instruction stringlengths 15 30k |
|---|
X509 Name Constraints in a 3-tier PKI - setting at the intermediate CA? |
We must first wonder if the preconditions hold, in particular 1; that is:
> In Bitcoin, given half the 52-character private key in WIF format, is it possible to reconstruct the whole private key?
The [WIF format][1] is essentially a 52-characters encoding per [Base-58][2] of the nearly random 256-bit bitstring for... |
As far as I can tell we don't have any good key exchange post-quantum candidates. SIKE was broken some time ago.
It is possible to reach an authenticated shared secret by having the public key holder do PKE to send a secret to the private key holder and even have it reply with its own secret back in order to reach a... |
The weakening of PQC as a result of lack of KEX? |
I'd like to find a mechanism to evaluate the SHA-256 compression function using multi-party computation, but I'm not sure what's possible given the current state of the art and would appreciate some pointers in the right direction.
Specifically, I have set of parties (which must be scalable to more than two!) who ea... |
Oded Goldreich in his book [[Foundations of Cryptography][1], 2004, Section 3.2.3] proves a theorem by polynomial number of hybrids.
----------
[![enter image description here][2]][2]
----------
In rather recent years, Marc Fischlin and Arno Mittelbach published a paper [FM21, [IACR 2021/088][3]] and prove le... |
The [`elliptic.js`](https://www.npmjs.com/package/elliptic) library allows instantiating ECDSA with the `edwards25519` curve.
I've rarely seen this combination in the wild. Is this fine? Are there any known bugs? |
Is it fine to use ECDSA with edwards25519? |
In an attempt to understand the mathematical operations related to encryption with elliptic curves, in particular finite field arithmetic (Modular reduction) I found in the Montgomery reduction that Montgomery form is an alternative finite field representation. what is this suppose to mean ? what it does differ from th... |
I'm trying to understand if using non-injective encodings for Elliptic Curve ElGamal encryption is dangerous.
A standard probabilistic encoding defined by [Koblitz][1] for elliptic curves over $\mathbb{F}_p$ works roughly as follows (see [this answer][2] for details):
- Fix some value $\ell < bitlength(p)$
-... |
We must first wonder if the preconditions hold, in particular 1; that is:
> In Bitcoin, given half the 52-character private key in WIF format, is it possible to reconstruct the whole private key?
The [WIF format][1] conveys the nearly random 32-byte [ECDSA][2] private key $d$ for curve [secp256k1][3], fixed data a... |
We must first wonder if the preconditions hold, in particular 1; that is:
> In Bitcoin, given half the 52-character private key in WIF format, is it possible to reconstruct the whole private key?
The [WIF format][1] conveys the nearly random 32-byte [ECDSA][2] private key $d$ for curve [secp256k1][3], fixed data a... |
We must first wonder if the preconditions hold, in particular 1; that is:
> In Bitcoin, given half the 52-character private key in WIF format, is it possible to reconstruct the whole private key?
The [WIF format][1] conveys the nearly random 32-byte [ECDSA][2] private key $d$ for curve [secp256k1][3], fixed data a... |
We must first wonder if the preconditions hold, in particular 1; that is:
> In Bitcoin, given half the 52-character private key in WIF format, is it possible to reconstruct the whole private key?
The [WIF format][1] conveys the nearly random 32-byte [ECDSA][2] private key $d$ for curve [secp256k1][3], fixed data a... |
We must first wonder if the preconditions hold, in particular 1; that is:
> In Bitcoin, given half the 52-character private key in WIF format, is it possible to reconstruct the whole private key?
The [WIF format][1] conveys the nearly random 32-byte [ECDSA][2] private key $d$ for curve [secp256k1][3], fixed data a... |
Oded Goldreich in his book [[Foundations of Cryptography][1], 2004, Section 3.2.3] proves a theorem by polynomial number of hybrids.
