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1

Revocation really is cancelling the certificate issuance -- the CA which has signed the certificate announces that it now denies it. A root CA being self-issued, it cannot be revoked. A root CA, by definition, is trusted a priori, not because its certificate was signed by some higher-placed CA in the hierarchy. Thus, there is nobody to emit revocation ...


2

make a Certificate Revocation for your root certificate and export it to a Certification Revocation List, putting it at the location you specified the CRL will be placed.


6

If someone steals a CA's certificate signing key, the already signed certificates remain valid. But that doesn't mean they are not harmed. The whole point of certificates is that only a trusted party can produce them, so that when you see a certificate, you can be confident that it is valid and that you're talking to the entity you intended to talk to. If an ...


2

You are correct that it would not cause any harm to the certificates that were already issued, but it does call into question which certificates are still trustworthy, and which are not. It's safer and easier to just treat all certs issues by that signing key as "compromised" and re-issue them. In this case the CA's signing certificate would be revoked with ...


5

A normal CA has a procedure in place for this. it starts with invalidating ALL certificates signed with the key, Than have the CA make a new Root Key and Certificate. than do all the steps involving the setup of a new CA. After that is done, reissuing all certificates that were affected and still valid. A problem if this is not mitigated soon after the ...


1

This has happened. One of the more well-known cases of this was the case involving Diginotar. See http://en.wikipedia.org/wiki/DigiNotar


0

For some good background, please see my presentation How to Build and Operate Your Own Certificate Management Center of Mediocrity. The gist of the presentation is that the thing most required isn't a list of the commands to run, but rather a deep understanding of all the various controls that go into operating a commercial CA, how they interact together, ...


3

Credentials seems appropriate.


1

Possible Authentication mechanism. Sources : Oracle Dovecot (An email server) Wikipedia techrepublic Although the other suggestion of Credentials by @neil-smithline could also be true.


0

It depends on a lot of things. Let's consider a message encrypted by OpenPGP, the most used encryption standard. By default, it includes in plain text a field containing the key ID the message has been encrypted to. However, note that the OpenPGP standard allows for this field to be empty i.e. containing a key ID = 0x0. So the correct answer to your ...


2

If you truly wish to be a CA take heed of the security implications of doing so. The private key used to generate the root CA for your intranet should literally be locked in a safe. And access to said safe should be physically monitored. Using a self signed root CA forces your users to not only trust that you are performing due diligence with the safe ...


0

The only way you could match a encrypted text to the key-pair it is used with would be to own the private key and successfully decipher the message. Apart from this, there is no telltale sign as to which public key has been used to, as any message could have been used for encryption. Though, the protocol could tell you. For example, the OpenPGP protocol ...


2

I will answer this in a two-level approach: General term answer and the specific SSL/TLS clarification in blockquotes. Public Key Cryptography (PKC) solves the problem of securely exchanging information without the need of previously agreeing upon a secret key. To be part of PKC, every agent needs to have a Private Key (which should only be kept by the ...


11

If your infrastructure is tiny, much of the details of running a CA (e.g. CRLs and such) can probably be ignored. Instead all you really have to worry about is signing certificates. There's a multitude of tools out there that will manage this process for you. I even wrote one many years ago. But the one I recommend if you want something really simple is ...


1

Follow these instructions to configure a Windows Based CA. Since you are issuing client certificates, be aware that SHA2 hashes aren't supported on XP. The simple answer is to: Install AD Install an Enterprise CA on the Domain Controller Edit the Certificate Template to issue End User Certificates (set the permission for users to self-enroll, or go to a ...


0

The keygen docs at Mozilla, and the keygen docs at w3 don't specify a return format after the POST. What should I return? The reason this information is not listed is because the KeyGen element sends an SPKAC to the server and once a CSR is generated and sent to the CA an x.509 signed client certificate is to be sent back to the client that ...


1

I designed an image as Short answers of questions: for reading texts of the image open image in new tab for more details go to my previous answer.


3

There is no way to do this simply. there are some tools that can help you to easily get started. like: XCA EJBCA openssl none of them are a full PKI aside from possibly EJBCA but thats not trivial to setup. XCA is a small frontend tool to get a graphical interface to generate,sign and revoke Certificates. EJBCA or Enterprise Java Beans Certificate ...


