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

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How to read certificate chains in OpenSSL

I'm trying to understand how to read the output of OpenSSL commands. Currently, I am trying to understand how Certificate Chains work. When I give the command (using a standard ca bundle) openssl ...
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Filtering safe primes for Diffie Hellman on OpenVPN

When creating Diffie Hellman parameters for OpenSSH, there's a two-step process which looks like this to generate and filter secure primes for Diffie Hellman key exchange: ssh-keygen -b 4096 -G ...
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Read back in “human readable” text from openssl ec -pubout

I'm looking to understand how/if the output of the openssl ec -in pub.pem -pubin -pubout -text -noout command can be used to reconstitute the public key. I'm hoping it can be a symmetrical operation? ...
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Generate CSR and private key with password with OpenSSL

I am using the following command in order to generate a CSR together with a private key by using OpenSSL: openssl req -new -subj "/CN=sample.myhost.com" -out newcsr.csr -nodes -sha512 -newkey ...
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Generation of the primes p,q and g for DSA using an Hash Function in OpenSSL

We can generate primes p,q and g for DSA in OpenSSL by using command: openssl dsaparam -text -out dsaparam.pem 1024 Is it possible to generate primes p , q and g using an Hash Function in OpenSSL ...
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782 views

OpenSSL check if a SSL certificate is SHA-1 or SHA256 signed

How do I check if an OpenSSL certificate issued to a site is SHA-1 or SHA-256? I have a quite a lot of intranet sites using OpenSSL certificates and I am a bit confused as when I check the certificate ...
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Guide on how to create certificates and setup an EAP-TLS on debian [closed]

I need to create an EAP-TLS authentication using a freeradius. Currently I am a working EAp-PEAP setup, it is working fine. However, I now needs to move to an EAP-TLS. For this I need to create some ...
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Is it safe to publish my development private key?

For my development environment, the following three SSL files allow me to access my application from https://localhost on my local machine. Private key: server.key Certificate signing request: ...
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Are SHA-2 certificates considered obsolete, or current?

A guide on this site on how to make a decent Certificate Signing Request (CSR) says that I should be using SHA-2 certificates to secure a HTTPS webserver. Are SHA-2 certificates considered obsolete, ...
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OpenSSL - Generate self signed certificates with different cipher suites

I want to generate a root certificate and SSL certificate (self-signed) for communication between an embedded device and our backend servers (IIS 8.0). I used OpenSSL to generate a certificate with ...
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1answer
148 views

Testing Poodle TLS vulnerability with OpenSSL in C++

I'm writing a command-line tool for SSL/TLS vulnerability testing and so far I was able to implement testing for all vulnerabilities that I need, except Poodle TLS. Is there any way I could utilize ...
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Which CRL should an intermediate CA crlDistributionPoint contain?

Given a root certificate authority (CA) and an intermediate CA signed by the root: Which CRL should the crlDistributionPoints contain to for the intermediate CA? The root CA's CRL or the ...
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How do I view the signature of an iOS application?

OSX had an issue where the certificate was expired and several apps could not be opened after that date. The command above illustrates how this could have been detected. Does iOS have a similar ...
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How to import Comodo certificates into Keystore?

I'm trying to create a Keystore. I've already generated a Private Key, generated and sent a certificate request to a CA (Comodo), and I've received a ZIP file from the CA (Comodo) containing four ...
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2answers
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Will OpenSSL's TLS-SRP still provide PFS if all credentials are public?

