instruction stringlengths 15 30k |
|---|
Are there any many to one encryption frameworks available? |
The classic standard assumptions (such as DDH, CDH) are not parametrized and always have constant size (are static). Consequently, the assumption when used in a reductionist proof is independent of any system parameters or oracle queries and only related to the security parameter.
In contrast, non-static ($q$-type)... |
The classic standard assumptions (such as DDH, CDH) are not parametrized and always have constant size (are static). Consequently, the assumption when used in a reductionist proof is independent of any system parameters or oracle queries and only related to the security parameter.
In contrast, non-static ($q$-type)... |
I am working on RSA CRT and there is a point that I don't understand :
So we have $n=pq$ and $c = m^e \bmod n$ an encrypted message.
To decrypt $c$ with RSA CRT, we have to compute :
$d_p = d \bmod (p-1)$ and $d_q = d \bmod (q-1)$
Why do we have to do a reduction $\bmod (p-1)$ and not $\bmod p$ ? (Same for ... |
Hint: try to prove that $a^{phi(n)/g} \equiv 1 \pmod p$ for all $a$ satisfying $gcd(a, n) = 1$.
Metahint: $phi(n)/g = (p-1) \times (q-1)/g$; is $(q-1)/g$ an integer? |
I have a question about RSA key generation:
this is a simple rsa algorithm:
Choose p = 3 and q = 11
Compute n = p * q = 3 * 11 = 33
Compute ?(n) = (p - 1) * (q - 1) = 2 * 10 = 20
Choose e such that 1 < e < ?(n) and e and n are coprime. Let e = 7
Compute a value for d such that (d * e) % ?(n) = 1. d=3
Public ke... |
Currently I am working on public key certificate. I got a question: Why public key certificate is needed for TLS/SSL? Wouldn't TLS/SSL itself is enough? What is the role of the certificate? |
Currently I am working on a public key certificate. I got a question: Why is a public key certificate needed for TLS/SSL? Wouldn't TLS/SSL itself is enough? What is the role of the certificate? |
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 prng i got this result:
------------------------------------------------------------------------------
RESULTS FOR THE UNIFORMITY OF P-VALUES AND THE P... |
Is there any particular reason why NTRUEncrypt lacks a formal security proof? That is, a demonstration that it achieves certain security notion (e.g. IND-CPA). I know there is a provable-secure variant from Stehlé and Steinfeld, but my question is regarding the original NTRU proposal. |
Why does NTRUEncrypt lack a formal security proof? |
Let $\mathcal{M}$ be our message space and $\mathcal{K}$ our key space. Now, let $\mathrm{E} : \mathcal{K} \times \mathcal{M} \to \mathcal{M}$ be a block cipher. Define the block cipher $\mathrm{EX}((k_1, k_2, k_3), m) := k_1 \oplus \mathrm{E}(k_2, m \oplus k_3)$, where $m \in \mathcal{M}$, $k_2 \in \mathcal{K}$, and $... |
I've thought up a way to represent the transformation of S-Box in DES by ANF. Let xi(1<=i<=6) be the input of one S-Box, yi(1<=i<=4) be the output, for example, then y1 = 1 + x1 + ... + x1x5 + ... + x3x4x5x6. Here the "+" is "xor" operation and the operation between two continuous inputs is "and". I've omitted many ter... |
I am looking for - or considering the design of a new - encryption algorithm that does not use variable keys, such that it is easy for a computer to encrypt and decrypt any message regardless of its source, yet it is possible but impractical for a human using their brain and a pencil and paper to decrypt for any non-tr... |
How about just plain old [DES](http://en.wikipedia.org/wiki/Data_Encryption_Standard)?
Each round is fairly simple, you take a few bits, duplicate (expand) them, XOR the data, shuffle bits, shift bits, replace them, and "un-expand" the the result. It's an operation that could theoretically be done on paper in about ... |
How about just plain old [DES](http://en.wikipedia.org/wiki/Data_Encryption_Standard)?
