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Questions tagged [pki]

PKI is short for Public Key Infrastructure. The foundation of a PKI is the certificate authority (CA), which issues digital certificates that authenticate the identity of organizations and individuals over a public system such as the Internet.

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Asymmetrical encryption with multiple sufficient key-pairs [duplicate]

I have the following requirement: There are N public/private RSA key pairs. The encrypted data must be decryptable by any of the private keys alone, but not by any other key. For encryption, the ...
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Authenticating to wireless with EAP-TLS in separate forests with the same trusted root CA

I'm looking at a scenario of having a standalone offline root CA sign a subordinate CA in two separate active directory forests on different campuses. If I then set up EAP-TLS on each site, will I be ...
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Can root and intermediate CAs use different asymmetric ciphers and key sizes?

For example, could a root CA use RSA-4096, one intermediate CA use RSA-2048, and another use ECDSA-256 (DH19)?
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PKI Validation - Usefulness of the public key with the identity certificate

I have some understanding of how PKI works, similar to this: - https://knowledge.digicert.com/solution/SO16297.html - https://security.stackexchange.com/questions/59566/ssl-certificate-chain-...
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Is DPKI going to use as much energy as miners do in Bitcoin Network?

Quoting the “Decentralized Public Key Infrastructure” white paper, page no. 5: Third-parties, who are called miners (or validators), still exist, but their role is limited to ensuring the security ...
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339 views

What happens when a root CA loses its private key?

Certificate Authorities normally keep their private keys inside dedicated Hardware Security Modules (HSMs). What happens when such a device is lost (fire, electronic fault, stolen, etc)? How would ...
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231 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
312 views

Does maximum length of CN in a x509 cert include the length of the OIDs?

This is a CN from a x509 certificate (I have done some substitutions just to mask the data but the length is not changed) CN=Alex Perry/pseudonym=88b2e76beE0e4e4b94b502020202262E/x500UniqueIdentifier=...
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How does registration authority verify entity's identity for SSL? [closed]

In the answer here: Verification of identity by certification authority, it states that for European eIdentity you must provide your passport or ID card, but that this practice is quite different ...
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180 views

Encryption in a Distributed PKI?

Given a PKI infrastructure with a root node that signs CSR's for nodes Alice, Bob, and Carol. Is it possible for Alice to encrypt some information, store it publicly somewhere, then later Bob or ...
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1answer
472 views

Who issued the first SSL certificate?

When SSL was introduced in ~1996, there was only a few CAs issuing certificates for that specific use and a few sites which actually used SSL. Which Certification Authority issued the first SSL ...
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Complexity of cross certification

I don't understand why are there $n\cdot(n-1)$ certificates issued when I'm using cross certification with $n$ CA's. Let's assume I have two PKIs. Why cant't I just cross-certificate the both trust ...
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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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3answers
2k views

Why do we need a digital signature?

First of all, I want to say that I'm totally new to cryptography. I searched on crypto stackexchange but couldn't find the answer to the following question.(probably because it's easy, but I still don'...
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How to configure a client browser cert to be authenticated by a server?

I currently am being asked to partake in a strange authentication format while working with a client, and was hoping for clarification. The client is using HTTPS with client certificate ...
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1answer
146 views

identity based cryptography (IBE) without key escrow

I am trying to find a method of implementing identity based cryptography to generate key pairs without the use of a trusted PKG that holds the private keys. Has there been any solutions to overcoming ...
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1answer
331 views

How can I verify a client's identity by requesting a digital certificate?

So I am registering users and I need to know they really are who they say they are. More importantly that they represent the company they say they represent. I was told I can ask them to send me a ...
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281 views

Is HIMMO For Real?

I've come across something out of Philips Research called HIMMO Key Pre-Distribution Scheme (https://eprint.iacr.org/2016/410.pdf and https://www.ietf.org/proceedings/96/slides/slides-96-cfrg-2.pdf) ...
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1answer
743 views

Blockchain use in record management

From my understanding of blockchain, I feel the main use of blockchain is to do something in a decentralised way as compared to the traditional centralised way which involves a middle man. Usually, ...
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1answer
48 views

What is the exact meaning of revocationWarning and revocationNotification in RFC 3161?

The RFC 3161 (Internet X.509 Public Key Infrastructure Time-Stamp Protocol) specifies that a time-stamping response has a PKIStatusInfo and, optionally, a timeStampToken. In turn, the PKIStatusInfo ...
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Collusion Resistance Proof for decentralized key generation in PKI

In public key infrastructure, all users generate public and private key pairs by themselves. In this case, will there be any collusion in key generation? Does the trusted third party resolve these ...
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1k views

Cryptography behind the Turing Imitation Key (TIK)

When browsing the internet I found out about this amazing phone. Well, it would be amazing if it was actually obtainable. It's called the Turing Phone, and it is supposed to come with as good as ...
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What are the most appropriate PKI based cryptographic protocols for peer to peer communicaton?

I've been trying to find out which is the most appropriate PKI based cryptographic protocol for peer to peer communication. I do understand that they vary with respect to the peer to peer architecture ...
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Smart Card choice for PKI implementation

I'm seeking to implement a national digital signature standard on a smart card. I feel like this is a good place to ask if anybody is acquainted with a hardware supplier offering smart cards that ...
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2answers
10k views

Finding Private key in RSA with public key, cipher text and plain text

Is there a known 'non-brute force' method of determining a private key in an RSA system when all other parameters are know? I found the values of a ciphertext ($C$), its corresponding plaintext ($P$) ...
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1answer
164 views

CRL number generation sequence: can I use a time stamp?