The obvious go-to for PFS is DHE (or ECDHE). But I'm wondering if using tls-srp but with fixed (and therefore can be considered publicly known) credentials can achieve PFS as well. I suspect this is ...
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1answer
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Do any browsers support Server Name Indication (SNI) but NOT SHA-2? [closed]

Yes, I know that SHA-2 signature validation is typically done by the operating system (with Mozilla Firefox/NSS and Chrome as of v39 being the exception).
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OpenSSL is not giving correct result for encryption and decryption for FIPS test vector for AES -CFB1

I am running FIPS test vectors against AES-CFB. I am getting correct results for aes-cfb128 and aes-cfb8 but getting wrong results for aes-cfb1. The values being used by me for aes-cfb1 tests are: ...
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1answer
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How to revoke certificates, or generate CRL files with Keytool

I didn't find how to use java keytool to revoke certificates or generate CRL files. Is it possible to do that with keytool? If no, how to do it with openssl ?
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How does obtaining a SSL certificate work?

I have been carrying out some work on SSL certificates and found that there are some places that charge you for an SSL certificate, but, how do they obtain the rights to do so? And, how, are they ...
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683 views

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. ...
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Client authentication using the pfx not working

I have a requirement to generate the client certificates(pfx) files from another server certificate which are provided by a CA. Firstly I tested the following based on ...
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1answer
33 views

Can I have CA with JSSE

Maybe the title isn't correct but what I am trying to understand is... I want to create a certificate for my CA which will be self-signed and then create certificates for my clients and my server. ...
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212 views

Log all crypto keys used for outgoing SSL / TLS connections on Linux server

Is there some environment variable that works how SSLKEYLOGFILE works for NSS-reliant programs but which would apply to all outgoing TLS / SSL connections on a Linux server and not just ones that use ...
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What is the openssl equivalent of using java's KeyPairGenerator?

I have been using java's KeyPairGenerator in order to generate public/private keys within a program so that I can encrypt and decrypt files(also using java encrypt/decrypt methods). I want to be able ...
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268 views

How can I use my HSM to turn a CSR into a certificate?

I create a CSR using OpenSSL, so I have public and private keys. Now I want to sign this CSR and convert it into an X.509 certificate. The only problem is, my signer is a custom HSM. I can send bytes ...
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Why is openssl key length different from specified bytes

I realize this is rudimentary question, but I can't seem to even google diagnose it. Why is openssl key length different from specified bytes? For example when I use the command: openssl genrsa -out ...
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How are man-in-the-middle attacks actually implemented? [closed]

For research purposes. I'm wondering, in a high level way, how MITM attacks are actually done in the real world. So over the internet the client talks to the server, or one person emails the other, ...
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What does it mean to “sign with a certificate”? [duplicate]

As part of the SSL handshake, the server responds to the browser with 2 things - The server's public key Some metadata, like what version of SSL is being used, the cipher algorithm being used, ...
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OpenSSL 0.9.6a PRNG algorithm weakness: How to exploit?

I saw an OpenSSL security advisory for Openssl 0.9.6a Recently a cryptographic flaw in OpenSSL's built-in pseudo-random number generator (PRNG) was pointed out to us by Markku-Juhani O. Saarinen ...
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7k views

SSL3 error when requesting connection using TLS 1.2

I've come across several hosts that throw SSL3 handshake errors even though I explicitly request TLS 1.2. Why is this? Am I using the openssl client wrong? $ openssl s_client -tls1_2 -connect ...
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2answers
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Determine if a server is asking for a client certificate using openssl s_client

I am using openssl to connect to servers to detect if they require a client certificate. Currently I am using this command: openssl s_client -connect pokyloky.com:5222 -state 2>&1 | grep ...
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SNI (server name indication) with SSL

Is it possible to use SNI (server name indication) in SSLv3 or SSLv2 handshake? From the search queries, it seems SNI is TLS extension. Is there any alternate to SNI?
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Why is this version of OpenSSL (1.0.1e) not vulnerable to Heartbleed?

I recently ran into a requirement that needed a web server set up with SSL, to show that its possible to extract the private key from a server with a vulnerable version of OpenSSL (Heartbleed). Hence, ...
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Can I rely on openssl_random_pseudo_bytes() being very random in PHP?

I came across an application which needs to generate a random token for each user. It is very important that each generated token is unique. Application code was as follows: $token = ...
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What guarantees does perfect forward secrecy make with respect to compromise of a private key?

