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Is differential calculus related to RSA? |
I am trying to implement Keccak in Java for my school work. And I am getting stuck in two places:
1. On the [summary page](http://keccak.noekeon.org/specs_summary.html) the padding is shown as
> P = M || 0x01 || 0x00 || … || 0x00
P = P xor (0x00 || … || 0x00 || 0x80)
However on the [specification page](... |
I came up with a truly new method of applying modulo-2-addition encryption function in stream ciphers which is inspired by a mechanism used to prove a mathematical theorem. How can I determine whether my method is cryptographically correct and considerable? If so, how can I officially submit or formally register it in ... |
**Public-key** encryption on microcontrollers
Erik-oliver Blaß , Martina Zitterbart.
["Towards Acceptable Public-Key Encryption in Sensor Networks"][1]. 2005.
["dsPIC DSC Asymmetric Key Embedded Encryption Library"][2]
an implementation of RSA, Diffie-Hellman, DSA, SHA-1, MD5.
(Are such 16-bit microcontroller... |
What is the proper/canonical way to do this?
For example, `0 < r1 < 1` and `0 < r2 < 1`. Presuming uniformly distributed probabilities for the two, combining/averaging them is going to bias very quickly towards 0.5
The specific use case I have is a game/sim I'm programming. An entity has a random number it was gi... |
At what stage is DHE and RSA used during the SSL/TLS handshake? |
In the context of this data, as shown in the image below, which one is a pre-master key and which one is a master key. It looks to me as if the final value of 2, for Alice and Bob is a master key which can be then used for creating a symmetric key (AES). Am I right?
![enter image description here][1]
[1]:... |
In this context of this data, which is a pre-master key, and which is a master key? |
In this example, which is a pre-master key, and which is a master key? |
Not sure if hash trees miss some of your requirements, but many of requirements you have could be satisfied with hash trees.
Note: The scheme described below is essentially "Merkle Hash Tree-based Storage Enforcing Scheme (MHT-SE)[Golle et al. 2002]".
> So my question is, if we relax the requirement of being able... |
Not sure if hash trees miss some of your requirements, but many of requirements you have could be satisfied with hash trees.
Note: The scheme described below is essentially "Merkle Hash Tree-based Storage Enforcing Scheme (MHT-SE)[Golle et al. 2002]".
> So my question is, if we relax the requirement of being able... |
Not sure if hash trees miss some of your requirements, but many of requirements you have could be satisfied with hash trees.
Note: The scheme described below is essentially "Merkle Hash Tree-based Storage Enforcing Scheme (MHT-SE)[Golle et al. 2002]".
> So my question is, if we relax the requirement of being able... |
In cryptography, if i've done a work, then how to measure whether it is meaningful or not?
If the work has never been done by previous people, then can I say that it's meaningful? |
How to judge a work that if it is meaningful in cryptography? |
With this amount of information it is hard to advice.
Previously when somebody asked about new algorithm he had produced. This is the answer: [Answer to Where could I submit my algorithm?][1]. No matter what kind of cryptographic work, generally large part of that answer applies.
If we knew anything about the work ... |
With this amount of information it is hard to advice.
Previously when somebody asked about new algorithm he had produced, he was answered: [Answer to Where could I submit my algorithm?][1]. No matter what kind of cryptographic work, generally large part of that answer applies.
If we knew anything about the work (li... |
Suppose I have generated a new cryptographical result - for example a new cryptographical primitive, or a cryptanalytic attack. How can I find out whether this result is meaningful (significant)?
If the work has never been done by previous people, can I say it is meaningful? |
How to judge if my work is meaningful in cryptography? |
In the context of this data, as shown in the image below, which one is a pre-master key and which one is a master key. It looks to me as if the final value of 2, for Alice and Bob is a master key which can be then used for creating a symmetric key (AES). Am I right?
> 1. Alice and Bob agree to use a prime number $p=... |
In the context of this data, as shown in the image below, which one is a pre-master-secret and which one is a master-secret. It looks to me as if the final value of 2, for Alice and Bob is a master-secret which can be then used for creating a symmetric key (AES). Am I right?
> 1. Alice and Bob agree to use a prime n... |
In this example, which is a premaster secret, and which is a master secret? |
With this amount of information it is hard to advice.
