An intermediate certificate authority (CA) is an entity that can sign certificates on behalf of the root CA. This creates a password protected key. An OK indicates that the chain of trust is intact. These are quick and dirty notes on generating a certificate authority (CA), intermediate certificate authorities and end certificates using OpenSSL. Self-signed certificates are not trusted by default and they can be difficult to maintain. In RHEL/CentOS 7/8 the default location for all the certificates are under /etc/pki/tls. It is the only the end-entity certificate. Besides key generation, we will create three files that our CA infrastructure will need. 3. Do not delete or edit this file by hand. Signing the Root Certificate. For more information, see Overview of TLS termination and end to end TLS with Application Gateway. However, if you have a dev/test environment and don't want to purchase a verified CA signed certificate, you can create your own custom CA and create a self-signed certificate with it. Use the intermediate CA key to create a certificate signing request (CSR). To request an SSL certificate from a CA like Verisign or GoDaddy, you send them a Certificate Signing Request (CSR), and they give you a certificate in return that they signed using their root certificate and private key. It includes OCSP, CRL and CA Issuer information and specific issue and expiry dates. Please note that the choice of “1” as a serial number is considered a security flaw for real certificates. You are right, the provided text and commands didn't matched so I have updated the command snippet. OpenSSL on a computer running Windows or Linux. We will copy this file to your custom certificate location i.e. Create your root CA certificate using OpenSSL. We will create root CA key using 4096 bits and 3DES encryption. Therefore, the final certificate needs to be signed using SHA-256. Next we will create intermediate CA certificate signing request (CSR) under /root/tls/intermediate/csr with expiry value lesser than the root CA certificate, Now the last step before we conclude openssl create certificate chain, we need to create immediate CA certificate using our Certificate Signing request which we created in above step. Thanks for providing this. I have already written multiple articles on OpenSSL, I would recommend you to also check them for more overview on openssl examples: On RHEL/CentOS 7/8 you can use yum or dnf respectively while on Ubuntu use apt-get to install openssl rpm. We will use v3_ca extension to create root CA certificate and v3_intermediate extension for intermediate CA certificate. Next, use the key to generate a self-signed certificate for the root CA: openssl req -new -x509 -sha256 -key root-ca-key.pem -out root-ca.pem. Create a parent directory to store the certificates. You can find OpenSSL bundled with many Linux distributions, such as Ubuntu. The -x509 option specifies that you want a self-signed certificate rather than a certificate request. Use the following commands to generate the csr and the certificate. A word of caution. it isn't really possible of course. The following code is an Azure PowerShell sample. In 2004, I set up a small certification authority using OpenSSL on Linux and the simple management scripts provided with OpenVPN. /root/tls and will modify the content of this file to create Root CA Certificate. set OPENSSL_CONF=C:\Program Files\OpenSSL-Win64\bin\openssl.cfg. private: This will be used to keep a copy of the CA certificate’s private key. Method 2 Generate the certificate using the mydomain csr and key along with the CA Root key. I have given few default values while the Common Name must be supplied as we have defined under policy key. 4. I have already written another article with the steps for openssl encd data with salted password to encrypt the password file. Configure openssl.cnf for Root CA Certificate. openssl> genrsa -aes256 \ -out intermediate/private/intermediate.key.pem 4096. At the prompt, type a strong password. The root key can be kept offline and used as infrequently as possible. How would I do that? In the below example I have combined my Root and Intermediate CA certificates to openssl create certificate chain in Linux. Sign the subca certificate request with root CA. Is there any way I can view the intermediate and root certificate content. Operating a CA with openssl ca The eq_distinguished_name key determine how OpenSSL gets the information it needs to fill in the certificate’s distinguished name. We can also create CA bundle with all the certificates without creating any directory structure and using some manual tweaks but let us follow the long procedure to better understanding. It might be worth trying adding those two extensions to your ext.conf first and testing the resulting new Root CA certificate using the -x509toreq method you posted. crlnumber is used to keep track of certificate revocation lists. And policy_anything for creating Intermediate CA certificates. It should now