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1

Would a service be impacted if the system does not have any interaction with browsers? Not by the browser sha-1 deprecation. However, sha-1 is used and being deprecated on many other scenarios. Digital signatures, TLS communications in general (clients may start refusing it soon or already refusing it), authentication systems. It should be abandoned as ...


0

When using client certificates the server sends a list of acceptable CA which issued the client certificate. Based on this list the browser will select the matching client certificate. If there is no client certificate issued by the CA expected by the server you get the error message. Thus the problem might not be the certificate itself, but simply that the ...


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There is probably a more elegant way to do it, but I add the following option to the [ v3_ca ] section of my OpenSSL configuration file: certificatePolicies = 2.5.29.32.0 The OID values are available at http://www.alvestrand.no/objectid/2.5.29.32.0.html .


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No. The authorized_keys file contains strictly only the public key, as described in the manual page for sshd: AUTHORIZED_KEYS FILE FORMAT Each line of the file contains one key (empty lines and lines starting with a ‘#’ are ignored as comments). [...] Protocol 2 public key consist of: options, keytype, base64-encoded key, comment. Accepting the ...


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Your question about when / how to renew the CA key is a good one, but I'm afraid that it doesn't have a generic answer; it depends on which applications are consuming those certificates and how they expect a CA to behave as it approaches its end-of-life. One thing that is universally true is that end-entity certs should never outlive any CA in their issuing ...


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Five years is a long time in Information Security. Ten years will see the security world decide that some algorithms and keys are too easily compromised. I have a client who had implemented SHA1 hashes in each tier in order to support unpatched Windows XP using a PKI environment that was built within the last four years. We had to rehash each CA's ...


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If you have your publick key on key servers you can only share fingerprint, a link for download your public key is good if you haven't key on key servers or even when you have on key servers because maybe not all people use same key servers. I use fingerprint and also I have a link to my public key on my blog. gpg --recv-key ...


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I'm assuming you're trying to deploy your own LDAP backed certificate service. The best matching schema for this purpose is the cosine schema available in all OpenLDAP installations. If you don't want to install the openldap server just to get the schema, then simply extract it from the source code here - http://www.openldap.org/software/download/ . The ...


3

SSH actually requires you to configure different keys for different users. Each user account on the destination machine has its own ~/.ssh/authorized_keys (doesn't necessarily have to have, it might not exist). Let's assume you have server and client. server has users set up as follows: /home/srv_user01 /.ssh/authorized_keys ...


5

Running ssh -vvv host, at some point, you will see something like: debug1: Authentications that can continue: publickey,password debug3: start over, passed a different list publickey,password debug3: preferred gssapi-keyex,gssapi-with-mic,publickey,keyboard-interactive,password The first two lines describe what methods are offered by the server and the ...


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WhatsApp will re-encrypt the message with the new credentials bound to the same number and re-send it. WhatsApp protects from passive interception, but it does not protect against a man-in-the-middle or someone who hijacks the phone network. Sad, really. Ref: How WhatsApp Needs to Improve Its Encryption ss7 attack leaves whatsapp and telegram encryption ...


6

This is an awesome idea - to manually trace through the cert validation process! I've enjoyed reading through your steps, since I've never actually done it myself! Answering your questions: First question: Is this the correct way of obtaining the certificate the *.wikipedia.org certificate was signed with? After all, how can I be sure ẁikipedia.org didn'...


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For the purpose of authenticating a server to a connecting user, the difference in the implementation which you observed is not really a technical one. Particularly: SSL does not require the use of a trusted third partyーyou can use SSL with self-signed certificates (which would be equivalent of how SSH keys authentication works). SSH can use a server ...


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Because they're used differently. TLS/SSL x509 certificates as commonly used in HTTPS is used to connect to public systems, i.e. systems that are accessed by a large number of people, most of whom had no prior out-of-band connection with the owner of the system. SSH, on the other hand, are primarily used to access private systems by a small number of server ...


3

A malicious user cannot exploit a publicly known fingerprint of a public key, because verification is not limited to comparing the fingerprint to a fixed value. Server presents two pieces of information to a client: a public key a message encrypted with its private key (which exists only on the legitimate server) On the client side the message is ...


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uhh, PCKS#11 is a language for sending cryptographic keys over a USB wire. More formally, PKCS#11 is a programming API for a PC to request cryptographic operations from a USB token or smart card. That picture really has nothing to do with PKCS#11. As far as I can tell from a quick look at your link, that picture defines the key hierarchy of the TrouSerS ...


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They MAY use the same certificate for any *.domain.tld. However, the problem with bugs like heartbleed is that, in case you get hold of the private part of the certificate you are able to intercept (read / modify) any *.domain.tld SSL/TLS traffic and it doesn't really matter what the originally used certificate is (unless HPKP is enforced).


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Because asymmetric (aka public key) encryption is SLOW... Literally thousands of times slower than symmetric encryption. It's faster to just encrypt a small amount of data (the hash) than a large amount of data.


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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 ...


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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 ...



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