instruction stringlengths 32 27.2k |
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This is about the new W3 WebcryptoAPI draft standard.
Here is a post by one of it's authors
https://plus.google.com/u/0/105761279104103278252/posts/CSwVZ1RUijo
It says its in part trying to change the "Javascript Cryptography Considered Hamrful" problem. However if you look at the "Javascript Cryptography Considered H... |
I am using tree hash mode of Skein on a 16 core processor. Will it automatically employ parallelism using more than one cores or do I have to use multi-threading within the tree hash for parallel processing?
Also, the tree hash mode requires three parameters: leaf size encoding, fan-out encoding and tree height. Except... |
I would like to ask for a clear (but maybe not so deep) explanation of what the term "perfect secrecy" means.
As far as I have researched and understood, it has to do with probabilities of assuming that a certain variable will be the key for a certain cipher text. And unless I'm confusing some concepts, the one-time pa... |
From what I've found, it is generally accepted a cryptographic hash function like SHA-2 has an evenly, randomly distributed output. Is there a way to test this without running through the entire 2^512 keyspace? Generate a large number of high-quality 512 bit random numbers? What about random 64 character "keyboard a... |
I found this example online:
In the elliptic curve group defined by
$$y^2 = x^3 + 9x + 17 \quad \text{over } \mathbb{F}_{23},$$
what is the discrete logarithm $k$ of $Q = (4,5)$ to the base $P = (16,5)$?
One (naïve) way to find k is to compute multiples of $P$ until $Q$ is found.
The first few multiples of $... |
is this RSA private key valid?
First, here's the RSA private key in question:
-----BEGIN RSA PRIVATE KEY-----
MIICXwKBAQACgYDDlegCjkr+Fwf48IVDJimiQdYrpDbrlyMazVeP88ELQLQrTUp/
BrCeC82CUFOyjjbuJagixYsuHhgueS3g/NXrR7XulWBjE2BruSeek8hmK+Ch+jzu
SMT+WbFIiUDHfJoERUHF02nJ12vFSuJ435/4+7vr/7zAo2M2E76et7a92wKBAwEA
AQKBgKuL7kVfnPM... |
I've been trying to understand cryptographic protocols and how to define their security. The problem is that while I can understand what the intuitive definition says, I have trouble understanding how this can be rigorously defined in terms of mathematics. In other words, how do we get a definition that can be used in ... |
I am working on application that allows users to upload files containing company data and then share those files with a list of other users that have specific roles within the system.
I want to encrypt the uploaded files to protect the data at rest while allowing the files to be shared by people who do not know the en... |
A good block cipher e.g. AES running in counter mode is commonly considered to be secure. Assuming a perfectly random key, one could in this case from $128$ bits generate up to $2^{128}·128$ bits for stream encryption.
However, these bits could evidently have only $1/(2^{128})$ bit of entropy each on the average. Isn't... |
I need an encryption algorithm that works fast on large files and doesn't increase the file size. It should use a key to encrypt/decrypt data. The files will be sent using REST and over HTTPS, but a good encryption/decryption method with a key is mandatory (to be used in a website).
The files will be saved on a 3rd par... |
I would like to use unpadded RSA for homomorphic encryption in a toy P2P game, for things like fair coin flips and shuffling.
How many bits of security does unpadded RSA have, in relation to its key size?
|
When you send an email using PGP to encrypt emails, is the recipients public key used to encrypt the email, or is your private key used? Are they both used?
At what points do each of the four keys from the two key pairs get used?
|
The standard CSP on Windows XP only supports RSA up to 512-bit, which means that it's the maximum key size I can use for authenticity verification of updates. The public key is embedded in the updater, and the update files are signed with the private key, using SHA256.
I know that RSA-768 was factored back in 2010, whi... |
I've just been reading up on Shor's algorithm, and I find it both fascinating and baffling. I don't understand much about it, other than that it can factor semiprimes in polynomial time.
