Questions tagged [public-key-infrastructure]

A public-key infrastructure (PKI) is a set of hardware, software, people, policies, and procedures needed to create, manage, distribute, use, store, and revoke digital certificates. In cryptography, a PKI is an arrangement that binds public keys with respective user identities by means of a certificate authority (CA). There are three main categories of PKI: Web / SSL certs, corporate networks, and Government ID / ePassport.

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Self-signed cert - how it works

I am new to SSL / digital certificates / signatures. What I know is that a digital signature must be verified/decrypted using the public key. So a cert that is signed by a CA must be verified/...
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662 views

What is the best way to reissue user certificates after configuration change in a template?

I have setup my MS-ADCS environment in my company and configured auto-enrollment. i have everything working great, but found out that I want my "Subject Name Format" to have a different value. We are ...
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346 views

What if somebody sends me genuine certificate that they do not own? [closed]

I just started learning about the digital certificates, its architecture and how it works internally. What will happen if someone sends me a genuine certificate for authentication which does not ...
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1answer
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Certificate serial and thumbprint number spacing

We have a Microsoft PKI setup at our organization. As per just about all certificates I've ever seen, new certificates issued by our issuing CAs will put the serial number and thumbprint in a HEX ...
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Is the Offline Root CA Obsolete?

There are countless “how-to” articles and best practices recommending use of an offline root certificate authority (CA). Though as the title suggests, is this recommendation obsolete? The context of ...
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577 views

Can we use a public key scheme for performing cryptographic commitment

Is it possible to use a public key scheme such as DSA as a commitment scheme? Are there any problems with doing this?
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Why one should prefer EST protocol instead of SCEP?

For many years SCEP was a simple and widely used protocol for obtaining X.509 certificates. However, not too so long ago another protocol called EST (RFC 7030) was developed. What are the main ...
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1answer
404 views

How can I use X.509 cross signing to replace a CA?

I have a self-signed CA that I want to rotate the key for. I want to use cross-signing to facilitate this, with gradual replacement of the certificate on the clients so they can still communicate. I'...
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Is there a compiled list of TEE (Trusted Execution Environment) manufacturer/CA certificates?

I may be misunderstanding TEEs (I just learned about them from an HN post), but I have question regarding the features that seem to allow what seems to be the perfect form of DRM (to my maybe limited ...
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1answer
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How to get public key if we know domain name?

I am solving some CTF lab. I send a request and get response in which it contains cookie. Cookie has three element. First is token and something that is ecdsa signed. The second is domain name. The ...
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How to properly create and use cross-signed CAs and certificates

I'm trying to create an environment with cross-signed CAs, and verify a certificate issued against one of the CAs, all using openssl. The best I got so far is getting openssl into an endless loop ...
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Identifying and understanding a cryptographic voting protocol

I am reading about a voting protocol using public key encryption. According to the notes, if A votes va, then A broadcasts Ra(Rb(Rc(Ea(Eb(Ec(va)))))). Here, Ra is a random encoding function which ...
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Malware abusing SSH agent active keys

I am thinking about this lately a lot, so I wanted to get someone else's opinion. Let's say that I have an SSH key agent (e.g. Pageant or ssh-agent) running in background with loaded keys (keys were, ...
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2answers
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Rotating encryption keys - how does it work?

I haven't found a duplicate which explains with sufficient clarity how does the process of rotating encryption keys work in simple layman terms. I know how private/public key cryptography works, I ...
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1answer
95 views

How to Manage Public Key with Asymmetric Cryptography

I'm working on an iOS chat project using Firebase RealTime Database. I want to use asymmetric cryptography for the management of messages between two users .. Browsing the net I found an excellent ...
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2answers
106 views

Delivering data securely when the data source is the key maker

Let's say we have the following: Bob needs to send data securely to Alice. Only Bob and Alice are allowed to read/see that data. Alice is not able/allowed to create keys. Alice can use any number or ...
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Why is it more secure to use intermediate CA certificates?

