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Questions tagged [pki]

PKI is short for Public Key Infrastructure. The foundation of a PKI is the certificate authority (CA), which issues digital certificates that authenticate the identity of organizations and individuals over a public system such as the Internet.

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TLS 1.3 digital certificates and ephemeral Diffie Hellman

There is a lot of confusing information out there regarding the role of digital certificates and the use of Ephimeral Diffie Hellman in how TLS 1.3 operates. Would it be correct to state that the the ...
termcap's user avatar
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X509 Name Constraints in a 3-tier PKI - setting at the intermediate CA?

I have been playing around with implementing a three-tier PKI recently. My PKI structure is as follows: Root CA Intermediate CA 1 (Name constraint: DNS .example.com, Email: .example.com, pathlen 1) ...
flashbang's user avatar
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Framework for manipulating digital signatures

for a research project, i am currently looking for a way to manipulate the digital signature of a HTTPS TLS message flow. More specifically, i am trying to create a working example for a malicious ...
ndrscodes's user avatar
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Using plaintext + ciphertext combination as substitute for authentication/signature in elliptic curve cryptography

I'm working on a system where I need to sign some data using an ECC private key and share the data and signature over a BLE ADV packet. Since an ADV packet is limited in space, I can't use a full ...
gabe_torres's user avatar
1 vote
1 answer
246 views

Decentralized identity, how to prevent duplicate uses of the same identity

In a system that relies on decentralized identity, is it possible to prevent duplicate uses of the same real-life identity, i.e. same real-life person creates more than one user entity (each is ...
rapt's user avatar
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2 votes
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How does padding in RSA prevent existenial forgery attacks in RSA?

I am trying to understand how adding padding like the PKCS1.5 RSA signature scheme can prevent the existential forgery attack in RSA. Is it just by changing the structure of the message?
CryptoGuru's user avatar
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1 answer
239 views

What is a website's private signing key used to sign?

I am trying to understand digital signatures and digital certificates. I know that digital certificates verify a server's public verification key but what does the website's (client) private ...
CryptoGuru's user avatar
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40 views

Timestamp quantity for PDF long time archive

How many timestamps are issued when someone signs a PDF with timestamp Long Term Archive (LTA)? Why is it necessary to issue more than one timestamp?
user3637971's user avatar
1 vote
2 answers
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How does TLS 1.3 provide authentication without using the public key to verify that the server has a private key?

In the TLS 1.2 handshake, after checking the certificate, the public key from the certificate was used to encrypt the data to create a symmetric encryption key, hence the authentication took place on ...
Nikita Khodakovsky's user avatar
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1 answer
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Is it possible to define a new custom signed attribute for CAdES?

Is it possible to introduce a new signed attribute in the CMS Advanced Signature format (RFC 5126) for a custom data type? I want to include location data from GPS or Galileo and extend CAdES for my ...
zima blue's user avatar
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1 answer
282 views

Does code signing Certificates need a key Pair? or a single Certificate

I know that SSL Certificates use a private key on the server side and the public key for verifying it on the client side. I am wondering, is it the same for Code Signing Certificates? Or do they just ...
PixelPaul's user avatar
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Is there any way to (irrevocably) *transfer* a private key to another person?

Let's say that Alice is the administrator of a group. For each message generated by a group member, Alice uses an administrator's private key ($sk$) to sign it, indicating that this message has been ...
Z. Chen's user avatar
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Can a user set his public key without knowing its corresponding private key? [closed]

I'm wondering if in public key infrastructure (PKI), a system user be able to set his public key without knowing its corresponding private key. Can this be done?
ali alizade's user avatar
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1 answer
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Is there a way to modify an existing RSA key pair so that the functionality remains?

I have an existing RSA key pair, how to 'derive' a different key pair based on the existing one so that the encryption decryption functionality remains but the original key isn't interchangeable with ...
Felix's user avatar
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2 answers
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Are PKI PQC algorithms slower than their nonPQ counterparts? (e.g. NTRU vs RSA)

Are the methodologies (hard problems being used to secure the encryption) in post-quantum algorithms inherently slower than what we have right now? If not, why weren't they used initially?
belkarx's user avatar
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Distributing the Master Public Key in Identity-based Encryption systems

I was just wondering how the private key generator should publish the master public key inside of an IBE system. This key is needed for all devices in the network to derive the public key of receiving ...
Alex Meyer's user avatar
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Comparing digital certification and blockchain certification

I am trying to understand the benefits of using blockchain technology in document certifications such as university diplomas. I would like to know the difference between digital certification and ...
Sangjin Kim's user avatar
4 votes
1 answer
353 views

Why does Index Calculus work?

