Questions tagged [certificates]
A certificate consists of a public key and information about the owner (e. g. the name of a person or server).
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Samsung .Cert File - Digging deeper
I don't know if I should ask this question in Android Stackexchange or here, but I am sure I am in a right place to ask.
My question is about following Samsung Certificate file:
File name: ...
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Software signing : multiple certificates [migrated]
I'm quite new to the cryptography field, and I'm trying to understand a few things:
I used binwalk on Linux to analyse ...
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1answer
21 views
How to determine curve's field size in a ECDSA Signature
There is a bug in some firmware I'm working that states the following:
If individual coordinates are shorter or longer than the curve’s field size they are processed incorrectly.
So I can get the ...
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How may I check if an expired certificate was valid at the time? [migrated]
I have an old let's encrypt (but disregard that, it could be any) certificate that is no longer active.
How may I check if it was valid at the time?
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1answer
27 views
Required certificate key usage for signing document
What's the required key usage/extended key usage for signing documents, eg.PDF, Word, PowerPoint, Excel, etc...
I am going to create a self-signed certificate that is needed to sign those documents. I ...
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2answers
2k views
Do certificates need to be stored as encrypted?
The titles says most of what we're confused with. Here's some details:
On an embedded device, we have a microcontroller and external flash memory. This memory can be easily read and written to in ...
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1answer
74 views
Automatic csr sending
In our project we have grpc server and clients which should satisfy mutual tls. So, there is CA and clients generate csr to sent to CA to signing it. Now I need to send csr manually to CA to sign it ...
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37 views
What is the difference of having to use a ca.crt to verify a signed file vs the .crt used to sign it?
This seemed like the most appropriate place to ask this question so here it goes:
I used to run a process that automatically generated a shim.key and ...
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37 views
Best model for client software encryption / decryption
I would like to develop a small solution (c#) that must secure data exchange with an untrusted server.
The model is that this software will run on a Windows client then Encrypt data before pushing it ...
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32 views
Any (proposed) internet standard (RFC) for trusted hosting of signed documents?
There's a problem with digitally signed documents - in particular that any print-out of them will be only a copy, not an original (by print-out I mean the print-out of the human readable form of the ...
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1answer
57 views
Different encryption standards and how they relate to auth and algorithms
The main confusion I have is around the different PKCS and relation with SSL (TLS). I have done a lot of research and have found bits and pieces but not necessarily how these relate, so let me explain ...
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445 views
Clarification on the TLS verification process
I am reading this article in my attempt to understand how the TLS verification and chain of trust works. In the piece I come across a section that I am not sure I understand.
In the simplified ...
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2answers
753 views
What exactly is Let's encrypts chain.pem file?
While trying to understand the use or meaning of the fullchain.pem file created by let's encrypt I stumbled upon this post in which ...
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3answers
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What are the contents of a certificate and how can I view it?
I understand on a conceptual level that a certificate is nothing more than just a verified public key. The next question I have, is how exactly do I see the contents of a certificate? Apart from the ...
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22 views
CMS encryption application using Windows system certificate store
Hy!
I'm looking for an application, which can make cms encryption/decryption, but with the use of the windows certificate store.
I already found out, that openssl can't do it out of the box (just by ...
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29 views
How is the identitiy of a subject in a Public Key Certificate verified by the Certificate Authority (CA)?
A general digital certificate issued by a CA might contain information about the individual/organization to whom the certificate belongs. As an example, consider this sample scenario:
This PKC ...
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1answer
42 views
Where can I read about DER certificate structure - fields and its registered values?
Where is an official documentation for ASN1 structure and values of x509 certs?
Using OpenSSL command like openssl asn1parse -in server.der -inform DER I can see ...
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data transferred when certificates are used
I tried to find some information about how certificates work on a technical level but wasn't really able to find something that answered all my questions.
Can one explain which data is transferred ...
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1answer
73 views
Allowed key types in an SSL certificate
What are the valid key types which can get signed (or generated and signed) by a CA to constitute an SSL certificate?
For the keys used in TLS, the key types I have seen are RSA and EC. Anything else?
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How to prove document ownership at a specific time [duplicate]
Problem
Given any piece of data, I could sign it with public key and made available online. This proves I am in possession of given data, but it doesn't tell I am the creator. The only possibility (I'...
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2answers
519 views
openSSL created CSR signature size of 73 bytes but should't it be 70 bytes
after creating CSR using openSSL with secp256r1 curve
inspecting the file using openssl asn1parse -i -in ecTest.csr
the size of ...
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3answers
4k views
Smallest possible certificate for IoT device
I'm developing an IoT system that uses small nodes connected through RF. This allows messages under 250 bytes long. You can check it at https://github.com/gmag11/EnigmaIOT.
All messages are encrypted ...
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0answers
109 views
What's the meaning of cached certificate revocation list and online certificate revocation list in X509RevocationMode Enum?
In this article, there are cached certificate revocation list and online certificate revocation list terms used.
I tried to find ...
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465 views
RSASSA-PSS in TLS 1.2
I know it is possible to use RSASSA-PKCS1-v1_5 with client certificates in TLS 1.3.
But what about the other way around: using RSASSA-PSS with client certificates in TLS 1.2?
Is it possible to use ...
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1answer
5k views
Difference Between PEM vs P12 vs CRT vs JKS vs keystore vs PKCS vs x509 certificates [duplicate]
Sorry noob here. I am so much confused about lot of files used client authentication certificates. Can anyone guide me on the difference between PEM vs P12 vs CRT vs JKS vs Keystore vs PKCS vs x509 ...
