# All Questions

1answer
42 views

### At what point does passphrase strength match the strength of the cipher?

Let's say that I have an ordinary hard drive encrypted with VeraCrypt 1.0e full disk encryption and implementing: -AES -RIPEMD-160 Hash Algorithm Now let's say that for an arbitrary machine, the ...
0answers
40 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 ...
0answers
49 views

### RSA or Paillier is good? [closed]

I want to implement file storage in cloud using homomorphic encryption. I want to use paillier encryption. Can you suggest the drawback of RSA to store and retrieving the files. Then only i can use ...
0answers
27 views

### S-Boxes and SP-Network

I work on an exercise and I have to study functions as : $f : \mathbb{F}_q \rightarrow \mathbb{F}_q$ with $q = 2^n$ which can define a S-Box for SP-Networks. There is a question that I can't answer ...
1answer
152 views

### 2048-bit RSA Decryption

Im in need of help with this study question. I heard that there was some relation between small a's and b's and being able to do a trick but I cant find where I read it in my book. Could someone help ...
0answers
27 views

### Linear Code - Hamming - Finding nearest vector

I am studying for my finals and I have a review problem I can't solve. For purpose of doing this problem by myself, I'll leave out certain details. So this is concerning Hamming distance I suppose. ...
1answer
66 views

### rotational cryptanalysis on modulo multiplication?

I saw the paper 'Rotational Cryptanalysis of ARX', it is effective against design primitives using XOR, addition, and rotation. http://www.iacr.org/archive/fse2010/61470339/61470339.pdf However ...
0answers
60 views

### How many bits should my random number be if I used 2048 bits to create my RSA key [closed]

I am using pyCrypto's RSA module/library and have created an public/private key using 2048 random bits from a hwrng. I then want a person/computer who has the public key to generate a random bit ...
1answer
78 views

### Probability of factoring keys as a function of bit length

kinda new here, I had a question pertaining to someone being able to factor one's RSA keys through the GCD. Anyways the question goes that there are two people: A and B. A makes his/her private key as ...
3answers
84 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 ...
0answers
14 views

### What is the best resource to learn completely about cryptography in iOS / Objective c? [closed]

Provide me the best resource to learn about cryptography in iOS / Objective c?
0answers
32 views

1answer
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2answers
106 views

### Memory-expensive hash from an array of hashes?

Why can't people make a hash function that requires dozens of mega bytes of memory instead of cpu to avoid all the cracking and hacking? What I have in mind myself is this: We have an input $X$, we ...
1answer
28 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 ...
1answer
105 views

### Is the salt used with PBKDF2 secret?

I have two network endpoints that need to use the same derived key. Can the server send the salt to the client 'in the clear'?
1answer
42 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 ...
4answers
190 views

### SHA1 Collisions - what about practical attacks?

I understand the theorical problem with hash collision but when it comes to practice, I get very confused. Suppose a attacker would like to forge a certificate (or any kind of strucutred piece of ...
1answer
115 views

### Secure double encryption using CPA and CCA

Do you mind if you give me any hints, links or ideas about how to improve the security of double regular encryption and decryption, by using CPA game and CCA game, it sounds interesting question, and ...
1answer
81 views

### Is any group of bits in a SHA-1 hash more/less unique than another?

Is there any bias in certain parts of the hash? E.g., first n bits are more/less unique than the last/middle n bits? Is there ...

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