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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6
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2answers
329 views

Custom data in SSL certificate

I am looking for a way to add extra, custom data in a SSL server certificate issued by a standard CA. Is this possible? I want to get a SSL server certificate issued by a standard CA, so that it'll ...
3
votes
1answer
226 views

How to trust a CA to sign a CRL but not a cert?

In my application, there are many parties that are trusted to revoke a cert (ie by signing a CRL), but are not trusted to sign (new) certs. How do I mark a CA to be trusted only for CRLs, and not for ...
2
votes
1answer
179 views

Personal cipher/digest preferences ignored when generating a new key pair in GnuPG

I have specified personal digest preferences in my ~/.gnupg/gpg.conf: personal-digest-preferences SHA512 SHA256 SHA384 SHA224 SHA1 then, I have generated a new key pair. But when I check the ...
3
votes
3answers
101 views

PKI usage in a cluster; per application instance or per application?

I'm having a cluster with nodes (let's call them A and B for the sake of example) running identical micro services (1, 2 and 3 - so the application 2 running on node A is called A2). The applications ...
4
votes
1answer
77 views

Cross-certification between worlds like X.509 and PGP?

Sometimes it can be advantageous to use existing trust relationships in one certification world - X.509 or PGP - to create trust in the other world. At the lowest level I can always take an X.509 cert ...
3
votes
1answer
248 views

Will Let's Encrypt allow a custom workflow? [closed]

The Let’s Encrypt management software will: Automatically prove to the Let’s Encrypt CA that you control the website Obtain a browser-trusted certificate and set it up on your web server ...
2
votes
0answers
146 views

How can I sign an rpm package using a smart card?

I have a smart card (not OpenPGP card), and I am preparing to sign an rpm using this card. After signing, I will get two files: my.rpm.sig, and my_id.cer. How can I sign my rpm using these extra ...
1
vote
0answers
31 views

Why do DNSKEY have a RRSIG for themselves?

Looking at all examlpes of DNSSEC, you see that the zone includes not only the DNSKEY , but also a RRSIG of the DNSKEY created with that same DNSKEY? Why is this? Why publish a self-signed RRSIG? What ...
0
votes
1answer
30 views

Validating the ROA certificate

Suppose I have a system, where the server requires the clients to attach their ROA certificate to prove that they have the right to that IP Prefix. Now if the client attaches the ROA certificate ( ...
1
vote
2answers
75 views

Signing an OpenPGP public key that is not uploaded to a key server

Is there any point in signing an OpenPGP public key that has not been uploaded to a key server? In other words: does anyone except person A who signs person B's public key notice that the signing has ...
3
votes
1answer
114 views

Best practice of deprecating old OpenPGP subkeys when migrating to a new subkey pair?

I've been using GnuPG with an offline master + online subkey setup for a while now. All my email is signed with the signing-only subkey and encryption is done with the encryption-only subkey. The ...
3
votes
1answer
135 views

RemoveFromCRL and DeltaCRL

I have a question about DeltaCRL with an entry which contains RemoveFromCRL reason. At the start, PKI has revoked the certificate with certificateHold reason. And create next CRL: Last Update: May ...
8
votes
1answer
5k 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 ...
4
votes
2answers
587 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 ...
6
votes
3answers
1k views

What if someone steals a Certificate authority's private key? [duplicate]

What if someone could steal a Certificate authority's private key? I know this will (probably) never happen, but what would happen to the certificates that were already signed with this private key? ...
1
vote
2answers
120 views

Man in the middle attack on browser downloads

I'm writing this post from chrome. If I go to a HTTPS site after this, the public keys built into the version of chrome I'm using will be used to verify the site's signature (unless I misunderstand). ...
0
votes
2answers
58 views

Generic term for certificates and keys

Is there a generic term to designate both public and private keys, certificates and maybe even passwords?
4
votes
2answers
101 views

Can the intended recipient be derived from a public-key encrypted ciphertext?

Assuming you have a list of possible recipients' public keys, and a ciphertext encrypted with one of those public keys, would it be possible to determine which public key?
2
votes
0answers
131 views

CMS/PKCS#7: specifying signatureAlgorithm with digest?

I'm confused about algorithm selection for Cryptographic Message Syntax (a.k.a. CMS, PKCS#7) signed objects (RFC5652 Section 5.1). The SignerInfo structure (RFC5652 Section 5.3) has two separate ...
16
votes
5answers
2k views

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 ...
7
votes
2answers
260 views

Can symmetric key cryptography provide identification?

I understand that PKI uses digital certificates to link a public key to an entity, but is there anything similar for symmetric cryptography. If, theoretically, PKI didn't exist, how do you know you ...
1
vote
3answers
800 views

What type of hashing method is used for the private key to encrypt for signing messages?

To use RSA for signing, Alice takes a hash of the message, encrypts the hash using her own private key, and appends the result (this is the signature) to the message. Eve can of course still decrypt ...
0
votes
2answers
363 views

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. ...
3
votes
1answer
225 views

HSM maintenance

I have a HSM that is an asset within a information security management system and the help desk team tells me that the device is displaying a critical failure alert. So my questions are: Must I ...
2
votes
1answer
875 views

Determine private key size using public certificate [duplicate]

I have a public certificate in a PEM (.pem) file -----BEGIN CERTIFICATE----- MIICsjCCAZqgAwIBAgIJAMA1YIQ2JLXDMA0GCSqGSIb3DQEBBQUAMBExDzANBgNV ... 29V/R9RZOoSBHDzGPL84wm4qojMuwQ== -----...
2
votes
1answer
327 views

Can I place a private key on a sim card?