I've read that using Intermediate CA certificates is more secure because this way the Root CA is offline. So, if the Intermediate is compromised it does not impact the Root CA. What I understand is ...
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1answer
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Public Key Crypto - sign Bob's name into Alice's message or encrypt Alice's name

I was reading Defective Sign & Encrypt in S/MIME,  PKCS#7, MOSS, PEM, PGP, and XML and in section 5.1  Naming Repairs By signing Bob's name into her message, Alice explicitly identifies him ...
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Why Diffie-Hellman instead of just share the secret [duplicate]

I read that D-H is used to make a shared secret between parties that then they use to encrypt the messages. This is used in TLS, for example, after the server has authenticated itself with a ...
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1answer
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Verify the requesting domain

I have a both a http and websocket server written in nodejs (for now) and it will be receiving requests from many different domains. The request is made from the client using JS. I need to verify 100%...
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Hierarchical PKI trust model

Suppose we have the hierarchical trust model as seen below. Alice will trust Doris' public key iff there is a Certifcation Path from her to Doris. Alice thus pocesses a valid certificate of A. ...
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Root CA and Intermediate CA security [duplicate]

I'm confused how intermediate CA's adds to the security of the PKI. I realize the compromise of root CA key is catastrophic as it would've to be consequently purged from the trust store of every ...
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2answers
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Console based PKI auth (Xubuntu Linux)

Normally, I use my PKCS#11 card to logon to a secured site using a browser plugin which initiated a local software dialog to input PKI card PIN. Is it anyhow possible to do the following? Run some ...
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1answer
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TLS Cipher Suites and PKI

I am currently trying to figure out what cryptographic algorithms are applicable when using mutual authentication for TLS with PKI-certificates. So when I am intitially creating a certificate, I ...
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2answers
174 views

What happens when the timestamper's certificate expires?

What happens when the timestampers certificate expires? If the code is now untrusted, can it be re-stamped without re-signing? If not, what good does this timestamp do me if my cert is valid until the ...
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Why digital signatures needs different algorithm

Why digital signatures uses algorithms such as DSA, ECDSA or RSA-PSS, and not just the RSA algorithm to encrypt the message hash with the private key? Is the choice more security or performance ...
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1answer
137 views

Concepts of PKI Encryption and Digital Signature Authentication [duplicate]

I am trying to understand how SSL uses PKI and Digital Signature authentication to ensure secure and verified communications. I've read various sources online and from what I can tell the basic ...
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How does Authy's 2FA work, if it doesn't connect to the server?

I thought I knew how two-factor authentication works: I enter the password. Server generates a random number (token) and sends it to me via SMS. I enter this token. Server checks that the token I ...
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1answer
202 views

Best way to manage private keys for users of an application?

We're building an application which will leverage blockchain for financial transaction within itself. We won't be forcing users to manage their own keys. Our clients (we're building a B2B platform) ...
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1answer
392 views

How does server use session key after tls handshake?

After TLS handshake both server and client agreed about session key to use as symmetric key. So server must store several session keys which each one belongs to a specific client. How server ...
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1answer
145 views

re-reading decoded openssl pubkey

I was playing with openssl just to see how reading of the public key from a certificate works; Gave a "letsencrypt.pem" certificate I have, I gave these commands. See the entire certificate text: ...
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2answers
396 views

openssl certificate chain output

I was reading the "Security with HTTPS and SSL" guide for android developers and reading this paragraph. The paragraph discusses the fact that servers do not always return the entire certificate ...
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Root CA with Extended Key Usage fields

I recently started using AWS's Certificate Manager to get free TLS certificates for my load balancer. When I was inspecting the certificate chain I noticed that the Root CA, Starfield Class 2 ...
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1answer
480 views

Limit OpenVPN client certificate to specific VPN with shared CA chain

I've created a private x509 pki structure with openssl that consists of a self signed Root CA, an Intermediate CA and two Signing CA's. The signing CA's are used to separate the signing of ...
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1answer
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Are very short messages secure using Public Key Encryption? [duplicate]

Say Alice publishes her public key and then disappears from public view. Bob then needs to send a message to her that's either "OK" or ":(" so he takes her public key, encrypts his message and then ...
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Product & Feature Comparison of EJBCA, Active Directory Certificate Services, or Entrust Authority Security Manager?