Could someone explain how it works in layman's terms and why it is reliant on quantum computing?
Keep in mind that while I understand... |
The Enigma algorithm is a encryption method that was developed (I believe) by the Germans in WWII. It went a little something like this:
When a letter was typed on the keyboard of the Enigma machine, it was first sent through the first rotor, which would shift the letter according to its present setting. The new lette... |
Cycles per byte seems to be a critical concern in designing and choosing stream ciphers. For example, from Wikipedia, RC4 has 7 cycles/byte on original Pentium chips.
How is this calculated? Do they just time the encryption of multiple megabytes and then divide by the CPU's clock speed? Do they look at the assembly cod... |
FIPS 180-3 defines the initial hash value for SHA-256 as the first 32 bits of the fractional parts of the square roots of the first 8 primes 2..19. What would be the risks of using a different value (for example: a random salt)? Conceptually, this would be the same as prepending the message with a block which hashed ... |
NIST Special Publication 800-57 defines a cryptoperiod as
the time span during which a specific key is authorized for use by legitimate entities, or the keys for a given system will remain in effect. A suitably defined cryptoperiod:
Limits the amount of information protected by a given key that is available for cryp... |
Say if I have a given pseudorandom generator G which takes a k-bit input and outputs a 3k-bit number.
How should I show that a specific construction using this pseudorandom generator is valid?
For example, if I want a generator which takes a 2k-bit input and output a 3k-bit number. Is the following scheme valid?
1. spl... |
I have a file, which was encrypted with AES-128 in ECB mode. I know the format of the original file and know that all files in this format have the same headers. So, I have an encrypted block and the original block.
Can I get the encryption key, using this information?
|
It is accepted that the javascript library lacks the ability to create an adequate PRNG. My understanding that this was mainly due to the limits of a sandboxed browser enviroment that javascript resides in.
Is this correct? Can server side javascript generate provably secure cryptography due to system wide access?
I ha... |
I need to build a system that stores encrypted transactions. Transaction involves always two parties. Payer and payee. Both must be able to download encrypted transaction from server and decrypt it using their own private key. And likewise issuing transaction must be possible by either one just by knowing both's public... |
There are elliptic curve variants of Diffie-Hellman, ElGamal, DSA and possibly other protocols/algorithms. I know that these elliptic curve variants have smaller key and ciphertext sizes which will make communications (or storage) more efficient.
Are there other advantages to the elliptic curve variants of these stan... |
I am trying to derive equations for s and t in the cryptanalysis of a Simple DES algorithm, but I haven't been able to deduce it. I have attached an image of the portion that I'm referring to, and I would appreciate it if someone could explain as to how the equations q and r are derived and what would be the derivation... |
What are the main differences between a nonce, a key and an IV? Without any doubt the key should be kept secret. But what about the nonce and the IV? What's the main difference between them and their purposes? Is it only that, in literature and in practice, an IV is being used as "initiator" of a block cipher encryptio... |
According to the wiki article on the RSA encryption function, the valid range of input $m$ is $0 \leq m \lt n$. However I have found that the following values of $m$ always return themselves when encrypted:
$0$
$1$
$n - 1$
$n - 2$
Have I implemented the algorithm incorrectly or am I misreading the wiki article?
|
Yesterday I was thinking about elliptic curve variants of popular protocols/algorithms (ECDH, ECES[1], etc) and the thought occured that I had never seen an elliptic curve variant of RSA. My understanding of RSA and elliptic curves told me that it should be possible.
After some searching I found the following explanati... |
I'm able to find a lot of scattered papers on the development of mental poker since RSA proposed the initial solution but no recent report (i.e. after 2005) on what is the status of the problem, eg:
What are the remaining open problems/challenges?
Can we call it solved? For example, has the "dropout" problem been so... |
I encode a hidden message as different delays between packets of another data stream.
