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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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 ...
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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 ...
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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 ...
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3answers
59 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 ...
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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 ...
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63 views

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 ...
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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?
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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 ...
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52 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 ...
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1answer
94 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 ...
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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 ...
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71 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 ...
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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. ...
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Rsa accumulator verification cost gor nonmembership testing

What is the verification cost of rsa accumulator gor non-membership testing. Is it O(N) or O(1). Can somebody explain it to me?
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Merkle tree verification cost calculation

I am trying to understand how to calculate verification cost of sorted merkle tree in case of exclusion proof. For example 5 revoked certificate are kept in merkle tree. How can i calculate storage ...
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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 ...
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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 ...
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Least knowledge ephemeral PKI?

I'm trying to build a PKI for document signing but only using 2nd party auth and no client persistence. I'm assuming I'd need to use something like a SCrypt key of the user credentials for the user'...
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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 ...
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77 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 ...
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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 ...
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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 ...
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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 ...
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141 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 ...
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54 views

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 ...
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863 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 ...
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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 ...
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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 ...
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Windows certreq full response file [closed]

I'm using the Windows certreq command line tool to submit a CSR for signing to a Windows Server CA. ...
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85 views

Include TSA Certificate in Timestamp Request

I'm currently working on Timestamping and stumbled upon a parameter fRequestCerts/requestSignerCertificates/certReq that according to the documentation (1, 2) tells a TSA to include the certificate ...
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1answer
71 views

How are public keys securely and reliably obtained across the internet?

I've just decided to start learning all about PKIs, and I have come across what seems like a paradox. When fetching a public key from either a server or a CA, how can we be sure that the public key ...
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PKI Multiple Samples start to expose Private Keys?

My understanding is that using a PKI, public/private key pair is generally secure to send message to people. That is, encrypt a message using the recipient's public key so they use their private key ...
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182 views

Characteristic of Public Key?

Is Public key used directly to encrypt a message or it is used to derive other keys ? Can we decrypt a message with same public key using which it was encrypted ? So far I understand, as PKI is based ...
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123 views

What is the RFC order of peer certificate verification, trust chain or expiry first?

If a certificate received from a peer: Is expired, has a valid signature, but from an untrusted root CA What error should be thrown? Untrusted certificate or expired certificate? I can't seem to ...
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188 views

HMAC computation using AES key

I want to compute an HMAC value of a data set using CKM_SHA256_HMAC mechanism with AES key. I have the error code CKR_KEY_TYPE_INCONSISTENT because it seems that I need to use a key of key_type ...
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Creating multiple “public” keys from one private key

Is it possible to create a public key out of a private key, then create another public key from the first public key. And treat the first public key as a private key (So you have two levels of private ...
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Asymmetrical encryption with multiple sufficient key-pairs [duplicate]

I have the following requirement: There are N public/private RSA key pairs. The encrypted data must be decryptable by any of the private keys alone, but not by any other key. For encryption, the ...
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Can public key cryptography survive quantum computers? [duplicate]

Quantum computation is based on the superposition principle of quantum physics. Bits in a normal computer are either 0 or 1. Quantum physics allows bits to be in a superposition of 0 and 1, in the ...
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Authenticating to wireless with EAP-TLS in separate forests with the same trusted root CA

I'm looking at a scenario of having a standalone offline root CA sign a subordinate CA in two separate active directory forests on different campuses. If I then set up EAP-TLS on each site, will I be ...
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Can root and intermediate CAs use different asymmetric ciphers and key sizes?

For example, could a root CA use RSA-4096, one intermediate CA use RSA-2048, and another use ECDSA-256 (DH19)?
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PKI Validation - Usefulness of the public key with the identity certificate

I have some understanding of how PKI works, similar to this: - https://knowledge.digicert.com/solution/SO16297.html - https://security.stackexchange.com/questions/59566/ssl-certificate-chain-...
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992 views

What happens when a root CA loses its private key?

Certificate Authorities normally keep their private keys inside dedicated Hardware Security Modules (HSMs). What happens when such a device is lost (fire, electronic fault, stolen, etc)? How would ...
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671 views

How to sign a CRL file if I have offline keys?

I am generating a CA for internal use. When generating a CA, the best practice I have observed is to keep the root CA offline and emit an intermediate CA certificate that will in turn emit the end-...
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1answer
2k views

Does maximum length of CN in a x509 cert include the length of the OIDs?

This is a CN from a x509 certificate (I have done some substitutions just to mask the data but the length is not changed) CN=Alex Perry/pseudonym=88b2e76beE0e4e4b94b502020202262E/x500UniqueIdentifier=...
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How does registration authority verify entity's identity for SSL? [closed]

In the answer here: Verification of identity by certification authority, it states that for European eIdentity you must provide your passport or ID card, but that this practice is quite different ...
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Encryption in a Distributed PKI?

Given a PKI infrastructure with a root node that signs CSR's for nodes Alice, Bob, and Carol. Is it possible for Alice to encrypt some information, store it publicly somewhere, then later Bob or ...
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Who issued the first SSL certificate?

When SSL was introduced in ~1996, there was only a few CAs issuing certificates for that specific use and a few sites which actually used SSL. Which Certification Authority issued the first SSL ...
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411 views

sign data and append certificate VS sign data and certificate

I am currently writing my masters thesis in which I need to develop a licensing module for an application. The license itself is a JSON Web Token which is signed using a RSA private key. Since we ...
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4k views

Why do we need a digital signature?

First of all, I want to say that I'm totally new to cryptography. I searched on crypto stackexchange but couldn't find the answer to the following question.(probably because it's easy, but I still don'...
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115 views

How to configure a client browser cert to be authenticated by a server?

I currently am being asked to partake in a strange authentication format while working with a client, and was hoping for clarification. The client is using HTTPS with client certificate ...