Previously when somebody asked about new algorithm he had produced, he was answered: [Answer to Where could I submit my algorithm?][1]. No matter what kind of cryptographic work, generally large part of that answer applies.
If we knew anything about the work (li... |
-- or: How to Play Poker Without a Dealer
I know this question is long but it's a really interesting theoretical problem about shared secrets and multi-party computation.
## General Problem: "Shared Random Generation"
Consider the following scenario: *N* parties want to play a simple game. For this, some rando... |
-- or: *How to Play Poker Without a Dealer*
I know this question is long but it's a really interesting theoretical problem about shared secrets and multi-party computation.
## General Problem: "Shared Random Generation"
Consider the following scenario: $N$ parties want to play a simple game. For this, some ran... |
I have only about 2 weeks of cryptography experience mostly in the form of questions on bitcoin.se.
Is [Curve25519-java][1] up to date with current Curve25519 standards?
Is Curve25519 itself secure?
In other words, is it safe to use as it a cryptocurrency key-generation and transaction signing & verification... |
Is Curve25519-java secure? |
-- or: *How to Play Poker Without a Dealer*
I know this question is long but it's a really interesting theoretical problem about shared secrets and multi-party computation.
## General Problem: "Shared Random Generation"
Consider the following scenario: $N$ parties want to play a simple game. For this, some ran... |
In other words: is there a way to mangle a public data-source (current date f.e. as YYYYMMDD or the top New York Times headline for the day) to sufficiently erase the source of the one-time pad's seed?
What are the other issues such a scheme would be running into?
Disclaimer: me being a crypto "noob" and just kind ... |
Is there a way to generate sound one-time pads out of public information? |
-- or: *How to Play Poker Without a Dealer*
I know this question is long but it's a really interesting theoretical problem about shared secrets and multi-party computation.
## General Problem: "Shared Random Generation"
Consider the following scenario: $N$ parties want to play a simple game. For this, some r... |
**Very short answer**: No
**Quite Short answer**: No, because a scheme can only be a One-Time-Pad if the entire pad is perfectly random and secret.
-----------------
Any scheme 'like' the One-Time-Pad ([OTP][1]) breaks down into two sections: first we form a pad and second we combine the pad with the plaintext... |
**Very short answer**: No
**Quite Short answer**: No, because a scheme can only be a One-Time-Pad if the entire pad is perfectly random and secret.
**Concise answer**: It sounds like you're trying to build a [stream cipher][4]. The security of it really comes down to how much of the scheme you think can be kept s... |
Is there a way to 'mangle' a public data-source (for example, the current date in YYYYMMDD or the top New York Times headline) to form a one-time pad that will sufficiently hide the pad's source?
What are the other issues such a scheme would be running into?
Disclaimer: I am new to cryptography and am just interes... |
The problem with new cryptographic algorithms is the amount of time and effort it takes to convince people of its security. There are many factors working against new development:
- Existing ciphers have been subjected to intense scrutiny, and yet are
barely trusted.
- Changes to existing ciphers or protocol... |
Is there a way to 'mangle' a public data-source (for example, the current date in YYYYMMDD or the top New York Times headline) to form a one-time pad that will sufficiently hide the pad's source?
What are the other issues such a scheme would be running into?
Disclaimer: I am not an expert cryptographer and am just... |
**Very short answer**: No
**Quite Short answer**: No, because a scheme can only be a One-Time-Pad if the entire pad is perfectly random and secret.
**Concise answer**: It sounds like you're trying to build a [stream cipher][4]. The security of it really comes down to how much of the scheme you think can be kept s... |
Any public key decryption can be decrypted given enough time and computing power. Is there a metric or term for this? Something like
*it would require on average 2^43 1024 bit hashes to find private key 'I' based on public key 'U'?*
Is there a term that would sum up this average amount of work?
I'm a programme... |
Is there a metric (term) for work required to decrypt a public key? |
To generate an RSA key, you need lots of random bits – more than 4000 for a 4096-bit key (usually more than the key size, since you need to throw away and retest parts if the prime tests fail).
