Encrypt and decrypt data in Salesforce using Apex Crypto class.

salesforce_apex_encryption_decryption.cls

// Generate your own initialization vector
Blob iv = Blob.valueOf('Lorem ipsum dolor sit amet');
  
// Generate an AES key
Blob key = Crypto.generateAesKey(256);

// Generate the data to be encrypted
Blob data = Blob.valueof('Encrypt everything!');

// Encrypt the data
Blob encrypted = Crypto.encrypt('AES256', key, iv, data);

// Decrypt the data
Blob decrypted = Crypto.decrypt('AES256', key, iv, encrypted);

// Decode the decrypted data
String decryptedStringData = decrypted.toString();

// Check the authenticity of data
System.assertEquals('Encrypt everything!', decryptedStringData);