In the previous video, We’ve talked about how digital certificates help with authentication and provide a safe and reliable key exchange process in TLS. Today we will learn exactly how to generate a certificate and have it signed by a Certificate Authority (CA). For the purpose of this demo, we won’t submit our Certificate Signing Request (CSR) to a real CA. Instead, we will play both roles: the certificate authority and the certificate applicant. So in the first step, we will generate a private key and its self-signed certificate for the CA. They will be used to sign the CSR later. In the second step, We will generate a private key and its paired CSR for the web server that we want to use TLS. Then finally we will use the CA’s private key to sign the web server’s CSR and get back the signed certificate. In order to do all of these things, We need to have openssl installed. If you’re on a mac, it’s probably already there. You can run openssl version to see which version it’s running. In my case, it’s LibreSSL version 2.8.3 Let’s open the browser and go to libressl.org Here we have a link to the manual of openssl. The first command we’re gonna used is req, Which stands for request. As you can see, This command is used to create and process certificate request. It can also be used to create a self-signed certificate for the CA, Which is exactly what we want in the first step. This -x509 option is used to tell openssl to output a self-signed certificate instead of a certificate request. In case you don’t know, X509 is just a standard format of the public key certificate. You can click on this lock button of any HTTPS website to see its certificate in X509 format. Alright, now let’s get back to the terminal and run: openssl req -x509 Then -newkey rsa:4096 This option basically tells openssl to create both a new private key with RSA 4096-bit key, and its certificate request at the same time. As we’re using -x509 option, it will output a certificate instead of a request. The next option is -days 365, Which specifies the number of days that the certificate is valid for. Then we use -keyout option to tell openssl to write the created private key to ca-key.pem file And finally the -out option to tell it to write the certificate to ca-cert.pem file. When we press enter, openssl will start generating the private key Once the key is generated, we will be asked to provide a pass phrase, which will be used to encrypt the private key before writing it to the PEM file. Why is it encrypted? Because if somehow the private key file is hacked, The hacker cannot use it to do anything without knowing the pass phrase to decrypt it first. Next, openssl will ask us for some identity information to generate the certificate. First the country code, The state or province name, The city name, The organization name, The unit name, The common name, or domain name, The email address. And that’s it! The certificate and private key files are successfully generated. If we cat the private key file, we can see it says “encrypted private key”. The certificate, on the other hand, is not encrypted, but only base64-encoded, because it just contains the public key, the identity information, and the signature that should be visible to everyone. We can use the x509 command to display all the information encoded in this certificate. This command can also be used to sign certificate requests, Which we will do in a few minute. Now let’s run openssl x509, and pass in the CA’s certificate file. We use the -noout option to tell it to not output the original encoded value. We want to display it in a readable text format, so let’s use -text option and press enter. Here we can see all information of the certificate, such as the version, the serial number, The issuer and the subject are the same in this case because this is a self-signed certificate. Then the RSA public key and signature. I’m gonna copy this command and save it to our gen.sh script. With this script, I want to automate the process of generating a set of keys and certificates. Before moving to the 2nd step, I’m gonna show you another way to provide the identity information without entering it interactively as before. To do this, we use the subject option I’m gonna add it to this openssl request command And copy this information from the certificate Then change it to the correct format. Now let’s add a command to remove all pem files at the top of this script Then run gen.sh in the terminal. We still being prompted for a pass phrase, But it doesn’t ask for identity information anymore, because we already provided them in the subject option. Great! Now the next step is to generate a private key and CSR for our web server. It’s almost the same as the command we used in the 1st step. Except that, this time we don’t want to self-sign it, So we should remove this -x509 option. This -days option should be removed as well, since we don’t create a certificate, but just a CSR. Then we change the name of the output key to server-key.pem And this file should be server-req.pem because we’re creating a certificate signing request. Now we should change all of these subject information to our web server’s information. OK, let’s run it. Enter a pass phrase to encrypt the web server’s private key Then here we go, The files are successfully generated. Here’s the encrypted private key And this is the certificate signing request. I think you can notice the difference: It’s not a certificate as before, but a certificate request instead. So now let’s move to step 3 and sign this request. For that, we will use the same x509 command that we’ve used to display certificate before. Let’s open the terminal and run this: openssl x509 This time we use the -req option to tell openssl that we’re gonna pass in a certificate request We use the -in option follow by the name of the request file Next we use the -CA option to pass in the certificate file of the CA And the -CAkey option to pass in the private key of the CA. Then 1 important option is -CAcreateserial. Basically the CA must ensure that each certificate it signs goes with a unique