Matlab AES Encryption Decryption Example

Advanced Encryption Standard helper class.

AES Encryption Decryption Example, works for strings and for structures.

Based on: https://howtodoinjava.com/security/java-aes-encryption-example/

"Data Encryption Standard (DES) encryption algorithm is considered highly insecure; messages encrypted using DES have been decrypted by brute force within a single day by machines such as the Electronic Frontier Foundation’s (EFF) Deep Crack."

"A more secure encryption algorithm is AES – Advanced Encryption Standard which is a symmetric encryption algorithm. AES encryption is used by U.S. for securing sensitive but unclassified material, so we can say it is secure enough."

1. AES Encryption and Decryption
Let’s see an example of using AES encryption in Matlab program.

classdef AES < handle
%UNTITLED Summary of this class goes here
% Detailed explanation goes here

properties (Access = private)
secretKey
cipher
end

methods
function obj = AES(secret, algorithm)
%AES Construct an instance of this class
% algorithm options are https://docs.oracle.com/javase/9/docs/specs/security/standard-names.html#messagedigest-algorithms
import java.security.MessageDigest;
import java.lang.String;
import java.util.Arrays;
import javax.crypto.Cipher;

key = String(secret).getBytes("UTF-8");
sha = MessageDigest.getInstance(algorithm);
key = sha.digest(key);
key = Arrays.copyOf(key, 16);
obj.secretKey = javaObject('javax.crypto.spec.SecretKeySpec',key, "AES");
obj.cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
end

function encrypted = encrypt(obj, strToEncrypt)
%ENCRYPT Summary of this method goes here
% Detailed explanation goes here
import java.util.Base64;
import java.lang.String;
import javax.crypto.Cipher;

obj.cipher.init(Cipher.ENCRYPT_MODE, obj.secretKey);
encrypted = string(Base64.getEncoder().encodeToString(obj.cipher.doFinal(String(strToEncrypt).getBytes("UTF-8"))));
end

function encrypted = encryptStructuredData(obj, structuredData)
encrypted = obj.encrypt(jsonencode(structuredData));
end

function decrypted = decryptStructuredData(obj, encryptedStructuredData)
decrypted = jsondecode(obj.decrypt(encryptedStructuredData));
end

function decrypted = decrypt(obj, strToDecrypt)
%DECRYPT Summary of this method goes here
% Detailed explanation goes here
import javax.crypto.Cipher;
import java.lang.String;
import java.util.Base64;

obj.cipher.init(Cipher.DECRYPT_MODE, obj.secretKey);
decrypted = string(String(obj.cipher.doFinal(Base64.getDecoder().decode(strToDecrypt))));
end
end
end

2. Encryption and decryption example
Let’s test if we are able to get the decrypted string back from encrypted string.

secretKey = "ssshhhhhhhhhhh!!!!";
algorithm = "SHA-1";
aes = AES(secretKey, algorithm);

originalString = "howtodoinjava.com";
encryptedString = aes.encrypt(originalString);
decryptedString = aes.decrypt(encryptedString) ;

disp(originalString);
disp(encryptedString);
disp(decryptedString);

Output:

howtodoinjava.com
Tg2Nn7wUZOQ6Xc+1lenkZTQ9ZDf9a2/RBRiqJBCIX6o=
howtodoinjava.com

Use the following functions for Matlab structures:
- encryptStructuredData(structureToEncrypt)
- decryptStructuredData(encryptedStructure)

Drop me your question and comments below.
Happy Learning !!