Tagged Questions

A piece of data used in public key cryptography that contains identifying information (i.e. email address or web address), a hash of a public key, and a digital signature that authenticates the data in the certificate.

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0
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1answer
997 views

X.509 certificate attack (small sha1 private key)

I've got a X.509 certificate, created by an unknown CA. The only thing I know is that the private key is very short, so I can retrive the private key. Is there any program I can use? The used ...
3
votes
1answer
273 views

How can I use certificates to secure my webservices? What is available to javascript?

I have a few web services that are accessed over public wifi connections and I think it would be a good idea to issue certificates to encrypt data, prevent MITM, and invalid impersonation (beyond what ...
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4answers
1k views

Does a renewed certificate open old messages?

I have a digital certificate that I use to exchange messages with peers, my certificate expiration date is due next year, suppose I renew this certificate before it expires, will I be able to open the ...
2
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1answer
174 views

how does OpenSSL create X.509 certs from SPKACs?

The SPKAC ASN.1 description: PublicKeyAndChallenge ::= SEQUENCE { spki SubjectPublicKeyInfo, challenge IA5STRING } SignedPublicKeyAndChallenge ::= SEQUENCE { publicKeyAndChallenge ...
4
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2answers
974 views

What did the certificate authority do with my CSR?

I needed to reach a web service which is not mine. The IT department of that web service has asked me to send them a CSR (certificate signing request). Then, he will send me back a signed certificate ...
8
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3answers
3k views

What issues arise from sharing a SSL certificate's private key?

Scenario: I am hosting a website for a my client, who we'll call S. S owns the domain s.com and I own the servers that actually host the website. S now wants to enable SSL on their website. I have ...
1
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2answers
2k views

openssl, create RC4-SHA certificate

gmail.com Google, fb,... use RC4-SHA. How does one create RC4-SHA self signed cert ? Or even with aes128 key ? I tried using using "genrsa -aes128", resulting cert was DHE-RSA-AES256-SHA openssl ...
2
votes
3answers
460 views

Server Certificates, certificate authority, and servers

I currently have a valid wildcard certificate installed on OS X 10.8.2 server. To make sure we know what I'm talking about the cert is *.domain.com (example only) I'd love to use this to secure as ...
148
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7answers
13k views

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 ...
1
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1answer
366 views

signatureAlgorithm vs. tbsCertificate -> signature

From the X.509 RFC: Certificate ::= SEQUENCE { tbsCertificate TBSCertificate, signatureAlgorithm AlgorithmIdentifier, signature BIT STRING } TBSCertificate ::= ...
5
votes
3answers
2k views

System time and certificates

Recently I accidentally changed the system time to a different month, and then I surfed to a secure site. I got a warning from Google Chrome that mentioned my system time and said the certificate ...
3
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4answers
1k views

Client Certificate in SSL HandShake insecure?

Imagine we have an application which is trying to establish a secure connection to a server by using SSL. Now we want the user to authenticate himself with a client certificate which he stores in an ...
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2answers
13k views

ssltest: Chain issues - Contains anchor

I've run ssltest on web application and it found "Chain issues - Contains anchor" (section "Additional Certificates (if supplied)") What does it mean? Should it be fixed? Can it be exploited?
-1
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1answer
122 views

XER encoded X.509 certs [closed]

Would anyone happen to have an example of an XER encoded X.509 certificate so I can play around with it? Thanks!
6
votes
2answers
917 views

How is certificate forgery with cheap CA's prevented?

In order to perform a successful man in the middle attack on HTTPS, one needs to either strip SSL layer and convert it to HTTP completely or needs to have a valid certificate from a CA for the same ...
2
votes
3answers
875 views

Public key Infrastructure

Here the MD5 hash is being encrypted with the private key of the sender. But I read in a paper that private key is only used for signing and not encrypting. Is the image wrong or can private key ...
5
votes
3answers
464 views

Issuing SSL certificates for device automation software package without domain names

We are developing the automation software for Windows which communicates with the certain devices via our own private connection protocol. That software package consists of several server (including ...
5
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2answers
162 views

How can a certificate be valid in the Hybrid Model but not in the Chain Model?

All dates in European format! I am learning about validity models, but the solution for this assignment confuses me. Translation: The relevant data for the applicable certificates are shown ...
4
votes
3answers
687 views

How do you verify a certificate belongs to a domain?

I'm using PHP and trying to verify a SSL certificate belongs to the SMTP domain/IP I'm connecting to. Currently I can verify the certificate is valid using the following code $resource = fsockopen( ...
7
votes
1answer
4k views

Which key usages are required by each key exchange method?

I'm only really concerned with RSA keys, so the exchange methods are RSA (generate a key, encrypt it, and send it over) and [EC]DHE_RSA (generate an ephemeral [EC]DH key, sign it, and use it for key ...
1
vote
1answer
407 views

When distributing a CRL over HTTP, what is the optimal refresh time? What logic affects this decision?

When distributing a CRL over HTTP, what is the optimal cache and max age settings (etc) for this distribution mechanism? Related information on a different answer Consider using HTTP instead ...
4
votes
1answer
2k 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 ...
1
vote
2answers
201 views

Secure cookies and Path Length Constraint

Using apache 2.2.3 on oracle enterprise linux. When setting following setting in httpd.conf: Header edit Set-Cookie ^(.*)$ $1;Secure , cookie generation (which happens on our registration page) ...
4
votes
3answers
4k views

How to distribute client certificates without exposing private key?

