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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1161
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3answers
621k views

How does SSL/TLS work?

How does SSL work? I just realised we don't actually have a definitive answer here, and it's something worth covering. I'd like to see details in terms of: A high level description of the protocol. ...
298
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6answers
233k views

What is certificate pinning?

I'm superficially familiar with SSL and what certs do. Recently I saw some discussion on cert pinning but there wasn't a definition. A DDG search didn't turn up anything useful. What is certificate ...
82
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12answers
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How feasible is it for a CA to be hacked? Which default trusted root certificates should I remove?

This question has been revised & clarified significantly since the original version. If we look at each trusted certificate in my Trusted Root store, how much should I trust them? What factors ...
33
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9answers
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How does SSL/TLS PKI work?

We have lots of questions that address portions of SSL/TLS as it relates to PKI, but none of them seem to bring everything together. A canonical answer that we can point people to I think would be ...
9
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4answers
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If the public key can't be used for decrypting something encrypted by the private key, then how do digital signatures work?

I'm learning asymmetric encryption in the use case of ssl/tls protocol. I can understand that the public key (like a padlock) can encrypt (lock) something and only the private key can decrypt (open)...
243
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7answers
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How do certification authorities store their private root keys?

Knowledge of a CA private key would allow MitM attackers to transparently supplant any certificates signed by that private key. It would also allow cyber criminals to start forging their own trusted ...
43
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5answers
44k views

How to achieve non-repudiation?

If I have a message that I need to send to another person, how do I achieve non repudiation ? Is digitally signing the message sufficient ?
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10answers
34k views

Why do we not trust an SSL certificate that expired recently?

Every SSL certificate has an expiration date. Now suppose some site's certificate expired an hour ago or a day ago. All the software by default will either just refuse to connect to the site or issue ...
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9answers
10k views

Can a HTTPS connection be compromised because of a rogue DNS server

If I'm visiting (just a desktop PC, client side) a site that has a valid HTTPS cert/connection, that can it be compromised if I'm using a rogue DNS server (not deliberately, I'm concerned about an ...
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4answers
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Checklist on building an Offline Root & Intermediate Certificate Authority (CA)

Microsoft allows a CA to use Cryptography Next Generation (CNG) and advises of incompatibility issues for clients that do not support this suite. Here is an image of the default cryptography settings ...
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3answers
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What is an SSL certificate intended to prove, and how does it do it?

If I get an SSL certificate from a well-known provider, what does that prove about my site and how? Here's what I know: Assume Alice and Bob both have public and private keys If Alice encrypts ...
44
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5answers
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Are there technical disadvantages in using free ssl certificates?

Note this question is related, except this one is about free SSL certs. There are providers who are offering totally free entry-level SSL certs (like StartSSL). I was wondering if they are ...
97
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4answers
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What is the difference between an X.509 “client certificate” and a normal SSL certificate?

I am setting up a web service through which my company will talk to a number of business customers' services. We will be exchanging information using SOAP. I would like to handle authentication with ...
54
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4answers
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How does the digital signature verification process work?

I am not able to understand that how the digital signature is verified. I know that digital signature will be attached to the message and sent by sender to receiver. then receiver uses the public key ...
56
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2answers
48k views

What are the risks of self signing a certificate for SSL

Let's say I sign a SSL certificate for myself, and I'm not using a certified CA. What are the risks and/or threats of doing it?
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3answers
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Digital Signature and Verification?

AFAIK , When Alice wants to write a message to Bob -- she uses Bob's public key and encrypt the message - and then Bob - using his private key - use to decrypt it. So public key is used to decrypt ...
93
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7answers
131k views

Certificate based authentication vs Username and Password authentication

What are the advantages and drawbacks of the certificate based authentication over username and password authentication? I know some, but I would appreciate a structured and detailed answer. UPDATE ...
36
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2answers
8k views

Can I restrict a Certification Authority to signing certain domains only?

Is it possible to create a CA certificate (even unsigned), which is only allowed to sign certificates for specific limited domain(s), so that it can't be misused for other domains?
28
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6answers
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Shouldn't GPG key fetching use a secure connection?

If I run this for example: gpg --keyserver hkp://keyserver.ubuntu.com --recv-keys 0xFBB75451 then does the importing occur in a secure way? I mean does it go over only secured connections? (HKP?) ...
24
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5answers
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Creating my own CA for an intranet

I need to create my own CA for an intranet and unfortunately it seems there's no good answer about this on Security.SE. There are many resources online about this, but all of them are different and ...
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8answers
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Is Spoofing a CA signed certificate possible?

I had never thought about this situation before, I may be completely wrong but I am going to have to clarify it anyway. When a communication starts with a server, during the client handshake, the ...
36
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4answers
58k views

Expired SSL Certificate Implications

What are the security implications of an expired SSL certificate? For example if an SSL certificate from a trusted CA has expired will the communication channel continue to remain secure?
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2answers
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Encryption and the “security time decay” of prior encrypted data

This question is on the assumption that any data once encrypted, may (eventually) be decrypted through Brute force (compute power/time) Exploits in the cryptography used Theft of private keys Most ...
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3answers
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Reset Windows trusted certificates store to its default [closed]

Over the time I have installed several additional trusted CA certificates to Windows trust store, sometimes because an app pushed me to do so, some other times for development and testing. Is there ...
15
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3answers
4k views

Difference between Certificate Authorities

I've been wondering for a long time about is. There are many certificate authorities having different types of certificates. But even certificates of the same security level cost a lot more with one ...
7
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4answers
723 views

What fields in a suspicious certificate should I look at?

