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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246 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 ...
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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?
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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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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. ...
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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
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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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 ...
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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 ...
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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 ...
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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
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, ...
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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 ...
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 ...
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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 ...
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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 ...
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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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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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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 ...
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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 ...
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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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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 ...
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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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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 ...
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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 ...
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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 ...
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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 ...
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1answer
67 views
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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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3answers
5k views

Why aren't IMSI catchers rendered ineffective by standard MITM defenses?

There's been a lot of reporting in the past few years about law enforcement agencies using IMSI catchers (also known as Stingrays after a popular brand of them) to intercept cellular communications. ...
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1answer
67 views

How can I enforce that an SSH private key has a passphrase?

My company is serious about security and willing to move to SSH key-pairs. Users can generate their SSH key pairs independently and I worry if they set a pass-phrase. Can I enforce this? Does signing ...
3
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2answers
121 views

Can a CN-only certificate bypass a name constraint if the CA goes rogue?

I am trying to cross-certify an internal issuer certificate, adding a name constraint for our domain. However, it seems that an attacker could bypass this protection by putting the desired host name ...
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2answers
102 views

How In-House Certificate Authority works (e.g. EJBCA)

I have a simple (dumb?) question with respect to EJBCA. I have been exploring how In-house CAs work and issue certificates. However, I am not able to understand who will be trusted on the top level in ...
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2answers
147 views

Why is weakness of SHA-1 considered a threat to TLS security

If I understand correctly the role that a hashing algorithm (e.g. SHA-1) plays in TLS certificates is as follows: The hashing function is applied to a subject's public key. The CA then uses their ...
1
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1answer
71 views

ECDSA implicit certificate using OpenSSL

I am trying to generate implicit ECDSA certificate only for signing and verification using OpenSSL. I tried google but I am getting many research papers. I understood that A messages need to be signed ...
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2answers
40 views

Client verification with PKCS#7

When a client sends you a pkcs#7 file to communicate with you, Is this because the file has their public key(certificate) and their chain and to avoid the confusion on your side what needs to be there ...
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1answer
99 views

CSR with only public key with openssl

So I have been doing my research and haven't found anything specific enough to my problem. As the question title states, I want to make a CSR with only the public key. What I have been able to do is ...
3
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1answer
128 views

Understanding how does certificate validation work

I'm using Wireshark for better understanding how is a SSL connection established. I captured the traffic of visiting three pages: reddit, facebook and this one. All HTTPS of course. Reddit: after the ...
2
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0answers
26 views

Finding the EMSA-PKCS1-v1_5 DigestAlgorithm field in the x509 certificate

From the RFC - https://www.ietf.org/rfc/rfc3447.txt A.2.4 RSASSA-PKCS1-v1_5 For each OID, the parameters field associated with this OID in a value of type AlgorithmIdentifier shall have a value ...
0
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1answer
45 views

Two issuing CAs in a two-tier PKI (Windows Server 2012)

I'm planning to setup two-tier PKI in my environment. We have two remote sites connected via a VPN. I think it is OK to set up both Root CA and Issuing CA on the 1st site. But, for example, I have ...
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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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34 views

Storing Keys on Embedded Devices

What is a reasonable way of storing private keys/certs on an embedded device that doesn't have trust-zone, TPM or write-once storage? Without hardware backing the key-storage the key must be stored in ...
0
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1answer
23 views

SSL key exchange [duplicate]

As I understand, when I log on to a website via HTTPS, the public keys are shared in the beginning of the conversation. I have read around the internet is that if a MITM manages to read the entire ...
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1answer
82 views

Mobile number tracking

Is there any way we can track our mobile when it is lost? I have done a google search on the same and found that we have websites which give us the details of where the SIM was purchased & ...
2
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1answer
81 views

How do “certificates” hold “keys”? [duplicate]

I am new to the realm of security and keep hearing about "certificates" containing "keys". But no one has been able to actually explain to me what is actually meant by this. I assume that the ...
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1answer
32 views

What's the actual danger of public key spoofing?

I am reading an excellent beginner's cryptography tutorial, and on this page there is the following blurb: Public-key cryptosystems have one significant challenge − the user needs to trust that ...