----------
[![enter image description here][2]][2]
----------
In rather recent years, Marc Fischlin and Arno Mittelbach published a paper [FM21, [IACR 2021/088][3]] and prove le... |
When the Electronic Frontier Foundation and _distributed.net_ [broke the DES Challenge III in less than a day](http://www.distributed.net/images/d/d7/19990119_-_PR_-_release-des3.pdf), revealing the message `See you in Rome (second AES Conference, March 22-23, 1999)`, what was the actual full value of the key they foun... |
What was the DES Challenge III key? |
I don't understand your concern. It sounds like you are assuming that public (and private) keys in lattice-based key exchange are static? I don't believe this is the case though. So if your bank (or whatever) ephemerally generates a new lattice-based public/private key for each connection, they are fine. This can be ve... |
Why not? I'll rephrase your question as "Now imagine the $\mathtt{G}$ key is pressed and returns to the plugboard as, say, a $\mathtt{Q}$. But what then happens if, on the plugboard, the $\mathtt{Q}$ is paired with $\mathtt{G}$? Then isn’t the current then directed to $\mathtt{G}$, the key that was pressed." @Eugene St... |
Why not? I'll rephrase your question as "Now imagine the $\mathtt{G}$ key is pressed and returns to the plugboard as, say, a $\mathtt{Q}$. But what then happens if, on the plugboard, the $\mathtt{Q}$ is paired with $\mathtt{G}$? Then isn’t the current then directed to $\mathtt{G}$, the key that was pressed." @Eugene St... |
I spoke too soon; it seems that distributed.net maintains an IRC channel, `irc.libera.chat/distributed`; I asked, and a regular there, _ertyu_, directed me to this blog post — apparently the "blog" and "news" sections of distributed.net are separate, which explains why I wasn't able to find it at first:
https:... |
I spoke too soon; it seems that distributed.net maintains an IRC channel, `irc.libera.chat/distributed`; I asked, and a regular there, _ertyu_, directed me to this blog post — apparently the "blog" and "news" sections of distributed.net are separate, which explains why I wasn't able to find it at first:
https:... |
Quick a disclaimer, I am pretty new to cryptography. I only understand the basics of asymmetric and symmetric encryption. In particular, RSA and AES.
I have a project where my service is receiving an encrypted SAML payload. As per the project description: a Public key 2048 was used to encrypt the payload and a Priva... |
What exactly is RSA_WITH_AES256_CBC_SHA256? |
Quick disclaimer, I am pretty new to cryptography. I only understand the basics of asymmetric and symmetric encryption. In particular, RSA and AES.
I have a project where my service is receiving an encrypted SAML payload. As per the project description: a Public key 2048 was used to encrypt the payload and a Private... |
We must first wonder if the preconditions hold, in particular 1; that is:
> In Bitcoin, given half the 52-character private key in WIF format, is it possible to reconstruct the whole private key?
The [WIF format][1] conveys the nearly random 32-byte [ECDSA][2] private key $d$ for curve [secp256k1][3], fixed data a... |
This answer, and the question, assume that the public key is not available to the attacker. This is unusual in cryptography, but a possibility in Bitcoin, where the hash of the public key (known as address) is enough for a so-called Pay-to-Public-Key-Hash.
> To guess the last 13 base58 characters by brute force woul... |
Given parameters $k,n,d$ with $1\le k\le n$, we want a $(k,n)$ Thresold Scheme to share any given $d$-bit bitstring $D$, by efficiently producing $n$ _shares_ $D_i$ each $e$-bit with $e$ a function of parameters, such that
1. Any set of $k$ shares makes it efficient to compute $D$.
2. With any set of $k-1$ shares it'... |
Given parameters $k,n,d$ with $1\le k\le n$, we want a $(k,n)$ Thresold Scheme to share any given $d$-bit bitstring $D$, by efficiently producing $n$ _shares_ $D_i$ each $e$-bit with $e$ a function of parameters, such that
1. Any set of $k$ shares makes it efficient to compute $D$.
2. With any set of $k-1$ shares it'... |
Given parameters $k,n,d$ with $1\le k\le n$, we want a $(k,n)$ Thresold Scheme to share any given $d$-bit bitstring $D$, by efficiently producing $n$ _shares_ $D_i$ each $e$-bit with $e$ a function of parameters, such that
1. Any set of $k$ shares makes it efficient to compute $D$.
2. With any set of $k-1$ shares it'... |
This answer, and the question, assume that the public key is not available to the attacker. This is unusual in cryptography, but a possibility in Bitcoin, where the hash of the public key (known as address) is enough for a so-called Pay-to-Public-Key-Hash.
