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 ...
173
votes
3answers
45k views
How does SSL 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.
...
19
votes
11answers
2k views
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 ...
8
votes
2answers
3k views
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 ...
10
votes
7answers
785 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 [not with free will, so e.g.: I'm "attacked"] a rouge DNS ...
21
votes
3answers
626 views
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 ...
5
votes
4answers
232 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 ...
11
votes
1answer
670 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 ...
4
votes
2answers
217 views
Extensions for SSL server certificate
I have some question about the X.509 v3 extensions. What extensions should appear in a proper certificate for a SSL server ?
28
votes
4answers
14k views
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 ...
12
votes
4answers
3k views
how digital signature verification process works
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 ...
10
votes
3answers
739 views
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 ...
12
votes
2answers
358 views
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
...
10
votes
4answers
651 views
Why isn't OCSP required by default in browsers?
According to the following screenshot, taken from firefox-3.6.17-1.fc14.i686, Firefox has an option to fail closed when unable to connect to OCSP servers.
Can someone please explain why this isn't ...
8
votes
3answers
562 views
Is it safe to store a single symmetric key encrypted with several different RSA public keys?
For the field-based encryption of a database containing sensitive information, I was thinking of the following design:
Every user has a smartcard used for client certificate login.
After login the ...
4
votes
5answers
444 views
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 ...
3
votes
1answer
152 views
What are the Netscape Cert Type attributes? Why/when are they needed?
What are the Netscape Cert Type attributes in a X.509 Certificate and how are they different with the X509v3 extensions?
Example:
There is the Client/Server Extended Key Usage (X.509) but there is ...
0
votes
1answer
251 views
Enterprise Encryption Considerations
What are the different aspects to consider for Enterprise Encryption policy?
So far the resources I have are:
https://www.owasp.org/index.php/Cryptographic_Storage_Cheat_Sheet
...
41
votes
10answers
2k 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 ...
6
votes
1answer
1k views
How does adding a random serial number improve a certificates' 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, ...
5
votes
4answers
4k views
Recommendations for a Certificate Management tool for Linux
A client is looking to roll out OpenVPN to all its mobile employees and will use certificates on both the server and all clients.
This creates a new challenge to manage all these certificates and ...
5
votes
2answers
1k views
Dealing with expired or revoked signing certificates with Infopath documents
Suppose I have an Infopath form that is digitally signed today by a valid, and active user.
When that user leaves the company, we disable the account and revoke the certificate. This causes a problem ...
11
votes
3answers
9k 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?
10
votes
2answers
651 views
SSL fingerprint inconsistency: what does it mean?
I apologize if this is not the best place to ask my question on the stackexchange network, I couldn't figure out where to get enough attention and be relevant.
Facebook provides a SSL host, it can be ...
8
votes
2answers
2k 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 ...
6
votes
4answers
688 views
What kinds of SSL certificates are usable for encryption?
I know that Verizon SSL certificates cost close to $600.
There are couple of cheap alternatives, but I never really understood why Verizon does not offer such certificates. Look for RapidSSL at ...
11
votes
2answers
2k views
How does RSA encryption compare to PGP?
On this answer ck says
RSA and PGP are different.
What you are essentially asking is how
do I run my petrol car on diesel? The
answer is you can't.
I would be interested in a more ...
8
votes
2answers
607 views
Are there really functioning quantum computers?
I saw this video on youtube on quantum computing. It says that a company called dwavesys has already made commercially available quantum computer. I checked on the website and it exists. I thought ...
7
votes
3answers
1k views
Certificate authorities for a PKI
Some people think the certificate authorities for a PKI should be the government, but others think certificate authorities should be private entities, such as banks, corporations, or schools. What are ...
6
votes
2answers
374 views
security of PKI, Certificates, certificate authorities, forward secrecy
I want to understand how certificates add to the security of information exchange.
Suppose i have a encrypted bidirectional connection between Alice and Bob, using a public key/private key pair. As ...
4
votes
1answer
481 views
AIA/CRL locations for Offline Root
I've read the answer to the following "Checklist on building an Offline Root & Intermediate Certificate Authority (CA)" and I have one questions based on the system I am trying building
It's an ...
2
votes
3answers
522 views
How can I share files with other individuals in the cloud in a secure way?
I would like to us a dropbox because it is easy and convenient.
But I want to encrypt the files with the public key of the intended recipient, so he will be the only one who can access the data in ...
0
votes
1answer
246 views
How do I constrain Windows Smartcards for AD Authentication so that “anyExtendedKeyUsage” is not implied?
This document describes how there are 3 ways to constrain a SmartCard certificate
The Enhanced Key Usage field defines one or more purposes for which
the public key may be used. RFC 5280 states ...
8
votes
3answers
2k 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?
7
votes
2answers
282 views
X.509 certificate policies question
I asked another question about certificate policy mappings. This is a different issue. This is about Certificate Policies.
To quote from the X.509 RFC:
In an end entity certificate, these ...
6
votes
2answers
224 views
Geographic equivilent of RFC 3161 (X.509 PKI Time-stamp Protocol)
First time poster here, hope to be around more often.
I'm in need of a cryptographically secure 'stamping' system that allows not only time but also location to be attached to data, while still ...
5
votes
3answers
239 views
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 ...
5
votes
2answers
663 views
OCSP and CRLs: Specified in CA or client certificate?
Here's an example PKI setup:
* Root CA (offline)
* Issuing CA
* Client 1
* Client 2
I'd like to specify a CRL distribution point for CRLs generated by Root CA, and an OCSP URL for Issuing ...
4
votes
4answers
755 views
Can an intermediate CA be trusted like a self-signed root CA?
Is it possible within the limits of the X.509 specification to mark an intermediate CA as trusted for a specific purpose, e.g. to verify a VPN, HTTPS etc. server key, just like it would work with a ...
4
votes
2answers
238 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 ...
3
votes
1answer
544 views
how do extended validation X.509 certs work?
https://www.forumatic.com/ uses an extended validation cert. wikipedia.org's entry on extended validation certs says that a cert is known to be an extended validation cert if the OID in the ...
3
votes
2answers
391 views
How practical is a certificate's “basic constraint” property in protecting my HTTPS / SSL session?
Suppose a leaf node creates a certificate for a different domain, acting as a CA.
Do most popular frameworks, or SSL chain validation tools verify the constraints? Are there any I should be ...
2
votes
1answer
54 views
Is it a good idea to generate certificate-specific CRLs? What is this technique called?
Suppose I create 3 certificates with the following CRLs
Cert1 http://crl.server.com/batch1/root1.crl
Cert2 http://crl.server.com/batch2/root2.crl
Cert3 ...
2
votes
1answer
243 views
What OID Issuance Policies are appropriate for SmartCard and Browser Certificates?
I'm investigating issuance policies for SMIME and Browser certificates with different levels of assurance.
For the purposes of S/MIME and Browser certificates, should I even use an assurance policy? ...
1
vote
1answer
913 views
What are the OIDs (KU and EKU) necessary for Smart Card Authentication in Windows?
MSFT smart card authentication is listed in PKINIT RFC 4556 however I don't see any OIDs listed.
Based on this and this KB article the EKU section of the certificate should contain "Client ...
