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0

Well, theoretically, you would never need to need the AIA. RFC 5280 mandates, that you send along each necessary certificate. And optionally, you may send along the Root CA cert as well. And that's the only certificate that is optional. Now not everybody configures their servers correctly. And this is where AIA comes in. If only the end entity ...


0

Generally you can't work backwards—in the obvious way—because you don't have enough information. RSA depends on the difficulty of factoring large numbers. You generate your RSA modulus n by multiplying two large primes, p and q. Multiplying p by q is easy. You can also reverse the operation by computing q = n / p (or p = n / q). What you can't easily do ...


1

Diti is almost right about the historical context, but the real historical reason is in the part he/she omitted. For quite some time, gpg used DSA keys by default, which can only be used for signing, and then had to attach an elGamal subkey (which can be used for encryption only) to get a fully functional key. For RSA, that isn't necessary, but it was kept ...


5

The power in a certificate is NOT in the certificate. It is in the private key. When a server "uses a certificate", it really uses the private key; and the server shows the certificate (that contains only the public key) to the client. The certificate is a proof that a given public key belongs to a specifically named entity. For instance, the certificate ...


0

I think that there is a misunderstanding of what pinning is. Pinning means that once you've trusted the certificate, you pin it for future use. However, the certificate does not itself provide authentication. Authentication consists of validation of a certificate (using a certificate chain for X509) + verification that the other party holds the private key. ...


-1

In this public-key encryption (or assymetrical encription), to encrypt something, you do the following: Take your message to be transmited (as a number) : let's say it's 5. Calculate 3 ^ 5 (3 raised to the "secret") = 243 Calculate the modulus of it, divided by another number: let's say 143. So, 243 / 143 = 100. There you go. Your encrypted secret is ...


23

Your question is a little like this (with apologies to Tom Stoppard): "why can I stir the jam into my rice pudding, but not stir it out again?" Some mathematical operations are as easy to do backwards as forwards. For instance you can add 100 to a number as easily as subtracting 100. However, some are more difficult to reverse. For instance, if I take x and ...


5

Max, the best tool ever created for thinking about cryptography is the Rubik's cube. If you presume a world where solving them is an unsolved problem, there are direct analogs for DiffieHellmanKeyExchange, RSA signing, RSA encryption, etc. You can play tricks with writing down moves and performing them on cubes and exchanging them; and the group theory ...


65

There are one-way functions in computer science (not mathematically proven, but you will be rich and famous if you prove otherwise). These functions are easy to solve one way but hard to reverse e.g. it is easy for you to compute 569 * 757 * 911 = 392397763 in a minute or two on a piece of paper. On the other if I gave you 392397763 and asked you to find the ...


2

What you need to do is read up on Public-Key Cryptography. The short answer is it is based on an algorithm that allows one key to encrypt and the other key to do the decryption, which is why you cannot work backwards. That is a simplified explanation of what is happening, if you want to get to the heart of the issue you can look at sources such as the ...


35

Juggling is easy: you just throw the balls at the right time, so that you have a free hand when they fall. With one ball or two balls, this is trivial. With three, it is easy enough. With more balls, it (surprisingly) becomes harder. Even substantially harder. In all generality, "reversing" encryption done using an n-bit key is like juggling with 2n balls. ...


-3

Well, you've kind of stated what a public key is for. A person generates a key pair - the public and private keys. If a file is encrypted with the private key, only the corresponding public key will decrypt that file. This has the rather pleasing additional benefit of guaranteeing the sender/encryptor of the file. Unless the private key is stolen ofc.


2

Owner and Signature Trust Signature trust means a user puts trust into the identity of another user. If Alice signs (or certifies, which is the term I will use from now on for signing other's keys) Bob's key, she declares (following whatever rules) she puts trust in his identity. These certifications are usually publicly available on the key servers. You ...


0

I think you are assuming Google is not trusted or that this is an oversight in the Certificate Authority trust model. I don't think there is a problem with Google running a certificate authority. Perhaps they can choose to constrain it to their own domains, but nothing stops them from entering into an agreement with an established Root CA (or buying on!) ...


1

I found a solution as I was looking for; http://blog.engelke.com/2015/03/03/creating-x-509-certificates-with-web-crypto-and-pkijs/ But I'll try pem modulus at first. Because it works on back-end and seems more simple.


-1

The short answer is "They are very very careful 'where' the private keys are." I think you may be misunderstanding or ignoring a basic part of how these kinds of keys work - when you sign something, it's a one-way mathematical operation that "proves" it was signed by one particular entity. (Technically, someone with access to said key, and knowledge of any ...


0

The real question is whether you're using a signing/authentication GPG subkey as your SSH key, or an encryption one. The former is fine, the latter is not: an RSA key must never be used to both encrypt and sign! (Authentication uses digital signatures.)


3

The two keys you show are encoded differently - obviously, the first is base64 encoded, and the second is hexadecimal encoding. You would need to determine the formats used and their encoding to determine how to reconcile the two. And in both cases it's a packed structure, not just raw key data but discrete bits of data like key type, exponent, and ...


70

Firstly, often encryption is terminated at the perimeter by infrastructure which is dedicated to offloading SSL decryption. It makes it much easier to manage when you only have maintain a high degree of key security for a small (proportionally) group of servers which are dedicated to the role. The rest of your regular application servers can operate like ...


2

From what I'm understand, what you're trying to do is to verify, after you are sure that the page arrived from the network untouched (since it's TLS), that it has not be modified by any client-side malware. Since it's a client-side malware, it's safe to presume it can change anything he wants on the client side, after the session is decrypted from the TLS ...


2

The structure is all wrong. If Google uses this intermediate cert only for signing Google-owned domains (which I think is the case) they can't do it with a restricted path certificate, because they need to sign google.com and google.co.uk and gmail.com and even com.google now that they own that TLD. In my opinion, the PKI was poorly designed to begin with, ...


1

It's possible that this CA certificate is linked to GeoTrust's root certificate by way of Geotrust's 'GeoRoot' service, which "Allows Organizations with Their Own Certificate Authority (CA) to Chain to GeoTrust's Ubiquitous Public Root ". See ...


0

Why does the subordinate CA lack the name constraints? Because browsers would ignore these settings anyway. Currently there is no technical way to restrict which certificates sub-CAs can issue.


0

The clients (eg browsers) while sending the extended clientHello during ssl handshake, are supposed to provide the OCSP responderIDs they trust. If the client doesn't provide the responderID, the responders known to the server will be used. check "certificate status request" in rfc 6066.



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