contain a line that refers to the intermediate certificate. no, i meant create a server certificate that uses the chain in a wildcard certificate i bought from a commercial CA. (change DOMAINNAME to match what you used in the openssl_root.cnf): Add a crlnumber file to the intermediate CA directory tree. So, let me know your suggestions and feedback using the comment section. Now to complete setup of openssl create certificate chain, we will also need intermediate certificate for the CA bundle. This is the domain of the website and it should be different from the issuer. First, we need to create a “self-signed” root certificate. OpenSSL verify Certificate Chain Next, you'll create a server certificate using OpenSSL. We were actually supposed to verify the certificate chain instead of intermediate cert. To do so, we need to generate a key first. OpenSSL Certificate Authority¶. When prompted, type the password for the root key, and the organizational information for the custom CA such as Country/Region, State, Org, OU, and the fully qualified domain name (this is the domain of the issuer). For better security, purchase a certificate signed by a well-known certificate authority. The policy key specifies the name of a section that will be used for the default policy. To convert the format of the Certificate to PEM format. To learn more about SSL\TLS in Application Gateway, see Overview of TLS termination and end to end TLS with Application Gateway. Next, you'll create a server certificate using OpenSSL.Create the certificate's key. Make sure you declare the directory you chose earlier /root/tls. Your Root CA certificate remains unaffected and all you need to do is to renew only one subset of certificates. The value is the name of a section containing the configuration for the default CA. It becomes problematic to have to overload a complex private CA heirarchy across all client nodes truststores (CA bundles) as opposed to only providing the root CA. Since .crt already contains the public key in the base-64 encoded format, just rename the file extension from .crt to .cer. Check your local laws and regulations relating to security, cryptography, etc. Now ensure that this self signed root certificate is used only to sign other certificates. Below are the options we have been changed compared to the root CA certificate configuration file: Generate intermediate CA key ca-intermediate.key.using openssl genrsa with 3DES encryption and our encrypted passphrase file to avoid any password prompt. I hope you have an overview of all the terminologies used with OpenSSL. [root@centos8-1 tls]# openssl verify -CAfile certs/cacert.pem intermediate/certs/intermediate.cacert.pem Or, you can use Azure CLI or Azure PowerShell to upload the root certificate. The details should generally match the root CA. The root certificate is a Base-64 encoded X.509(.CER) format root certificate from the backend certificate server. Following are the steps involved in creating CA, SSL/TLS certificates. For TLS binding instructions, see How to Set Up SSL on IIS 7. For example, at least nine characters, using upper case, lower case, numbers, and symbols. There is a school of thought that the web server certificate should include the intermediary CA chain with it, and present it to clients, and the client's trust store (CA Bundle) should only contain the root CA. The index.txt file is where the OpenSSL ca tool stores the certificate database. When we create private key for Root CA certificate, … For our purposes, this section is quite simple, containing only a single key: default_ca . The openssl ca command and utility is a lightweight piece of software that can be used to perform minimal CA (Certification Authority) functions. We will also create sub directories under /root/tls/intermediate to store our keys and certificate files. It expects the value to be in hex, and it must contain at least two digits, so we must pad the value by prepending a zero to it. OpenSSL is somewhat quirky about how it handles this file. The only differency in signing a certificate to be a ca certificate is an extension that is defined with v3_ca. CSR – Certificate signing request; SSL – Secure Socket Layer; TLS – Transport Layer Security; Certificate Creation Workflow. Use the following command to generate the key for the server certificate. First step is to build the CA private key and CA certificate pair. When I cat on the end-entity certificate, I see only a single BEGIN and END tag. We will apply policy_match for creating root CA certificates so we have added this as a default value for policy under CA_default. If the intermediate key is compromised, the root CA can revoke the intermediate certificate and create a new intermediate cryptographic pair. For creating new CA chain bundle you can follow the same steps as I have mentioned here. Openssl create certificate chain requires Root CA and Intermediate certificate, In this article I will share Step-by-Step Guide to create root and intermediate