Openssl Command To Generate Public Key

Openssl Command To Generate Public Key Average ratng: 8,9/10 5086 reviews

One of the most versatile SSL tools is OpenSSL which is an open source implementation of the SSL protocol. /monster-hunter-generations-4-star-village-key-quests.html. There are versions of OpenSSL for nearly every platform, including Windows, Linux, and Mac OS X. OpenSSL is commonly used to create the CSR and private key for many different platforms, including Apache. However, it also has hundreds of different functions that allow you to view the details of a CSR or certificate, compare an MD5 hash of the certificate and private key (to make sure they match), verify that a certificate is installed properly on any website, and convert the certificate to a different format. A compiled version of OpenSSL for Windows can be found here.

OpenSSL: Working with SSL Certificates, Private Keys and CSRs. If you use to generate certificates, the private key will contain public key information, therefore the public key does not have to be generated separately. This might be important if, for example, not all the target systems know the details of the named curve.

  1. To illustrate how OpenSSL manages public key algorithms we are going to use the famous RSA algorithm. Other algorithms exist of course, but the principle remains the same. Note this command will create the pair of keys and the certificate request.
  2. This small tutorial will show you how to use the openssl command line to encrypt and decrypt a file using a public key. We will first generate a random key, encrypt that random key against the public key of the other person and use that random key to encrypt the actual file with using symmetric encryption.

If you don't want to bother with OpenSSL, you can do many of the same things with our SSL Certificate Tools. Below, we have listed the most common OpenSSL commands and their usage:

General OpenSSL Commands

These commands allow you to generate CSRs, Certificates, Private Keys and do other miscellaneous tasks.

  • Generate a new private key and Certificate Signing Request
  • Generate a self-signed certificate (see How to Create and Install an Apache Self Signed Certificate for more info)
  • Generate a certificate signing request (CSR) for an existing private key
  • Generate a certificate signing request based on an existing certificate
  • Remove a passphrase from a private key

Checking Using OpenSSL

If you need to check the information within a Certificate, CSR or Private Key, use these commands. You can also check CSRs and check certificates using our online tools.

  • Check a Certificate Signing Request (CSR)
  • Check a private key
  • Check a certificate
  • Check a PKCS#12 file (.pfx or .p12)

Debugging Using OpenSSL

If you are receiving an error that the private doesn't match the certificate or that a certificate that you installed to a site is not trusted, try one of these commands. If you are trying to verify that an SSL certificate is installed correctly, be sure to check out the SSL Checker.

  • Check an MD5 hash of the public key to ensure that it matches with what is in a CSR or private key
  • Check an SSL connection. All the certificates (including Intermediates) should be displayed

Converting Using OpenSSL

These commands allow you to convert certificates and keys to different formats to make them compatible with specific types of servers or software. For example, you can convert a normal PEM file that would work with Apache to a PFX (PKCS#12) file and use it with Tomcat or IIS. Use our SSL Converter to convert certificates without messing with OpenSSL.

  • Convert a DER file (.crt .cer .der) to PEM
  • Convert a PEM file to DER
  • Convert a PKCS#12 file (.pfx .p12) containing a private key and certificates to PEM

    You can add -nocerts to only output the private key or add -nokeys to only output the certificates.

  • Convert a PEM certificate file and a private key to PKCS#12 (.pfx .p12)

Originally posted on Sun Jan 13, 2008

Skip to main content

Encrypt and decrypt files to public keys via the OpenSSL Command Line

Published: 25-10-2018 Author: Remy van Elst Text only version of this article


Openssl Command To Generate Public Keys

Table of Contents

This small tutorial will show you how to use the openssl command line to encryptand decrypt a file using a public key. We will first generate a random key,encrypt that random key against the public key of the other person and use thatrandom key to encrypt the actual file with using symmetric encryption.

Openssl Command To Generate Public Key In Command Prompt

Because of how the RSA algorithm works it is not possible to encrypt largefiles. If you create a key of n bits, then the file you want to encrypt mustnot larger than (n minus 11) bits. The most effective use of RSA crypto is toencrypt a random generated password, then encrypt the file with the passwordusing symmetric crypto. If the file is larger then the key size the encryptioncommand will fail:

We generate a random file and use that as the key to encrypt the large file withsymmetric crypto. That random file acts as the password so to say. We encryptthe large file with the small password file as password. Then we send theencrypted file and the encrypted key to the other party and then can decrypt thekey with their public key, the use that key to decrypt the large file.

Openssl command to generate public key git

The following commands are relevant when you work with RSA keys:

  • openssl genrsa: Generates an RSA private keys.
  • openssl rsa: Manage RSA private keys (includes generating a public key from it).
  • openssl rsautl: Encrypt and decrypt files with RSA keys.

The key is just a string of random bytes. We use a base64 encoded string of 128bytes, which is 175 characters. Since 175 characters is 1400 bits, even a smallRSA key will be able to encrypt it.

Get the public key

Let the other party send you a certificate or their public key. If they send toa certificate you can extract the public key using this command:

Generate the random password file

Online malwarebytes license key generator. Use the following command to generate the random key:

Openssl Generate Key File

Do this every time you encrypt a file. Use a new key every time!

Update 25-10-2018

The key format is HEX because the base64 format adds newlines. The -passargument later on only takes the first line of the file, so the full key is notused. (Thanks Ken Larson for pointing this to me)

Encrypt the file with the random key

Use the following command to encrypt the large file with the random key:

The file size doesn't grows that much:

It's encrypted however:

Encrypt the random key with the public keyfile

Openssl Command To Generate Public Key For Windows

Use the following command to encrypt the random keyfile with the other personspublic key:

You can safely send the key.bin.enc and the largefile.pdf.enc to the otherparty.

You might want to sign the two files with your public key as well.

Decrypt the random key with our private key file

If you want to decrypt a file encrypted with this setup, use the followingcommand with your privte key (beloning to the pubkey the random key was cryptedto) to decrypt the random key:

This will result in the decrypted random key we encrypted the file in.

Decrypt the large file with the random key

Once you have the random key, you can decrypt the encrypted file with thedecrypted key:

This will result in the decrypted large file.

Tags: ca, certificate, decrypt, encrypt, openssl, pki, ssl, tls, tutorials