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

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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 = md5(...
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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 one:...
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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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1answer
361 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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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 (1.3.6.1.5.5.7....
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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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330 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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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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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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2answers
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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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6answers
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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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1answer
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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 ...
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1answer
149 views

How can Heartbleed checkers determine if a site is vulnerable?

As far as I know, there is not a way to obtain OpenSSL's version from a website. Then what kind of information does a Heartbleed checker obtain so it can determine if a site is safe from Heartbleed or ...
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Secure backup encryption with OpenSSL

I know, the general advice is "keep your hands off crypto stuff". And the standard way to encrypt backup data securely would be using GnuPG. However, for a rather academic exercise, I would like to ...
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3answers
341 views

Security RESTful web application in Java

We are developing two web applications: Application A : Restful web-services running on a GlassFish Server . Application B : Dynamic web application running on a Tomcat Server . I am accessing ...
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1answer
398 views

How to generate keystore for root signed certificate?

I need to create keystore and truststore with root signed certificates. I have these files (at this step they are identical for client and for server): client_cert.pem client_prv_key.pem root_cert....
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1answer
121 views

OpenSSL Certificate Expiry

I'm trying to use OpenSSL to verify that an SSL certificate is still valid, but I keep getting strange results. The example site that I'm testing with (expired.badssl.com) has an expired SSL ...
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1answer
307 views

Using cipher suite: deployment commands

Can someone point me in using the correct OpenSSL commands to use a certain cipher suite. For example DHE-RSA-AES256-GCM-SHA384 (I am not using ECDH suite because of supposed NSA backdoor controversy/...
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1answer
176 views

Is there an official standard and/or name for PEM certificate bundles?

This is a question that's not really about security proper. It's about security/crypto nomenclature. It's been bugging me a bit, so here goes: I know two approaches for bundling related certificates/...
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How secure is a ODBC connection from MySQL(5.6) to MS Access

I have created a connection from a MySQL server (unpopulated) to Access using their ODBC driver but don't know anything about how secure this connection may or may not be. I do not have openSSL set up ...
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Why does StartTLS block connection to apache

When I run this command: openssl s_client -connect my.server:443 -starttls smtp Why does Apache 2.4 & OpenSSL 1.0.1h(running on server 2008R2) stop responding to request from other machines ? ...
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1answer
296 views

For maximum security is it best to link OpenSSL libraries statically or dynamically?

When linking to OpenSSL (or other cryptographic libraries) would it be more secure to use a shared library and have address space layout randomization, or to use a static library and not have ASLR?
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How to inform other sysadmins their email encryption is broken [closed]

Does anyone have a good template email to use to send to remote system/mail/security administrators to alert them to the fact that emails to them would not be getting through either at all or securely ...
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1answer
48 views

A collection of tests and demos for security headers and TLS configurations [closed]

There are (or have been) various websites designed to educate and provide examples on good / bad configurations of security headers and TLS configurations (e.g. https://badssl.com/) I want to build a ...
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Concepts of a secure note sharing system

I am trying to design a system that will allow for staff members in our small company to securely share sensitive customer information (text) and see them on a web page alongside less sensitive ...
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2answers
490 views

OpenSSL x509: Is there an order in subjectName fields?

Is there an order to respect in subjectName field when creating a x509 certificate with OpenSSL command? In other words, what are all possibilities of displaying subjectName of x509 certificate in ...
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1answer
403 views

Create Public Key using OpenSSL instead of PuTTYgen for PKCS#8

I'm trying to create a public key pair for ssh-rsa authentication. If I'm using puttygen.exe, the "OpenSSH authorized_keys file" string looks like this: "ssh-rsa AAAAB3 ... 6yIK9Nbw== rsa-key-...
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How does the OpenSSL Alternative chains certificate forgery (CVE-2015-1793) attack work?

The security advisory for the issue can be found here: https://www.openssl.org/news/secadv_20150709.txt OpenSSL Security Advisory [9 Jul 2015] Alternative chains certificate forgery (CVE-2015-...
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1answer
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What encryption is applied on a key generated by `openssl req`?