Now, to generate an RSA key, you would love to have the bits being uncorrelated. But if your PRNG has 160 bits of state, yo... |
There are multiple metrics for work or effort needed:
- Amount of operations it takes (one operations is, for instance, one invocation of hash function or number of modular multiplication operations)
- Amount of money it takes
- Amount of memory it takes
- Amount of time it takes
- Strength in bits
Amoun... |
I have been looking at an embedded microcontroller which has a cryptographic hardware engine (in particular the [PIC32MZ family][1]). These devices have what they advertise as a cryptographically secure PRNG, as well as a true random number generator.
The features of the random number generators are,
> - TRNG:
... |
Can a LFSR be cryptographically secure? |
Is there an algorithm or technique to encrypt all the datatypes such as (video , image , text , fax, audio ,file,etc...) -one algorithm encrypt every thing-?
also if I try to build such this algorithm ,what is the problems that may i face? such as server powerful or processing time, etc ? |
is there an algorithm to encrypt all the datatypes? |
> Is there an algorithm or technique to encrypt all the datatypes
Most encryption algorithms simply encrypt binary data, meaning they don't care what the data represents to the user. So, for example AES (under a suitable mode-of-operation depending on your actual use-case) would solve your question.
> if I try t... |
> Is there an algorithm or technique to encrypt all the datatypes
Most encryption algorithms simply encrypt binary data, meaning they don't care what the data represents to the user. So, for example AES (under a suitable mode-of-operation depending on your actual use-case) would solve your question.
You mention ... |
Is there an algorithm or technique to encrypt all the datatypes such as (video , image , text , fax, audio ,file,etc...) -one algorithm encrypt every thing-?
also if I try to build such this algorithm ,what is the problems that may i face? such as server powerful or processing time, etc ?
-----
**Clarificat... |
I have been looking at an embedded microcontroller which has a cryptographic hardware engine (in particular the [PIC32MZ family][1]). These devices have what they advertise as a cryptographically secure PRNG, as well as a true random number generator.
The features of the random number generators are,
> - TRNG:
... |
Why not just apply hash function on the whole message? Why convert that message into blocks and hash those blocks? To avoid collisions? |
Why use CBC-MAC? Why not just apply hash function on the whole message? |
Hi I am a little new to security, but in researching digital certificates it seems the only format people describe is X.509.
Are there other formats? If so what are they and where can I find information on them? |
Are there other digital certificate formats than X.509? |
AES uses a key that is at most 256 bit.
I assume AESCrypt uses AES.
When a file is encrypted with AEScrypt, there is no limit to the length of the password.
What is the relation between the AESCrypt password and the key size of the underlying AES encryption?
|
[QKD](http://en.wikipedia.org/wiki/Quantum_key_distribution) aims at exchanging key material to be used with encryption based on [OTPs](http://en.wikipedia.org/wiki/One-time_pad) between two parties and thus to achieve perfect secrecy for transmitted messages.
There are, however, several drawbacks for practical use... |
Here's a method to sign the message with RSA: http://upload.wikimedia.org/wikipedia/commons/thumb/2/2b/Digital_Signature_diagram.svg/800px-Digital_Signature_diagram.svg.png
Why hash the data before signing it? Why not sign the whole message? It'll save time if you sign the hash value, but I've heard there are also s... |
Why hash the message before signing it? Digital signature with RSA |
Let say `e = 5`, `n = 119` and `d = 77`. If I encrypt, for example, 15 I get `m1 = 15 ^ 5 mod 119 = 36` and `m2 = 15 ^ 77 mod 119 = 36`. Why? Is it always like that in RSA? |
Why encrypting with private and public keys produce the same result? |
Let say `e = 5`, `n = 119` and `d = 77`. If I encrypt, for example, 15 I get `m1 = 15 ^ 5 mod 119 = 36` and `m2 = 15 ^ 77 mod 119 = 36`. Why? Is it always like that in RSA? Is it bad? |
Let say `e = 5`, `n = 119` and `d = 77`. If I encrypt, for example, 15 I get `m1 = 15 ^ 5 mod 119 = 36` and `m2 = 15 ^ 77 mod 119 = 36`. Why? Is it always like that in RSA? Is it bad?