7

The whole point of all encryption is that it's safe for the attacker to get your ciphertext, because they don't have the key. This is true for public-key encryption as well; it's perfectly safe for you to broadcast your ciphertext to the world, and certificates aren't related to that in any way. The reason you use certificates in public-key cryptography is ...


3

This in an interesting problem; with only symmetric encryption, how do you secure a communication channel (ensuring both privacy and authentication)? Researchers have been working on the problem for centuries and the best solution they've come up with is: Public Keys! That's a tongue-in-cheek way of saying that authentication is a fundamental problem in ...


4

The following is a possible series of steps you could take. I'm considering that you have a secondary, online HSM for the period during which the affected HSM is removed from service for repair. Destroy all key material on the HSM Notify vendor of device problem and serial number Return device in tamper evident packaging to vendor address using secure ...


1

You don't use a hash function to encrypt things. You use an encryption algorithm. You don't use an encryption algorithm to sign things. You use a signature algorithm. The text you quote uses to traditional explanation of signatures as "encryption with a private key", which is a very confusing way of stating things, and works only for a specific signature ...


0

How is the hash derived, and how is it secure? The hash is derived using a cryptogaphic hash function. Hash function usually have the following three properties: Preimage resistance: From a given hash you can't (easily) find out the corresponding input to the function 2nd Preimage resistance: From a given hash and a given input you can't (easily) ...


0

Here's a link to a related question. The general answer is that before the message is signed with Alice's private key, it will be hashed with a hash function of Alice's choice. RSA is not tied to any specific hash function. Alice will include in the header of the message which combination of hash function + signing algorithm she used. For example: in TLS ...


3

As an Introduction sentence: PKI(Public Key Infrastructure) and PKC(Public Key Cryptography) with together are considered as PKT (Public Key Technology). Short answers: for reading the image open it in new window Now is the time to answer the questions. 1. What is the difference between Public Key Infrastructure and Public Key Cryptography? I ...


0

The whole idea that there needs to be a path from Alice to Doris is incorrect. There just needs to be a valid certificate chain from Doris to a trusted certificate in the trust store of Alice. And Doris - of course - needs to prove that she has the private key. So all Alice requires is a trusted certificate A, C or the certificate of Doris (explicit trust). ...


0

I think you need to be more specific about what you mean by "What happens if Alice explicitly does not trust C." Alice, and only Alice, has decided not to trust C, or A has revoked C's certificate? My understanding of Alice's (abstract) process is: // find a signature that she can verify 1. Alice will see that cert_Doris is signed by cert_C and ask "do I ...


8

Public Key Cryptography designates the class of cryptographic algorithms that includes asymmetric encryption (and its cousin key exchange) and digital signatures. In these algorithms, there are two operations that correspond to each other (encrypt -> decrypt, or sign -> verify) with the characteristic that one of the operations can be done by everybody while ...


1

Since we should all be familiar with the layers a la the OSI model: PKI sits atop public key crypto. The public referred to here is a misnomer, in the sense that it does not really mean a generalised audience, but that the keys, or at least the public key, can be in the open, and also by extension able to be freely distributed, though in reality this might ...


1

Until the early 1970's, the only way to encrypt and decrypt messages was using symmetric algorithms, in which the same key is used for both operations. The key has to be exchanged securely by some means before two parties can communicate privately. Public key cryptography, or asymmetric encryption, is a novel way to encrypt and decrypt messages using two ...


4

What is the difference between Public Key Infrastructure and Public Key Cryptography? How are they related? I think the difference between Public-key infrastructure and Public-key cryptography is pretty clear from their Wikipedia definitions (quoted after the tldr). TLDR: Public key cryptography is another name for asymmetric algorithms, while PKI is ...


-1

Public Key Infrastructure refers to the systems and processes for managing the exchange and validation of security certificates. Public-key cryptography provides the technical parts for the actual encryption/decryption, but PKI is what provides reasonable assurance that the certificate is from a valid and authenticate identity, and "vouches" for trust. In a ...


-2

While I do cite quite a few references the majority of your question(s) are available online. With that said a preferred resource would be to visit the OpenSSL Wiki for usability, attack vectors, algorithms & implementation questions, GAIC for performance, best practices and high level information and NIST for standards regarding the use of PKI as well ...


