OpenSSL

OpenSSL Version 1.1.1

Encryption for:
- data
- communication
- traffic
- secret
- signing
plain --> cipher

Types of encryption

Symmetric encryption ==> Same key for encrypt/decrypt
 Algorithms examples:
 - AES
 - DES
 - Triple DES
 - Serpent
 - Twofish

Asymmetric encryption ==> Different key for encrypt/decrypt
 Algorithms examples:
 - RSA
 - DSA
 - PGP
 - SHA-1
 - SHA-2
 - SHA-24
 - SHA-256
 - SHA-512

$ whereis openssl
$ which openssl

$ openssl version
$ openssl help
$ openssl help list
$ openssl list -help
 Valid options are:
 -help                   Display this summary
 -1                      List in one column
 -commands               List of standard commands
 -digest-commands        List of message digest commands
 -digest-algorithms      List of message digest algorithms
 -cipher-commands        List of cipher commands
 -cipher-algorithms      List of cipher algorithms
 -public-key-algorithms  List of public key algorithms
 -public-key-methods     List of public key methods
 -disabled               List of disabled features
 -missing-help           List missing detailed help strings
 -options val            List options for specified command

$ openssl rsautl

Symmetric 
 encryption
 $ openssl enc -aes-256-cbc -in sslmessage -out sslmessage.enc

decryption
 $ openssl enc -aes-256-cbc -d -in sslmessage -pass pass:test

 Asymmetric 
generate private key 
$ openssl genrsa -out key1.pem 512
$ openssl genrsa -out key1.pem 4096

generate public key from private key
$ openssl rsa -in key1.pem -outform PEM -pubout -out key1.pub

$ openssl rsa -in key1.pem  -text
$ openssl rsa -in key1.pem  -noout

Encrypt
$ openssl rsa -in key1.pem -des3 -out key1.enc
$ openssl genrsa -des3 -out key1.enc