> To guess the last 13 base58 characters by brute force woul... |
Is it possible to perform reverse rsa encryption ? (using the public key for decrypting and the private key for encrypting) |
Are you looking for a way to 'sign' a message with a private key, so that someone with the public key can verify it (and no one without the private key can modify it)?
Well, there are algorithms (called, oddly enough, signature algorithms) that can do that. Some of them are ECDSA, EdDSA and BSS (focusing on the one... |
I have a database table that needs to be shared between multiple parties. There is a sensitive column than must be obfuscated in a way that preserves equality relationships between records. A trusted party must have the ability to reverse the obfuscation. Is there a composition of cryptography primitives that satisfies... |
Are there asymmetric encryption algorithms that preserve equality? Are they safe to use for data obfuscation? |
Given parameters $k,n,d$ with $1\le k\le n$, we want a $(k,n)$ Thresold Scheme to share any given $d$-bit bitstring $D$, by efficiently producing $n$ _shares_ $D_i$ each $e$-bit with $e$ a function of parameters, such that
1. Any set of $k$ shares makes it efficient to compute $D$.
2. With any set of $k-1$ shares it'... |
Given parameters $k,n,d$ with $1\le k\le n$, we want a $(k,n)$ Thresold Scheme to share any given $d$-bit bitstring $D$, by efficiently producing $n$ _shares_ $D_i$ each $e$-bit with $e$ a function of parameters, such that
1. Any set of $k$ shares makes it efficient to compute $D$.
2. With any set of $k-1$ shares it'... |
The following is mostly known to lattices people (and mentioned at the end of the Quanta article), but I also reached out to Keegan to clarify some questions I had.
There are (roughly) two main types of lattice basis reduction
1. LLL: Poly-time computable, but relatively weak guarantee on output basis, and
2. BK... |
## problem statements
### background
Large corpora are available to us,
each written in one of K different natural languages,
which use a Roman-like alphabet (perhaps Greek, Cyrillic, ...).
Plaintext is produced in one of those languages,
with roughly typical word frequencies (so "the" is ranked first in ... |
Protocol for verifying novel compression algorithm? |
is factoring RSA given 30% MSB of p and 30%MSB of q possible in polynomial time?
Notice that it is known that given 50% MSB of p or q it is doable in polynomial time using Coppersmith's theorem |
I've been learning about aggregate signatures lately, are there any overviews or learning materials about aggregate signatures (including security properties)? |
I have a database table that needs to be shared between multiple parties. There is a sensitive column than must be obfuscated in a way that preserves equality relationships between records. A trusted party must have the ability to reverse the obfuscation. Is there a composition of cryptography primitives that satisfies... |
I have a database table that needs to be shared between multiple parties. There is a sensitive column than must be obfuscated in a way that preserves equality relationships between records. A trusted party must have the ability to reverse the obfuscation. Is there a composition of cryptography primitives that satisfies... |
By the pigeonhole principle, we can demonstrate that arbitrary lengths of random data are uncompressible in the general case.
But let us imagine another universe, in which I claim that I have created a compression algorithm that can compress arbitrary random data by a certain ratio.
In such a case, I don't want t... |
By the pigeonhole principle, we can demonstrate that arbitrary lengths of random data are uncompressible in the general case.
But let us imagine another universe, in which I claim that I have created an oracle that can compress arbitrary random data by a certain ratio.
In such a case, I don't want to show you my ... |
By the pigeonhole principle, we can demonstrate that arbitrary lengths of random data are uncompressible in the general case.
But let us imagine that I claim that I have created an oracle that can compress arbitrary random data by a certain ratio.
In such a case, I don't want to show you the internal details of m... |
> Are there asymmetric encryption algorithms that preserve equality?
It's easy to make such algorithm from any secure asymmetric encryption algorithm: replace the source of randomness in the encryption by the output of a Pseudo Random Number Generator seeded by a hash of the plaintext.
But as explained in @poncho... |
> Are there asymmetric encryption algorithms that preserve equality?
