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 ...

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1answer
15 views

OpenVPN seamless migration from 1024-bit RSA to 2048-bit RSA keys

The company I work for has a few OpenVPN servers used by over 200 employees. The servers were deployed a few years ago using the default easyrsa settings and now we want to upgrade to stronger ...
3
votes
3answers
369 views

Why are SSL certificates valid only from a certain date?

Each SSL certificate is valid starting from a specific date and up to the expiration date. What's the point in that "valid from" date? Why do we want a certificate to only be valid after a specific ...
1
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1answer
24 views

X509Certificate - How to set validation Policies?

I have an X509Certificate (say Certificate-A) for signing purpose. While validating this certificate, I have to check its path with Intermediate & Root certificate which I have implemented fully. ...
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3answers
43 views

Detect message tampering without shared key and without certificate authority

Is it possible to detect if a message has been tampered with, without using MAC (i.e. shared key) and without using a "trusted" third party (i.e. certificate authority)? I'm pretty sure it's not, but ...
0
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1answer
24 views

list of PKCS7 certificate file extensions

RSA (the company) devises and publishes the public key cryptography standards. In those standards PKCS #7 is a standard which defines how to encrypt and sign messages using PKI. PKCS#7 defines a ...
1
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1answer
49 views

Using client certificates for website authentication

I was wondering if there currently exists a Content Management System that supports PKI and client certificates for website authentication instead of username/passwords. If not, what's a good place to ...
3
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1answer
204 views

Heartbleed - is this scenario possible? how bad would it be?

Let's make the following assumptions: A trusted root certificate was being served with a vulnerable version of OpenSSL. Prior to public disclosure, a malicious entity was aware of and exploited the ...
-1
votes
3answers
136 views

Can a smart card with PKI certificate be used to protect a document?

I want to use a smart card (or USB cryptotoken) with a PKI certificate for manual authorisation. Is this possible? I want to put a file (e.g. a word file or even a simple text file) into a smart ...
1
vote
2answers
83 views

Where to find or purchase non-SSL certificates

I hope this is the right stackexchange - if not, please advise. As to the actual question: have a system we've developed that makes heavy use of asymmetric cryptography in various different ways ...
0
votes
1answer
85 views

Trusted Certificate Authorities - how do they work?

microsoft.com for example can use a Verisign Certificate for their domain. What are the chances that an attacker could ask verisign for a m1crosoft.com domain and get approved? It is very simillar, ...
4
votes
1answer
180 views

WebRTC P2P SSL - Where are the keys generated?

My understanding is that with the WebRTC peer-to-peer data API, communications between peers are encrypted via a modified form of SSL. Where are the keys for the peer-to-peer SSL connection generated, ...
27
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11answers
3k 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 ...
29
votes
7answers
4k views

How dangerous might be publishing a public key?

Maybe this question sounds obvious, but I wonder how dangerous might be publishing a public key for an asymmetric encryption system? I know public keys are meant for encrypting messages by anyone ...
22
votes
5answers
2k views

Why is Bruce Schneier recommending symmetric crypto over public key crypto

I just read the article written by Bruce Schneier, the crypto guru. In the article, he says : Prefer symmetric cryptography over public-key cryptography. But, he doesn't shed any light as to ...
0
votes
1answer
484 views

Can I ensure that a public key derived from a private key is unique?

In asymmetric cryptography, is it possible to ensure that public key derived from a given private key is unique, no matter the algorithm?
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4answers
79 views

When should I use symmetric encryption instead of RSA?

I'm currently using GPG RSA keys to encrypt binary files. Many people recommend using symmetric keys to encrypt large files, and then encrypt the symmetric key with a public key. At what file size ...
3
votes
1answer
53 views

Public keys without the certificates

There are two clients and a server. Each client generates an RSA key pair and uploads public key to the server. The server associates the public key with the user identifier that is specified during ...
0
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4answers
43 views

Is it ok to send user's private key away, even if protected with a SSL channel? [duplicate]

I'm developing a webserver that performs digital signatures of (xml, pdf and office) documents and then validates those signatures. My idea is: an user puts its SmartCard and through a PIN, he gets ...
0
votes
1answer
49 views

Possible to Derive Private Key from Public Key Given Enough Computing Power? [closed]

Is it possible via brute force to derive a private key from a public key (such as a website's SSL certificate)? If so, how much computing power would you need to make it feasible, compared to say, ...
1
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2answers
72 views

SSL/TLS : Authentication mechanism

I have these doubts regarding authentication in SSL/TLS : Will there be an authentication involved for all SSL connections ? For eg. when I browse the internet, using the most up-to-date browser, ...
1
vote
2answers
136 views

How to maintain security and trust with a PGP keypair for a team or group of people?

I've seen many instances where a company or organization generates and uses a PGP keypair for a team or group of people. Most likely they all have a copy of the private and public keys on their ...
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votes
2answers
40 views

Achieving PFS with public key cryptography

I'm seeking to understand how Perfect Forward Secrecy (PFS) works for non SSL applications. More specifically, I'm interested in how Moxie Marlinspike accomplishes this in TextSecure and other ...
3
votes
3answers
170 views

Why do you need to encrypt symmetric key?