I understand how the Index Calculus algorithm works - I know & understand the steps. I understand how the steps are derived. However, I am not able to figure out why it works. I can understand why ...
user93353's user avatar
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How or in which format should Schnorr signature keys be stored? [closed]

I would like to know if there is any standard for storing public and private keys for Schnorr signature
Razvan Marian's user avatar
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1 answer
292 views

Pollard's p - 1 - how do you set the bound & how do you set the base numbers

In Pollard's p-1 algorithm for factoring N, you try to find a L such that p - 1 divides L. Then you check $gcd(pow(a,L,N)- 1, N)$. If 1 < gcd < N, then you have found one of the factors. I have ...
user93353's user avatar
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Why is factorial used in Pollard's $p - 1$ algorithm?

Why exactly do we use factorial for finding an $L$ which is divisible by $p - 1$? Pollard's algorithm is about B-powersmooth numbers & not B-smooth numbers. So where exactly does the factorial ...
user93353's user avatar
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2 votes
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Does applying a "PushEntropy"-function increase security of a private key?

I was just reviewing the source-code of the NBitcoin-package. As far as i can see when you create a new bitcoin-keypair Key privateKey = new Key(); (without passing ...
anion's user avatar
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2 answers
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Automatic csr sending

In our project we have grpc server and clients which should satisfy mutual tls. So, there is CA and clients generate csr to sent to CA to signing it. Now I need to send csr manually to CA to sign it ...
user87968's user avatar
1 vote
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How does TLS 1.3 sign key exchange?

From this site: https://tls13.ulfheim.net/ and from https://www.rfc-editor.org/rfc/rfc8446#section-2 I can't find the part in which the exchange of keys is signed, isn't one of the parties "...
macie's user avatar
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Exploitability of AES in CBC Mode For Recovery of Plain Text

I'm aware of existing literature that shows in a comprehensive manner just how simple it is to tweak the ciphertext of AES-CBC such that the decrypted message ends up being entirely different than ...
librehash's user avatar
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What are the rules regarding to numbers in RSA?

I'd like to have a small sanity check first: As far as I understand, diffie-hellman is all about that fact that, given the generator ($g$), the modulo ($n$) and the remainder ($c$), it's hard to find ...
YoavKlein's user avatar
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5 votes
2 answers
663 views

Clarification on the TLS verification process

I am reading this article in my attempt to understand how the TLS verification and chain of trust works. In the piece I come across a section that I am not sure I understand. In the simplified ...
Finlay Weber's user avatar
7 votes
3 answers
11k views

What exactly is Let's encrypts chain.pem file?

While trying to understand the use or meaning of the fullchain.pem file created by let's encrypt I stumbled upon this post in which ...
Finlay Weber's user avatar
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3 answers
173 views

What are the contents of a certificate and how can I view it?

I understand on a conceptual level that a certificate is nothing more than just a verified public key. The next question I have, is how exactly do I see the contents of a certificate? Apart from the ...
Finlay Weber's user avatar
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38 views

Enforced complete decryption in pki schema

I want to use PKI to encrypt a message. How this generally done is to PKI encrypt an AES key and then encrypt the message. The problem(in my case) with this method is that you can also ask someone to ...
ovanwijk's user avatar
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Elgamal Encryption: Why does Bob get to reuse his keypair while Alice has to generate a new one for every message?

From Christof Paar's book The protocol consists of two phases, the classical DHKE (Steps a–f) which is followed by the message encryption and decryption (Steps g and h, respectively). Bob computes ...
user93353's user avatar
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2 votes
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Why is confusion & diffusion not required PKI encryption schemes like Elgamal encryption?

The Elgamal encryption scheme is a Multiplicative Mask with the shared key. It doesn't seem to have any confusion or diffusion. So why is it not necessary here as compared to Block Ciphers?
user93353's user avatar
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1 answer
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How to securely share AES key between two remote devices (client and server) through UDP protocol?

I have two separate system (client) and (server). I am having a problem which is to encrypt a message from the client and decrypt at the server. In order to do that, I am required to transmit my key ...
zebiskin's user avatar
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1 answer
121 views

What if the CSR is intercepted in transit while sending it to CA?

