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- Use Openssl To Generate Key Pair
- Openssl Commands For Creating Private Key
- Openssl Command To Generate Symmetric Key
Sep 28, 2017 Symmetric-Key Encryption using openSSL September 28, 2017 October 2, 2017 buddie-බුඩී 2 Comments I wrote few blog posts on Asymmetric Key encryption using PHPSecLib library recently and this blog post is on Symmetric-Key Encryption and I ll be using PHP openSSL. Generating Keys for Encryption and Decryption.; 3 minutes to read +7; In this article. Creating and managing keys is an important part of the cryptographic process. Symmetric algorithms require the creation of a key and an initialization vector (IV). The key must be kept secret from anyone who should not decrypt your data. OpenSSL is a C library that implements the main cryptographic operations like symmetric encryption, public-key encryption, digital signature, hash functions and so on. OpenSSL also implements obviously the famous Secure Socket Layer (SSL) protocol. OpenSSL is avaible for a wide variety of platforms. How to Generate a Symmetric Key by Using the dd Command Determine the key length that your algorithm requires. Generate the symmetric key.% dd if=/dev/urandom of= keyfile bs= n count= n. Store your key in a protected directory. The key file should not be readable by anyone but the user.% chmod. 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.
How to Generate a Symmetric Key byUsing the dd Command
A key is needed to encrypt files and to generate the MAC of a file.The key should be derived from a random pool of numbers.
If your site has a random number generator,use the generator. Otherwise, you can use the dd commandwith the Solaris /dev/urandom device as input. For moreinformation, see the dd(1M) manpage.
- Determine the key length that your algorithm requires.
- Listthe available algorithms.
- Determine the key length in bytes to pass to the dd command.Divide the minimum and maximum key sizes by 8. When the minimumand maximum key sizes are different, intermediate key sizes are possible.For example, the value 8, 16, or 64 can be passed to the dd commandfor the sha1_hmac and md5_hmac functions.
- Generate the symmetric key.
- if=file
- Is the input file. For a random key, use the /dev/urandom file.
- of=keyfile
- Is the output file that holds the generated key.
- bs=n
- Is the key size in bytes. For the length in bytes, dividethe key length in bits by 8.
- count=n
- Is the count of the input blocks. The number for n shouldbe 1.
- Store your key in a protected directory.The key fileshould not be readable by anyone but the user.
Example 14–1 Creating a Key for the AES Algorithm
In the following example, a secret key for the AES algorithm is created.The key is also stored for later decryption. AES mechanisms use a 128-bitkey. The key is expressed as 16 bytes in the dd command.
Use Openssl To Generate Key Pair
Example 14–2 Creating a Key for the DES Algorithm
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In the following example, a secret key for the DES algorithm is created.The key is also stored for later decryption. DES mechanisms use a 64-bit key.The key is expressed as 8 bytes in the dd command.
Example 14–3 Creating a Key for the 3DES Algorithm
In the following example, a secret key for the 3DES algorithm is created.The key is also stored for later decryption. 3DES mechanisms use a 192-bitkey. The key is expressed as 24 bytes in the dd command.
Openssl Commands For Creating Private Key
Example 14–4 Creating a Key for the MD5 Algorithm
In the following example, a secret key for the MD5 algorithm is created.The key is also stored for later decryption. The key is expressed as 64 bytesin the dd command.