Looking at a certificate for a web-site (in Windows/Google Chrome) I see it lists the following fields Version Serial number Signature algorithm Issuer Valid from Valid to Subject Public Key Basic ...
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2answers
4k views

Can a RootCA be revoked?

I have created a New Trusted certification authority which issues certificate to the end entity and the end entity will use this certificate as trusted one for all their PKI operations. Some how the ...
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2answers
4k views

ECDSA ciphers and forward secrecy question about key exchange

I have heard that with forward secrecy that the ECDSA ciphers generate different keys for "each session" because they are not dependent on the private key of the server. My question is how is "each ...
47
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4answers
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What's the common pragmatic strategy for managing key pairs?

I have a small number of different workstations (plus client devices like iPhone) that I use for to connecting to numerous servers using SSH. Originally when I learned about PKI, I created a single ...
33
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5answers
7k views

Are self-signed certificates actually more secure than CA signed certificates now?

Are self-signed certificates actually more secure than CA signed certificates now? I ask this because recent leaks about the NSA spy programs and the secret FISA courts mean that the US government ...
38
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3answers
30k views

How to set up OpenSSH to use x509 PKI for authentication?

I do not mean simply putting the public RSA key of a x.509 certificate into ~/.ssh/authorized_keys - I'm looking for a way to set up a ssh such that x.509 certificates signed by a pre-defined CA will ...
26
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5answers
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How are Chrome and Firefox validating SSL Certificates?

How are Chrome and Firefox validating SSL Certificates? Are they requesting data from an SSL certification website, like GeoTrust, to validate the certificate received from the web server?
28
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3answers
9k views

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 ...
23
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1answer
29k views

SSL certificates and cipher suites correspondence

I have been learning about the SSL/TLS protocol (from https://tools.ietf.org/html/rfc5246) and have a few conceptual questions about the protocol. The client and server exchange "hello" messages ...
10
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4answers
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SSL Client Certificate authentication

Is it possible to make a program which uses client certificate authentication with only public and private key (I have not generated any certificate, I have only public and private key). Simply, I ...
12
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1answer
5k views

How does adding a random serial number improve a certificate's security?

This article says: "Finding collisions is a tricky process, since it requires you to muck with the bits of the public key embedded in the certificate (see this paper for more details). Also, ...
10
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1answer
2k views

Manually walking through the signature validation of a certificate

Since I am not too familiar with the Web of Trust and Public Key-Infrastructure I decided to learn about it by following the signing chain of a X.509 certificate issued to CN=*wikipedia.org (Serial ...
12
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2answers
8k views

SSL Certificate revocation check

In the SSL protocol I don't see where the certificate is checked for revocation status. https://developer.mozilla.org/en/Introduction_to_SSL Is the Certificate Revocation and Status Checking not ...
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3answers
4k views

What stops a hacker from installing its own CA certificate?

Taking a look at this (now rather old) article about the generated rogue DigiNotar certificates, it states the following: ...Such is the case with that small company in the Netherlands, DigiNotar....
6
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3answers
7k views

What is the web of trust?

I'm studying network and system security and I came across the phrase "web of trust". From Wikipedia: In cryptography, a web of trust is a concept used in PGP, GnuPG, and other OpenPGP-compatible ...
18
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2answers
5k views

How would I implement “Broadcast Encryption”?

I have a stream that I want to encrypt for broadcast to 10,000 subscribers. I know I should encrypt this data using a symmetric key; and also intend that this symmetric key will be rotated every 30 ...
8
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1answer
17k views

Why is a CA certificate required for EAP-TLS clients?

When setting up clients with WPA2 EAP-TLS, most clients (ie: my phone, my computer) require both a client public/private keypair (for obvious reasons) and a certificate authority certificate. It's ...
6
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2answers
368 views

Using a verified certificate to sign others

This relates to PKI and certificates generally but websites more specifically. Could you get a verified certificate from a CA that is signed and fine for use, and then use it to sign your own ...
8
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1answer
3k views

How long do keys stay on keyservers?

Do GPG/PGP keyservers "garbage collect" old keys which have expired, been revoked, or simply haven't been updated in a decade? Or does the server (theoretically) keep every key it has ever seen from ...
8
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2answers
603 views

Is there a way to negotiate a secret between 2 parties with no prior knowledge?

Is there a way for 2 parties to negotiate a shared secret (for example, a session key) without having a pre-shared knowledge? SSL does this by using asymmetric encryption. Is there any other way to ...
5
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1answer
369 views

What's the purpose of a PGP transition statement?

PGP key holders occasionally replace their old PGP master keys with newer PGP master keys (for example, to use securer algorithms). When doing this, PGP key holders want their new key to be signed by ...
5
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3answers
2k views

How are possible uses for X.509 (SSL) certificates denoted?

X.509 certificates can be used for servers, clients, email, code signing and more applications. http://twitpic.com/6gdxaq indicates that a certificate can have different of these 'capabilities' on it -...
2
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1answer
207 views

Is it complicated to deploy my own CA?

We want to implement a free solution to sign digitally internal documents. No legal value of this sign are requested. We want to consider to deploy an internal CA. Why is it always said that keeping ...
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2answers
2k views

Understanding Certificate Pinning [duplicate]

I am attempting to implement certificate pinning across a suite of mobile apps. I have been reading a lot about the different strategies (pinning to the CA/intermediate, pinning to a leaf cert, ...
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2answers
5k views

Does SSL/TLS provide non-repudiation service?

I understand that SSL/TLS provides confidentiality and integrity. But does it provide non-repudiation? I read in one book it does not. But I wonder why? What does it mean? If it means Alice can ...