1

The public and private key have the same size (with regards to security, the file size differs of course). It's identical to the size of the modulus when it is regarded as an unsigned integer (and the key size is a full number of bytes, i.e. a multiple of 8 - otherwise it is the location of the highest bit set to one). You are however showing a full X509 ...


3

In answer to (3)- It was not until recently that API's to do this were readily available without having some significant resources behind you. Here is a guide to doing what you describe in (1) and (2). http://nelenkov.blogspot.com/2013/09/using-sim-card-as-secure-element.html There are some applications doing this- the article comments say a bitcoin app is ...


2

WARNING: Creativity ahead, which is often bad for security (at least without thorough review). This sounds like a case in which an SSH agent could be useful. An SSH agent provides a socket interface over which SSH clients can ask the agent to perform key operations for them, which enables the following common uses: You can have the long-running agent ...


4

1: Use hardware tokens, like a Yubikey configured for challenge-response based authentication. Or smartcards. You load up the key on them all and hand them out. They're designed to keep the secrets secret. 2: Stop using a single key, start using one keypair per user for accountability and practical revocability.


0

Well besides the sudo answer (which is really clever btw), another solution is a restricted shell. In this case you would have to write one. In this case the only commands you need to accept are "ssh <hostname>" and "exit" so it's not so hard. I'm really only posting this for completeness, but the general technique is valuable in other contexts.


4

The whole concept of trying to explain signatures with the terminology of encryption is flawed. It simply does not work. So let's unravel the whole thing, and this will require some formalism. Formally, a cryptographic signature system consists in three algorithms: KeyGen: takes as input a "security parameter" (say, the length of the key we want to ...


-1

A digital signature is best understood by completely decoupling it from encryption. A signature algorithm generically consists of two operations, SIGN and VERIFY. SIGN takes a message and a private key and produces a blob of data known as a "signature;" VERIFY takes a message, a signature produced by SIGN, and a public key and outputs whether the signature ...


0

For RSA encryption, the public and private keys can both be used for encryption or decryption. The only difference between them is that you keep one key private while you advertise the other. What your text is referring to is that, when you're encrypting a message to send to someone, you use their public key to encrypt it. You, of course, couldn't use ...


6

The message digest is a hash of the original message. You can't reconstruct the message from the digest. Bob computes the digest and compares it to the one Alice sent him. If it matches, Bob knows that the message hasn't been changed, since any change in the message will cause a change in the digest. He also knows that the message came from Alice, ...


1

Digital signature includes two steps: a) Message digest evaluation. The main purpose for evaluating a digest is to ensure that the message is kept unaltered; this is called message integrity. b) Digest signature. A signature is in fact an encryption using the issuer’s private-key. Included in the signature is also the hashing algorithm name used by the ...


0

If that term doesn't suit the bill for you, try substituating it for 'Encryption vector' which is what the key is when encrypting and the inverse 'Decryption vector'. In the end it's just a number though.


0

If you have ever operated a personal bank locker, it can be operated through two keys: one is given to the owner and another is kept in the bank. The locker can be locked through a single key that the owner (customer) of the locker possesses. Hence key can be used for locking. For unlocking the locker, the owner needs her key as well as the key possesses by ...


8

Locks are typically operated by keys, whether you are locking or unlocking them. In cryptography, the cipher is the lock. In public-key cryptography, this lock happens to be locked with one key (designated public) and unlocked with a different key (designated private), but neither of those is any less a key for that.


23

The word key was introduced well before asymmetric encryption was even thought to be a thing. In the symmetric context, you use the same key both for encrypting and decrypting, and here the key analogy absolutely makes sense, in that physical keys are often used for both locking and unlocking. When asymmetric encryption came along, the term key was well ...


5

This 'problem' is often encountered by people who are just learning about cryptography and public / private key cryptography. So I understand your confusion. The reason we call both a 'key' is because its cryptographic function is to be a cryptographic key which has nothing to do with common day keys and locks. In many analogies for laymen the lock - key ...


22

A piece of music has a key, but no lock. A standardized test has an answer key but no lock. A piano has 88 keys but no locks. A database table key has absolutely nothing to do with a database lock. A cryptosystem also has keys but no locks. The word key has a dozen or more meanings that have nothing to do with locks. A key in a cryptosystem is in many ...


-1

A key is for unlocking, right. That's what a public key do, it unlocks the access to the data/material, so it is basically a key to access or unlock the data.



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