My implementation now is that for each bit,
if the bit is 0, a inter-packet delay between min and middle is generated and
if the bit is 1, a inter-packet delay between middle and max is generated.
Here's my code in Python:
binary_st... |
Skein uses an additional compression function call to finalize the output, even when the output isn't larger than the native output size.
The Skein paper says:
Due to Skein’s output transformation, it remains an open problem how to create collisions or second preimages for the Skein hash function, even if one can crea... |
According to the original paper, Lamport one-time signature scheme uses two one-way functions: $F$ and $G$. The former one, $F$, is used to create a public key by hashing elements of the private key (and also for hashing signature elements when verifying it); the latter, $G$, is used to hash a message when signing and ... |
I have been trying to understand exactly how a length extension attack works on SHA-1. I'll detail below what I've understood so far so that I can convey my understanding of the same and hopefully get advice on where I'm going wrong.
Let's assume that for a message $m$, a secret $s$ is prepended to it and the SHA-1 has... |
Assume Alice and Bob communicate over an insecure channel using one-time perfectly-secret encryption together with one-time secure message authentication code. Say Eve has the ability to eavesdrop and to inject messages into this insecure channel, but not to block or delay messages (i.e. Eve can mostly only replay auth... |
I need to encrypt relatively short strings (generally less than 100 characters). If possible, I want to avoid leaking the length of these strings. How can I do that?
The thing that came to my mind is to pad the text to 1 KiB with random data, separating the content from the padding with a 0x00 byte. Is this a good idea... |
I'm doing some exercises before my exam, and I am stuck with task number 4 in this file: http://www.cs.umd.edu/~jkatz/crypto/f10/hw1.pdf
Could you help me with this task?
When using the one-time pad encryption scheme, it can occur that $k=0^l$ and then the ciphertext is equal to the plaintext! It has been suggested to... |
Suppose I have an algorithm that relies on multiple iterations of a hash function like SHA1 to slow down an attacker trying to bruteforce a hash.
digest[0] = hash(password + salt)
for i in 1..r:
digest[i] = hash(digest[i-1] + password)
The final digest[r] is then used as the hash. How does this compare to a more ... |
If two parties want to communicate with securely using OTP , how is the key ( that is lengthy as plain text) shared with other party for decryption ?
|
In my notes, there are 2 definitions of perfect security:
"For $M \in \{0,1\}^m$, define the distribution $D_M$ on strings as follows: to choose a random member of $D_M$, choose a random $K \in \{0,1\}^n$ and output $Enc(M,K)$. Then $Enc,Dec$ is perfectly secure if $D_M$ is exactly the same for every $M$. That is, ... |
I came across this little HRNG widget and was really intrigued as I have been looking for a decent but afordable source for truly random bits to use in a one-time pad.
The question is, would a HRNG like this one generate bits with sufficent randomness to provide the perfect secrecy one-time pads are known for? Such a d... |
Both Pohlig-Hellman and RSA perform encryption and decryption by exponentiation modulo some integer ($p$ prime for PH, $n$ composite for RSA). They both use a key $e$ as the exponent to encrypt a message. They both use the inverse element of key $e$ to decrypt. In both, the encryption key $e$ can be a randomly chosen i... |
Why is QKD usually associated with OTP?
QKD is about key distribution, whereas OTP is about using a key as long as the message to get perfect secrecy. Can anyone explain how they are related?
|
Why AES based encryption is not recommended for encrypting images with high redundancy in their content? for example, the encryption of an image which shows a bird in the blue sky. Most of the pixels are blue in that case.
|
I have this situation, where, in a game, people send messages to each other (game moves etc...) These messages need to be encrypted, and should only be readable by the destination person. I am using RSA for this, but, recently I got a doubt. Is it possible that, if the message is one of n possible messages, can somebod... |
Let $P_i(x)$ be polynomials $i=1,...,n$, $s$ some value, and $g$ a generator of a group $G$ where the discrete logarithm is hard.