Why http://crypto.stackexchange.com/questions/2474/why-hash-or-salt-when-signing/2480#2480 works then? |
Let say $e = 5$, $n = 119$ and $d = 77$. If I encrypt, for example, $m=15$ I get:
$$m_1 = m^e=15 ^ 5 \mod 119 = 36\qquad\text{and}\qquad m_2 =m^d= 15 ^ {77} \mod 119 = 36$$. Why? Is it always like that in RSA? Is it bad?
My question was prompted by an answer to http://crypto.stackexchange.com/questions/2474/why-has... |
For example, say you have a client and server. You use asymmetric encryption to securely deliver two seeds from server to client. Each user then seeds two PRNGs (one for incoming data, one for outgoing). Then when they send data over the network, they add a new randomly generated byte (from the outgoing PRNG) to each u... |
Would data be secure if a cryptographically secure PRNG was used for encryption? |
I've been having trouble with coming up with a random number generator that produces a random number between two parties. My current scheme is this:
User 1 gives user 2 the hash of their randomly generated seed, user 2 responds with their unhashed seed. User 1 generates the random number by feeding his own unhashed ... |
It is well known that it's possible to fool *Fermat test* with *Carmichael numbers*. But, is it possible to deliberately fool many-rounded *Miller-Rabin test* by constructing some special number *without using brute forcing strategy*? I know that one round of *Miller-Rabin* distinguish with probability 25% that number ... |
Is it possible to fool Miller-Rabin test? |
Why should user 1 disclose the resulting random number in addition to disclosing his own seed,
<br>
when user 2 can compute the resulting random number from the two seeds?
That might be safe enough, but it's far from secure.
<br>
For one thing, each user obtains user obtains proof that the "random number" is onl... |
In addition to the performance problems poncho already mentioned when using RSA signatures without hashing I just want to add on the security warning of poncho:
**Reordering**
If you have a message $m>N$ with $N$ being the RSA modulus, then you have to perform at least 2 RSA signatures as $m$ does not longer fit ... |
Excuse me, I want to ask about **distinguishing attack on CBC MAC**. The topic is write in paper which is published by Ketting Jia, Xiaoyun Wang, Zheng Yuan, and Guangwu Xu. The title is "***Distinguishing Attack and Second-Preimage Attack on the CBC-like MACs.***" In that paper said that "**if there is a collision in ... |
I want to ask about **distinguishing attack on CBC MAC**, as in the paper published by Ketting Jia, Xiaoyun Wang, Zheng Yuan, and Guangwu Xu: [***Distinguishing Attack and Second-Preimage Attack on the CBC-like MACs.***][1]
In that paper said that "**if there is a collision in the structure, the MAC function is rand... |
The proofs and security of block ciphers constructed especially of Luby Rackoff Constructions and Feistel Networks is based on the number of queries and round functions. The security measure is always based on the probability with which the attacker can distinguish the randomness in the cipher text. For example Patarin... |
Why is the security of block cipher not a function of key and tweak? |
The proofs and security of block ciphers constructed especially of Luby Rackoff Constructions and Feistel Networks is based on the number of queries and round functions. The security measure is always based on the probability with which the attacker can distinguish the randomness in the cipher text. For example Patarin... |
I want to ask about **distinguishing attack on CBC MAC**, as in the paper published by Ketting Jia, Xiaoyun Wang, Zheng Yuan, and Guangwu Xu: [***Distinguishing Attack and Second-Preimage Attack on the CBC-like MACs.***][1]
In that paper it is said that "**if there is a collision in the structure, the MAC function i... |
in general if an attacker gets hold of a known plain text and corresponding cipher text. Since the encryption algorithm is usually known. He can brute force all possibilities of bits in the key. Now what is the implication of having additional tweak on brute forcing the algorithm ?
Is this correct to say that now t... |
Consider a KPA attack, where the attacker gets known plain text and the corresponding cipher text. Since the encryption algorithm is known, he can brute force all possibilities of key bits. **What is the implication of having additional tweak on brute forcing the algorithm**?