After google searching about this idea and yielding very little in results I've come to resort to stack exchange: Is it possible to place a private key on a sim card? Is it possible for a smart ...
17
votes
9answers
7k views

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 ...
5
votes
4answers
433 views

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)...
0
votes
1answer
42 views

Asymmetric Encryption Digital Signatures

Here is the paragraph I can't quite get my head around. Alice sends a message to Bob and wants him to be sure the message has come from her. • She publishes her public key. • She computes ...
15
votes
9answers
3k views

Why is a public key called a key - isn't it a lock? [closed]

I'm totally confused by the public key and private key terms. From my understanding, the "public key" is used for encrypting data, it's more like a lock which can lock something in and only the "...
5
votes
2answers
193 views

PKI/Why does Microsoft require my cert before encrypting an email?

Microsoft doesn't allow sending public-key encrypted messages using Outlook 2003-2012 on Windows 7-8x environments without first creating your own Digital ID or private key for signing. Per Microsoft,...
2
votes
1answer
511 views

SSH: What's the difference or interplay between /etc/ssh/[host files] and ~/.ssh/[public key]

I'm new to SSH after a decade of dabbling with Ubuntu and other Linux builds. Today I successfully setup SSH, but I had a few hangups and headaches along the way. Although the system is now running ...
0
votes
2answers
405 views

Is there any use in an AIA Extension in a Certificate directly issued by a Root CA?

While most documentation I've read states that there is no requirement to have the AIA extension in a self-signed Root certificate (logical enough), I can't find anything that tells me not to do so in ...
1
vote
2answers
562 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, ...
44
votes
7answers
17k views

Why can't you work backwards with public key to decrypt a message?

As the title suggests, I am curious to know why you can't work backwards using a message, public key and encrypted message to work out how to decrypt the message! I don't understand how a message can ...
3
votes
1answer
259 views

PGP Owner Trust Field & Signature Trust Field Distinction

I'm reading Cryptography and Network Security Principles and Practices (5th ed, p584) and reading about PGP keyrings, I'm a little confused about the differences between the owner trust field and the ...
2
votes
1answer
181 views

Security Structure of an API

I've been developing a web application and APIs for 8 months. I implemented OAuth 2.0 client credentials for authentication. And now I have to implement TLS to my APIs. I've been dealing with SSL/TLS ...
6
votes
1answer
109 views

Relationship between HTTPS and SSH Public Keys

I can use my private key to generate a public key for use with ssh. I can use the same private key to generate a CSR, to generate a CLIENT certificate for HTTPS. Specifically, my SSH public key is: ...
79
votes
2answers
6k views

How are private keys kept private?

This may sound like a stupid question but seriously how are private keys kept private? If you're someone like Google you have some huge number of servers to which the public can establish secure ...
2
votes
1answer
153 views

Use the server's key to digitally sign the HTML content it delivered?

Is there any way to prove that a HTML page was delivered to my browser, and not modified in any way, after it was delivered over TLS? I need to prove integrity, and authenticity of the sender, ...
4
votes
4answers
420 views

Should name constraints be present on a subordinate CA issued to an organization?

I was looking at Google's Internet Authority G2. Its a subordinate CA (critical, CA:TRUE, pathlen:0) certified by GeoTrust. The dump is below. Presumably, GeoTrust certified that CA for Google so ...
5
votes
1answer
686 views

Asymmetric / end to end encryption for web messaging app

Background I'm trying to design a secure and sustainable web app for messaging. The purpose is to learn how to create secure web application. The application is suppose to be written in Javascript ...
2
votes
0answers
286 views

Mitigating the risk of disabling EPA on ADFS

I'm currently investigating the deployment of an Active Directory Federation Services (ADFS) server for providing Single Sign-on for various services. By default, ADFS enables support for Extended ...
1
vote
1answer
476 views

Crypto Ransomware - How decryption is done when user accept to cooperate?

When you have been "hacked" and you accept to pay for decrypting your encrypted files, how the attacker do the job ? I understood that a symmetric key is used, itself encrypted by the attacker public ...
3
votes
2answers
381 views

Is it dangerous to use the same key (RSA) for both encryption (PGP) and authentication (SSH)?

Alice wants to send an encrypted message to Bob, but she also wants to connect to Carol's server. Are there any dangers associated with using the same RSA key for both PGP and SSH (other than a lack ...
7
votes
1answer
426 views

RSA key generation: gpg vs openssh

When I generate RSA key for ssh (both server-side and client-side): dpkg-reconfigure openssh-server ssh-keygen the key generation is completed instantly. However, when I generate RSA key for gpg, ...
0
votes
1answer
259 views

Begin of Certificate/ End of Certificate dash “-----”

What significance does the dash "-" holds along with the line -----BEGIN CERTIFICATE----- or -----END CERTIFICATE-----. I checked multiple docs and linked RFC's as well but could not find the ...
16
votes
4answers
3k views

Is it dangerous to publicly share ciphertext?

Alice wants to share a message with Bob, but Alice and Bob can never be in the same place at the same time. We can assume they both know each others public keys (or agreed on a shared key, if that ...
1
vote
1answer
66 views

What bits of data is revoked in a CRL? Is it the hash(CSR) or hash(CSR + PKI signature)

My understanding is that a CSR contains the public key from the client, and the response is a signed version of that CSR, with certain attributes (EKU, expiration) and other attributes the CA decides ...
1
vote
1answer
62 views

Https certificate change effects on established secure channels

I've a question regarding https certificate changes. Does anyone know any side-effects to changing the certificate, one signed with RSASHA1 to one signed with RSASHA256 for ex, while users already ...