I'm reading this pki article and as you can see near the bottom, the quick animation and description: The sending computer encrypts the document with a symmetric key, then encrypts the symmetric ...
323
votes
3answers
115k 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. ...
0
votes
1answer
18 views

OID for creation date/time (X509 certifcate field)

X509 certificates used in PKI{X} have notBefore and notAfter dates. I'd like to stamp a certifcate with a creation stamp, and the stamp is distinct from notBefore and notAfter. Is there an OID for a ...
1
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2answers
96 views

Digital Signatures of XML, PDF and Office Documents on every platform

I'm trying to develop a website that performs digital signatures on client-side and then sent the signed document to the server-side. I want to do the signatures on client, due to the fact of not ...
0
votes
3answers
128 views

Is it ok to send user's private key away, even if protected with a SSL channel?

I'm developing a webserver that performs digital signatures of (xml, pdf and office) documents and then validates those signatures. My idea is: an user puts its SmartCard and through a PIN, he gets ...
0
votes
2answers
86 views

Protecting against/detecting a specific Man in the Middle attack

I'm working on a specific (hypothetical) situation, where I have two client machines attempting to perform a public key exchange, via a server. There's no possibility for a direct connection between ...
1
vote
1answer
76 views

Is there any way to restrict multiple access to my server at the same time using one client certificate?

My Server is Windows 2008. Mr. X is accessing my web server using Mr. X's certificate. In that time, an outsider is also trying to access my server using Mr. X's certificate (somehow he got it). Is ...
1
vote
3answers
103 views

How encryption/decryption works when one generate random key?

I am new to this and want to ask a basic question.Suppose I used my password (say "ABC123") to generate a key using PBKDF2 algorithm (or any such algorithm).For encrypting a file I'll input my ...
4
votes
3answers
473 views

In what ways does increasing SSH host key length increase security

I have read on a few guides on "how to secure SSH servers" that it is a good thing to increase ServerKeyBits from the default of 768 to 2048. Most of these guides seem to be for the entry ...
6
votes
8answers
2k views

How can I share files with other individuals using the cloud in a secure way?

I would like to use 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 ...
1
vote
0answers
66 views

Import securely RSA private key through PKCS#11

I have a cryptographic device that supports the following mechanisms: How I could securely import RSA private key into it? Because there is no support for wrap/unwrap using symmetric key is there ...
1
vote
0answers
32 views

Message and Key Security

I'm reading Post-Quantum Cryptography, and in the page 106 in the beginning of the Section 3 it says: In this section we consider the message security (opposed to key security) of code-based ...
15
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3answers
18k 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?
0
votes
2answers
341 views

Client Authentication by certificates in Google APP Engine java

I am writing an application in Google APP Engine java which authenticate the user by its certificate. I have created a self signed certificate using keytool at client side. I also enable the HTTPS ...
1
vote
1answer
30 views

In a 3 tier (or more) PKI, is it permissible that a Name Constraint only be defined on the middle tier?

I'm working with an Issuing CA that doesn't support name constraints that are defined at a higher level. Assuming that it issues certificates that are compliant with the Name Constraints that are ...
37
votes
4answers
22k 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 ...
3
votes
1answer
58 views

Internal code-signing certificate on Windows

I'm looking to improve defense-in-depth on a system, primarily by closing some holes in injected DLLs. Certain applications installed on the system cause helper DLLs (e.g. shell extensions, BHOs, ...
1
vote
3answers
137 views

Why can't someone break email or https encryption by somehow getting access to the encryption key?

To repeat, "Why can't someone break email or https encryption by somehow getting access to the encryption key?" In other words, why can't someone intercept the key, or the algorithm to create the ...
6
votes
5answers
236 views

Why are private certificates not trusted?

When we go to websites that have generated certificates themselves you see this red screen that says do not go there!: However when it is trusted by some companies it's all good. So I have a couple ...
4
votes
3answers
243 views

Managing and storing lots of SSH keys in the cloud

I have a pool of cloud servers (~50) that need to talk to many other remote cloud servers (~4000) using SSH. Each remote server has its own SSH key, so we need a place to store all of these remote ...
10
votes
3answers
2k views

SSH password vs. key authentication

I've usually been told that public key authentication is strongly preferred over password authentication for SSH. However our previous admin was against public keys and only issued passwords and took ...
1
vote
3answers
95 views

Using public/private key without signed certificate

I am working on a java program and I am now working on its network security. I want to use a secure connection since it transfers a lot of sensitive information. On all security guides it is mentioned ...
0
votes
1answer
74 views

Public Key Cryptography : Key length

While symm. crypt. has around 256 bits of a key, why does public key crypt have a key that is much longer (1000's) ???
5
votes
3answers
247 views

Does checking the fingerprint of a self signed certificate improve security?

I am currently developing a component for an application that does TCP communication with a device inside a local area network. I use TLS to provide data encryption, integration and authorisation. ...
1
vote
1answer
71 views

Protecting data on an embedded device

I am to release a system-on-chip device that, during its lifetime, will come to store sensitive data. I want to make that data hard to extract or duplicate. Encrypting is good for dealing with MiTM, ...
0
votes
2answers
438 views

Cryptography behind chip based credit cards (smart cards)?

Why are chips safer than magnetic stripes? The answers to the above question explain that the chip based cards can not be cloned as the "secret number" is embedded in the chip and protected by the ...
11
votes
3answers
329 views

How are private keys handled in an enterprise?

We would like to start using digital signatures and possibly encryption for e-mails in our company. My knowledge of public-key cryptography is entirely theoretical with no practical experience. In ...
2
votes
1answer
176 views

Root certifcate key usage (non-self-signed end entity)

This discussion does not include self-signed end entity certificates for hosts like web servers and mail servers. OpenSSL's default configuration for a CA certificate has the following keyUsage: ...