0
votes
1answer
68 views

Crack RSA with additional information [duplicate]

Suppose $N=3953$, Alice encryption key is $e_A = 337$ and bobs is $e_B=23$. Eve happens to know the corresponding decryption keys, $d_A=3385$ and $d_B=2663$. Can I use this information to find the ...
0
votes
1answer
65 views

ECIES with AES-GCM

The Elliptic Curve Integrated Encryption Scheme (ECIES) describes how to derive a "temporal" key, encrypt a message (eg. using AES) and creating a MAC. However, from my understanding using AES in GCM ...
0
votes
0answers
81 views

Affine transformation in finite field SubBytes

Can anyone please explain how this computation was done? I picked it up from How are the AES S-Boxes calculated? The affine transformation is as follows. The input bits are multiplied against the ...
0
votes
0answers
72 views

Pseudorandom number generators based on hard problems in mathematics

I know that Dual_EC_DRBG's security is based on the ellitpic curve discrete logarithm problem, Micali-Schnorr is based on the difficulty of factorization, and MQ_DRBG is based on multivariate ...
0
votes
1answer
335 views

SHA-512 Length Field - What is it?

If I am using SHA-512 on a message and need to determine the padding field and length field, how do I determine the length field? I think I understand the padding, but not the length field. For ...
0
votes
1answer
66 views

Hashing - Digital Signing and Trivial Stretching

Two very basic questions: 1. Digital Signing Why is it not possible to just simply replace the hash value from the request? Examples: ...
0
votes
1answer
60 views

Is the key deducible with AES CTR when we know about the plaintext, IV and the ciphertext? [duplicate]

Simply as stated, with AES running in CTR mode, can somebody work out the key (without brute-forcing) given we know about the plaintext, IV and also the ciphertext. Assuming we also know about the ...
0
votes
0answers
19 views

Can a tree hash with leaf-size of 1 byte support verification of content with elided ranges, at a cost of at most 2 supplied internal-node hashes?

Perhaps someone can confirm my intuition: A tree hash with leaves of size 1 (for example Blake2 in a tree-hash mode) would of course not be very efficient. But it seems that it might be a suitable ...
0
votes
0answers
81 views

Strategies for securing public key storage on software

I´m kind of new in this so I apologize in advance for any noob mistakes (feel free to point it out) We are developing a licensing mechanism on our software, and I would like some advice. The ...
0
votes
0answers
77 views

Deriving a decryption equation

Consider a very simple symmetric block encryption algorithm, in which 32-bits blocks of plaintext are encrypted using a 64-bit key. Encryption is defined as C = (P⊕KL)⊗KR where C = ciphertext; K = ...
0
votes
1answer
66 views

Self changeable key [closed]

If key changes itself when it send/receive message what would be could breaking method? So: $E: m×k$ in which $k$ is last generated key $D: c×k$ in which $k$ is last generated key $k{_n} = ...
0
votes
0answers
47 views

Key establishment protocols other than Diffie-Hellman

Are there any key agreement/exchange/establishment protocols which are NOT based around the Diffie-Hellman protocol or handshakes using public key cryptograaphy? DH seems to form the basis of this ...
0
votes
0answers
52 views

Security comparison of the following PBE algorithms - PBKDF2WithHmacSHA1 Vs PBEWITHSHA256AND256BITAES-CBC-BC

Which among these conform to the PKCS#5 OR PKCS#12 standards ? Are they JCE compliant - In other words which providers have implemented them in a JCE compliant manner ? How do they fare in terms of ...
0
votes
0answers
48 views

Are Barreto-Naehrig Curves suitable for pairing-based cryptography?

