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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
61 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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195 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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94 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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71 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
477 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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677 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
926 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
234 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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44 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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2k 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
49 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
727 views

RSA certificate needed in CVC format

I had a client requirement asking me to provide an existing base64 encoded certificate in a CVC format. Could someone point me in the right direction here to understand what this format is? How can I ...
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1answer
244 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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2answers
545 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
152 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
112 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
668 views

EC Public Key length in ASN.1 DER

I have two X.509 certificates in DER format. A: ...
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1answer
635 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
40 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
69 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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2answers
534 views

What exactly is the contents of the LDAP userSMIMECertificate attribute?

I'm trying to setup an LDAP with user certificates. I have already learned that certificates can be stored in either the userCertificate attribute in DER format, or ...
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1answer
468 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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1answer
545 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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353 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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577 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
630 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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877 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
152 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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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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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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498 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
49 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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36 views

Include TSA Certificate in Timestamp Request

Im currently working on Timestamping and stumbled upon a parameter fRequestCerts/requestSignerCertificates/certReq that according to the documentations tells a TSA to include the certificate that was ...
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15 views

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; ...
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127 views

TPM 2.0 Reissued EK Cert

Unlike the TPM 1.2 module, the TPM 2.0 specification allows the platform user to create own ...
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44 views

Benefits of using SSL certificate over a raw key pair for non-browser use?

For applications not involving CA signed certificates – or web browsers for that matter – it would seem to be easier to use a raw key pair if possible, rather than deal with potential formatting ...
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95 views

Certificate Master Public Key with Pairing

I am currently working on CipherText Policy Attribute Based Encryption (CP-ABE) scheme. If we see the scheme, we can notice that the Authority may generate a Master Public Key and a Master Private Key(...
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2answers
112 views

Are there example certificates available for test purposes?

Are there example certificates (PEM format) for testing available somewhere ? For test purposes I would need a certificate signed with SHAS256/ECDSA P-256, together with a complete chain to test ...
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1answer
133 views

Can I discard a specific X509 signature from file?

I'm writing a program to sign files using X.509 certificates and .NET framework classes. My users can sign the same file more than once without any problem (like a revision process). So, a file may ...
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46 views

Direct Anonymous Attestation

Could anyone explain me Direct Anonymous Attestation in general terms. I have been trying to read the paper but I really cannot seem to get my head around it. It may seem like a dumb question but I am ...
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85 views

IX509Extension XCN encoding?

I understand from reading MSDN that the X509 v3 extensions must be handcrafted. This involves the CRL, AIA, name and policy constraints, policy mapping, private key usage period, and subject ...
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139 views

Why rogued certificate from hash collision is harmful

I cannot understand why rogued certificate is thought harmful though It can be used to impersonate some website. The attacker can craft a rogued certificate with different identities and public key ...
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1answer
1k views

Meaning of Signature hash algorithm field in certificate

I'd like to understand what is the meaning of this field, especially considering that when calling a crypto library to sign data the digest method is specified by the caller. For example, this simple ...
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1answer
461 views

Unique assignment of X.509 certificate to each client

I'm trying to implement a short scale electronic voting application in a domain comprised of no more than 100 clients. System administrator is able to create new election instances and each client is ...
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1k views

RSA - Why should we sign hash rather than raw content? [duplicate]

Apart from obvious performance considerations, is there any mathematical or crypto reasons that imply that we sign a hash rather than a raw content ? I read that it was because the hash must fit in ...
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2answers
573 views

What is the most important piece of information in a X.509 certificate?

X.509 has a structure which contains information like version number, serial number, signature algorithm, issuer, subject name, subject public key, signature of the issuer etc. However, I'm having ...
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2answers
42 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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1answer
108 views

Is the only use for the private key of a root certificate signing certificates issued by it?

A root certificate can be used to issue intermediate certificates. The private key of the root certificate is needed in order to sign any intermediate certificates. However, after that, we only need ...