1
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0answers
118 views

A fast non-cryptographic hash function that is “strong enough”?

I'm designing a simple one-time-password mechanism for authentication against a possibly-insecure server - i.e. I don't want to use symmetric shared secrets. The first idea that came into mind was ...
1
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0answers
24 views

Cryptography: Oblivious Transfer with at most one transfer?

I am trying find a transfer method for this problem. Suppose Alice and Bob both has access to a function F with two parameters. Func(x,y) randomly returns "p" to alice and "q" to Bob such that x*y=p ...
1
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0answers
32 views

byte length and offset for k3d3/ed25519 byte[] variables?

I've discovered for myself that java's BigInteger is very slow, so I'm trying to weakly optimize this java implementation of ed25519 which I will fork and post if ...
1
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0answers
94 views

Rabin code same message sent with different $N$

I use Rabin code with modulus $N$. Now assume that Alice sends me a message $m$ $(1\le m\le N)$ encoded by Rabin code. Unfortunately after Alice sent me the text I lose the information about the ...
1
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0answers
69 views

Which is better ECDHE with TLS 1.0

I have a webserver which support only TLS 1.0 Which is the better cipher in this group for the best security? ...
1
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0answers
79 views

Distributed integer factorization?

I'm looking around for publicly published work on factorization of large numbers using distributed systems of any kind. So far I've come across the PDF "Mapreduce for integer factorization" by Javier ...
1
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0answers
76 views

Computing IV for CBC from PBKDF2 + HKDF

Note that this question is somewhat similar to Can I use my random IV (for AES) as a salt for PBKDF2? My current encryption format computes two random PBKDF2 salts (encryption and HMAC, 8 bytes each) ...
1
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0answers
61 views

Is allowing a user to specify a Curve25519 signing key secure?

The cryptocurrency Nextcoin has users create Curve25519 signing keys with a minimum length of 70 characters. Is that secure? Would it be better to use a random number generator? Is it possible to ...
1
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0answers
46 views

Is this the proper way to generate an Ed25519 signing key? If not, how?

In the test of this Java implementation of Ed25519, the signing key is generated this way: byte[] sk = new byte[32]; Arrays.fill(sk, (byte)0); Is that correct? ...
1
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0answers
93 views

Can you show how that RSA does/doesn't provide anonymity?

Considering a CPA-secure version of RSA where the ciphertext is just a rundom element from $Z^*_N$. Does that meet the anonymity requirement in which an cpa adversary cannot distinguish between a ...
1
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0answers
147 views

Random Number Generation with a Entropy pool versus Seed

To give a little background I'm currently implementing a crypto library in JavaScript. I have started porting across Linux's random number generator because its both publicly scrutinized, it is ...
1
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0answers
51 views

When do I need to renew keys for Salsa20 or HMAC?

I currently have a system which uses two keys sourced from a single key subjected to HKDF. One key is used in the Salsa20 stream ...
1
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0answers
104 views

Pohlig-Hellman exponentiation block cipher

Let $G$ be a group of order $n$ and let $e,d$ be integers such that $ed\equiv 1 \pmod{n}$. Then the exponentiation maps $x \mapsto x^e$ and $y \mapsto y^d$ are inverse maps on $G$. These maps give us ...
1
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0answers
74 views

Is it possible to modify SSL handshakes to enable PFS while still using RSA during the handshake?

I know we could possibly be using DH key exchange, that would enable PFS. However, what if we make modifications on our SSL 3.0 handshake such that the only cipher we use is RSA for the achieving PFS? ...
1
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0answers
94 views

Where can I find examples of ECC implemented in VHDL?

I am looking into implementing ECDSA signature and ECDH key agreement in a Xilinx FPGA. All the examples I have found of VHDL implementations skip over how to construct the low level ECC primitives ...
1
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0answers
58 views

Can you provide an example in relation to Hidden Field Equations Multivariate?

I'm reading about Hidden Field Equations Multivariate scheme. My lecture states that the central map is a univariate polynomial $$P(X)=\sum_{i=0}^{r-1}\sum_{j=0}^{r-1}p_{ij}x^{q^i+q^j} \in K[X]$$ ...
1
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0answers
95 views

Is there any analysis of freebsd's “geli” encrypted geometry provider?