If Barreto-Naehrig Curves are suitable for pairing-based cryptography, can I use the library available at Optimal ATE Pairing?
0
votes
0answers
52 views

How does CTR-ESSIV work ? (cryptsetup Linux)

I'm using Wikipedia and Handbook of Applied Cryptography as references. I know that ESSIV generates an initialization vector (IV) by combining a hashed key with the sector number. However, I only see ...
0
votes
0answers
43 views

RSA algorithm in this doesnt (ever) give right decryption [duplicate]

Lets consider p=47 q=57 msg=3 n=p*q=2679 ф(n)=2576 now e=11, and inverse of e is 1171 modulo ф(n) y=msg^e=333(mod n) ///Encryption y^d=1131(mod n) ///Decryption but this is not original message ...
0
votes
0answers
59 views

compression with codebook and Cryptography

a question about the difference between code book based compression method and key based cryptography. As I know Crypto != Compression. The Shannon said Crypto is try to reduce the information of ...
0
votes
0answers
101 views

Python implementation of a blind signature scheme which doesn't involve RSA

RSA seems a bit creepy after the Snowden revelations and i'm looking for a simple python based blind signature library to fiddle around with. So far i've been unable to find anything. What am i ...
0
votes
0answers
54 views

Decrypt a message which is encrypted using XOR? [duplicate]

This is a puzzle asked in a contest. Given that encryption , decryption happens as per following rule/code: ...
0
votes
0answers
23 views

Kryptos K2 keyword derivation [duplicate]

So I've been doing some reading on Kryptos, and to be honest the keyword for K2, ABSCISSA, has a pretty weak derivation. (The method using the eee's). Isn't there a better way to come to that? I dont ...
0
votes
1answer
65 views

Non-repudiation and digital signature of a dishonest participant

Let's assume a dishonest Alice who sends, encrypts & digital signs a message to Bob. Bob stores the decrypted message and the digital signature in a database. However Alice is a bad girl and ...
0
votes
0answers
25 views

Reducing key shares in Damgård-Dupont threshold RSA

I'm working on understanding and implementing Damgård, I., & Dupont, K. (2005). Efficient Threshold RSA Signatures with General Moduli and No Extra Assumptions. Public Key Cryptography-PKC ...
0
votes
0answers
27 views

Proving the complement property of DES? [duplicate]

I'm trying to show that for a given plaintext (P), key (K), and cipher (C) in the DES algorithm: ...
0
votes
0answers
50 views

Problem in understanding Blakley's Secret Sharing Scheme

I need to implement Blakley's Secret Sharing Scheme. I have read below mentioned two research papers but still unable to understand how to implement it. Safeguarding cryptographic keys Two Matrices ...
0
votes
0answers
44 views

Is signing a message just encrypting it with private key? [duplicate]

I have a simple question, When I sign a message (in RSA) does the program encrypt the text with my private key? Because I can decrypt it with my public key. Yes or no. Is signing a message just ...
0
votes
1answer
34 views

Cipher for human interpretation [duplicate]

Please suggest algorithms to encrypt and decrypt text messages that can be easily performed by human in a considerably short time. It doesn't have to be really secure, but sufficient to fool ...
0
votes
1answer
62 views

Converting a number to a member of a multiplicative cyclic group

I am currently trying to make an implementation of the ElGamal encryption for educational purposes. As I understand it, when using the encryption with multiplicative cyclic groups, one generates a ...
0
votes
0answers
21 views

Data anonymization and search with wild-cards

Broadcast encryption technique proposed by Water et al. http://www.slideserve.com/nairi/revocation-systems-with-very-small-private-keys takes a leap from earlier schemes as it provides smaller user ...
0
votes
0answers
70 views

chameleon signature vs regular signatures

I am trying to understand the practical usage of sanitizable signatures particularly on Chameleon Hashing and Signatures. Chameleon hash, or trapdoor function allow parties with the knowledge of the ...
0
votes
1answer
126 views

Is RC4 +XOR secure for small data?

I need to encrypt transmission between my device (with AVR processor) and base. I create packet data - it will be encrypted into string: ...
0
votes
1answer
38 views

Hiding and Binding key in Groth-Sahai NIZK proof system

In context of Groth-Sahai NIZK proof system, I have a couple of doubts on Hiding and Binding keys. In case of hiding keys (highlighted in red), how is it ensured that $\tau(A) \subseteq \langle ...
0
votes
0answers
121 views

Two questions on EMSA-PKCS1-v1_5

If I implement EMSA-PKCS1-v1_5 in the following two non-standard ways, what kind of things could go wrong? The padding structure will be referred as (00|01|PS|00|DER(Digest Algo)|Digest), where | is ...
0
votes
0answers
40 views

Problems in the results of NIST PNRG suite

I am a beginner in the field of cryptography.I have problems interpreting the NIST (sts-2.1.2) suite results. After running the statistics with 100 samples (each sample of 1000000 byte length) a new ...
0
votes
0answers
84 views

Is ASCON cipher broken?

http://eprint.iacr.org/2015/030 present several attacks of ASCON but does not have a conclusion section. I'm having troubles estimating what are the consequences on the use of ASCON. What's your ...
0
votes
0answers
88 views

How does multi platform encrypted cloud storage work?

