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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3answers
865 views

How does the certificate trust model work in detail?

How does the whole achitecture between the certificate authority (e.g VeriSign) and its clients (e.g foo.com) work. How does my browser know that foo.com hasn't created its own certificate, wrote "...
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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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2answers
905 views

Why is the signature field in X.509 a BIT STRING, despite there being ASN.1 (DER) data inside?

As can be seen from the following ASN.1 definition of an X.509 certificate, the Signature field is a BIT STRING. ...
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1answer
125 views

What should I think about these unique certificate serial numbers [closed]

I was looking at the serial numbers of the certificates for www.google.com and wordpress.com. Wordpress was listed by openssl as: 04:0B:D4:F8:25:88:C5 This serial is listed as the serial for both ...
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1answer
77 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
51 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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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
203 views

Secure Design and CRL?

I was at my College Security Lesson, the professor said that Certificate Revocation Lists (CRLs) violate some of the Secure Design principles. Secure Design Principles: Fail-Safe Defaults Economy of ...
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1answer
123 views

Is allowing both digitalSignature and keyEncipherment certificate usages a bad practice?

From what I see, many server and client RSA certificates in the real deployments have the "key usage" mask containing both digitalSignature and keyEncipherment. Isn't this a bad (that is, potentially ...
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1answer
87 views

Direct Anonymous Attestation to replace CA

In term of authentication, I have the impression that to trust an entity it is mandatory to have a Certification Authority involve. Today I stumble upon an article something called Direct Anonymous ...
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1answer
537 views

Best practice to create certificate by CA

I suppose that I have this scenario: Root CA Intermediate CA Practice 1: The Root CA generates her own $PK_r$ and $PB_r$ key, and after it makes her certificate $Cert_r$. The Intermediate CA ...
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1answer
714 views

How to verify CA certificate from Yubico with openssl?

I'm going to verify the CA certificate from Yubico. I copied the whole certificate from -----BEGIN CERTIFICATE----- to ...
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1answer
995 views

Can you explain partial private key extract algorithm in certificateless Public key cryptography?

Related to the algorithms of certificate-less Signature approach of Al-Riyami and Paterson… Why is there a need for a "partial private key extract algorithm"? Why should it be needed when calculating ...
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1answer
258 views

Certificate == signed public key

For primes p and q used to create a keypair, I understand that the following operation is used to create a signature: $M^d (\bmod\ N)$ where d and N have their usual meanings and M is the message. ...
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1answer
30 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
135 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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1answer
476 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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4k views

Why does curl need both root and intermediate certificates in order to securely connect to an HTTP server?

I have created a root certificate, an intermediate certificate, and a server certificate: ...
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1answer
56 views

Key derivation with implicit certificates

The big advantage of implicit certificate is their small size and fast processing. This article presents a way how to compute implicit certificates. In the end Alice is able to derive both her ...
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1answer
281 views

how to avoid attack on Certificate Revocation List by the owner of the private key?

suppose A owns the private key, and its correspondent certificate locates in site of CA. B request for A's certificate from CA for verifying the signature sent to him/her. There is an attack ...
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1answer
575 views

How to sign a CRL file if I have offline keys?

I am generating a CA for internal use. When generating a CA, the best practice I have observed is to keep the root CA offline and emit an intermediate CA certificate that will in turn emit the end-...
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2answers
669 views

Is it safe to include the public certificate in xml digital signatures?

My understanding of XML Digital Signatures: Let's use a SAML token as an example. Note - for the sake of simplicity I'm omitting some details like CanonicalizationMethod, base64 encoding, etc. In ...
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2answers
168 views

Create broken chain certificates for testing

In our software we receive certificates in binary DER format from our clients. They are in advance used to perform certain identity checks between server and client. To ensure the certificates are ...
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1answer
1k views

How can a company have its own Certificate Authority for internal use?

It is possible for a company to deploy its own CA ? How would browsers accept the certificates ? Supposing a company does not want to use the role of a commercial server like Windows Server or any ...
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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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1answer
750 views

EC Public Key length in ASN.1 DER

I have two X.509 certificates in DER format. A: ...
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1answer
673 views

I've got my private key compromised. How does CRL work?

How does certificate revocation list (CRL) work? How can I send a request to the CA to add my current private key to the CRL, so no one except me can add my certificate to the CRL? Related: - How can ...
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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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1answer
174 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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1answer
656 views

What does the PFX file extension stand for

PFX is commonly used as a synonym of PKCS#12 certificate stores. However, I've never seen an explanation why these stores are called PFX (on Microsoft platforms) in multiple articles, including those ...
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1answer
399 views

sign data and append certificate VS sign data and certificate

I am currently writing my masters thesis in which I need to develop a licensing module for an application. The license itself is a JSON Web Token which is signed using a RSA private key. Since we ...
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1answer
679 views

Raw signature of public key vs full certificate

I'm working on an device that will have its own keypair to sign data that it acquires. The public key will be signed with a provisioning key to ensure authenticity of the device. I want to put the ...
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1answer
1k views

How is the PKCS #10 signature generated?

I'm generating certificate signing request in iOS, which does not provide proper ready-made API for CSR generation. Now the library I have used for CSR generation produces the different signature for ...
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1answer
680 views

Rogue CA Certificate MD5 Collision Control

Papers from Marc Stevens et al show that X509 certificates that rely on MD5 signatures can break the assumed security model, that is, it allows for a forged certificate to have the same signature as a ...
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1answer
1k views

SSL pinning - how to safely hide the certificate?

We are doing an iPhone app and read multiple forums which says SSL pinning makes it possible to avoid man in the middle as we trust our web services server through the certificate which will be pre ...
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1answer
155 views

How are messages from server secured when using SSL certificate

In case of using SSL the certificate server has a primary key and a public key that is published to all clients - as far as I understood. So in this case when message is encrypted by public key (on ...
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1answer
2k views

RSA and ECDSA Certificate Sizes

Is there a table (or a whitepaper from official sources) that compares the size of X509 certificates generated with RSA (starting from 1024 bits) and ECDSA (starting from 160 bits) ? Thanks for the ...
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1answer
6k views

How can we get CA's public key?

To get a public key of some organization or someone we want to send an encrypted message to, we need to make a request to CA asking that organization's public key. CA then returns X509 certificate. It ...
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1answer
547 views

How do I sign data that's been encrypted using public key? (RSA)

I've received a public key to encrypt my data for the other end to decrypt using their private key. Now, they want us to sign the data as well to ensure non-repudiation. I thought that I should only ...
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1answer
50 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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57 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
48 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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43 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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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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27 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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32 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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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

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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64 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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GlobalSign cert in Trusted root for Google Services shows Sha1. Security postures

"GlobalSign" certificate in Trusted Root Certification Authorities for Google Services shows Sha1. Security postures are different than just 2-3 yr ago. At my home, router bought 2016, networked; ...