RFC 5280 states that the CRL number should monotonically increase. I have seen this common practice of incrementing the CRL number by 1, every time a new CRL is generated. But can I use a Unix (epoch ...
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902 views

What is the threat to a PKI when the root CA certificate is generated using SHA1?

We have thousands of servers that have been issued certificates signed by our CA using SHA256 but the our root CAs own certificate was generated using SHA1. Assuming SHA1 is no longer secure for our ...
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1answer
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X509 certificates: Two Algorithm Identifiers?

I'm wondering why there are two Algorithm Identifiers in a X509 certificate. One is in the "to be signed" part and the other one is at the end right before the actual signature. Are they used for the ...
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222 views

Must root certificates be self signed?

Root certificates are normally self-signed. What is the reason behind that convention? I mean, one must trust the root certificate in a non cryptographic way anyhow.
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If you were to design a PKI from scratch, what would you do? [closed]

In what ways would you simplify? What would be changed to be more modern or extensible? Suppose you have no requirement to adapt to previous protocols. Links to proposed designs, existing protocols,...
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1answer
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Is it not secure if we use weak passwords to protect exported PKCS #12 files with private keys?

Consider a practical scenario as described in Microsoft's Expand Export a Certificate with the Private Key. We can see a certificate with private key can be exported as a PKCS #12 file, where the ...
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1answer
2k views

How to determine the RSA Private key size from the Public.key file?

Question: How to determine the RSA Private key size from the Public.key file? Just roughly, how big it could be? ...
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1answer
856 views

TLS Handshake : Server authentication or only Server ‘s Certificate authentication?

I have some difficulty understanding the way in which the Server is really authenticated by Client in TLS handshake (in case of using RSA key exchange). When Client receives Server ‘s Certificate and ...
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1answer
614 views

Is there a standard for public key encrypting and signing short messages?

Some systems, that operate over flaky bearers, need to send signed, encrypted messages that are entirely self contained - i.e. send a single 300 byte UDP rather than have a 10Kb, two-way, certificate ...
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1answer
140 views

Certificate for the public key

I am new to Network Security and learning about various security features like Diffie-Helmann and others. I understand that the Public key send by the server to the client needs to certified that it ...
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2answers
2k views

TLS encryption with a self-signed PKI and Python’s asyncio module

I want to enable TLS encryption with a custom / self-signed PKI for a self-contained distributed system built with Python 3’s asyncio. I’ve read Python’s ssl docs as well as several tutorials: http:...
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Compromised Issuing CA [closed]

I'm configuring a PKI infrastructure with an offline root CA and several issuing CAs. Among other topics, I'm struggling to decide how the revokation of an Issuing CA certificate works. My Root CA ...
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Why is public key cryptography not widely used in governments? [closed]

Are there any practical limitations? Govt driving license, passport, SSN could be digitally signed making it easy for anyone to validate. They can have a qr code in them which can be easily validated ...
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1answer
235 views

SSL certificate / SSL configuration - FIPS-197 compliance

What does it mean when we talk about FIPS-197 compliance in the context of SSL certificates, their deployment and usage ? I am almost certain that the FIPS-197 compliance in the context of SSL ...
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2answers
5k views

How does a certificate authority issue a digital certificate?

I am new to cryptography and I want to know the details of how a Certificate Authority issues a digital certificate. From what I know (please correct me if I'm wrong at any parts of my explanation): ...
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3answers
333 views

DH and PKI for KeyExchange

My question is fairly simple. I have more than two nodes which needs to communicate very efficiently from computational point of view. One of the nodes can become a coordinator between the nodes. ...
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1answer
124 views

PKI Infrastructure

I've got a very simple but for me a difficult question. I analyzed the public key cryptography and understand the process. But I didn't understand why is only the receiver able to decrypt to message. ...
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1answer
353 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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4answers
127 views

Possible to use an accumulator to “license” or restrict the qty of certificates being used?

Suppose in a future version of x509 PKI, it is possible to limit the quantity of certificates being used, what would that look like? Here is a concept that won't work in the real world, but ...
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2answers
638 views

Smart Card - Entropy during on-board public key generation

I know that some (advanced) smart cards or tokens allow generating key pair directly on the device, but I wonder how the card can gather entropy during the process. Any idea ?
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1answer
117 views

Build set with PKI from reliable broadcast / random beacon

I am trying to build a protocol (or find an existing one) for creating a set $S_2$ with PKI from a set of parties $S_1$ that initially does not know anything about the other parties. We assume end-to-...
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Corporate PKI - SHA1 deprecation [closed]

Here is the context. Suppose you have a corporate PKI with : AC_Root (offline in safe store - SHA1 signature) SubRootA ans SubrootB (offline in safe store - SHA1 signature) SubSubRootC, SubSubRootD, ...
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210 views

Cryptosystems used to generate public key certificate

Where can we find the cryptosystems used to generate public key certificate? Are the cryptosystems under the signature algorithm and signature hash algorithm? Do I need to analyze the packets ...
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2answers
645 views

ECDH anonymous key exchange to avoid PKI

I want to use TLS to encrypt the communication between peers in a P2P network. Each peer has a well known 256bit peer identifier (the public key of a 256bit elliptic curve keypair). Both peers need ...
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1answer
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How is an X.509 public key used for TLS?

Wikipedia's TLS article says: The client responds with a ClientKeyExchange message, which may contain a PreMasterSecret, public key, or nothing. (Again, this depends on the selected cipher.) This ...