Each round is fairly simple, you take a few bits, duplicate (expand) them, XOR the data, shuffle bits, shift bits, replace them, and "un-expand" the the result. It's an operation that could theoretically be done on paper in about ... |
Another way to is to take a page out of the book of Public Key Cryptography. In this case, I will illustrate how [RSA](http://en.wikipedia.org/wiki/RSA_%28cryptosystem%29#Operation) can be used.
In this example, I have encrypted a number between `65` (which decodes to `A`) and `90` (which decodes to `Z`), assuming I... |
I've thought up a way to represent the transformation of S-Box in DES by ANF. Let
$x_i\;(1\le i\le 6)$ be the input of one S-Box,
$y_i\;(1\le i\le 4)$ be the output, for example, then
$$y_1= 1\oplus x_1\oplus\dots\oplus x_1x_5\oplus\dots\oplus x_3x_4x_5x_6$$
Here the "$\oplus$" is "xor" operation and the operation ... |
I've thought up a way to represent the transformation of S-Box in DES by ANF. Let
$x_i\;(1\le i\le 6)$ be the input of one S-Box,
$y_i\;(1\le i\le 4)$ be the output, for example, then
$$y_1= 1\oplus x_1\oplus\dots\oplus x_1x_5\oplus\dots\oplus x_3x_4x_5x_6$$
Here the "$\oplus$" is "xor" operation and the operation ... |
How about just plain old [DES](http://en.wikipedia.org/wiki/Data_Encryption_Standard)?
Each round is fairly simple, you take a few bits, duplicate (expand) them, calculate (shuffle bits, shift bits, replace them) the next value from a key, XOR the data with the resulting key, and "un-expand" the the result. It's an ... |
I'm trying to understand the "Invalid-curve attacks against ladders" section of [SafeCurves Twist Security page][1] and I have difficulties to apply it to short Weierstrass curves.
That section claims that in order to thwart invalid curve attacks an efficient technique is to use a single coordinate ladder to compute... |
This page on [Twist security][1] mentions a _combined attack_ and a _twist rho_ attack, with cost $2^{58.4}$ something, applicable in particular to NIST P-224 curve, with no <strike>mention</strike> precise definition of associated protocols.
What are theses attacks (in the simplest meaningful terms possible please.... |
What are these twist attacks with cost $2^{58.4}$ on NIST P-224 curve, and when does they apply? |
What are these twist attacks with cost $2^{58.4}$ on NIST P-224 curve, and when do they apply? |
I'm trying to understand the "Invalid-curve attacks against ladders" section of [SafeCurves Twist Security page][1] and I have difficulties to apply it to short Weierstrass curves.
That section claims that in order to thwart invalid curve attacks an efficient technique is to use a single coordinate ladder to compute... |
This page on [Twist security][1] mentions a _combined attack_ and a _twist rho_ attack, applicable in particular to NIST P-224 curve with cost $2^{58.4}$ something, with no <strike>mention</strike> precise definition of associated protocols.
What are theses attacks (in the simplest meaningful terms possible please..... |
This page on [Twist security][1] mentions a _combined attack_ and a _twist rho_ attack, applicable in particular to NIST P-224 curve with cost $2^{58.4}$ something, with no <strike>mention</strike> precise definition of protocols concerned by the attack(s), beyond:
> Some of the ECDLP security requirements for the twi... |
I am trying to understand the [Boneh-DeMillo-Lipton fault attack][1] on RSA CRT signature.
Suppose that we sign a message $m$ with RSA-CRT :
$d_p = d \bmod (p-1)$ and $d_q = d \bmod (q-1)$
$s_p = h(m)^{d_p} \bmod p$ and $s_q \not= h(m)^{d_q} \bmod q$ where $h$ is a hash function
By CRT we get $s$ the signat... |
How can a good pseudo-random number genarator be made? |
What does it mean and what is it used for, I have been hearing this term a lot lately. Form the context I've heard it talked about it seems to be connected with zero knowledge? |
What is SNARKs? |
What does it mean and what is it used for, I have been hearing this term a lot lately.