I was studying PKI the other day and I had a serious thinking about the following question. What is CSR? - It is a block of encoded text that is given to the CA when applying for an SSL certificate ...
KingsNeverDie's user avatar
3 votes
1 answer
399 views

MPC protocols in plain/CRS/PKI models

I have seen that in MPC multiple models in different dimensions can be envisioned, like asynchronous vs synchronous networks, access to broadcast channels, and so on. However, a particularly ...
Daniel's user avatar
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3 votes
3 answers
2k views

What's the downside of using X.509 in SSH instead of PKI

ssh uses public keys for authentication and not signed X.509 certificates. Specify a drawback which would be the use of X.509 certificates instead of public keys. I've tried to look up a lot of ...
Cryptofan12's user avatar
2 votes
1 answer
377 views

Encrypt text message with Wireguard public key

With its public and private key(s), Wireguard looks a bit like PGP. But it is used for encryption of network packets and not normal text messages. I'm on a system with Wireguard already installed and ...
wgquestions's user avatar
5 votes
1 answer
6k views

Converting raw ECC private key into ASN.1 DER encoded key

I created a random integer array of 32 bytes to use as my private key for secp256k1 curve. ...
Dogus Ural's user avatar
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0 answers
58 views

FLT is partly applying to RSA equation, and also relation between ED mod phi and Phi + 1 mod N

After numerous attempts from myself and all of you guys, I finally came to understand RSA. I can now prove it and understand how I got there. But I still have some very few polishing questions. 1) We ...
C0DEV3IL's user avatar
3 votes
1 answer
309 views

Relation between $N = P \times Q$, and $\Phi(N)$

When studying RSA, and proving simple concepts to myself, I went and understood groups and rings, but I failed to understand Lagrange's theorem. I did understand how from invertible finite groups I ...
C0DEV3IL's user avatar
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0 answers
47 views

Conditioning access to private key?

I would like to provide a public/private keypair to a user, but require that the user obtain an authorizing key before being allowed to use the private key. I don't want the authorizing party to have ...
Dave M.'s user avatar
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1 vote
1 answer
147 views

In PKI, with a hash-encrypted message (first hashed, then encrypted), how is the plaintext ever retrieved?

Consider a normal PKI encryption flow - hash the plaintext, then encrypt the hash with the private key of the sender and then encrypt it with the public key of the recipient. All this is good - and I ...
user2736158's user avatar
4 votes
1 answer
3k views

What is the difference between PKCS1 v1.5 and PKCS7? Is PKCS7 a superset of specifications in PKCS1 1.5?

I have a requirement wherein we have to verify the PE binaries generated for an aarch64 platform. These binaries are then signed using the opensource sbsign tool ...
Faisal's user avatar
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2 votes
0 answers
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What are some examples of out of bound channels that work over the Internet in practice?

If I want to verify a public key (be it RSA, PGP, etc.) with another client over the Internet only, what are some viable out-of-bound channels for verification? Which channels have been used in ...
09182736471890's user avatar
-1 votes
2 answers
236 views

A simple misunderstanding of SSL/TLS

I just came to learn about Deffie Hellman Key Exchange. And a little bit about RSA. I came to DH from something about SSL. From what I understood before is that SSL uses DH and TLS uses RSA, but after ...
C0DEV3IL's user avatar
2 votes
1 answer
381 views

Understanding need for PKI

For simplicity let's say I only have RSA and AES on my hands and I want Alice to talk with Bob over a secure channel. With secure I am implying no MITM and Alice and Bob know they are talking to each ...
Num Lock's user avatar
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1 vote
1 answer
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How are certificate status obtained on browsers?

There are two ways of checking the status of a digital certificate:- Offline Authentication (CRL) Online Authentication (OCSP, SCVP) Several browsers (like Mozilla Firefox) have given up the use of ...
Vasu Deo.S's user avatar
1 vote
1 answer
2k views

How is Cross-Certification implemented?

I am currently learning about Certificates in Public Key Infrastructure. Cross-Certification exists as an alternative because the concept of a single monolithic CA certifying every possible user in ...
Vasu Deo.S's user avatar
1 vote
1 answer
83 views

Nomenclature of Certificate Authorities and Certificates in PKI

In PKI there are different terms to identify certificate authorities in the chains. All terms I know of are as follow: Root Subordinate Super Intermediate I see all terms used interchangeably in the ...
Fleshgrinder's user avatar
1 vote
0 answers
67 views

Sign file (Client-Server) PKI-CA [closed]

I have a use case, the IoT system sending a signed file to the data center and I have an internal CA to read the corresponding public key to verify the signature on the signed file. I am not sure ...
yls's user avatar
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