certificates and then use these certificates to create certificate CA bundle in Linux. The x509_extensions key specifies the name of a section that contains the extensions that we want included in the certificate. openssl req -new -key device.key -out device.csr. OpenSSL encrypted data with salted password. Also, they may use outdated hash and cipher suites that may not be strong. The values under [ req ] section are applied when creating Certificate Signing Requests (CSR) or Certificates. Overview of TLS termination and end to end TLS with Application Gateway, Quickstart: Direct web traffic with Azure Application Gateway - Azure portal, HOW TO: Install Imported Certificates on a Web Server in Windows Server 2003, Create your own custom Certificate Authority, Create a self-signed certificate signed by your custom CA, Upload a self-signed root certificate to an Application Gateway to authenticate the backend server. When you access the website, ensure the entire certificate chain is seen in the browser. It identifies the root certificate authority (CA) that issued the server certificate and the server certificate is then used for the TLS/SSL communication. It allows the root key to be kept offline and unused as much as possible, as any compromise of the root key is disastrous. Create CSR using SHA-1 openssl req -out sha1.csr -new -newkey rsa:2048 -nodes -keyout sha1.key After you have created the OpenSSL configuration file, the next step is to create a self-signed root certificate that will be used to sign your localhost test certificate. Browse to your website, and click the lock icon on your browser's address box to verify the site and certificate information. Created CA certificate/key pair will be valid for 10 years (3650 days). Thank you, I really appreciate you taking the time and effort to explain such a complex topic. 05-04-2012 Luke Virtualization Certificate Authority, Certificate signing, openssl, Root CA, srm, vcenter 4 Comments Leave a Reply Cancel reply Your email address will not be published. The -sha256 option sets the hash algorithm to SHA-256. The CSR is a public key that is given to a CA when requesting a certificate. Within the CA’s root directory, we need to create two sub directories: certs: This will be used to keep copies of all of the certificates that we issue with our CA. Unable to load CA private key, Thanks for the great instructions and the wasted lifetime, I found the bug, it was my fault. I … If this key is compromised, the integrity of your CA is compromised, which essentially means that any certificates issued, whether they were issued before the key was compromised or after, can no longer be trusted. This removes authentication certificates that were required in the v1 SKU. Use the following command to create the certificate: Use the following command to print the output of the CRT file and verify its content: Verify the files in your directory, and ensure you have the following files: In your web server, configure TLS using the fabrikam.crt and fabrikam.key files. This is useful in a number of situations, such as issuing server certificates to secure an intranet website, or for issuing certificates to clients to allow them to authenticate to a server. [ ca] # `man ca` default_ca = CA_default The [CA_default] section in the openssl_root.cnf file contains the variables OpenSSL will use for the root CA.If you're using alternate directory names from this demo, update the file accordingly. The previous commands create the root certificate. openssl genrsa -out device.key 2048. To upload the trusted root certificate from the portal, select the HTTP Settings and choose the HTTPS protocol. In some countries, using the OpenSSL package can be against the law. A policy definition is a set of keys with the same name as the fields in a certificate’s distinguished name. Open a command prompt, change the directory to your folder with the configuration file and generate the private key for the certificate: openssl genrsa -out testCA.key 2048 We'll set up our own root CA. Or, you can use OpenSSL to verify the certificate. The command can sign and issue new certificates including self-signed Root CA certificates, generate CRLs (Certificate Revocation Lists), and other CA things. Check the list of contents under /root/tls, We will have a default configuration file openssl.cnf in RHEL/CentOS 7/8 under /etc/pki/tls/openssl.cnf which is added by the openssl rpm. Set the appropriate number of days for your company. You don't need to explicitly upload the root certificate in that case. So I will not repeat the steps here again. After further consideration, your issue may simply be down to the fact that your replacement Root CA certificate doesn't have the basicConstraint and possibly the keyUsage extensions. Network Security with OpenSSL, Related Searches: Openssl create certificate chain, root ca certificate, intermediate ca certificate, verify certificate chain, create ca bundle, verify ca certificate, openssl verify