I've done a few obvious searches on google and google scholar and not turned up any security analysis of FreeBSD's geli. Is there some out there, or has it gone unanalyzed since its introduction ...
1
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0answers
157 views

What is the chance of a collision when using SHA-3?

I currently am writing a web app and am using two random hashes that are before and after the string and are both 50 char long (alphabet, numbers, and special chars). ...
1
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0answers
89 views

$\phi$ function in Dual_EC_DRBG

I am trying to understand the operation of the Dual_EC_DRBG. I'm reading the formal specification (SP 800-90) and can't seem to find a definition of the $\phi$ function used throughout the definition ...
1
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0answers
141 views

How good is the RandomPool generator in Crypto++ library?

How good is the RandomPool generator in Crypto++ library? I never heard of it before… I wonder if there is a Fortuna C implementation that I could use in an Objective-C project. Also: How secure is ...
1
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0answers
65 views

How can user privacy be preserved in certificateless cryptography?

In certificateless cryptography, how can a user preserve his privacy from Key Generation Center? If the KGC becomes malicious, how can the user's privacy be preserved? I read "Privacy-Preserving ...
1
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0answers
35 views

TCR hash functions from MD5

I'm reading Collision-Resistant Hashing: Towards Making UOWHFs Practical (pag. 10 and 11) and here say The most direct way to construct a TCR hash function is to key a function like MD5 or SHA-1. ...
1
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0answers
108 views

Design requirements for a keyed hash function?

I am actually preparing for a cryptography exam, and I found a question asked by the professor in the class, below are the lines that I copied from the slide : Example: Let $Ek$ be the encryption ...
1
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0answers
115 views

Best group if one wants the discrete log problem to be hard?

Suppose one is implementing a cryptographic scheme over a group where one needs the discrete logarithm to be hard - what is the recommended group to use? I'm looking for a group where calculations are ...
1
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0answers
68 views

Generating a valid signature on El-Gamal without knowing the private key

Suppose we are given $p$, the large prime, $g$ which is the primitive root for $p$, $b$ which is calculated as $b=g^x$ mod $p$ where $x$ is the private key and $0<x<p-1$. Also suppose we know ...
1
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0answers
93 views

What scheme will allow merging and splitting the result of a function?

I am wondering if it's possible to have a scheme as follows. Here is the scenario: we have a set of objects (e.g. strings) {O1, O2, ..., On} we have a set of users {U1, U2, ..., Um} each user asks ...
1
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0answers
83 views

Could MITM securely identify identity?

Consider protocol like QUIC or MinimaLT which are essentially layer4 replacement for TCP/UDP (riding on top of UDP currently because of fear of random firewalls dropping new L4 protocol). From crypto ...
1
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0answers
36 views

MD Construction Doesn't Propagate TCR

I'm reading a proof of the proposition of CollisionResistant Hashing Towards Making UOWHFs Practical Suppose there exists a compression function $F: \Sigma^k\times\Sigma^{c+m'} \rightarrow ...
1
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0answers
54 views

Perfect Forward Secrecy in MTI/A0

Would the property of perfect forward secrecy still be achieved in MTI/A0 for a session key that was established between C and D when one LL-key aD is revealed so that both LL-keys aC and aD are ...
1
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0answers
126 views

About Elliptic Curve ElGamal, 3 simple problems I have trouble with

In Elliptic Curve ElGamal, why are a=b=1 always legal for primes whose lengths are no shorter than 11(2) bits long? Is there any reason why the Point at Infinity can always be encoded as (0,0)? ...
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0answers
161 views

Factoring large numbers

I am trying to factor few integers that are each between 115 and 135 digits long. I have just, little over a month ago, began my study of Cryptography. I was wondering if anyone knew of any efficient ...
1
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0answers
112 views

How to develop a public key cryptosystem based on a hard problem?

Recently, I found a function that is performed on a sequence to return another sequence. All known algorithms for finding the input, given the output are of exponential complexity. I want to propose ...
1
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0answers
45 views

Can you help me understand this strange implication direction in security reduction for OAEP 3-round?

I'm reading the paper OAEP 3-round, where they introduce a 3-round version of the OAEP (which originally used only two rounds). However, in their security statement for this construction (Theorem 4 ...
1
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0answers
104 views

Can keys from Bitcoin's Hierarchical Deterministic Wallets be correlated (reducing privacy)?