Assume a prover wants to convince a verifier having access to the values $g^{P_i(s)}$ that it knows polynomials $q_i(x)$ such that the following equation holds:
$q_1(s)*P_1(s)+q_2(s)*P_2(s)+... |
I am wondering is there any encryption algorithm available which produces comparable string.
I am expecting the output as shown below.
Data | output
---------------------------------------------
testData | uTrildHcKpM
testData_1 | uTrildHcKpMiopu
Please let me know if you happen to know such algorit... |
If Alice encrypts two messages $a$ and $b$, such that $x=E(a)$, $y=E(b)$. Can Alice prove (without revealing $a$, $b$ or the private key) that $a = b$?
Obviously the proof must not be too long and it should be practical to compute and verify (either interactively or non-interactively).
This is possible for the Pohlig-H... |
It seems to me that anything that was sufficiently good as a KDF would work just fine as a password hash, though the reverse might not be true. Are there considerations specific to password-hashing that don't apply to KDFs?
To clarify: This is about key-stretching KDFs. Not the kind for diversifying keys (eg. HKDF)
|
For example, if the entropy of a password is 30 bits, what is the entropy of the password when you hash it with MD5?
|
Possible Duplicate:
RSA encryption with private key and decryption with a public key
This wording is creeping everywhere (e.g. there): "I encrypt with the private key" and even sometimes, "I decrypt with the public key." Does it make any sense?
|
Title says all; Is it safe to hold key file's hash (MD5 or SHA1) in application (hard-coded)?
Thanks
|
I have a password with a prescribed format:
111 + (2 Random lowercase letters) + (random digit)
As you can see, it starts with a fixed value of 111, followed by two random lower case letters, and then lastly a random digit. Now, I would like to calculate the password entropy. To do so, I am calculating:
Fixed value 1... |
Let's say I have a message, a Private Key and a Public Key.
Normally if you want to see if the message is unaltered and is from the sender you would have the message part + signature part, which you can verify using the senders Public key.
This will lead to some extra data, which I want to work around
[ message (1 kb) ... |
Read a post on Schneiers blog (and again 2011) about increasing the number of rounds for AES from to "AES-128 at 16 rounds, AES-192 at 20 rounds, and AES-256 at 28 rounds" to raise the security. However, I did wonder where these figures came from. According to Schneier "hey're off the top of my head, and certainly not ... |
We have a server, which sends content encrypted with AES128 or RC4 to a flash client over an insecure HTTP channel. The encryption key is negotiated using Diffie Hellman.
The problem:
Diffie Hellman can be MITM-ed.
flash client can be easily reversed (can be obfuscated though), so if I use a hardcoded key, it can be e... |
In a security context course, we need to reproduce the old DES hashing scheme in the crypt program, on an old unix system.
I am actually reading the crypt page on wikipedia:
The traditional implementation uses a modified form of the DES
algorithm. The user's password is truncated to eight characters, and
those are... |
Are there any stream ciphers (or a deterministic random number generators, that should work as well I guess?) that cannot be parallelized?
For example, if I seed it with a specific value, and then "run" it for a year, generating more and more bits, and finally get a bitstream off it, then that bitstream will be impossi... |
How is key scheduling done in the International Data Encryption Algorithm (IDEA). I did some research, but to no avail.
I could not understand this statement from Wikipedia:
...further groups of eight keys are created by rotating the main key left 25 bits between each group of eight."
Could someone explain this to me... |
I know a plaintext - ciphertext couple of length 6 for a hill cipher where its key is a [3x3] matrix.
Based on what I've read and learned, to attack and crack keys of [n x n], if we know a plaintext - ciphertext duo of length $n^2$ then we have our set of n equations with n variables, and this is generally solvable. Ho... |
Most of the current key exchange techniques are based on public-key cryptography. Are there any key exchange/establishment techniques based on symmetric-key cryptography too?
