Questions tagged [openssl]

OpenSSL is an open-source implementation of basic cryptographic primitives, X.509 certificate utilities, and SSL and TLS protocols.

OpenSSL is an open-source implementation of the SSL and TLS protocols.

It is written in C and it implements basic cryptographic functions. Wrappers are available for a wide variety of computer languages.

For the typical security developer, OpenSSL is the go-to library/API for cryptographic operations, certificate-related utilities, and SSL/TLS implementations. OpenSSL has a reputation of being reliable and fast, and is often considered to be the reference implementation that other crypto implementations are checked against.

Project homepage: https://www.openssl.org/

Source code: https://github.com/openssl/openssl

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Provide subjectAltName to openssl directly on the command line

Is it possible to provide a subjectAltName-Extension to the openssl req module directly on the command line? I know it's possible via a openssl.cnf file, but that's not really elegant for batch-creation of CSRs.
Michael Seiwald
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How to explain Heartbleed without technical terms?

Most of my friends who are not experienced in computers want to know what Heartbleed is and how it works. How would one explain Heartbleed to someone without a technical background?
user36976
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SSL3 "POODLE" Vulnerability

Canonical question regarding the recently disclosed padding oracle vulnerability in SSL v3. Other identical or significantly similar questions should be closed as a duplicate of this one. What is the POODLE vulnerability? I use [ product / browser…
tylerl
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How exactly does the OpenSSL TLS heartbeat (Heartbleed) exploit work?

I've been hearing more about the OpenSSL Heartbleed attack , which exploits some flaw in the heartbeat step of TLS. If you haven't heard of it, it allows people to: Steal OpenSSL private keys Steal OpenSSL secondary keys Retrieve up to 64kb of…
user43639
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What is DROWN and how does it work?

There is a new recent attack "on TLS" named "DROWN" . I understand that it appears to use bad SSLv2 requests to recover static (certificate) keys. My question is: How? How can you recover static encryption or signature keys using SSLv2? Bonus…
SEJPM
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How do I use "openssl s_client" to test for (absence of) SSLv3 support?

In order to mitigate the "Poodle" vulnerability , I'd like to disable SSLv3 support in my (in this case, TLS, rather than HTTPS) server. How can I use openssl s_client to verify that I've done this?
Roger Lipscombe
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Which elliptic curve should I use?

I am currently renewing an SSL certificate, and I was considering switching to elliptic curves. Per Bernstein and Lange , I know that some curves should not be used but I'm having difficulties selecting the correct ones in OpenSSL: $ openssl ecparam…
executifs
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How is the Heartbleed exploit even possible?

I have read about the Heartbleed OpenSSL vulnerability and understand the concept. However what I don't understand is the part where we pass 64k as the length and the server returns 64kb of random data because it does not check whether we really…
Talha Sayed
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What should a website operator do about the Heartbleed OpenSSL exploit?

CVE-2014-0160 http://heartbleed.com This is supposed to be a canonical question on dealing with the Heartbeat exploit. I run an Apache web server with OpenSSL, as well as a few other utilities relying on OpenSSL (as client). What should I do to…
Deer Hunter
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How do I get the RSA bit length with the pubkey and openssl?

I have a public key generated with ssh-keygen and I'm just wondering how I get information on the keylength with openssl?
Evan Carroll
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Converting keys between openssl and openssh

If I use the following openssl req -x509 -days 365 -newkey rsa:2048 -keyout private.pem -out public.pem -nodes I get private.pem and public.pem If I use ssh-keygen -t rsa -f rsa I get rsa and rsa.pub Is it possible to convert from the format of rsa…
anshul
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Heartbleed: Why does the client supply the length of the message at all?

"The fix for this bug is simple: check that the length of the message actually matches the length of the incoming request." Why do we even have the client report the length at all? If we can know the length of the incoming request, can't we just…
Elliot
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Does the heartbleed vulnerability affect clients as severely?

If I have a web crawler (using a non-patched version of OpenSSL) that can be coaxed to connect to an evil https-site, can they get everything from my process memory? To attack a server you can keep reconnecting to get more 64kb blocks (if I…
Gurgeh
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What do the dots and pluses mean when OpenSSL generates keys?

When OpenSSL generates keys you'll always see a series of periods/dots ( . ) and pluses ( + ). openssl dhparam -text -noout -outform PEM -5 2048…
Evan Carroll
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Generate CSR from existing certificate

Can we generate the CSR (certificate signing request) used for certificate signing from the signed certificate? It should work with the original private key when signed again with different authority.
NPC
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