0
votes
1answer
3 views

Using HMAC SHA256 to protect payment files in local trusted network

in a project that I am working on we have been tasked with eliminating PGP while providing sufficient security to protect payment files only within the Company's trusted network. We arrived at HMAC ...
0
votes
1answer
17 views

Applying DES twice to give 57 bits?

Given two 56bit keys, k1 and k2, why does Ek1(Ek2(M)) only give 57 bits of security? So basically im unsure why it only gives 57 bits of security, i understand that one key will provide 56 bits. Only ...
2
votes
1answer
10 views

Is MCrypt's 8-bit OFB mode secure?

I just stumbled across a Stack Overflow post which points out that the libmcrypt library (notably used in PHP) implements a somewhat unusual set of block cipher modes: it calls the usual CFB and OFB ...
-1
votes
1answer
13 views

Retrieve value of private key after encryption with the public key

Is there a way to find an RSA private key after it is encrypted with the corresponding public key? Does there exist an algorithm to recover the private key in this special case?
-2
votes
0answers
20 views

Need urgent help solving a riddle [on hold]

We got this riddle during a contest. This code requires 36 characters to be used: a->z AND 0->9. Can you solve it? hacgp6by68astytga5azagndca8jopc Need help solving it.
-2
votes
0answers
14 views

suitable method for encryption and decryption

I want to encrypt and store important data in mysql so that no one else can access its original form and I want to decrypt those data whenever required. Which encryption scheme is suitable for this ...
0
votes
0answers
24 views

What are the links between Cryptography and Algebraic Topology?

I have asked "What are application of Cryptography in Algebraic Topology". But I want to know whether are there any relation between Algebraic Topology and Cryptography. Are there any application of ...
-2
votes
0answers
12 views

Unlock my ZipCrypto deflate

Can anyone help me I have forgot my password for my file.. ZipCrypto deflate. I need a software to unlock the file. Please anyone assist me on this matter
1
vote
2answers
69 views

How does SafeNet MobilePASS generate passwords? (TOTP Variant)

This question is similar to How does SafeNet MobilePASS generate passwords? The question and answer there is related to the HMAC Variant of SafeNet Mobilepass. I'm looking for details on the TOTP ...
5
votes
1answer
757 views

What are the constraints for an IV using AES in CBC mode?

I'm designing a protocol for use into a VPN software. The VPN frames are encapsulated into AES-256 CBC encrypted frames. I understand that IVs must be uniquely used for each message encrypted with ...
18
votes
1answer
28k views

What is safer: ZipCrypto or AES-256?

Like in title: which one of these encryption methods (ZipCrypto, AES-256) is more secure and why? I am asking about it because I'd like to know which should be preferred when compressing files with ...
1
vote
1answer
105 views

Is there a need to encrypt data when send over https? [closed]

I was monitoring web traffic from my Android mobile using Man in the middle proxy. I installed certificate signed from my server in my mobile and I could see all applications sending sensitive ...
4
votes
2answers
203 views

Given a message and signature, find a public key that makes the signature valid (ECDSA)

This question is a variant on Given a message and signature, find a public key that makes the signature valid, which discusses the analogous question for RSA. It was suggested to me by this post over ...
-1
votes
1answer
32 views

What does L_n is the bit length of the group order n states need for my calculation in ECDSA algorithm?

I am doing the program of implementing ECDSA for which I am trying to solve the equation scenario. In ECDSA that signature generation algorithm which states as hash value from the SHA-1 and where $l$ ...
0
votes
1answer
19 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 ...
1
vote
0answers
99 views

Is chaotic encryption secure?

I know this sounds too broad. But I noticed that there was a chapter on chaotic crypto in the recent Handbook of Information and Communication Security Editors: Stavroulakis, Peter, Stamp, Mark (Eds.) ...
2
votes
1answer
44 views

Key space vs Cardinality of 1024-bit RSA

I have been trying to figure out the encryption key space, and cardinality of 1024-bit RSA. From my understanding, the key generated from 1024-bit will be primes greater than $2^{1023}$ but less than ...
0
votes
1answer
24 views

nonce of AES-GCM in SSL

It seems that the nonce of AES-GCM in SSL has 3 parts: salt, 4 bytes, generated in handshake, not changed in whole session nonce_explicit, 8 bytes, chosen by the sender and carried in each SSL ...
1
vote
1answer
48 views

Attribute-based broadcast encryption with respect to ABE

What is the exact difference between attribute-based encryption (ABE) and attribute-based broadcast encryption (ABBE)? Is ABBE equivalent to broadcast encryption on top of ABE?
0
votes
1answer
40 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 ...
1
vote
1answer
43 views

Vigenère, auto-correlation vs Kasiski examination

What are the differences between 'Kasiski examination' and 'auto-correlation' ? In Cryptool site, they state that autocorrelation analysis is more efficient and clearer than the Friedman or Kasiski ...
0
votes
0answers
40 views

What are application of Cryptography in Algebraic Topology [on hold]

What are application of Cryptography in Algebraic Topology, specially in Category theory?
5
votes
3answers
126 views
+50

Fault-based transition for crypto proof (a la Shoup) with big probability of fault - does it work?

background In [Shoup2004], Victor Shoup synthesizes the 'sequence of games' technique for proving security properties: Roughly it consists in a sequence from game_0 to game_n, game_0 consisting in ...
1
vote
1answer
36 views

Is authentication length always a subset of encryption length?

