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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1answer
44 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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1answer
270 views

Revoke a GPG key using previously generated revoke certificate after renewd (change expiration date)

I have few sub-questions Do secret keys get expired, or just the public key gets expired? Do I have to back up the master sec key each time I renew it? For an ...
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8 views

Extract Certificates from Package File on Mac

I would like to manually verify the certificate chain on a package from my MacOS Catalina. I know that you can use the codesign --extract-certificates to extract certificates from applications, but I ...
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1answer
74 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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0answers
61 views

Include TSA Certificate in Timestamp Request

I'm currently working on Timestamping and stumbled upon a parameter fRequestCerts/requestSignerCertificates/certReq that according to the documentation (1, 2) tells a TSA to include the certificate ...
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4answers
8k views

Diffie-Hellman Key Exchange with Authentication: Man-in-the-Middle query

I have been reading up on MiTM attacks, and the prevention of them using public key certificates. Recently I learnt about Diffie-Hellman Key Exchange with Authentication, and how it uses signed ...
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0answers
41 views

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
21 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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17 views

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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13 views

Rsa accumulator verification cost gor nonmembership testing

What is the verification cost of rsa accumulator gor non-membership testing. Is it O(N) or O(1). Can somebody explain it to me?
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13 views

Merkle tree verification cost calculation

I am trying to understand how to calculate verification cost of sorted merkle tree in case of exclusion proof. For example 5 revoked certificate are kept in merkle tree. How can i calculate storage ...
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25 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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31 views

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
23 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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1answer
462 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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25 views

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
43 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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29 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
369 views

How is Cross-Certification implemented?

I am currently learning about Certificates in Public Key Infrastructure. Cross-Certification exists as an alternative because the concept of a single monolithic CA certifying every possible user in ...
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1answer
45 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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12answers
15k views

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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26 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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1answer
52 views

Is this pairing scheme for establishing trust between two devices with self-signed TLS certs secure from MITM?

Assume two devices (A and B) with self-signed TLS certificates (this part can't change). We want these devices to trust each other. One way to do this is to simply copy A's cert over to B's allowed ...
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2answers
3k views

Where is Signaturevalue in Certificate?

Where is the Digital Signature value in my certificate? I can find Signature Algorithm and Signature Hash algorithm. Also why there are two fields specifying the Signature's Hash? With Signature ...
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1answer
64 views

I am new to digital certificate 509V3 concept. can some one please clarify the below points [closed]

I am using RSA 2048 with SHA 256 primitive in certificate: How to verify the user certificate n + 1 with Root certificate n? why it is required to perform Certificate chain verification? How to ...
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1answer
147 views

What security do digital signatures provide (like used when signing PDFs)?

I want to ask you one question about digital signatures as they are (for example) used when digitally signing PDFs. We know that if our document has a digital signature, we can detect if the original ...
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1answer
114 views

Signature Verification: High level

I'm trying to understand how certificate signing and verification works conceptually. I know the classic example with asymmetric cryptography- the sender encrypts data with public key of receiver, ...
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57 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
102 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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79 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
64 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 ...
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67 views

Do people sign my subkey?

So, I've generated my GPG key pair. Created a subkey for signing and a subkey for encryption. Exported the whole thing, removed my master key pair to a secure place, re-imported only the subkeys. Now, ...
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1answer
139 views

How are all necessary parameters shared between signer and verifier in the ED25519 signature scheme?

I want to use the ED25519 signature scheme in my application which requires frequent sharing of secret data between two entities in the public domain. I know that the Schnorr signature scheme has a ...
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1answer
85 views

Why do we need HMAC?

AFAIK, HMAC solves the collision problem of hash algorithms by mixing in a pre shared secret. Can't we just use the pre shared secret to symmetrically encrypt data and leave out the hashing?
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1answer
869 views

How android apk file signing works?

There are a number of pages on web to tell how to sign apk file for Android. But none I've found telling how it works under-the-...
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37 views

what is the difference between self issued and an intermediate certificate

Hashicorp vault has an API they call Sign Self-Issued. The use case is for rotating root CAs. A user creates a new root self signed CA and then passes it to this API and what is returned is roughly ...
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1answer
120 views

What does (06) in “CRL Signing (06)” mean?

In "Certificate details -> key usage -> CRL Signing (06)", what does "(06)" in "CRL Signing (06)" mean?
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2answers
119 views

How are CRL implemented?

The source from where I learn states:- CRL (Certificate Revocation List) is the primary means of checking status of certificates offline. But I can't seem to understand how is it possible for a ...
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2answers
393 views

What is cryptographic sealing?

While revising my CAdES library I encountered some "sealing issue" in digital signatures. The Win SDK signtool.exe has a /seal ...
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1answer
50 views

How are certificate status obtained on browsers?

There are two ways of checking the status of a digital certificate:- Offline Authentication (CRL) Online Authentication (OCSP, SCVP) Several browsers (like Mozilla Firefox) have given up the use of ...
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33 views

Pitfalls of wildcard certificates with unique key pairs?

I am having difficulty finding information regarding using wildcard certificates with unique key pairs. I understand if you duplicate key pairs across multiple servers and one becomes compromised, an ...
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3answers
7k views

Does “Shattered” actually show SHA-1-signed certificates are “unsafe”?

Note: I am not advocating anyone continues using SHA1-signed certificates: they are dead as far as security is concerned and should no longer be used. I'm just trying to clarify my understanding of ...
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1answer
159 views

CSR signature using elliptic curve [closed]

We've been asked to generate a certificate signing request using elliptic curve and we can't use any third-party library as it's an embedded application with very limited resources). We are used to ...
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0answers
55 views

What security is provided by a certificate? [closed]

I've been working on the topic of certificates for a little while, and here is what I understand: A certificate is basically a public key + some data about the owner of the certificate + a signature ...
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1answer
603 views

Windows certreq full response file [closed]

I'm using the Windows certreq command line tool to submit a CSR for signing to a Windows Server CA. ...
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1answer
66 views

How are public keys securely and reliably obtained across the internet?

I've just decided to start learning all about PKIs, and I have come across what seems like a paradox. When fetching a public key from either a server or a CA, how can we be sure that the public key ...
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1answer
136 views

Understanding hybrid cryptography's concepts: signing and CA

After learning about symmetric encryption, public-key encryption, one-way hash, digital signature and digital certificate, I was tasked to think of an imaginary hybrid cryptosystem. I was thinking ...
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3answers
6k views

Is there a complete list of Signature Algorithm names?

I need to analyze the output of rbsec's sslscan which reports a server's SSL/TLS configuration as reported by OpenSSL. I'm interested in the Certificate's Signature Algorithm in particular, and I was ...
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1answer
95 views

What is the RFC order of peer certificate verification, trust chain or expiry first?

If a certificate received from a peer: Is expired, has a valid signature, but from an untrusted root CA What error should be thrown? Untrusted certificate or expired certificate? I can't seem to ...
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1answer
151 views

X.509 strong authentication protocols

Is there also a protocol definition in X.509? In "Handbook of Applied Cryptography" by A. Menezes there is a reference to X.509 strong authentication protocol, nevertheless, I could not find the ...

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