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6

Either you give the public key to Bob when you physically meet him and mutually verify identities (as at a key-signing party), or Bob verifies your public key through a trusted introducer (e.g. a Certification Authority) This is the "Infrastructure" part of PKI.


4

TL;TR: there is maybe (or maybe not) some substance to the patent but I consider the claims made in the press widely exaggerated. I don't see any substance for the claims of helping against MITM. And it addresses different use cases than TLS, so no need to compare. While there was lots of press end of 2014 about this issue it basically repeats the same ...


4

You have got that wrong, at least the encryption. Asymmetric Encryption is done using public key of the receiver. Therefore it provides Secrecy (nobody without private key can not read the message). But it does not provide Integrity -- anyone can encrypt any message and send it to you with your public key. Wikipedia is a good friend: Digital signature ...


3

The only intuitive answer (I got) is it reduces maintenance cost of CAs, since there will be loads of public keys it has to maintain. Otherwise, they can just scrap of keys whose time period is over. No, that might be a reason but this is more due to several security reasons. The first reason: better change your password every x months. Lets consider ...


2

CRLs have problems, for example: online revocation checks are slow and compromise privacy. What happens if a client can't get through to a CRL server? If the client refused to go ahead until the CRL server was available, then attacker could cause a mass denial of service by dropping TCP packets targeted at this server. This would grind the Internet ...


2

The authentication to ssh server goes in two steps. The first one is validation if your public key is in the authorized_keys file (or output of the appropriate command), the second one checks if the signature provided by the appropriate private part is the same. In the server log, you can see: sshd[9951]: debug1: test whether pkalg/pkblob are acceptable ...


2

The main reason for this is that the asymmetric encryption algorithm used in the signing (RSA) cannot be used to encrypt large amount of data and it is extremely slow. In particular, RSA cannot encrypt data that is larger than its key size: RSA, as defined by PKCS#1, encrypts "messages" of limited size. With the commonly used "v1.5 padding" and a ...


1

Your main question is: Problems with H can weaken the scheme; this is why people stopped using MD5 and are moving away from SHA1. So why not just skip step 3 and encrypt c directly? Yes, MD5 can currently be broken in about 224.1 guesses (24.1 bits of security). SHA1 currently offers about 80 bits of security against the same attacks. You're claiming ...


1

The passphrase is used to encrypt the private key, which prevents it from being used to digitally sign commits. This protects your private key from being abused by an attacker if it becomes compromised (e.g. you accidentally commit your private key to a public repo) unless they can crack your password.


1

In your question you are only taking about keys, where a key can signed by someone else but the key is not associated with an identity itself: If John also has a key signed by Peter, presents it to Bob, Bob verifies, but John says that his username is Alice, than what to do? You then propose the concept of adding the identity: Is it ok if Peter ...


1

Fundamentally, to trust a computer, you need to verify that it knows something that only the computer you're expecting knows. This is how all certificates work: you assume that because they signed something with a key that only they could possibly know then it's actually the person you wanted to talk to. The same applies for computers: the computer has to ...



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