In my setup primary assumption is both communicating parties can have pre-shared key and further they need to exchange messages to derive a long... |
Suppose we can construct a secure (IND-CPA) encryption scheme for fixed length messages. I was wondering if there is a natural way to extend this construction for messages of variable length such that it is still an IND-CPA secure scheme.
|
I am currently working on IDEA (International Data Encryption Algorithm), and I don't know how to perform Multiplication Modulo and Addition Modulo.
This is how IDEA operates:
IDEA operates on 64-bit blocks using a 128-bit key, and consists of
a series of eight identical transformations (a round, see the illustration)... |
This question is a bit different from other questions here, but I think it is suitable to correctly understand the terminology of cryptography.
Consider the following two sets of terms:
Encryption scheme, signature scheme
Identification scheme, commitment scheme, secret-sharing scheme
The latter are actually "protoco... |
Suppose I have a file with random binary strings of the same length in each line.
If I'm computing the conditional entropy $H(Y|X)$ where $Y$ is the variable string of fixed length $l$ which is after $X$, and $X$ is the variable string of length $m$, and I find (lets say) $l=5$ and $m=10$ that the value of conditional... |
Scenario:
We have a central server $S$.
We have a number of peripheral servers $P_i$
We have some individuals $U_j$
A given individual may be "known" to one or more peripheral servers. Each peripheral server generates unique IDs for the individuals it knows and stores a map $f_i: U_j \to \textrm{ID}$ and the correspon... |
I have a need to encrypt credentials for a third-party app used by a secured internal app. Over on ITSec.SE, I was helpfully shown a scheme to encrypt the third-party credentials based on a hash of the credentials for the internal app.
I picked AES as the encryption algorithm, but the problem is that the password-base... |
I'm implementing Shamir secret sharing in C using OpenSSL.
I've split up the private key and I'm ready to start decrypting the original message using some of the shares. I set $n = 5$ (5 shares total) and $t = 3$ (3 shares required to decrypt).
The way my encrypted message is stored is in a ${\rm msg} = (c_1, c_2)$ fo... |
EDIT: I've been confusing this the whole time. What I've been wanting to say this whole time is addition modulo $2^{32}$ not addition modulo 32 as the question originally said. Thanks for pointing that.
I can't find any information on this and I really want to know. We discussed in class number theory and after making... |
The main problem is to use a block cipher to generate a random key.
I would like to generate 256-bits key which can be as random as possible. I generate it in the following way:
Pick a plaintext $p_0$ of 64 bits and a 256-bit key $k_0$. ( can be given from keyboard as seed)
Implement a cipher which goes from 64-bits t... |
As it is well known that QKD systems are prone to simple MITM attacks… what authentication techniques are being used in QKD to prevent those attacks in practice?
|
For example, assume I have two 4x4 matrices of bits:
1 1 1 1 1 1 1 0
0 0 0 0 0 1 1 1
1 0 0 1 1 0 1 1
0 1 1 1 1 0 1 0
I want to apply matrix multiplication for the modified IDEA (International Data Encryption Algorithm). How does one multiply a matrix of bits with another matrix of bits?
|
If I transform natural plaintext by:
making each letter two decimal digits, considering the whole as a decimal number;
multiplying by the key (some integer constant), giving the ciphertext;
would frequency analysis still work?
Exemple:
Plaintext: G o l d U n d e r S e a
Number: 071512042114040518190501 x 91... |
From a paper via Schneier on Security's Another AES Attack (emphasis mine):
In the case of AES-128, there is no known attack which is faster than the 2128 complexity of exhaustive search. However, AES-192 and AES-256 were recently shown to be breakable by attacks which require 2176 and 2119 time, respectively. While t... |
Recently a few papers have appeared that describe a new approach to factoring, using elliptic curves over $\mathbb{Q}$. See, e.g.,
Factoring integers and computing elliptic curve rational points, Iftikhar A. Burhanuddin and Ming-Deh A. Huang.