serial number, So with this option, a file containing the next serial number will be generated if it doesn’t exist. Finally we use the -out option to specify the file to write the output certificate to. Now as you can see here, Because the CA’s private key is encrypted, OpenSSL is asking for the pass phrase to decrypt it before it can be used to sign the certificate. It’s a countermeasure in case the CA’s private key is hacked. OK, now we’ve got the signed certificate for our web server. Let’s print it out in text format. This is its unique serial number. And we can also see a ca-cert.srl file Which contains the same serial number here. This issuer section contains the information of the CA, which is Tech School in this case. By default, the certificate is valid for 30 days. We can change it by adding the -days option to the signing command. As you can see, now the validity duration has changed to 60 days. If you remember the Youtube certificate that we’ve seen in the previous video, This certificate is used for many Google websites with different domain names. We can also do that for our web server by specifying the Subject Alternative Name extension when signing the certificate request. Here we can see the -extfile option that allows us to state the file containing the extensions. We can see the format of this config file in this page. Let’s search for subject alternative name. Here it is. There are several things that we can use as the alternative name, Such as email, DNS, or IP. And it looks something like this. So let’s try it! I will create a new file server-ext.cnf And set the subject alternative name to DNS: *.pcbook.com We can set multiple domain names, Let’s say *.pcbook.org as well I also add an IP 0.0.0.0, which will be used when we develop on local host. Now in this certificate signing command, let’s add the -extfile option and pass in the name of the extension config file. Now the result certificate file has a new extensions section with all the subject alternative names that we’ve chosen. Awesome! So looks like our automate script is ready, Except for the fact that we have to enter a lot of password to protect the private keys. In case we just want to use this for development and testing, We can tell openssl to not encrypt the private key, so that it won’t ask us for the pass phrase. We do that by adding the -nodes option to the req command like this. Now if I run gen.sh again, It doesn’t ask for passwords anymore. And if we look at the private key files, It is now PRIVATE KEY, not ENCRYPTED PRIVATE KEY as before. Cool! One last thing before we finish, I will show you how to verify if a certificate is valid or not. We can do that with the openssl verify command Pass in the trusted CA’s certificate And the certificate that we want to verify If it returns OK then the certificate is valid. And that’s it for today’s video. I hope it’s useful for you. Thanks for watching and I’ll see you guys in the next one.
To create RSA key pair, move to Asymmetric tab and select a key size (2048, 3072, 4096, 8192, or 16384). After that, hit the Generate button and specify the filename. It will then generate a pair of public and private keys in a matter of some time. The time taken to create RSA key pairs.
May 29, 2016 The most effective and fastest way is to use command line tools: codeopenssl genrsa -out mykey.pem 4096 openssl rsa -in mykey.pem -pubout mykey.pub /codeIt’ll generate RSA key pair in code mykey.pem/code and code mykey.pub/code.
If you're using opensslpkeynew in conjunction with opensslcsrnew and want to change the CSR digest algorithm as well as specify a custom key size, the configuration override should be defined once and sent to both functions.
OpenSSL can generate several kinds of public/private keypairs. RSA is the most common kind of keypair generation. Other popular ways of generating RSA public key / private key pairs.
To use the RSA key pair generator to generate a 4096 bits RSA key and save that key in PEM format in private.key, use./genkey type=rsa rsakeysize=4096 filename=private.key format=pem The larger the requested keysize, the longer it will take to generate the key itself. You also need to take into account the performance of the system.
You may generate an RSA private key with the help of this tool. Additionally, it will display the public key of a generated or pasted private key.
Description
RSA is an asymmetric encryption algorithm. With a given key pair, data that is encrypted with one key can only be decrypted by the other. This is useful for encrypting data between a large number of parties; only one key pair per person need exist. RSA is widely used across the internet with HTTPS.
To generate a key pair, select the bit length of your key pair and click Generate key pair. Depending on length, your browser may take a long time to generate the key pair. A 1024-bit key will usually be ready instantly, while a 4096-bit key may take up to several minutes. For a faster and more secure method, see Do It Yourself below.
Openssl Generate Pem Key
CryptoTools.net does not yet have a tool for facilitating the encryption and decryption of data using RSA, but you may Do It Yourself with the instructions below.
Openssl Generate Rsa 4096 Key Pair Key
Do It Yourself
Openssl Generate Public And Private Key Pair
For these steps, you will need a command line shell with OpenSSL. Ideally, you should have a private key of your own and a public key from someone else. For demonstration, we will only use a single key pair.
Generate Private Key
Run this command to generate a 4096-bit private key and output it to the private.pem file. If you like, you may change the key length and/or output file.
Derive Public Key
Given a private key, you may derive its public key and output it to public.pem using this command. (You may also paste your OpenSSL-generated private key into the form above to get its public key.)
Encrypt Data
We can now use this key pair to encrypt and decrypt a file, data.txt.
Decrypt Data
Openssl Generate Rsa Private Key
Given the encrypted file from the previous step, you may decrypt it like so.