I'm desgining a B2B web service based on WCF. As the number of clients is relatively small and security is a priority, i have chosen to go with X509 client certificates for client authentication. I'm ...
2
votes
2answers
624 views

distribution mechanisms for CRLs

From the X.509 RFC: DistributionPoint ::= SEQUENCE { distributionPoint [0] DistributionPointName OPTIONAL, reasons [1] ReasonFlags OPTIONAL, cRLIssuer ...
1
vote
2answers
6k views

How to get private key from certificate and base 64 encoded key?

Sorry for the poor question. Suppose I have a certificate of the following lines: -----BEGIN CERTIFICATE----- //22 Lines of encoded junk -----END CERTIFICATE----- And then this base64 encoded ...
2
votes
2answers
1k views

Key Exchange using PKI

I'm new to the field of cryptography and trying out a sample program to understand PKI key exchange mechanism. I tried creating a self signed certificate using openssl openssl req -x509 -nodes ...
26
votes
4answers
4k views

What alternatives are there to the existing Certificate Authority system for SSL?

Whilst the current CA system works very well for a lot of people, it does put a lot of power into individual CAs' hands, and makes a CA hack potentially devastating for customers and business. What ...
1
vote
2answers
171 views

Certificate security in intranet environment?

We have this topology in our company: A new rule says that each document being sent by Outlook should be encrypted. We decided using PGP. We already have a certificate (self-signed). The problem ...
1
vote
0answers
124 views

Why not buy cheap SSL certificates? [duplicate]

Possible Duplicate: Is there any technical security reason not to buy the cheapest SSL certificate you can find? The comparison in Godaddy's website, makes it clear: they're just cheaper ...
5
votes
1answer
418 views

Which attributes of a X509v3 certificate are never really used?

Are there any extensions/extended key usage attributes of a X.509Certificate that are rarely or never used in practice? Either due to never being part of an issued certificate or because they are ...
10
votes
2answers
1k 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 ...
11
votes
5answers
1k views

Why is this certificate valid for so many domains?

If you look at the (invalid) certificate for https://i.imgur.com/ it says only valid for the following names: The certificate is only valid for the following names and then a list of about 100 names. ...
3
votes
1answer
1k 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 ...
2
votes
1answer
486 views

Can Diffie-Hellman Anonymous be used as a cipher for SSL for one-way certifiate-based authentication

I want to use Diffie-Hellman anonymous cipher for SSL. I also want to use a one-way certificate for server authentication. Is this possible?
16
votes
4answers
3k views

What is the potential impact of these SSL certificate validation vulnerabilities?

I just finished reading through this paper by Georgiev et al, which demonstrates a wide range of serious security flaws in SSL certificate validation in various non-browser software, libraries and ...
4
votes
2answers
171 views

What is the state of the Windows Update certificate after Flame?

May 28, The Flame malware is discovered in Iran and by Kaspersky Labs. June 5, Dan Goodin (Ars Technica) points out that Flame had hijacked WindowsUpdate, spreading signed malware through that ...
2
votes
2answers
838 views

Revoked certificate validation using past times

I'm working on XAdES implementation for Java, as such I require cryptographic implementation to be able to verify certificates in the past. Unfortunately I have problems verifying revoked ...
6
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2answers
607 views

ASN.1: ENUMERATED vs INTEGER

From the X.509 specs: CRLReason ::= ENUMERATED { unspecified (0), keyCompromise (1), cACompromise (2), affiliationChanged (3), ...
3
votes
2answers
2k views

What are the implications of adding a self signed certificate to the Windows Trusted Root Certification Authorities store?

I'm a budding website developer, so please bear with my ignorance. Say I had to encrypt my website with HTTPS and I got sick of having to click "Continue" every time a warning came up about an ...
2
votes
1answer
126 views

Which .CER file format is more secure for purposes of an AIA record?

What file format is most appropriate or secure for the AIA record in a PKI certificate? The options I'm aware of are: DER encoded binary X.509 (.cer) Base-64 encoded X.509 (.cer) I also have the ...
1
vote
1answer
142 views

What keys are involved in an X.509 certificate?

I'm trying to examine some instances where an X.509 certificate uses public and private keys for a paper I'm going to write. However, the only thing I have explicitly seen so far is in one of the ...
3
votes
2answers
2k views

x.509 CRLs: next update?

An X.509 certificate revocation list contains a field specifying when the next such list is expected to be issued. I'm trying to figure out the importance of this field...I know that sometimes ...
5
votes
3answers
765 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
3answers
4k views

How is an X509 certificate signer verified?

Lets say I create a self-signed certificate A and use it to issue certificate B. I put certificate A in my trusted root authorities so that all certificates signed by it are accepted. My question is, ...
2
votes
1answer
134 views

How can I determine if a CA Cert can be used for DPI-SSL

I would like to know if a CA Cert I installed can be used to perform DPI-SSL decryption without my knowledge. Would there be any indication? Can you look at the cert properties to determine if it can ...
394
votes
3answers
168k 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. ...
6
votes
3answers
517 views

What risks would exist in transmitting an encrypted PKCS12 via Https

I have a scenario in which I would like to automate the deployment of client certificates generated by an issuer I control. The approach I am considering is given below, and I would appreciate ...
3
votes
2answers
148 views

Using a verified certificate to sign others

OK my Google Fu has failed me as I'm not exactly sure what I'm searching for. This relates to PKI ad certificates generally but websites more specifically. Could you get a verified certificate from ...
4
votes
1answer
77 views

Standards for CA cert revocation and time-constrained cryptographic algorithm parameters

I'm working on software that will be in use for foreseeable future (15 years+) that will need to validate XAdES-A signatures (long term archival, similar to PAdES-A, but for XML). That means, it will ...