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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252 views

How to make sure that the public key has not been tampered with during transit?

I understand how public key infrastructure works. There is a private and public key, and someone may use the public key to encrypt data that can only be decrypted with the private key. However ...
0
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0answers
21 views

Use MDC to provide origin authentication for public key encryption?

Why can't we use an manipultation detection code (MDC) to provide origin authentication when using public-key encryption?
0
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1answer
33 views

Are there any risks in wrapping asymmetric encryption in symmetric?

The web app I am developing should be end-to-end-encrypted, but for slightly better user experience, I do not want the user to enter private keys into the client. Instead I am planning to store the ...
0
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0answers
17 views

How can I use unique PKI from host to client [on hold]

I have hundreds of machines i would like to have unique credentials/certs on. I also have a even more cell phones i need to run diagnostics on the machines. Is there a way i can do this? I will also ...
2
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1answer
22 views

AuthorizedKeysCommand of sshd_config getting called twice

AuthorizedKeysCommand paramter present in the file /etc/ssh/sshd_config. The bash script which i called using this command is getting called twice. The config file is as follows #RSAAuthentication ...
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2answers
10k views

What damage could be done if a malicious certificate had an identical “Subject Key Identifier”?

I'm looking at the the Subject Key Identifier attribute of a CA certificate and am trying to understand the role it plays in validation and infer how validating client software could get it wrong. ...
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1answer
42 views

X509 / SSL certificates in practise

After learning the theory behind cryptography I'm having quite some problems understanding how SSL or X509 certificates works in practise and I simply cannot find useful information in the internet. ...
1
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1answer
84 views

Can Passpoint X.509 certificates be used to MITM SSL connections on Passpoint networks?

Passpoint/Hotspot 2.0 public networks like LinkNYC require users to install X.509 certificates, for EAP authentication. Can these certificates be used by the provider to execute man-in-the middle ...
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2answers
95 views

Can I move my private-key to a better token?

I recently purchased a personal signing certificate from GlobalSign - it wasn't cheap either. It arrived yesterday. GlobalSign gave me a "blank" USB security token device - a SafeNet eToken 5100. ...
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2answers
40 views

Does PKI signature verification require secure distribution of public keys?

I'm looking at a software project where the GPG public keys of the maintainers are found on a website using HTTP. According to the GNU Privacy Handbook, "The signature is verified using the ...
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0answers
49 views

Elliptic Curve Diffie-Hellman (ECDH) Key Exchange in Plain English

Can someone please explain to me what Elliptic Curve Diffie-Hellman Key Exchange is in plain English? Similar to the top answer found here: "Diffie-Hellman Key Exchange" in plain English ...
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1answer
29 views

Does password protected git public key protect my repository?

When generating my public key for GIT access, I decided to set up a password for it. My push procedure looks like this now: Enter passphrase for key '/c/Users/USERNAME/.ssh/id_rsa': Counting objects: ...
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1answer
138 views

Safely store passwords in specific scenario

I have a specific network environment. Its a DTN(Delay Tolerant Network) network without continous connectivity, situated on the sea, where nodes are ships. There is also a server that is a part of ...
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2answers
33 views

Why there is time period of key pairs in public key cryptography?

In Public Key Infrastructure, every key pair is associated with its life time. I don't understand why we have a life time when we have functionality such as certificate revocation list(crl) which ...
1
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1answer
32 views

Multi-User-Server Public-Key-Based Authentication

So, lets say we have Alice, John, Peter and Bob. Alice, John and Bob all know Peter's public key and trust Peter. Alice wants to connect to Bob's server, so she presents her public key, which was ...
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1answer
114 views

PKI management with easy-rsa

I recently setup an OpenVPN server with easy-rsa and have questions about certificate revocation: In the event that someone's private key gets compromised and I have to revoke the certificate with ...
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1answer
39 views

Whatsapp encryption: are the public keys requested from the server every new message or only at session setup?

I was reading trough Whatsapp white paper (and all related questions here) and couldn´f find an answer to this question: are the public keys for the recipient requested by the sender from Whatsapp ...
4
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2answers
105 views

Centralized key management for IOS and Android Code Signing

What is the best way for an enterprise to manage code signing certificates? The default seems to be that Apple and Android keys get stored by each developer on their machines. I see systems like ...
0
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1answer
124 views

Code signing certificate validation by Java

Despite several web search, I can’t find an accurate explanation on code signing certificate validation by Java. I am wondering if the code signing certificate (the “final cert”) must already be in ...
2
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1answer
276 views

How CERT.rsa is interrelated with PackageInfo signatures

I am a newbie in security and cryptography, but I am developing Android applications and now wanna to dive deeper into the Android security mechanisms. I am trying to understand how CERT.rsa (as I ...
2
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1answer
95 views

Generating shared secret key using existing receivers public key and senders private key

I have the public key of the receiver, and the private key of the sender. I want to generate a new key by using the receivers public key and senders private key (also known as the signing key) to ...
7
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4answers
30k views

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 ...
1
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2answers
107 views

sharing private key sTunnel

All of the sTunnel guides and implementations at work do the same thing, they say once the private key and the public cert are created on the server, you need to cat them together and then share with ...
2
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1answer
106 views

What is the difference between a digital signature and whole message encryption?

I am newbie in information security I am trying to understand the difference between a digital signature and encryption of a message. Lets consider simple example of email message. I understand how ...
1
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1answer
31 views

Is there a secure method of distributing keys to network-booted diskless nodes?

I have a bit of an 'initial trust' issue. We are using CoreOS to run Kubernetes, and secure both the etcd API and the Kubernetes API servers using client certificates. We are using iPXE to boot ...
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1answer
45 views

Same certificate but different private keys on different servers. Does this work?