<br>
From the context I've heard it talked about it seems to be connected with zero knowledge? |
What are SNARKs? |
I read in the answer [here][1] that when encrypting twice with same key would result in plain text. Which cipher algorithms are they ? also what is this property in general ? is it considered weak ?
[1]: http://crypto.stackexchange.com/questions/2314/does-encrypting-twice-using-the-same-block-cipher-produce-a-se... |
I read in the answer [here][1] that when encrypting twice with same key could result in plain text. Which cipher algorithms are they? What is this property called in general? Is it considered weak ?
[1]: http://crypto.stackexchange.com/questions/2314/does-encrypting-twice-using-the-same-block-cipher-produce-a-secu... |
I read in the answer [here][1] that when encrypting twice with same key could result in plain text. Which block-cipher algorithms are they? What is this property called in general? Is it considered weak ?
[1]: http://crypto.stackexchange.com/questions/2314/does-encrypting-twice-using-the-same-block-cipher-produce-... |
I am looking for - or considering the design of a new - encryption algorithm that does not use variable keys, such that it is easy for a computer to encrypt and decrypt any message regardless of its source, yet it is possible but impractical for a human using their brain and a pencil and paper to decrypt for any non-tr... |
I read in the answer [here][1] that when encrypting twice the plain text with same key could result in plain text as shown below
$encrypt_{key}((encrypt_{key}(plain)) = plain $
Which block-cipher algorithms are they? What is this property called in general? Is it considered weak ?
[1]: http://crypto.stackexc... |
I read in the answer [here][1] that when encrypting twice the plain text with same key could result in plain text as shown below
$encrypt_{key}((encrypt_{key}(plain)) = plain $
Which block-cipher algorithms are they? What is this property called in general? Is it considered weak?
[1]: http://crypto.stackexch... |
I have just started learning cryptography and I am trying to make sense of the direct sum on some binary numbers.
I am trying to find a column of a state space after a Mixcolumns operation has been performed.
For example, to find $c_0$, I have
$c_0=((02)\cdot10000100)\oplus((03)\cdot(10000001))\oplus1000000... |
How bad is the following strategy for a password manager on a local machine?
The user wants to sign up for somesite.com where he needs a password.
The user has previously generated a secret key `K` which he remembers and isn't stored anywhere. Now using a good hash function the site's URL somesite.com is hashed tog... |
Good afternoon! I got some mismatches while counting Round Keys at non bitsliced version of Serpent. I have used official AES submission outputs (file ecb_iv.txt).
AES submission package test vector:
Key: 0000000000000000000000000000000100112233445566778899aabbccddeeff
First K0{w0,w1,w2,w3}
Rewriting ... |
Good afternoon! I got some mismatches while counting Round Keys at non bitsliced version of Serpent. I have used official AES submission outputs (file ecb_iv.txt).
AES submission package test vector:
Key: 0000000000000000000000000000000100112233445566778899aabbccddeeff
First K0{w0,w1,w2,w3}
Rewriting ... |
Good afternoon! I got some mismatches while counting Round Keys at non bitsliced version of Serpent. I have used official AES submission outputs (file ecb_iv.txt).
AES submission package test vector:
Key: 0000000000000000000000000000000100112233445566778899aabbccddeeff
First K0{w0,w1,w2,w3}
Rewriting ... |
Assume that we are given an element $g\in \mathbb{F}_{p^n}^*$ and $g$ does not belong to any of the smaller subfields contained in $\mathbb{F}_{p^n}$. If the degree of $g$ is some number $q$, how much is the time it takes to solve the DLOG problem in the group generated by $g$ dependent on $n$? I.e. if the order of the... |
DLOG in $\mathbb{F}_{p^n}^*$? |
In continuation to [this][1] question about length of primes , I am in doubt about the restriction on length of primes itself .
In Paillier cryptosystem , equal length of primes are used .