I'm currently beginning analysis in this field and stumbled across the thread titled: "Comparison and difference between CAs" The question seems largely unresolved. Does there exist any product or ...
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58 views

Bloom filter to prevent replay attacks in signed HTTP requests

I'm thinking about an authentication sheme of a REST API in a setting where the only thing the server stores about a client, is their public key (the asymmetric encryption scheme should not matter). ...
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2answers
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Does the symmetric key exchange through asymmetric encryption have to be done asymmetrically?

To communicate over a public channel, it seems often that 2 parties first use some asymmetric-encryption way to exchange a symmetric key. And then use the symmetric key for subsequent communication. ...
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2answers
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What is the difference between digital notary and certification authority?

Is the difference purely legal or is there a technical difference between a notary notarizing the document signer's identity and a certification authority certifying a signer's certificate?
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2answers
164 views

Correct procedure for encrypting data with public key and password-protecting the private key

I see myself in the need to use PKI in a program on Linux. The following code summarizes the approach I would take. Generate a key pair, store it on disk. The private key is encrypted with AES for ...
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1answer
400 views

Should we use x509 V1 certificate for a new root CA?

I read a couple of articles that kind of gives the impression that the norm is to use a V1 x509 pkc for a root CA. This is one of them. However the rfc5280 makes no such suggestion. My question is, ...
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4answers
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How do mobile apps prevent HTTPS MITM attacks when the user installs the attacker's CA certificate?

I am using a mobile app that installs a fake trusted CA certificate and therefore can capture the HTTPS traffic of other apps. Most of the time, this MITM attack is successful. However, I noticed ...
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0answers
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Protecting private keys of common chat applications with 2FA

Say a user uses a common chat application like Telegram, Signal, Whatsapp, Ricochet. His device gets hacked and private keys get stolen. For normal PGP usage with email you can use two factor ...
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Generating ECDSA certificate and private key in one step

Similar to how it can be easily done for RSA: openssl req -x509 -nodes -newkey rsa:2048 -rand /dev/urandom -keyout example.key -out example.crt -days 365 I'd like to generate an ECDSA cert/key in ...
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1answer
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What happens if my private key gets stolen in the web of trust?

If I'm a trusted user in the web-of-trust but my private key gets stolen by Eve, how would other users find out that my key is compromised and thus cannot be trusted anymore? Is there a way for them ...
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2answers
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What is the Session ID parameter indicate in Client Hello and Server Hello messages

I was trying to understand the TLS handshake in depth. I set up Wireshark and captured the github.com traffic. While inspecting the Client Hello and Server Hello, I found a parameter Session ID. ...
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2answers
468 views

Correct settings to generate private intermediate CA

I am using 'xca' in Linux to set up a private CA. xca only includes templates for the Root CA and End-User CA, no intermediates. What are the correct settings (fields and flags) for an intermediate (...
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2answers
731 views

PKCS#12 File - security impacts when imported in Web Browser or Windows Store?

When a PKCS12 file is imported into a Web browser or Windows store the user is prompted for private key password. How does the browser or operating system manage this password? Is it secure?
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1answer
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Should I distribute Root CA or Intermediate CA certificates to client?

I've been following this tutorial to create a Root CA, intermediate CA, and server certificate. I can verify: the intermediate certificate with the root certificate the server certificate with the ...
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2answers
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What is a link certificate?

I read an article and there was a link certificate short introduced (about a half sentence). Now I want to know what exactly a link certificate is? Assumption: A link certificate is used, when an old ...