Cryptography Stack Exchange
Cryptography Stack Exchange

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.

PKI is short for Public Key Infrastructure… a framework for creating a secure method for exchanging information based on public key cryptography. 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. The certificates are also used to sign messages , which ensures that messages have not been tampered with. For more on how certificates and public keys are used, see digital certificate.

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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 certificate and whom was it issued to?
Mark
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uniqueness of the RSA public modulus

What is the probability that two separate RSA public moduli are the same? For example, consider a 2048-bit modulus. The number seems to be huge, but the choice for prime factors p and q is much more restrictive: They both should be 1024-bit in…
Naka Wai
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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): If Alice wants to request a digital certificate,…
user2935569
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Is there any way to (irrevocably) *transfer* a private key to another person?

Let's say that Alice is the administrator of a group. For each message generated by a group member, Alice uses an administrator's private key ($sk$) to sign it, indicating that this message has been checked by her. One day, Bob takes over from…
Z. Chen
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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.
user27950
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What happens when a root CA has its private key compromised?

What happens when a root CA has its private key compromised? Then all children in the tree are compromised too? And then all certificates are compromised? What needs to happen then? Related: - How can we get CA's public key? - I've got my private…
evening
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Can we design a public-key infrastructure without certificate authorities?

In a recent essay, Bruce Schneier tasks the engineering community with redesigning and rebuilding the vulnerable parts of the Internet's backbone. We need to figure out how to re-engineer the Internet to prevent this kind of wholesale spying. We…
pg1989
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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) that seems to solve an IoT need I have. It also…
MountainLogic
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Is 512-bit RSA still safe for signature generation?

The standard CSP on Windows XP only supports RSA up to 512-bit, which means that it's the maximum key size I can use for authenticity verification of updates. The public key is embedded in the updater, and the update files are signed with the…
Polynomial
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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 fullchain.pem is explained as: fullchain.pem is a concatenation of cert.pem and chain.pem in one file. In most…
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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 ($P$) and the values of the public key ($e$,$N$) are…
cobbs
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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 purposes what exactly is the threat to our…
Marcus
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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 description of how the browser validates a certificate…
Finlay Weber
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Converting raw ECC private key into ASN.1 DER encoded key

I created a random integer array of 32 bytes to use as my private key for secp256k1 curve. const uint8_t secret[] = {0xb2,0x9a,0xc6,0xbd,0xc7,0x3d,0xc4,0xe1, 0x85,0xa7,0x3c,0x96,0xf8,0x1c,0x58,0x43, …
Dogus Ural
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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 ?
crypto-learner
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