Factoring integers using elliptic curves over Q, Xiumei Li, Jinxiang Zeng, ... |
In simple steps here the system:
first write text.
hand cipher
then divide into groups of three letters:
han dci phe r
then choose a key consisting of three letters, for example car and encrypt first three letters with the key han + car => kbf.
Then take the result kbf and encrypt the second three letters dci + kbf... |
In wiki about RC4 cipher they said,
Because the algorithm is known, it is no longer a trade secret.
Is that mean the cipher text will be more secure if the algorithm unknown to the attacker.
About AES is it really full paper public so anyone with knowledge can read how its work or there is something hidden
|
I have the following definition (highlights by me):
An (efficient secret-key) encryption scheme $(Gen,Enc,Dec)$, where $Gen$ and $Enc$ are PPT algorithms and $Dec$ is a Deterministic Polytime Algorithm, is one-time computationally-secret if for any PPT adversary $A$ it holds that the probability of the following exper... |
I'd like to combine a random key file with a password to generate a secure seed for a CSPRNG. The key file is assumed to have very high entropy, but the password will be whatever the user provides. What's the best way to combine the two in order to seed the PRNG? The goal of course is that the output of the PRNG will b... |
I'm looking into encrypting files like this: First, I SHA-1 hash the password. Let's say the password is something normal like "hello123", and then hashed. Then I encrypt a file using this:
openssl aes-256-cbc -a -salt -in file -out file.enc
(using the hash for the password).
So it's basically just an AES-256-CBC encr... |
Lets say I want to build a simple chat program that has encryption that is impossible to crack for anyone, even a theoretical government with a massive super computer. Ok here's my idea. You'll need to read all the points to get the whole picture I think.
Only two people can communicate with each other with the chat p... |
If I have a group $\mathcal{G}$ of order $N=npq$ and subgroups $\mathcal{G_n,G_p,G_q}$ of order $n$, $p$, $g$ respectively and if $g$ is a generator of $\mathcal{G}$ why then $g^{nq}$ is a generator of $\mathcal{G_p}$, $g^{np}$ is a generator of $\mathcal{G_q}$ and $g^{pq}$ is a generator of $\mathcal{G_n}$ ? I am tryi... |
I am doing some research on cryptography, so I generated a random string of numbers resembling a creditcard number(according to MOD10 validation) and encrypted it with SHA1 algorithm for encryption. But to make this interesting, I decided to make my database column size exactly 2/3 smaller than the encrypted text so th... |
Assume you chain random number generators, i.e use the result of one PRNG as the seed for the next. What kind of errors can that introduce in the randomness of the numbers generated?
|
I'm looking at a square attack against a reduced version of AES-128 with only 4 rounds (with block and key size of each 128 bit). I have a set of 256 plaintext-ciphertext block pairs.
What is the complexity of the computations, in number of encryptions, partial encryptions, memory usage, and data requested?
|
Is there a way to decrypt a AES cipher Text which was encrypted twice with some key, when having a part of this key? (the last 3 bytes of the key are missing)
|
I think I roughly understand how the RSA algorithm works.
However, I don't understand why we need the $N$, which we use as a modulus, to be $pq$ for some large primes $p, q$.
I vaguely know it has something to do with factorization, but I am kind of lost. So, hypothetical questions.
What would happen if the $N$ was no... |
I found a simple algorithm for factoring semiprime numbers, you can read about it in Factoring Semiprimes and Possible Implications for RSA (paywall-free).
It basically works like this:
You reverse the digits in $N$, let's call this value $Ň$
You pick an integer, $k$ (normally 1, but can be other values)
A variable, $... |
I'm preparing myself to exam, but I have a lot of troubles with rigorous proofs.