certificate, openssl view certificate, openssl get certificate info, openssl ca -config openssl.cnf -extensions v3_intermediate_ca -days 2650 -notext -batch -passin file:mypass.enc -in intermediate/csr/intermediate.csr.pem -out intermediate/certs/intermediate.cacert.pem, My Version: A certificate chain or certificate CA bundle is a sequence of certificates, where each certificate in the chain is signed by the subsequent certificate. openssl genrsa -des3 -out ca.key 4096 openssl req -new -x509 -days 3650 -key ca.key -out ca.crt During the process you will have to fill few entries (Common Name (CN), Organization, State or province .. etc). I have an implementation question however as we have run into variations on where the intermediary certificates should be vs the root CA certificates. For each key or field, there are three legal values: match, supplied, or optional. It’s important that no two certificates ever be issued with the same serial number from the same CA. openssl req -config /etc/openssl.cnf -new -x509 -keyout private/cakey.pem \ -out cacert.pem -days 3650 This last command is better than “CA.pl -newcert” as it will place the files in the required locations and create a root CA valid for 10 years. SHA-256 is the default in later versions of OpenSSL, but earlier versions might use SHA-1. Yes, silly typo. Next we will create index.txt file which is a database of sorts that keeps track of the certificates that have been issued by the CA. The root certificate is a Base-64 encoded X.509(.CER) format root certificate from the backend certificate server. We will also need a serial and index.txt file as we created for our Root CA Certificate. Lastly I hope the steps from the article for openssl create certificate chain with Root and Intermediate Certificate on Linux was helpful. If you don't have an existing application gateway, see Quickstart: Direct web traffic with Azure Application Gateway - Azure portal. Not like this, but like this: Sorry You'll use this to sign your server certificate. For instructions on how to import certificate and upload them as server certificate on IIS, see HOW TO: Install Imported Certificates on a Web Server in Windows Server 2003. 5. But for this article we will create a new directory structure /root/tls/ to store our certificates. In case the CSR is only available with SHA-1, the CA can be used to sign CSR requests and enforce a different algorithm. The following sample adds a trusted root certificate to the application gateway, creates a new HTTP setting and adds a new rule, assuming the backend pool and the listener exist already. openssl> genrsa -aes256 -out private/ca.key.pem 4096. The Application Gateway v2 SKU introduces the use of Trusted Root Certificates to allow backend servers. Please use shortcodes for syntax highlighting when adding code. OpenSSL on a computer running Windows or LinuxWhile there could be other tools available for certificate management, this tutorial uses OpenSSL. Now lunch the openssl.exe by running the below command > “C:\Program Files\OpenSSL-Win64\bin\openssl.exe” Use the “” to run the command. Certificate Authorities can certify that another entity is a Certificate Authority. $ openssl x509 -req -extfile < (printf "subjectAltName=DNS:YOUR_DOMAIN_NAME") -days 120 -in SERVER.csr -CA rootCA.crt -CAkey root_rsa.key -CAcreateserial -out SERVER.crt -sha256. # cd /root/ca # openssl req -config openssl.cnf -new -nodes -days 365 -keyout private/server.key -out server.csr Use the following command to generate the key for the server certificate.openssl ecparam -out fabrikam.key -name prime256v1 -genkey Create the CSR (Certificate Signing Request) The CSR is a public key that is given to a CA when requesting a certificate.The CA issues the certificate for this specific request. Creating a User Certificate for Authentication: Follow all the steps in _Creating SSL Certificates for … It's assumed that DNS has been configured to point the web server name (in this example, www.fabrikam.com) to your web server's IP address. The root CA is only ever used to create one or more intermediate CAs, which are trusted by the root CA to sign certificates on their behalf. Once the key is created, you’ll generate the certificate signing request. We will create new directory structure /root/tls/intermediate under our parent folder /root/tls to keep both the certificate files separate. We will use v3_intermediate_ca extension from /root/tls/openssl.cnf to create the intermediate CA certificate under /root/tls/intermediate/certs/intermediate.cacert.pem. Create a Root Certificate (this is self-signed certificate) openssl> req -config openssl.cnf \ -key private/ca.key.pem \ -new -x509 -days 7300 -sha256 -extensions v3_ca \ -out certs/ca.cert.pem. This guide demonstrates how to act as your own certificate authority (CA) using the OpenSSL command-line tools. [root@centos8-1 tls]# openssl verify -CAfile certs/cacert.pem intermediate/certs/ca-chain-bundle.cert.pem, Thank you for highlighting this. i asked before i really understood the concepts involved. Certificates are usually given a validity of one year, though a CA will typically give a few days extra for convenience. The private key should be stored in hardware, or at least on a machine that is never put on a network. Lets quote from the official dokumentation of openssl to understand it: “The basicConstraints extension CA flag is used to determine whether the certificate can be used as a CA. Hi - can I chain more certificates on to a certificate I purchased from a CA? To openssl create certificate chain (certificate bundle), concatenate the intermediate and root certificates together. 