I'm trying to understand if the feature "Hierarchical Deterministic Wallets" in Bitcoin allows for complete privacy of all derived keys, and if any of those keys can be associated with each other ...
1
vote
0answers
138 views

Diffie-Hellman exchange

So for a Diffie-Hellman problem, I am given the prime $p$ for the Diffie-Hellman exchange. I am also given $g$, secret number for machine as $A$, secret number for station as $B$, a Diffie-Hellman ...
1
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0answers
59 views

Partial encryption of a file?

I want to partially encrypt a large block of data using AES. Meaning: given plaintext[0:1100], I would like to encrypt ...
1
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0answers
125 views

PGP encryption options

I recently began using PGP desktop and found several options for my encryption capabilities. Which of these (AES, Cast, Triple DES, TwoFish, IDEA) is the most recent, firstly, secondly may the NSA not ...
1
vote
0answers
192 views

Does BouncyCastle (for ECC) resist timing attacks?

I need to extend the TLS protocol to be able to use other key exchange scheme based on elliptic curves. I am planning to use BouncyCastle's implementation in Java and in .NET. I am worring about ...
1
vote
0answers
456 views

Decrypting a message without the private key using CRT

I am given 5 different encryption modulus, $N$, each ranging from 78 to 88 numbers long. Then for the encryption exponent, each has the same which is 5. Then I am given 5 different encrypted messages, ...
1
vote
0answers
217 views

Understanding elliptic curve encryption

I'm having a hard time understanding the elliptic curve encryption. One thing thing I don't understand is listing all the points on the curve (mod p). Suppose I have the following elliptic curve: y^2 ...
1
vote
0answers
126 views

How to perform benchmark of block/stream ciphers?

I would like to perform some benchmarking of different block and stream ciphers for general data (lossless and lossy data) encryption and decryption (with focus on power consumption). To get general ...
1
vote
0answers
49 views

How does Dissent protect against Sybil Attacks?

Dissent claims to be able to be resistant to Sybil attacks. Dissent seeks to offer accountable anonymity, giving users strong guarantees of anonymity while also protecting online groups or forums ...
1
vote
0answers
56 views

Can you help me understand this “Message Modification by Meet-in-the-Middle” related to Tiger Hash?

I found this paper that explains how to attack a reduced round tiger hash, but I'm having a hard time understanding some of the mathematical notation. Could someone explain the section "Message ...
1
vote
0answers
230 views

RSA Attack with some known values

There is an RSA implementation which I need to attack to get the encrypted messages. Some of the values are known. Plain text value for input. So if I enter a message, say it "A", the plain text is ...
1
vote
0answers
66 views

LogSpace Merkle Traversal

I am studying LogSpace Merkle Tree Traversal algorithm in "Post Quantum Cryptography". I don't understand the Table 1 on page 58. My question is: Why within of the $2^h$ rounds for $NEED_h$ exist ...
1
vote
0answers
114 views

Can anyone explain most popular RSA attacks like I'm 5?

Suppose I implement RSA myself in C and I use just the formulas from number theory. What attacks would my implementation be vulnerable to? Can anyone explain this to me like I'm 5?
1
vote
0answers
141 views

Can you help me clear a confusion about small subgroup attack on HMQV?

First,i want to show you with a picture how the HMQV works. There are some notations you might not familiar, it doesn't matter. I just want to show you the procedure. Next it's an attack on HMQV ...
1
vote
0answers
139 views

IV and Headers inside cipher text

I am a bit confused about the use of IV, and key hash. Is the key hash and IV stored inside the headers of the cipher text? Isn't it a security risk to store this header information? By key hash I ...
1
vote
0answers
87 views

Merkle path authentication

In point 4 of the Algorithm 4.2 (Classic Merkle Tree Traversal) of *"Post_Quantum_Cryptography.pdf"* shows *"Stack_h.update(2)"* each stack receives two updates. I am trying understand to understand ...
1
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0answers
88 views

openssl logs showing keyblock length of only 88 bytes instead of 136 bytes

I was decrypting TLS encrypted data from wireshark using the openssl(TLS1.0 version) TLS logs which provides the complete key block which of size 136 bytes.Now i moved to TLS(1.2 version) in that Key ...

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