Let $\Pi=(Gen,Enc,Dec)$ be an efficient secret-key encryption scheme that is not fixed-length. That is, for any $n$ and any $k \leftarrow Gen(1^n)$ the encryption algorithm $Enc_k(\cdot)$ can encrypt arbitrary length messages $m \in \lbra... |
I'm preparing myself to exam, but I have a lot of troubles with rigorous proofs. This post is very long, but this is because I remind here 2 long definitions.
At the beginning I want to remind the definicion of CBC-MAC.
Let $F$ be a pseudo-random function. We define the CBC-MAC as $(Gen,Mac,Vrfy)$ as follows:
(a) $Gen... |
I'm preparing myself to exam, but I have a lot of troubles with rigorous proofs. It's the task from two-years ago exam. At the bottom I reminded one definition.
Let $(Gen_E,Enc,Dec)$ be an IND-CPA-secure encryption scheme.
Let $(Gen_M,Mac,Vrfy)$ be a secure MAC.
Define an encryption scheme as follows:
$Gen'$ upon inp... |
i'm trying to figure out when an Intialization Vector (IV) should be used.
There are anecdotal reports that WEP was broken because of weak IV's. It's also claimed that if two pieces of plaintext are encrypted with the same Key+IV, then it's trivial to recover the plaintext.
To test this, i've encrypted two pieces of ... |
Most of the research papers give imaginary applications of multi-party computation.
Either they talk about Yao's millionares' problem or two or more corporates willing to compute some intrustion detection stuff collectively on their private data without revealing their network logs or similar.
In reality, what are the ... |
I have just read about the perfect security of an OTP encryption and what came to my mind was that what if the Pad used for encryption/decryption did not have to be transported separately from the message, but instead together with it?
And what if it was computed using an algorithm from the message itself (from all the... |
I have programmed an implementation of Pollard's Rho factoring algorithm using C++ and the GMP library.
It is reasonably fast with large numbers, however I haven't implemented any form of cycle detection (I just try and avoid the problem, see below), and it struggles with small numbers.
Here is the pseudo code of my im... |
Given a set of SHA1 hash code, if we knew a portion of the plaintext for each particular hash code, and also the remaining portion of the plaintext is a constant value for each hash code.
Is it possible for us to recover what is the constant value?
|
I'm working on a encryption system where each party can store exactly a single ElGamal private key in a device. This is a hardware limit. The system must be expanded to support signatures and encryption.
Can each party use the same key-pair for both schemes?
I know that encryption/signature key lifetimes and security k... |
Alice is going to use some existing RSA scheme (employing industry-standard signature or/and encryption with proper padding), which she can't change, or influence beyond her choice of key. In this scheme, all public modulus $n$ are exactly $b$ bits with $b$ even (e.g. $b=4096$); and any odd public exponent $e$ with $3\... |
In a special ElGamal encryption scheme, every user has an ElGamal encryption key-pair using the same cyclic group $G$ and generator $g$.
The system has a special function :
$$ \mathrm{ShuffleEncrypt}(m_1, m_2, h_1, h_2 ) = \text{RandomPermutationOf} ( \operatorname{Enc}( h_1,m_1) , \operatorname{Enc}( h_2, m_2) ) = ( a... |
Since i cannot comment on questions, I give my own:
If a secret key encrypt algorithm can encrypt messages of arbitrary length and the encrypt algorithm is probabilistic then: suppose the adversary selects two messages of different length, $||m_0||=n$, $||m_1||=l$ and $n<l$. She gets back a ciphertext $c$. How can she ... |
When a bit error happens in an IV, what would the result of decrypting a cipher-text be in the different encryption modes like ECB, CBC, CFB, OFB, and CTR?
|
I build the computer appliance system that consist of software server and multiple controllers. The system I want to build must be pluggable in the sense that when I connect a controller C to the network, the server S will immediately finds it after initial message exchange(Step 1). After an initiation phase both C and... |
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