41

... change the public key in the certificate and send it to client. Digital signature is same, all the properties except public key are same. So how can browser understand the difference? The browser checks that the signature of the certificates fits the certificate. Since the public key is included in the signature and the public key is changed, the ...


25

At the end of the TLS negotiation (the "Finished" message), the client and the server take a hash of the entire conversation they've had so far, and they compare it. If it differs - as it would if someone performed a MitM attack on the certificate - then the connection is dropped. To quote RFC 5246: The Finished message is the first one protected with ...


24

Certificates don’t exist in isolation. To be trustworthy, a certificate must be signed by an issuer; these issuers are called Certificate Authorities. Each browser (or operating system) maintains their own list of a few hundred trusted CAs (called Root CAs) that it already knows and trusts; and your employer or school may have their own private issuing root ...


4

These misconceptions come from people trying to explain digital signatures to the layperson. Once someone understands the concept of asymmetric encryption, a common way to explain signatures is "encryption with private key", but in reality there is no such thing (for a very technical explanation, see here). You're far better off thinking of asymmetric ...


2

Yes, this is possible A security challenge for the Web Authentication API can by any byte array (of at least 16 bytes), and it will be signed by the clients secure private key. It can therefore also be used to sign documents or messages of all types by passing the document as a PublicKeyCredentialRequestOptions.challenge in the call to navigator.credentials....


2

RSA encryption is based on a trapdoor function, which is to say a pair of functions. I'll call them D and E. The functions are designed so that D(E(x)) = x and E(D(x)) = x (for any x). In other words, D and E are inverses. What makes it a trapdoor function is that if you have a public key, you can only compute E (practically speaking). If you have a ...


1

You should provide the user with a message digest (ex - sha256) so that user can validate the accuracy and completeness of software. Digests are designed in a way that even a single bit flip in your application will result in a different digest. You can calculate the sha256 digest using following command on a mac machine (Tested on mojave) openssl dgst -...


1

IANAQSA, and you seem to be getting into the Issuer business. You really need a QSA. You are asking about the requirements upon issuers (most PCI-DSS questions are from the POV of merchants, acquirers, and processors; the other side of the equation). Issuers are also held to the PCI-DSS, but obviously they have different constraints. For example: 3.3 ...


1

The question as you ask it isn't really matter of one being globally better or worse than the other. These are two tools that perform different tasks. Encryption - A message encrypted with someone's public key, can only be decrypted by someone in possession of the matching Private key. Who was the message really from? No promises there! Signing - When ...


1

It would be possible for a hacked website to host a fraudulent key that has signed a fraudulent piece of software, however, one could verify they have the correct key from other places on the internet, and many time these signing keys are signed as valid by somebody else. Once they are confirmed as valid, they will be used for years into the future until the ...


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