Is this correct to say that now the atta... |
[Here](http://upload.wikimedia.org/wikipedia/commons/thumb/2/2b/Digital_Signature_diagram.svg/800px-Digital_Signature_diagram.svg.png)'s a method to sign the message with RSA:
![http://upload.wikimedia.org/wikipedia/commons/thumb/2/2b/Digital_Signature_diagram.svg/800px-Digital_Signature_diagram.svg.png][1]
Why hash ... |
In addition to the performance problems poncho already mentioned when using RSA signatures without hashing I just want to add on the security warning of poncho:
**Reordering**
If you have a message $m>N$ with $N$ being the RSA modulus, then you have to perform at least 2 RSA signatures as $m$ does not longer fit ... |
I want to send out short messages to the world which listeners could verify to be send from me.
The way this is usually done is to encrypt the message with a private key where the readers decrypt it with my public key. My problem is that I need small messages, smaller than 64 bytes in base64, plain RSA won't work si... |
Short length asymmetric encryption? |
In a nutshell, this is my question:
[http://stackoverflow.com/questions/21003216/why-do-i-need-to-add-the-original-salt-to-each-hash-iteration-of-a-password?noredirect=1#comment31574539_21003216][1]
[1]: http://stackoverflow.com/questions/21003216/why-do-i-need-to-add-the-original-salt-to-each-hash-iteration-of... |
Why do I need to add the original salt to each hash iteration of a password? |
I understand it is important to hash passwords over multiple iterations to make things harder for an attacker. I have read numerous times that when processing these iterations, it is critical to hash not only the result of the previous hashing, but also append the original salt each time.
In other words, I think I n... |
I've learnt the formulas needed for the DSA (http://en.wikipedia.org/wiki/Digital_Signature_Algorithm). But most importantly, I don't quite understand what represents those formulas and why they are the way they are? For example, why when v = r then signature is verified, why r and s have such formulas etc.? RSA digita... |
Why DSS has such formulas? |
I've learnt the formulas needed for the DSA (http://en.wikipedia.org/wiki/Digital_Signature_Algorithm).
<br>
But most importantly, I don't quite understand what represents those formulas and why they are the way they are. For example, why if v = r then the signature is verified, why do r and s have such formulas etc.... |
Why does DSS have such formulas? |
Consider a KPA attack, where the attacker gets known plain text and the corresponding cipher text. Since the encryption algorithm is known, he can brute force all possibilities of key bits. **What is the implication of having additional tweak on brute forcing the algorithm**?
Is this correct to say that now the atta... |
While calculating RSA encryption key we take modulo $\varphi(n)$ rather that modulo $n$. I couldn't understand why its so? |
Where does $\varphi(n)$ part of RSA come from? |
Where does the $\varphi(n)$ part of RSA come from? |
I've a couple of questions about this, the scenario is embedding a key pair in a hardware device which will speak with other hardware devices over tls. computing resources are an issue so i want to make intelligent choices about where they go on.
1) All the recommendations are in the case of rsa to use 2048 bit key... |
We want $e$ to be a coprime to $\varphi(N)$ and not coprime to $N$ for the following reason:
- The RSA function is (the popular notation though): $c=[m^e\mod N]$.
- To inverse that function we need $d$ and $e$ such that $(m^e)^d=m^{ed}=m\mod N$ but $e$ and $d$ are coprime to $N$ or $\varphi(N)$?
- Note that $m^... |
I've a couple of questions about this, the scenario is embedding a key pair in a hardware device which will speak with other hardware devices over tls. computing resources are an issue so i want to make intelligent choices about where they go on. We're using TLS to authenticate one device to another, and to ensure in... |
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 eavesdropper cannot distinguish between a message encrypted using Alice's public key and a message encrypted using Bob's public key? |
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 message encrypted using Alice's public key and a message encrypted using Bob's public key?
EDIT:
My question is relate... |
I've a couple of questions about this, the scenario is embedding a key pair in a hardware device which will speak with other hardware devices over tls. computing resources are an issue so i want to make intelligent choices about where they go on. We're using TLS to authenticate one device to another, and to ensure in... |
Say I have an embedded device which is only capable of doing HMAC-SHA1 transformations (that device is, in fact, a YubiKey).
Would it be secure to feed it like a block cipher in counter mode to get a random pad suitable as an stream cipher?
Of course, I'm talking about not repeating the counter value ever to encr... |
Can I use HMAC-SHA1 in counter mode to make a stream cipher? |
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