to come up with something basic. ...
109 views

### AES-CTR in BouncyCastle with string key, without IV or salt [closed]

Our team is encrypting data using a javascript snippet. My problem is I'm supposed to parse them back in my Java code. I am having troubles identifying parts of the algorithm. The code says it's CTR ...
64 views

### Correctness in Multi-party Computation: Real/Ideal Paradigm in Malicious case

I need to know: 1- What does exactly correctness mean in this context? 2- How is correctness implied in malicious model? 3- If the correctness means " the adversary cannot cause the output to be ...
69 views

### How was the MDS matrix used in AES chosen?

$$\begin{pmatrix}2&3&1&1\\ 1&2&3&1\\ 1&1&2&3\\ 3&1&1&2\end{pmatrix}$$ In the above MDS matrix used in AES encryption, why are the numbers $2$,$3$ and ...
48 views

47 views

### SHACAL-2 vs. AES as underlying block cipher for Secure Hash (aka SHA-256)

The hashing scheme SHA-256 (for instance) is based on Merkle-Damgard construction with the underlying compression function based on the block cipher SHACAL-2 configured in Davies Meyer mode. SHACAL-2 ...
51 views

### RSA: Why must e be relative prime to phi(n) [duplicate]

I've got a question concerning fields used in RSA: Let's use the following symbols for my example: {p,q} = primes {e,n} = public key {d,n] = private key I learnt that an inverse element exists if a ...
115 views

### Encryption of plain text using stream cipher algorithm

We know that in stream cipher algorithms plain text and generated key are Xored byte by byte. Generated key depends on how much plain text there is and on that basis key will generate and plain text ...
36 views

### What is the signifcance of inside threat in “How to Construct Multicast Cryptosystems … Secure Against CCA2”

In How to Construct Multicast Cryptosystems Provably Secure Against Adaptive Chosen Ciphertext Attack, the paper states under preliminaries: We consider the scenario where a single party, called ...
31 views

### Deterministic outputs based on non-connected inputs

I am looking for a one way function that can generate outputs deterministically. However, revealing any of the inputs dont allow the person to generate other inputs. E.g: lets say we have a list of ...
107 views

### Super-simple encryption of short strings

I want to anonymise the initials of experiment participants by giving each a pseudonymic set of initials, by encrypting their true initials. Their initials are only two or three letters in length. ...
67 views

### Are there drawbacks to encrypting data locally before being encrypted in cloud backup (multiple encryption)?

I am planning on backing up my hard drive using a cloud backup service but have become skeptical of the industry based on incidents like these: ...
64 views

### Is there any patent free EC point compression available? If not, should I GPL/LGPL my code?

I'm currently using the BouncyCastle implementation in uncompressed mode, and considering releasing an optimized version of EC code that uses point compression. It appears the only thing limiting me ...
58 views

### How is the MAC or HMAC secret shared with the other party for verification?

I've seen people everywhere say to use a MAC or HMAC with block ciphers. I think I understand the basics, but I'm still not sure how the HMAC secret is distributed so the other party can verify that ...
72 views

### Attribute-based encryption for cloud storage

I'm trying to understand attribute-based encryption schemes. Almost all articles describe that they are designed for cloud storage, but as I understand, almost all computing (encryption & ...
31 views

### Combining cascaded encryption keys into one key

Is there an encryption algorithm where it's possible to combine multiple encryption keys into one, so that: $E_{AB}(Data) = E_A(E_B(Data))$ KeyAB should be computable from KeyA and KeyB, but it must ...
71 views

### Knowing N and a relationship between the 2 prime numbers(p and q) find p and q generated with RSA

Let there be $p$ and $q$, 2 prime numbers for which the following relationship is true: $|p-q| < 2 \cdot N^{1/4}$. The algorithm first generates the prime number $p$, then it generates $q$ close ...
First, some well-known results are as follows. For random variables $X$ and $Y$, we have $$H(X,Y) \leq H(X) + H(Y).$$ The equality is achieved when $X$ and $Y$ are independent. Second, in one-time ...