Symmetric Encryption and Decryption with a key file
Generate a random 256-bit key To generate a random 256-bit key using /dev/urandom, you can directly extract the random data without the need for additional hashing. Here’s how you can do it: $ dd if=/dev/urandom of=/path/to/your/keyfile bs=1 count=32 In this command: if=/dev/urandom specifies the input source as /dev/urandom. of=/path/to/your/keyfile specifies the output file where your key will be saved. bs=1 sets the block size to 1 byte. count=32 specifies that we want 32 bytes (256 bits) of random data. Example: $ dd if=/dev/urandom of=symmetric_keyfile.key bs=1 count=32 Encryption We can use this command to encrypt the sample.txt file: $ openssl enc -in sample.txt -out sample.txt.enc -e -aes256 -pbkdf2 -kfile symmetric_keyfile.key Decryption $ openssl enc -in sample.txt.enc -out sample_decrypted.txt -d -aes256 -pbkdf2 -kfile symmetric_keyfile.key