When a key is generated with openssl genrsa, the encryption is selected with a command line argument such as -aes128. After the key is generated, we can see what encryption was used in the file. Ex: ...
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1answer
188 views

OpenSSL implementation vulnerabilities vs TLS 1.0 holes

I have been reading a fair bit on OpenSSL vulnerabilities and the various SSL protocols' strengths. As far as I understand it any protocols older than TLS 1.0 are to be avoided at all cost (some would ...
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1answer
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Chrome showing SSL warning about SHA-1 when the sites don't use SHA-1

My version of Chrome on an iMac (latest 43.0.2357.130 (64-bit)) is showing an SSL warning for well-known sites (Hackernews, GitHub, DigitalOcean): This site uses a weak security configuration (SHA-...
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1answer
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In SSL server handshake, does server also send CA certificate [duplicate]

In the TCP SSL sever handshake, does the server also send CA certificates? Does the server need to send all intermediate CA certificates in the Server Hello?
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How to pass cipher list to OpenSSL s_client

How we can pass a cipher list to the OpenSSL s_client program? We can pass single cipher by this: openssl s_client -cipher 'ECDHE-RSA-AES256-SHA' -connect www.google.com:443 But how to pass a list ...
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Can Client Certificates be tied to a Specific Server Certificate?

I have a Root Certificate Authority and and Intermediate Certificate Authority. I have created a certificate for the server. SSL on Apache is working fine. Browser recognizes my Chain of Trust with ...
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1answer
370 views

EC private key, RSA certificate. Is this realisable?

I was wondering if is it possible to generate EC private key: openssl ecparam -name sect571r1 -out ecparam.pem openssl ecparam -in ecparam.pem -genkey -noout -out eckey.pem then generate ...
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2answers
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Why is there a “des-ede3-cbc” in my rsa private key?

I have created an OpenSSL RSA private key and certificate request with 4096 bit with the following command: openssl req -newkey 4096 When I view the private key with openssl asn1parse -in privkey ...
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1answer
737 views

Create PKCS7 signature, signed by X.509 CA, which embeds an XML file

I have to create a PKCS7 signature file signed by an X.509 certificate and I have to embed an XML file within. How to do that with OpenSSL or any other tool?
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2answers
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Openssl ciphers: what does Au=ECDH mean?

I am trying to get a grasp on different stages of SSL. I have referred to some fantastic answers about how SSL/TLS works and specifically about authentication mechanisms, and numerous other sources. ...
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1answer
233 views

Are OpenSSH vs OpenSSL public key format names mismatched?

I generated a key pair vis OpenSSH and later wanted to generate PEM encoded public key. I noticed that generated public key differs when generated by OpenSSH vs OpenSSL when using same format name (...
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HPKP and Elliptic Curve certificates

There is quite some information on the web on how to extract the base 64 encoding of the SHA-256 fingerprint (which is needed for the Public Key Pinning header) for RSA certificates (e.g. by Mozilla). ...
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Certificate authority has changed for personal website - but I haven't changed anything?

I have the Certificate Patrol addon (website) installed in Firefox. While I mostly ignore the (far too many) warnings, today I saw that the certificate authority for my personal website has changed. ...
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1answer
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Nginx - SSL Website shows up on desktop but not mobile

So I bought a Comodo SSL from Namecheap and put my site up on a Ubuntu droplet on DigitalOcean on a nginx server. My default virtual host file on /etc/nginx/sites-available/: server { listen ...
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how to do 2 way ssl authentication without using a self signed CA

I have a requirement to set a 2 mutual ssl authentication between our apache and an application. I have purchased a cheap SSL from rapid SSL in order to do this. RapidSSL sent a zip folder with ...
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1answer
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How to trust a CA to sign a CRL but not a cert?

In my application, there are many parties that are trusted to revoke a cert (ie by signing a CRL), but are not trusted to sign (new) certs. How do I mark a CA to be trusted only for CRLs, and not for ...
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2answers
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Browser rejects certificate, but openssl s_client works

I'm migrating a secure website. I've installed the same certificate on the new host and pointed the domain name to the new IP address (via my hosts file). However, when I try to hit that server with a ...