We have a SAN cert that is used on multiple servers. Is it possible to have the cert re-keyed and only use the new private key on a particular server while keeping all of our other servers using the ...
2
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1answer
46 views

What does it mean to sign a public key and what's wrong with signing someone else's key?

I just stumbled upon this comic and I'm not sure if I understand what's going on. I googled and I figured that somehow people can sign other people's public keys and then they that person is ...
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1answer
222 views

Distribute S/MIME public keys and CA cert for email security

I have my own CA. I want to distribute S/MIME certificates for 10 different users. I saw S/MIME keyservers from http://wiki.cacert.org/KeyServers, but I don't want to use public servers. What is the ...
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1answer
30 views

How secure is it to bundle unencrypted private key and a CSR into PKCS12 certificate?

I want to create a self-signed certificate to digitally sign my documents. I want to do so using my existing key pair, but to accomplish this I'd have to export my private key unencrypted into a file, ...
2
votes
1answer
687 views

Determine private key size using public certificate [duplicate]

I have a public certificate in a PEM (.pem) file -----BEGIN CERTIFICATE----- MIICsjCCAZqgAwIBAgIJAMA1YIQ2JLXDMA0GCSqGSIb3DQEBBQUAMBExDzANBgNV ... 29V/R9RZOoSBHDzGPL84wm4qojMuwQ== ...
3
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0answers
44 views

Will WinVerifyTrust return true for a file signed by a revoked certificate, before it was revoked?

I've seen mentions online that drivers that were signed by certificates that were later revoked are still trusted by Windows' driver integrity. Apparently if the file was signed before the revocation ...
28
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4answers
40k 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?
1
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0answers
55 views

Key Hierarchy and key Encryption

If i have two 56-bit DES keys, and I use these two key to encrypt a 256-bit AES key. Like this: K_AT encrypts K_BT and K_BT encrypts K What is the effective security of key K? Is it 2 X 56 Bits?
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0answers
23 views

key hierarchy management and master key

Now, I have this equation, {{K_ab}K_bs}K_as. K_ab is encrypted by K_bs then whole packet is encrypted by K_as I think the key structure is K_as is the master key, K_bs is under K_as and K_ab is the ...
6
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1answer
250 views

Are RSA Key Pairs unique?

I generate RSA key pairs mostly using the following command: ssh-keygen -t rsa -b 4096 -C "someemail@hostname.com" which produces a public-private RSA key pair. If I run this command again and ...
0
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1answer
51 views

Review of a protocol

I am wondering if anyone could give a second opinion whether the following is secure or not. I have a system which consist of a mobile device, FTP server and a PC. The mobile device is to upload ...
681
votes
3answers
348k 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 ...
3
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1answer
42 views

What security impact is caused by a TLS server continuing the handshake when presented with an invalid SNI?

RFC 6066 defines Server Name Indication as an extension, whereby virtualised web servers may be given an SNI extension in order to know which certificate should be presented. It has the following to ...
3
votes
3answers
45 views

Is it possible to prove that a TLS server key has changed?

I know of a site that is currently using SSLv2 and I'm refusing to connect to them until they Disable SSLv2 Re-key their servers I'm insisting on #2 because due to DROWN, servers running SSLv2 ...
1
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0answers
46 views

find owner of private key

On one of the old dev servers I manage there is an RSA public and private key pair ~/.ssh/id_rsa.pub and ~/.ssh/id_rsa in a staging user account (used for automation and testing prior to ...
14
votes
1answer
438 views

How would one verify that the public key from WhatsApp's servers belongs to the person I expect it to?

WhatsApp had recently announced end-to-end encryption on all communications. While that's an impressive move, I still have a big open question mark. The articles and this white paper suggest that the ...
4
votes
1answer
74 views

Should 'openssl verify' recognise an exceeded 'Path Length' constraint on a root/intermediate CA?

Background Following the guides here and here I am setting up a multi-level PKI. I have increased the pathlen config to 3, such that I can generate one root certificate that I can use to sign the ...
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0answers
137 views

WhatsApp end-to-end encryption for all devices [closed]

The news is out, WhatsApp switched on encryption for a billion people. It supports all devices and encrypts texts, photos, videos and calls. There are so many questions that just came to my mind ...
14
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4answers
7k views

SSL root certificate optional?

I may have been under the wrong impression on how servers should be setup and what certificates actually get sent over during the server hello certificate message. I came across this today from ...
4
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5answers
2k views

Why would someone want to encrypt RSS feeds?

I heard the idea of encrypting the RSS feeds using public key encryption system from someone and since then I am intrigued by the idea. But then I started to wonder what would be the basic need for ...
0
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1answer
1k views

Security weaknesses in using RSA encrypted MD5 hash of certificate content

Suppose you have an Internet banking site based on a secure web server running the HTTPS protocol via port 443. The server authenticates itself to clients through an X.509 certificate signed by a ...
1
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1answer
26 views

Impose certificate extensions through the certificate authority instead of the client

As I understand the creation of a x509 certificate is a simple 3 step process: The client generates a private and a public key. The clients generates a certificate signing request for the pair and ...
5
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2answers
89 views

Public key for SSH over the internet differs from a key for SSH over the LAN

I have a Raspberry Pi and can access it via SSH (authentication via user password) when my laptop is in the same network. Now I want to access it over the internet. I already set my router to forward ...
137
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5answers
96k 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 ...
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4answers
2k views

P12 - Extract public part (certificate) without knowing the p12 password

I would like to extract the public part of a revoked P12 which doesn't belong to me. I can't open it with KeyStore Explorer because I am prompted for the password, is it possible with OpenSSL ? The ...