As explained in @poncho's [answer][1], that property is unusual for asymmetric encryption since it causes a severe flaw: it's possible to check a guess of the plaintext by trial encryption. E.g. for a birthdate in the 20<sup>th</sup> or 21<sup>th</... |
> Are there asymmetric encryption algorithms that preserve equality?
As explained in @poncho's [answer][1], that property is unusual for asymmetric encryption since it causes a severe flaw: it's possible to check a guess of the plaintext by trial encryption followed by comparison with the ciphertext.
That flaw i... |
> Are there asymmetric encryption algorithms that preserve equality?
As explained in @poncho's [answer][1], that property is unusual for asymmetric encryption since it causes a severe flaw: it's possible to check a guess of the plaintext by trial encryption followed by comparison with the ciphertext.
That flaw i... |
> Are there asymmetric encryption algorithms that preserve equality?
As explained in @poncho's [answer][1], that property is unusual for asymmetric encryption since it causes a severe flaw: it's possible to check a guess of the plaintext by trial encryption followed by comparison with the ciphertext.
That flaw i... |
First of all apologies if this is not the right place. I am not very knowledgeable in cryptography but I thought you can at least point me in the right direction of research.
The following is a toy problem I tried to to analyse for fun and see if it's possible to find and answer.
It might be the case that the ... |
> Are there asymmetric encryption algorithms that preserve equality?
As explained in @poncho's [answer][1], that property is unusual for asymmetric encryption since it causes a severe flaw: it's possible to check a guess of the plaintext by trial encryption followed by comparison with the ciphertext.
That flaw i... |
> Are there asymmetric encryption algorithms that preserve equality?
As explained in @poncho's [answer][1], that property is unusual for asymmetric encryption since it causes a severe flaw: it's possible to check a guess of the plaintext by trial encryption followed by comparison with the ciphertext.
That flaw i... |
We are given an El Gamal variant and are requested to find the decryption scheme and the security of the encryption. The variant operates on a group $\mathbb{G}$ of prime order q and g, h are two generators of the group $\mathbb{G}$ (the relation between g and h is unknown). The key generation and encryption are the fo... |
One common approach to deal with these kinds of questions is *differential privacy*, google it. A search here on crypto stackexchange [yields][1] quite a lot of questions and answers.
Very briefly and in its simplest instantiation, it's about querying a database to obtain information about the database without leaki... |
Of course this is a question with an answer that is due to evolve.
A 2002 paper about [twirl stated that the cost would be around 10M\$ and an other 10M\$ to manufacture the device](https://cs-people.bu.edu/tromer/twirl/). A later 2007 paper [claimed to have improved the design and created an actual fpga](http://www... |
What would be the cost of factoring a 1024‒bits ʀꜱᴀ modulus today ? And which method would be the most cost‑effective? |
Of course this is a question with an answer that is due to evolve.
A 2002 paper about [twirl stated that the cost would be around 10M\$ and an other 10M\$ to manufacture the device](https://cs-people.bu.edu/tromer/twirl/). A later 2007 paper [claimed to have improved the design and created an actual fpga](http://www... |
I'm trying to write a webserver.
I'm using TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 (secp256r1).
I generated a CA certificate using OpenSSL (using prime256v1).
I generated the hash using server_random + client_random + curve_info + temp_publickey (just binary connect).
But when I test, OpenSSL returns them:
... |
Of course this is a question with an answer that is due to evolve.
A 2002 paper about [twirl stated that the cost would be around 10M\$ and an other 10M\$ to manufacture the device](https://cs-people.bu.edu/tromer/twirl/). A later 2007 paper [claimed to have improved the design and created an actual fpga](http://www... |
Of course this is a question with an answer that is due to evolve.
A 2002 paper about [twirl stated that the cost would be around 10M\$ and an other 10M\$ to manufacture the device](https://cs-people.bu.edu/tromer/twirl/). A later 2007 paper [claimed to have improved the design and created an actual fpga](http://www... |
How could a 1024‒bits ʀꜱᴀ modulus be most economically factored today ? And which method would be the most cost‑effective? |
Of course this is a question with an answer that is due to evolve.