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Detecting revoked keys long after a document is signed
Scenario: A document is signed with a compromised private key, with a long-term time stamp. The normal expiration date of the key pair is D. The rightful owner of the key pair discovers the compromise ...
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1answer
145 views
Manually creating a GPG Public Key
I want to manually create a GPG public key that can be imported into GPG, i.e. I want to create a file with a Public-Key Packet, a User ID Packet and a Signature Packet (for an example see here). I ...
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86 views
Generate version 3 x509 certificate from version 1 CA
Please do forgive me for my naivety. I have inherited a legacy system wherein the CA which signs the certificate is of version 1. Is it possible to generate a x509 version 3 certificate which is ...
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1answer
71 views
What if the CSR is intercepted in transit while sending it to CA?
I was studying PKI the other day and I had a serious thinking about the following question.
What is CSR? - It is a block of encoded text that is given to the CA when applying for an SSL certificate ...
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114 views
is it possible to achieve authenticated key agreement without using PKI or pre-shared secret?
After reading different techniques to achieve authenticated key-agreement (X3DH, HMQV, Asynchronous Ratcheting tree, An efficient protocol for authenticated key agreement, I understood that all these ...
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1answer
88 views
OpenSSL - What Data Is Used To Create A Certificate's Digital Signature?
I am coming up-to-speed on OpenSSL certificates. In all of my research I see where "data" is hashed to create a hash value that is used as the basis for a certificate's digital signature. This hash ...
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1answer
185 views
How message digest hash is used in RSA digital certificate verification
This is how I understand digital signature verification to work in general:
Plaintext gets run through a hashing mechanism to make a message digest (IBM's terminology, there appear to be plenty of ...
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1answer
162 views
How to compute certificates using Diffie-Hellman key exchange with certificates and Elgamal signature scheme
We consider the Diffie–Hellman key exchange scheme with certificates. We have a system with the three users Alice, Bob and Charley. The Diffie–Hellman algorithm uses p = 61 and α = 18. The three ...
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Review: peer-to-peer encrypted communication
I'd like to ask you to review security of the following communication scheme:
network is strictly P2P, based on DHT (peer discovery)
root user can create a virtual private network (network private ...
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1answer
29 views
Is a Qualified Digital Certificate backward compatible with existing certificate code?
I'm trying to determine if our digital signature generation code will work without change using a European Qualified Digital Certificate in place of the RSA signing certificate that we normally use.
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Sorted merkle tree versus rsa accumulator
When compared to sorted merkle tree and rsa accumulator, which one is the best? Rsa accumulator has constant proof and it adds/deletes at constant cost. What is the verification cost for rsa ...
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57 views
Rsa accumulator storage size
Rsa accumulator's storage complexity is known as O(1). However, how can i calculate size of accumulator value in byte?
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certificate revocation list file size
Crl files are growing linearly. I wonder with 10 revoked certificate, what is the storage size of crl file and so on. For every revoke certificate, how much increase the size of the crl?
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1answer
86 views
X.509 ECDSA signature field in DER format includes '00' between bit string and sequence of r and s
I created a X.509 certificate with ECDSAwithSHA256(OID=1.2.840.10045.4.3.2) by openssl.
ECC parameter is secp256r1.
Following is the signatureAlgorithm and signatureValue.
...
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Implementing ESignature and digital certificate
I'm having some issue understanding the mechanism of electronic signature and how implementing it
Here what I understood, correct me if I'm wrong:
(Client is here an android or ios device. Server ...
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1answer
52 views
Enforce weak RSA in TLS
I'm going to give a small talk on the mathematical background of RSA. My audience will consist mostly of software engineers and to make the mathematical stuff tangible, I wanted to demonstrate how to ...
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1answer
4k views
PKCS12 password of container and private key
As I understand pkcs12 defines a container structure that can hold both a certificate and one or more private keys.
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32 views
Keeping a backup of asymmetric keys with the help of a certificate authority without losing the privacy
First I'll explain the problem, then I will also give a solution(it might be wrong) I've found for it, you let me know what you think about this solution and whether you have a better one.
Assume a ...
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1answer
52 views
How is a digital certificate generated?
I understand that the role of a Certificate Authority is to SIGN (not encrypt) a certificate. The signed certificate will theoretically contain:
Plain text of data, including the server's public key
...
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Who verifies the trust of certificate authorities?
Background
I am a novice in the field of cryptography and cyber-security, and while studying asymmetric-key encryption, I learned about the potential of a man-in-the-middle attack.
To mitigate this ...
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34 views
Will CT (Certificate Transparency) override the use of CAA and/or DANE/TLSA records?
I'd want to know if some of these competing technologies has more chance to survive. It seems they are thought to solve a similar problem by different manners and I'd want to stick to the most ...
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96 views
How does DHE-RSA work and why is PFS guaranteed?
How does it work and why is forward secrecy guaranteed? I understood that it is not susceptible to a man-in-the-middle attack by using certificates in the beginning.
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1answer
189 views
Create self signed certificate from modulus, private and public exponents of RSA
I have the values of RSA public exponent $e$, the secret exponent $d$ and the modulus $n$.
How can I create (for example using openssl) a self-signed certificate using the RSA key $(n,d), (n,e)$? Is ...
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193 views
How to validate the authenticity and integrity of an XML document?
I am working on a C++ desktop application that reads an XML (also created by my org) from a public server (does not require authentication). I would like to make sure that the downloaded XML has not ...
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1answer
76 views
Observing cipher suites and certificate algorithms without man-in-the-middle
I manage a proxy server. Is it technically possible to observe and determine which cipher suite is selected between end points (client and server) without changing their SSL certificate, without ...