My doubt is whether this restriction is to ensure the following [condition][2] only
$$\gcd(pq,(p-1)(q-1))=1$$
or , the... |
Is equal length of primes in Paillier cryptosystem is mandate for security reasons? |
I've just been reading about a new drop-in replacement for the RC4 stream cipher, but why develop new stream ciphers when AES can be made into a stream with a little XORing? |
Why develop new stream ciphers when block ciphers can be trivally made into streams? |
According to this:
http://www.cims.nyu.edu/~regev/teaching/lattices_fall_2004/ln/rsa.pdf
One can calculate the message m, if there was no padding scheme involved.
My question: is it possible to find m if the $n_a n_b n_c$ moduli are unknown?
Also: if one can see the encrypted version of a known plaintext, can... |
Good afternoon! I got some mismatches while counting Round Keys at non bitsliced version of Serpent. I have used official AES submission outputs (file ecb_iv.txt).
AES submission package test vector:
Key: 0000000000000000000000000000000100112233445566778899aabbccddeeff
First K0{w0,w1,w2,w3}
Rewriting ... |
I don't consider myself to be an expert in this field, so forgive me if there is an obvious answer. I am having a tough time finding an algorithm that can sign data and output a 32-byte signature, *that is in common use*. Specifically, I'd like to find an algorithm that frequently available in many security APIs that... |
Are there any digital signature algorithms in common use that result in 32-byte signatures? |
In RSA signature scheme, it is a common practice to 'sign' the hash value of the message so that the length can be fit.
Question: If we have $s=m^dmod n$ where $d$ satisfies $ed \equiv 1 mod n$ and we also know $s$ and $m$, is this still considered secure? |
In RSA signature scheme, it is a common practice to 'sign' the hash value of the message so that the length can be fit.
Question: If we have $s=m^d \bmod n$ where $d$ satisfies $ed \equiv 1 \pmod{n}$ and we also know $s$ and $m$, is this still considered secure? |
This lecture by Dan Boneh should answer all your questions and more:
https://www.youtube.com/watch?v=F4x2kQTKYFY
ps. I saw you also had a question about NIZK proofs, so you should check out the full list of videos:
https://www.youtube.com/playlist?list=PLXF_IJaFk-9C4p3b2tK7H9a9axOm3EtjA
which also has almos... |
This lecture by Dan Boneh should answer all your questions and more:
https://www.youtube.com/watch?v=F4x2kQTKYFY
ps. I saw you also had a question about NIZK proofs, so you should check out the full list of videos
https://www.youtube.com/playlist?list=PLXF_IJaFk-9C4p3b2tK7H9a9axOm3EtjA
which has almost 3 ho... |
i read something about Diffie Hellman. What i don't understand: Alice selects a randomly generated Number, calculates X = g^x mod p and sends X to Bob.
If she calculates g^x, she needs to calcluate g+g+g+g+g... until she has calced to g^x. Than she calculates it mod p and sends the Result to Bob.
If Eve listens,... |
Why is it hard to calculate Logarithm on Diffie Hellman? |
> **Possible Duplicate:**
> [Taking advantage of one-time pad key reuse?](http://crypto.stackexchange.com/questions/59/taking-advantage-of-one-time-pad-key-reuse)
> [How does one attack a two-time pad (i.e. one time pad with key reuse)?](http://crypto.stackexchange.com/questions/2249/how-does-one-attack-a-two-tim... |
I've thought up a way to represent the transformation of S-Box in DES by ANF. Let
$x_i\;(1\le i\le 6)$ be the input of an S-Box,
$y_i\;(1\le i\le 4)$ be the output, for example, then
$$y_1= 1\oplus x_1\oplus\dots\oplus x_1x_5\oplus\dots\oplus x_3x_4x_5x_6\oplus\cdots$$
Here the "$\oplus$" is "xor" operation and the... |
There is such a putting in Bishop's <Introduction to computer security>, page 118 as following:
>Definition 8–2. A cryptographic checksum function (also called a strong hash function or a strong one-way function) h: A → B is a function that has the following properties.