A 2002 paper about [twirl stated that the cost would be around 10M\$ and an other 10M\$ to manufacture the device](https://cs-people.bu.edu/tromer/twirl/). A later 2007 paper [claimed to have improved the design and created an actual fpga](http://www... |
How could a 1024‒bits ʀꜱᴀ modulus be most economically factored within months today ? And which method would be the most cost‑effective? |
I know that information can be changed by changing the frequency of electromagnetic vibrations.My question is, can I change the frequency according to my encryption algorithm? That way I can get a frequency that doesn't match anywhere. This would increase the reliability of my algorithm.
cable radiates. Can I algorith... |
Of course this is a question with an answer that is due to evolve.
A 2002 paper about [TWIRL][1] stated that the cost would be around 10M\$ and an other 10M\$ to manufacture the device. A later 2007 [paper][2] claimed to have improved the design and created an actual FPGA, though at that time they were still used sp... |
How could a 1024‒bits RSA modulus be most economically factored within months today? |
This excerpt is directly from the official "Tiger" reference implementation:
https://biham.cs.technion.ac.il/Reports/Tiger/tiger-src.zip
```
/* The number of passes of the hash function. */
/* Three passes are recommended. */
/* Use four passes when you need extra security. *... |
Shamir secret sharing<sup>1</sup> is a common method to split an arbitrary secret (login credentials, private key) between $n$ persons, so that a threshold of $k$ persons is required to rebuild the secret. The _share_ given to each person is about the size of the original secret<sup>2</sup>.
The question asks how to... |
Let a plain text message `M` be DES encrypted with two different keys (`K1` and `K2`) to produce the encrypted messages `E1` and `E2` (for `K1` and `K2` respectively).
Lets assume we setup a brute force attack which tests all possible keys `K1` and `K2` until the decrypted messages `M1` and `M2` are equal.
Is it ... |
Let a plain text message `M` be DES encrypted with two different keys (`K1` and `K2`) to produce the encrypted messages `E1` and `E2` (for `K1` and `K2` respectively).
Lets assume we setup a brute force attack which tests all possible keys `K1` and `K2` until the decrypted messages `M1` and `M2` are equal.
Is it ... |
Let a plain text message `M` be DES encrypted with two different keys (`K1` and `K2`) to produce the encrypted messages `E1` and `E2` (for `K1` and `K2` respectively).
Lets assume we setup a brute force attack which tests all possible keys `K1` and `K2` until the decrypted messages `M1` and `M2` are equal.
Is it ... |
Let a plain text message `M` be DES encrypted with two different keys (`K1` and `K2`) to produce the encrypted messages `E1` and `E2` (for `K1` and `K2` respectively).
Lets assume we setup a brute force attack which tests all possible keys `K1` and `K2` until the decrypted messages `M1` and `M2` are equal.
Is it ... |
Let a plain text message `M` be DES encrypted with two different keys (`K1` and `K2`) to produce the encrypted messages `E1` and `E2` (for `K1` and `K2` respectively).
Lets assume we setup a brute force attack which tests all possible keys `K1` and `K2` until the decrypted messages `M1` and `M2` are equal.
Is it ... |
In standard Shamir's Secret Sharing schemes the shares are generated from randomly generated polynomials. I was wandering if it would be possible to create some predefined shares that a user would be able to use. e.g. in a threshold of 5, 2 shares are predefined by the user and the 3 others are generated like normal.
... |
Is it possible to create a mix of predefined and generated shares for shamirs secret sharing? |
I am a self taught front-end developer and I am just trying to get my cryptography terminologies straight. I will make some statements. Can someone correct my mistakes?
# Question 1
I read that **cipher** is an **algorithm** used for encrypting and or encrypting data. Did I mis-understand?
# Question 2
I... |
The pseudonymous giant, Gwern, has written [a lovely survey paper](https://gwern.net/self-decrypting) on this topic that stretches from Rivest to Vitalik and beyond. It's an excellent starting point if you want to get a broad overview.
-----
If you don't want to read the entire paper, here is a summary/highlights... |
For RSA or elliptic cryptography, can we use the same public/private keys for several exchanges, or is it unsafe ? Does it lower the security of the protocol ?