I'm really interested in end-to-end encrypted cloud storage and couldn't find out how following scenario could work: A user of a cloud provider which provides zero-knowledge-authentication (like for ...
0
votes
0answers
250 views

Public key encryption and big files with NaCL

I am trying to encrypt big files using NaCL (actually PyNaCL) - see http://nacl.cr.yp.to/box.html After reading some docs, I came up with this prototype : Bob wants to send a big file to Sarah. They ...
0
votes
1answer
68 views

PKI Infrastructure

I've got a very simple but for me a difficult question. I analyzed the public key cryptography and understand the process. But I didn't understand why is only the receiver able to decrypt to message. ...
0
votes
0answers
28 views

How to find the factors of the modulus? [duplicate]

In the article "A Method for Obtaining Digital Signatures and Public-Key Cryptosystems", the original RSA article, it is mentioned that Miller has shown that n (the modulus) can be factored using any ...
0
votes
0answers
67 views

Simplifying the zero-knowledge proof example? [duplicate]

There is this http://en.wikipedia.org/wiki/Zero-knowledge_proof#Abstract_example. Now I'm curious about this. Why is it not possible for Victor to stand at the entrance and watch Peggy take one path ...
0
votes
1answer
43 views

Can one deduce the symmetric key size used to encrypt a given a piece of ciphertext?

Assume an attacker captures a piece of ciphertext encrypted with a symmetric key. He knows all the details of the algorithm used to encrypt except for the size of the key used in this case. Can he ...
0
votes
3answers
78 views

private keys for multiple devices [closed]

I have an architecture where: a user can have multiple devices (phones) the server needs to broadcast the payload to all devices through the same channel (basically, all devices listen and receive ...
0
votes
1answer
47 views

Unique assignment of X.509 certificate to each client

I'm trying to implement a short scale electronic voting application in a domain comprised of no more than 100 clients. System administrator is able to create new election instances and each client is ...
0
votes
0answers
70 views

Are there any known inverse hash lookups for the zero string?

Just wondering, are there any known inverse hashes / hash lookups in common hashes (md5, sha1, sha2, etc.) for the zero string hash value? (i.e. bytes 0x00 00 00 00 00 ...) Or more specifically, for ...
0
votes
0answers
153 views

Variant of the Decisional Bilinear Diffie Hellman problem

I am working on a cryptographic scheme and I need to rely on the following problem, which I have nicknamed the "Hybrid Decisional Bilinear Diffie Hellman (hDBDH)" problem: Let $e: \mathbb G_1 ...
0
votes
1answer
110 views

Split 32-bit LFSR into two 16-bit LFSR which xor to same sequence [duplicate]

Today I was thinking about exactly this. Is it possible, for a 32-bit LFSR e.g. ...
0
votes
1answer
80 views

Is adaptive security the same as full security?

This question contains a great answer about adaptive security, but I haven't yet found a proper definition what full security is. Does a stronger security than adaptive security exist or are the two ...
0
votes
0answers
133 views

RSA - Why should we sign hash rather than raw content? [duplicate]

Apart from obvious performance considerations, is there any mathematical or crypto reasons that imply that we sign a hash rather than a raw content ? I read that it was because the hash must fit in ...
0
votes
0answers
30 views

emulating progressive encryption with RC4 / OpenSSL

PHP's OpenSSL bindings do not support progressive encryption by default. ie. if you do ...
0
votes
0answers
119 views

Preventing Quantum Attacks on Cryptography [duplicate]

With the advancement of technology in quantum computing, it's becoming more evident that we need to start thinking about protecting the future integrity of our cryptographic standards. What can we do ...
0
votes
0answers
47 views

Is basic RSA secure? [duplicate]

I'm pretty new to cryptography, had RSA in my math lectures a few years back and decided to try it myself. I've implemented a rather basic version of RSA using a hash from a passphrase to create the ...

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