With perfect forward secrecy, if an attacker gains access to a certificate private key, my understanding is that all traffic previously encrypted using that private key remains safe from decryption. ...
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Is it possible to salt the SHA1 or SHA256 hash function of OpenSSL?

I would like to salt the hash function of OpenSSL external, so that I can assign a salt on my own. Is that possible or is the hash function of OpenSSL alsways internal "salted"?
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Private key to PEM

I'm new to security and I'm trying to decode some SSL encrypted communication between my machine and server. I managed to obtain private and public keys as far as I understand private key is this ...
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1answer
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Difference between certificates with “extension fields” and “Non Repudiation” usage

For example we have two certificate pairs: First pair: Server cert with "Non Repudiation" (sometimes called Content Commitment) usage, Client cert without any "extension fields". Second pair: ...
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Does SSL doesn't work without a secondary Symmetric/Asymmetric session key?

I keep reading that Symmetric session key is used in SSL after handshake only for faster performance but isn't true a secondary session key either Symmetric or Asymmetric key generated by the client ...
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273 views

Cannot connect using ECDH-RSA-AES256-SHA

I try to establish an SSL connection using the ECDH-RSA-AES256-SHA cipher using OpenSSL, but it fails saying "no shared cipher": On the server, I run: $ openssl s_server -cert selfsigned_cert.pem ...
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1answer
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Sign certificates using a web server certificate issued by a public CA

I have obtained a certificate from GoDaddy. It's usage and constraints are as follows: Key Usage Digital Signature, Key Encipherment (a0) Enhanced Key Usage: Server Authentication ...
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Will my hosting provider be able to see my SSL private keys?

I'm trying to learn the best way to implement a secure web and e-mail server. Getting SSL certificates is a must, but what happens with the private keys? I've seen that you have to store them on the ...
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1answer
276 views

Can SHA256 signature support be deduced from TLS cipher suites or any other part of ClientHello (if no signature_algorithm sent)?

Websites aiming to maintain maximum compatibility with (legacy) browsers may wish to serve SHA2-signed certificate chains to those user agents that support them, and SHA1 to those that don't. The TLS ...
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2answers
486 views

Best way to scan for and eliminate earlier versions of SSL/TLS in a production environment

Due to new PCI DSS standards mandating that nothing lower than TLS 1.2 be used in a PCI environment, I am tasked with phasing out anything lower than TLS 1.2 on every device in this environment by our ...
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3answers
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Difference between OpenSSL and keytool

I was wondering about differences between using OpenSSl or Keytool and generating certificates by them. I think Keytool is used by Java community but for someone who is not remotely connected to Java ...
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verifying digest signed with private key using a C program

I'll explain all the steps I've done so far and conclude with my question. using OpenSSL 1.0.1e-fips 11 Feb 2013 Generating a private and public key openssl genrsa -des3 -out private.pem 2048 ...
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Are all SSL/TLS implementations vulnerable to the Heartbleed bug? [closed]

I've learned the theory behind the SSL/TLS protocols and how effective they are to achieve a secure communication between clients and servers. Do all the implementations OpenSSL, PolarSSL, MatrixSSL, ...
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Can people know the server I'm connecting to despite being on SSH/HTTPS? [duplicate]

I understand that by connecting securely over SSH or HTTPS, the data that I transfer is cryptographically secure. However, can someone spying on my connection still determine the server I'm sending it ...
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importing CA certs into OpenSSL CLI

I created a CA cert and a cert signed by the CA cert and then tried to sign a CMS / PKCS7 message with the CA-signed cert and got the following error: unable to get local issuer certificate I.e. it ...
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how to validate PKCS7 signed message signed with a self-signed cert via OpenSSL CLI

openssl cms -in demo.p7m -inform DER -verify verifies the signature on a CMS / PKCS7 encoded message but if the cert that did the signing is self-signed I get a "self signed certificate" error. ie. it ...