>1. For any x ∈ A, h(x) is easy to compute.... |
What type of cipher could give ciphertext where for example *random* ASCII chars between say F-z (symbols and numerals inclusive), but with only a few spaces? Frequency of chars shows some similarities to alphabetic frequency and is 200 chars in length.
I've been reading up on ciphers and have not come across any comm... |
Type of cipher used where ciphertext has no discernible pattern, spaces. Type? |
Public key certificate is a digitally signed document which verifies the sender is indeed the person. May I know how can the receiver tell the sender is indeed the person solely based on information on the public key certificate? What are contained in the certificate? Does a public key certificate contain the same info... |
I was having a discussion with a colleague yesterday whose education and experience exceeded mine. He said something yesterday that sounded incorrect to me intuitively, but I don't have the knowledge to contradict it.
He claimed that the only reason a secure cryptographic hash is better at detecting tampering or co... |
Public key certificate is a digitally signed document which verifies the sender is indeed the person. May I know how can the receiver tell the sender is indeed the person solely based on information on the public key certificate? What are contained in the certificate? Does a public key certificate contain the same info... |
I have read about long message attacks on some cryptographic hash functions. However, I don't quite understand what is being referred to as a "long message".
Also, do long message attacks only apply for such "long" messages or can they also be used (any exceptions?) with "normal" messages? ("Normal" as opposed to "... |
What, cryptographically speaking, is a "long message"? |
You actually don't trust the certificate by itself. A certificate is like a diploma that a company (or a domain, i.e. www.crypto.com) obtained from some trusted party, called CA, or Certificate Authority. This diploma states that www.crypto.com is allowed to communicate with you using the public key written in the dipl... |
Sorry, 64-bit RSA is terminally unsafe: [hand the modulus to Wolfram][1] and its factorization is returned among other trivia. Some [mention of use of 64-bit RSA in commercial products][2] can still be found, but do not count on Crypto.SE for any recommendation about that.
More generally, we know no method comparabl... |
Consider I have two ciphertext $c_1$ and $c_2$ encrypted using RSA encryption. By definition if I multiply them I'd get $c_1.c_2 \ modN$. My question is what would happen if $c_1.c_2 >N$. Can we still decrypt it and obtain the product of two plaintext? |
When homomorphic encryption goes wrong? |
Yes; as long as the product of the two plaintexts $p_1 \cdot p_2 < N$, you'll get their product; it doesn't matter what the ciphertext values actually are.
The relevant question is: what happens if the plaintexts overflow; that is, what if $p_1 \cdot p_2 \ge N$? In that case, when you decrypt, you'll get the result... |
The Congress of ThéOùça enacted that civilian use of any public-key encryption system is authorized on the territory of ThéOùça, subject to meeting certain security requirements published by the Ministry of Defense. These read:
>..must operate per the internationally recognized RSAES-OAEP algorithm and all other requi... |
The Congress of ThéOùÇa enacted that civilian use of any public-key encryption system is authorized on the territory of ThéOùÇa, subject to meeting certain security requirements published by the Ministry of Defense. These read:
>..must operate per the internationally recognized RSAES-OAEP algorithm and relevant requir... |
The Congress of ThéOùÇa enacted that civilian use of any public-key encryption system is authorized on the territory of ThéOùÇa, subject to meeting certain security requirements published by the Ministry of Defense. The essence of these is:
>..must operate per the internationally recognized RSAES-OAEP algorithm and re... |
The Congress of ThéOùÇa enacted that civilian use of any public-key encryption system is authorized on the territory of ThéOùÇa, subject to meeting certain security requirements published by the Ministry of Defense. The essence of these is:
>..must operate per the internationally recognized RSAES-OAEP algorithm and re... |
You actually don't trust the certificate by itself. A certificate is like a diploma that a company (or a domain, e.g. www.crypto.com) obtained from some trusted party, called CA, or Certificate Authority. This diploma states that www.crypto.com is allowed to communicate with you using the public key written in the dipl... |
Okay, I came up with this, it's not a complete answer and the attack presented is pretty weak without a follow-up algorithm for breaking a somewhat unbalanced modulus but let me know if you spot any flaws or have any ideas to improve it...