40C711AC187F0000:error::system library:file_open:Permission denied:crypto/store/loader_file.c:919:calling stat(/root/tls/private/andre-root-ca-key.pem) The root CA signs the intermediate certificate, forming a chain of trust. Next openssl verify intermediate certificate against the root certificate. We'll use the root CA to generate an example intermediate CA. The x509_extensions key specifies the name of a section that will contain the extensions to be added to each certificate issued by our CA. In this step you'll take the place of VeriSign, Thawte, etc. This is best practice. As if we choose to create private key with encryption such as 3DES, AES then you will have to provide a passphrase every time you try to access the private key. I have used below external references for this tutorial guide The CA issues the certificate for this specific request. Use the root private key to sign the root certificate. After openssl create certificate chain, to verify certificate chain use below command: Nice instructions, but there is a small mistake: First, just like with the root CA step, you’ll need to create a private key (different from the root CA). Since no certificates have been issued at this point and OpenSSL requires that the file exist, we’ll simply create an empty file. We will have a default configuration file openssl.cnf … The private key should never be disclosed to anyone not authorized to issue a certificate or CRL from our CA. In my examples, I will use a Ubuntu server, the configuration of openSSL will be similar though on other distributions like CentOS. Typically, the root CA does not sign server or client certificates directly. andre@Heimserver:~/Zertifikat Baustelle/root/tls$ openssl ca -config apache_intermediate_ca.cnf -extensions v3_intermediate_ca -days 3650 -notext -batch -passin file:andrepass.enc -in intermediate/csr/apache_intermediate.csr.pem -out intermediate/certs/apache_intermediate_ca.crt If not, you can edit the hosts file to resolve the name. After openssl create certificate chain, to verify certificate chain use below command: To verify certificate chain for online pages such as Google: To show certificates from the certificate chain for Google: In this tutorial we learned how to create certificate chain using openssl with root and intermediate certificate. It identifies the root certificate authority (CA) that issued the server certificate and the server certificate is then used for the TLS/SSL communication. CA Key and Certificate Creation. Now you have to create key file for your CA certificate > genrsa -out can.key 2048 . Using configuration from apache_intermediate_ca.cnf OpenSSL create certificate chain with root and intermediate certificate Could not open file or uri /root/tls/private/andre-root-ca-key.pem for loading CA private key The purpose of using an intermediate CA is primarily for security. Creating a root CA certificate and an end-entity certificate. We applied the v3_ca extension, so the options from [ v3_ca ] should be reflected in the output. Thank you for highlighting this, I have updated the article. Linux, Cloud, Containers, Networking, Storage, Virtualization and many more topics, The majority of the files that the CA uses are visible to anyone on the system or at least to anyone who makes any use of the certificates issued by our CA. This removes authentication certificates that were required in the v1 SKU. We will use openssl command to view the content of private key: Use below command to create Root Certificate Authority Certificate cacert.pem, To change the format of the certificate to PEM format, Execute the below command for openssl verify root CA certificate. If your web server can't take two files, you can combine them to a single .pem or .pfx file using OpenSSL commands. Use the following command to generate the CSR: When prompted, type the password for the root key, and the organizational information for the custom CA: Country/Region, State, Org, OU, and the fully qualified domain name. Application Gateway trusts your website's certificate by default if it's signed by a well-known CA (for example, GoDaddy or DigiCert). Is anyone else seeing this used as a practice? These are the extensions we will use with openssl create certificate chain. Sign in to your computer where OpenSSL is installed and run the following command. Next we