- Openssl Key Password
- Generate Certificate Request Openssl
- How To Generate Aes Key
- Openssl Generate Private Key
- Ubuntu Openssl Generate Aes Key Bank
- Ubuntu Openssl Generate Aes Key Generator
- Openssl Encrypt Private Key File
Encrypt and decrypt files to public keys via the OpenSSL Command Line
Re: How to create AES128 encrypted key with openssl Sure, just get 128 bits of data from /dev/random and you have an AES 128 key that can be used to encrypt anything you like (and decrypt it too). But you can never make an SSL certificate out of such a key. OpenSSL is based on public-key cryptography: e.g., a pair of private/public key. AES is a symmetric crypto system: e.g., one key being used at both ends. In this way, they're very different. I believe many implementations using OpenSSL use RSA or DSA to actually exchange an AES or Blowfish or similar key which actually encrypts the channel. AES128, AES256, AES cipher suites using 128 bit AES, 256 bit AES or either 128 or 256 bit AES. AESGCM AES in Galois Counter Mode (GCM): these ciphersuites are only supported in TLS v1.2. AESCCM, AESCCM8 AES in Cipher Block Chaining - Message Authentication Mode (CCM): these ciphersuites are only supported in TLS v1.2. An AES key, and an IV for symmetric encryption, are just bunchs of random bytes. So any cryptographically strong random number generator will do the trick. OpenSSL provides such a random number generator (which itself feeds on whatever the operating system provides, e.g. CryptGenRandom on Windows or /dev/random and /dev/urandom on Linux). The command I'm using to generate the key is: $ ope. Stack Exchange Network Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
Published: 25-10-2018 | Author: Remy van Elst | Text only version of this article
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.
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.
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
Use the following command to generate the random key:
![Ubuntu Openssl Generate Aes Key Ubuntu Openssl Generate Aes Key](/uploads/1/2/6/0/126060484/598853713.png)
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
-pass
argument 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:
![Openssl generate private key Openssl generate private key](/uploads/1/2/6/0/126060484/971501880.png)
Openssl Key Password
It's encrypted however:
Encrypt the random key with the public keyfile
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.Generate Certificate Request Openssl
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:
How To Generate Aes 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:
Openssl Generate Private Key
This will result in the decrypted large file.
Tags: ca, certificate, decrypt, encrypt, openssl, pki, ssl, tls, tutorialsIn this article you’ll find how to generate CSR (Certificate Signing Request) using OpenSSL from the Linux command line, without being prompted for values which go in the certificate’s subject field.
Below you’ll find two examples of creating CSR using OpenSSL.
In the first example, i’ll show how to create both CSR and the new private key in one command.
Ubuntu Openssl Generate Aes Key Bank
And in the second example, you’ll find how to generate CSR from the existing key (if you already have the private key and want to keep it).
Both examples show how to create CSR using OpenSSL non-interactively (without being prompted for subject), so you can use them in any shell scripts.
Create CSR and Key Without Prompt using OpenSSL
Use the following command to create a new private key 2048 bits in size
example.key
and generate CSR example.csr
from it:Option | Description |
---|---|
openssl req | certificate request generating utility |
-nodes | if a private key is created it will not be encrypted |
-newkey | creates a new certificate request and a new private key |
rsa:2048 | generates an RSA key 2048 bits in size |
-keyout | the filename to write the newly created private key to |
-out | specifies the output filename |
-subj | sets certificate subject |
Generate CSR From the Existing Key using OpenSSL
Use the following command to generate CSR
example.csr
from the private key example.key
:Option | Description |
---|---|
openssl req | certificate request generating utility |
-new | generates a new certificate request |
-key | specifies the file to read the private key from |
-out | specifies the output filename |
-subj | sets certificate subject |
Automated Non-Interactive CSR Generation
The magic of CSR generation without being prompted for values which go in the certificate’s subject field, is in the
-subj
option.Ubuntu Openssl Generate Aes Key Generator
-subj arg | Replaces subject field of input request with specified data and outputs modified request. The arg must be formatted as /type0=value0/type1=value1/type2=…, characters may be escaped by (backslash), no spaces are skipped. |
The fields, required in CSR are listed below:
Openssl Encrypt Private Key File
Field | Meaning | Example |
---|---|---|
/C= | Country | GB |
/ST= | State | London |
/L= | Location | London |
/O= | Organization | Global Security |
/OU= | Organizational Unit | IT Department |
/CN= | Common Name | example.com |
You’ve created encoded file with certificate signing request.
Now you can decode CSR to verify that it contains the correct information.