To me it doesn't matter, as receiving multiple encrypted message does not give more information about the factorisation of the public key. Am I correct ? |
Can we use several times the same RSA and ECC keys? |
Shamir secret sharing<sup>1</sup> is a common method to split an arbitrary secret (login credentials, private key) between $n$ persons, so that a threshold of $k$ persons is required to rebuild the secret. The _share_ given to each person is about the size of the original secret<sup>2</sup>.
The question asks how to... |
Shamir secret sharing<sup>1</sup> is a common method to split an arbitrary secret (login credentials, symmetric or private key) between $n$ persons, so that a threshold of $k$ persons is required to rebuild the secret. The _share_ given to each person is about the size of the original secret<sup>2</sup>.
The questio... |
I am a self taught front-end developer and I am just trying to get my cryptography terminologies straight. I will make some statements. Can someone correct my mistakes?
# Question 1
I read that **cipher** is an **algorithm** used for encrypting and decrypting data. Did I misunderstand?
# Question 2
I foun... |
For RSA or elliptic cryptography, can we use the same public/private keys for several exchanges, or is that unsafe? Does it lower the security of the protocol?
To me it doesn't matter, as receiving multiple encrypted messages does not give more information about the factorisation of the public key. Am I correct? |
Is it possible to create a mix of predefined and generated shares for Shamir's Secret Sharing? |
Would it be possible to use ChaCha20 as a block cipher? With the key, the entire block function can be reversed. |
The ***salt*** that is used with a `PBKDF` is **not** a confidential information, it only needs to be *differen*t (with very high probability) for each encryption key that is generated from the password. The actual ***password*** is the confidential information that needs to be protected! Therefore, it is perfectly "sa... |
The ***salt*** that is used with a `PBKDF` is **not** a confidential information, it only needs to be *differen*t (with very high probability) for each encryption key that is generated from the password. The actual ***password*** is the confidential information that needs to be protected! Therefore, it is perfectly "sa... |
I'm working on a network where nodes communicate using AES-CCM encryption, within a context of tight bandwidth limitations, making every bit count. The setup uses a nonce that combines a 16-bit node address, a timestamp incremented every 100 seconds (with only the offset transmitted), and a 10-bit counter unique to eac... |
I'm working on a network where nodes communicate using AES-CCM encryption, within a context of tight bandwidth limitations, making every bit count. The setup uses a nonce that combines a 16-bit node address, a timestamp incremented every 100 seconds (with only the offset transmitted), and a 10-bit counter unique to eac... |
In FIPS 204 (https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.204.ipd.pdf): "The vector $\textbf{t}$ is compressed in the actual public key by dropping the $d$ least significant bits from each coefficient, thus producing the polynomial vector $\textbf{t}_1$. This compression is an optimization for performance, not secu... |
How to reconstruct low order bits of $t$ of CRYSTALS-Dilithium from a small number of signatures? |
in reference [here][1] the FFT trick for $X^n+1$ is discussed with reference to the Number Theoretic transformation. On page 5, the Chinese Remainder Theorem is used to define the mapping.
[![enter image description here][2]][2]
So far so good. But I am particularly interested in how to arrive at the statement t... |
in reference [here][1] the FFT trick for $X^n+1$ is discussed with reference to the Number Theoretic transformation. On page 5, the Chinese Remainder Theorem is used to define the mapping.
[![enter image description here][2]][2]
So far so good. But I am particularly interested in how to arrive at the statement t... |
I am curious about this structure of quotient ring in Ring LWE. So R=Z[x]/(x^n+1), where x^n+1 is irreducible polynomial and n is a power of 2. So, this structure would not be a ring anymore, it will be field. So, why is it called ring and referred it as Ring LWE? |
> So $R = \mathbb{Z}[x]/(x^n+1)$, where $x^n+1$ is irreducible polynomial and n is a power of 2. So, this structure would not be a ring anymore, it will be field. So, why is it called ring and referred it as Ring LWE?
As mentioned in the comments, there are two points to highlight.
1. One doesn't work with $R$ di... |
TLDR: None worth academic interest.
___
All modern encryption techniques intended for digital computers are applicable, and secure, for all kinds of digitized data, including text and image. There is no need for such encryption specialized to image or text. Argument: the modern baseline for encryption security is res... |
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