Do in all the use cases, if I have to encrypt and authenticate, encrypt-then-authenticate or authenticate-then-encrypt, like in IPSEC, SSL or SSH or others, if I were to do these operations to a ...
0
votes
1answer
31 views

What type of encryption is this? [on hold]

I need to know what type of encrpytion is this, ed6467d63c907d220447b00bf875e4e017702ff5
0
votes
1answer
50 views

Prove there is PRG that is not necessarily one-to-one

We assume that there is at least one PRG .Now prove there is a PRG like $G:\{0,1\}^{n} \rightarrow \{0,1\}^{l(n)} $ such that it is not necessarily one-to-one.
0
votes
1answer
38 views

Integrity compromised - HASH modified

As we are all aware that HASHing is user to verify integrity in cryptography. I have a query about hashing. Suppose a man in the middle attacker manipulates the data and creates new HASH (by running ...
0
votes
0answers
36 views

encryption key ends with same pattern [on hold]

We have used "AES algorithm".key length is 256 bit.It is using same secret key to generate multiple encryption key.ALL encryption key ends with same pattern.What is the reason for this.transformation ...
10
votes
3answers
613 views

How Brittle Are LCG-Cracking Techniques?

There are published techniques for cracking LCGs, but to my eye those techniques seem very brittle — very minor changes can add nonlinearity that renders techniques like the LLL algorithm unusable. ...
3
votes
1answer
79 views

Build set with PKI from reliable broadcast / random beacon

I am trying to build a protocol (or find an existing one) for creating a set $S_2$ with PKI from a set of parties $S_1$ that initially does not know anything about the other parties. We assume ...
0
votes
1answer
42 views

Are keys generated by the user or block cipher algorithms themselves? [on hold]

We know block cipher algorithms. In the block cipher algorithms, Key Scheduling is the one crucial part. I see that in some simulation programs of the AES,DES,TripleDES encryption algorithms. In ...
0
votes
1answer
38 views

How do I control an access code safely?

Upon registration an user has to specify an access code of five digits. This access code is also used as a password for the encryption and decryption of certain strings. The user types in "12345" ...
0
votes
1answer
46 views

Finding Vignere Cipher key

I am new to cryptography and I am just trying to find key for random text. Can please explain the easy way how we can find the key in small number of steps ? if we have text like Peit Wokm! Mhfa ...
5
votes
2answers
73 views

What is a Key Derivation Function?

From Wikipedia: In cryptography, a key derivation function (or KDF) derives one or more secret keys from a secret value such as a master key or other known information such as a password or ...
0
votes
0answers
41 views

Why is the call to RSA_generate_key_ex() failing sometimes? [on hold]

I'm trying to randomly generate a pair of RSA asymmetric keys, however with my current implementation, the RSA_generate_key_ex() method seems to hang forever. I'm unable to extract an error code ...
-3
votes
0answers
50 views

Is there any method to avoid the differential cryptanalysis? [on hold]

May I know the Best ways to avoid the Differential Attack in block cipher algorithms (AES,Speck,Simon etc). The probability of differential cryptanalysis is achieved mostly equal to 1 in speck light ...
4
votes
3answers
425 views

Is this a good entropy collector and whitening technique?

I'm just reviewing a program someone wrote to provide high quality random data using an entropy collector and a hash based whitening technique. I'll try summarize the process: Collect entropy from ...
0
votes
2answers
45 views

Fortuna: why are source ID and data length added together with entropy data into the pools

Section 9.5.6 of Cryptography Engineering states that The concatenation [of source number, length of data, and data itself] is then appended to the pool. Why are we including source number and ...
3
votes
1answer
45 views

dh parameters someone else generated

Am am auditing some software that includes compiled in DH parameters (2048 bits). I can't be sure who generated the DH parameters or how they were generated. Question: Can DH parameters be weak ...
0
votes
0answers
18 views

Does it make sense to have multiple values of authentication and cipher offsets while encrypting a packet?

Consider a packet with N segments. cofsset(cipher offset - from where one must cipher) lies in arbitrary Segment "A". aoffset (authentication offset - from where one must authenticate) lies in ...
0
votes
1answer
42 views
0
votes
0answers
18 views

EC based password authenticated key exchange protocol

I would like to know: What is the currently best (efficiency and security wise) known EC based password authenticated key exchange protocol? (i.e. is there any EC based protocol may be similar to DH ...
0
votes
0answers
49 views

Popularity of ECMQV authenticated key agreement protocol

I've got a few ECMQV related questions: Why is ECMQV a more efficient EC-based authenticated key agreement protocol? Why is ECMQV so popular? Is it because no other protocol of its strength exists? ...
-1
votes
0answers
51 views

can you attack to this protocol? [on hold]

can you attack to this protocol? ‎$ ‎A‎\rightarrow{B}‎‎\quad:\ P{_B(r_1,A)}‎\\A‎\leftarrow‎{B}\quad:\ P{_A(r_1,r_2)}\\A‎\rightarrow‎{B}\quad:\ r_2‎$ ‎$P_A,P_B\ are\ public\ keys\ and\ r_1,r_2\ are\ ...
0
votes
1answer
71 views

SSL / TLS digital signature exchange

If server is sending its digital signature, in which message / where does the digitally signature is provided to the client. Is it after the server_hello message because there the public key of the ...
4
votes
3answers
87 views

Is there a way to use bcrypt with passwords longer than 72 bytes securely?

From my understanding BCrypt truncates the password to 72 bytes. If a password is longer than 72 bytes, what is a way to store that password using bcrypt securely without compromising it? Or is this ...
0
votes
1answer
30 views

Why perfect secrecy can be ensured when a plain message and a cipher-text based on one-time pad are correlated?

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 ...
22
votes
2answers
3k views
0
votes
0answers
15 views

Website Certificate with different public key [migrated]

I've installed a ssl certificate from https://www.startssl.com/ in a server running with plesk. The website is the following: https://refood.sal-pimenta.pt/ As you can see the certificate is fine but ...

15 30 50 per page