----------
If $n = pq$ with $p, q$ prime and $\gcd(pq, (p - 1)(q = 1))... |
Okay, I came up with this, it's not a complete answer and the attack presented is pretty weak without a follow-up algorithm for breaking a somewhat unbalanced modulus but let me know if you spot any flaws or have any ideas to improve it...
----------
If $n = pq$ with $p, q$ prime and $\gcd(pq, (p - 1)(q = 1))... |
The Congress of ThéOùÇa enacted that civilian use of any public-key encryption system is authorized on the territory of ThéOùÇa, subject to meeting certain security requirements published by the Ministry of Defense. The essence of these is:
>..must operate per the internationally recognized RSAES-OAEP algorithm and re... |
I'd like to implement something like a write-once public/private encrypted shared secret (no better quick description for the lack of terminology knowledge). I guess, i'm trying to implement HSM.
The scheme goes as follows:
1. given a secret (e.g. 512 characters long string)
1. generate a public & private key pa... |
Can public key be recovered from chipher text & encrypted private key? |
The Congress of ThéOùÇa enacted that civilian use of any public-key encryption system is authorized on the territory of ThéOùÇa, subject to meeting certain security requirements published by the Ministry of Defense. The essence of these is:
>..must operate per the internationally recognized RSAES-OAEP algorithm and re... |
Okay, I came up with this, it's not a complete answer and the attack presented is pretty weak without a follow-up algorithm for breaking a somewhat unbalanced modulus but let me know if you spot any flaws or have any ideas to improve it...
----------------
If $n = pq$ with $p, q$ prime and $\gcd(pq, (p ... |
Good afternoon! I got some mismatches while counting Round Keys at non bitsliced version of Serpent. I have used official AES submission outputs (file ecb_iv.txt).
AES submission package test vector:
Key: 0000000000000000000000000000000100112233445566778899aabbccddeeff
First K0{w0,w1,w2,w3}
Rewriting ... |
I am trying to make a pseudo-random number generator so that I can use it in a synchronous stream cipher for encrypting plain text. I want it to generate numbers which are as random as possible.
What are good elements that my algorithm must have in order to do so?
This is for an interschool science competition. |
How can a good pseudo-random number generator be made? |
Suppose a server uses TLS to protect communication between us and the server. I observe that in TLS handshake protocol, password is not mentioned anywhere. Then why we need to have a password? What is its purpose? |
I want to implement [Mental Poker][1] in JavaScript as a toy program and lead in to a larger serious project so I did my research and found [Massey-Omura cryptosystem and the Shamir three-pass protocol][2] however I couldn't find any implementations of them, and the information on how to do SRA is scant. Would anyone b... |
Suppose a server uses TLS to protect communication between us and the server.
<br>
I observe that in the TLS handshake protocol, password is not mentioned anywhere.
<br>
Then why do we need to have a password? What is its purpose? |
Why do we need password in a server which uses TLS? |
I realize servers such as Google, Yahoo, which use RSA has 2048 bits public key. After comparing those keys, I realize that the public keys share a common property, that is first 9 bytes and last 5 bytes are always the same. Since those public keys have 270 bytes altogether, this means there are only 256 useful bytes,... |
I know Python is a powerful programming language but is it secure for cryptography?
I mean is it possible to reverse engineer the program(wrote by python) and find the algorithm of cryptography or other things? |
Is python a secure programming for cryptography? |
Can someone explain this to me?
For example how M chanes to 0c?
Changing plaintext to state:
![enter image description here][1]
[1]: https://i.stack.imgur.com/MivND.jpg |
The point of cryptography is having algorithms that are secure even when the attacker knows them. Google security by obscurity to see why it's bad.
EDIT: You could clarify your question. Are you afraid of side channel attacks? |
I know Python is a powerful programming language but is it secure for cryptography?
I mean is it possible to reverse engineer the program(written in python) and find the algorithm of cryptography or other things? |
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