will use this Root and Intermediate CA bundle to sign and generate server and client certificates to configure end to end encryption for Apache web server in Linux. We will use this file later to verify certificates signed by the intermediate CA. To upload the certificate in Application Gateway, you must export the .crt certificate into a .cer format Base-64 encoded. The output also shows the X509v3 extensions. For example, Apache, IIS, or NGINX to test the certificates. The one notable exception is the CA certificate’s private key. You’ll be asked various questions (Country, State/Province, etc. While there could be other tools available for certificate management, this tutorial uses OpenSSL. The Issuer and Subject are identical as the, openssl genrsa -des3 -passout file:mypass.enc -out private/cakey.pem 4096, openssl rsa -noout -text -in private/cakey.pem -passin file:mypass.enc, openssl req -new -x509 -days 3650 -passin file:mypass.enc -config openssl.cnf -extensions v3_ca -key private/cakey.pem -out certs/cacert.pem, openssl x509 -noout -text -in certs/cacert.pem, echo 01 > /root/tls/intermediate/crlnumber, openssl genrsa -des3 -passout file:mypass.enc -out intermediate/private/intermediate.cakey.pem 4096, expiry value lesser than the root CA certificate, openssl req -new -sha256 -config intermediate/openssl.cnf -passin file:mypass.enc -key intermediate/private/intermediate.cakey.pem -out intermediate/csr/intermediate.csr.pem, openssl x509 -noout -text -in intermediate/certs/intermediate.cacert.pem, openssl verify -CAfile certs/cacert.pem intermediate/certs/intermediate.cacert.pem, cat intermediate/certs/intermediate.cacert.pem certs/cacert.pem > intermediate/certs/ca-chain-bundle.cert.pem, openssl verify -CAfile certs/cacert.pem intermediate/certs/ca-chain-bundle.cert.pem, openssl s_client -quiet -connect google.com:443, openssl s_client -showcerts -connect google.com:443, Step 2: OpenSSL encrypted data with salted password, Step 3: Create OpenSSL Root CA directory structure, Step 4: Configure openssl.cnf for Root CA Certificate, Step 6: Create your own Root CA Certificate, Step 7: Create OpenSSL Intermediate CA directory structure, Step 8: Configure openssl.cnf for Intermediate CA Certificate, Step 10: Create immediate CA Certificate Signing Request (CSR), Step 11: Sign and generate immediate CA certificate, Step 12: OpenSSL Create Certificate Chain (Certificate Bundle), overview of all the terminologies used with OpenSSL, Beginners guide to understand all Certificate related terminologies used with openssl, Generate openssl self-signed certificate with example, Create your own Certificate Authority and generate a certificate signed by your CA, Create server and client certificates using openssl for end to end encryption with Apache over SSL, Create SAN Certificate to protect multiple DNS, CN and IP Addresses of the server in a single certificate, steps for openssl encd data with salted password to encrypt the password file, all the certificates without creating any directory structure, generate server and client certificates to configure end to end encryption for Apache web server in Linux, OpenSSL create certificate chain with root and intermediate certificate, 10 easy steps to setup High Availability Cluster CentOS 8, Create Certificate Authority and sign a certificate with Root CA, Understand certificate related terminologies, Configure secure logging with rsyslog TLS, Transfer files between two hosts with HTTPS, 5 useful tools to detect memory leaks with examples, 15 steps to setup Samba Active Directory DC CentOS 8, 100+ Linux commands cheat sheet & examples, List of 50+ tmux cheatsheet and shortcuts commands, RHEL/CentOS 8 Kickstart example | Kickstart Generator, 10 single line SFTP commands to transfer files in Unix/Linux, Tutorial: Beginners guide on linux memory management, 5 tools to create bootable usb from iso linux command line and gui, 30+ awk examples for beginners / awk command tutorial in Linux/Unix, Top 15 tools to monitor disk IO performance with examples, Overview on different disk types and disk interface types, 6 ssh authentication methods to secure connection (sshd_config), 27 nmcli command examples (cheatsheet), compare nm-settings with if-cfg file, How to zip a folder | 16 practical Linux zip command examples, How to check security updates list & perform linux patch management RHEL 6/7/8, Steps to install Kubernetes Cluster with minikube, Kubernetes labels, selectors & annotations with examples, How to perform Kubernetes RollingUpdate with examples, Kubernetes ReplicaSet & ReplicationController Beginners Guide, How to assign Kubernetes resource quota with examples, 50 Maven Interview Questions and Answers for freshers and experienced, 20+ AWS Interview Questions and Answers for freshers and experienced, 100+ GIT Interview Questions and Answers for developers, 100+ Java Interview Questions and Answers for Freshers & Experienced-2, 100+ Java Interview Questions and Answers for Freshers & Experienced-1.