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In this article, we’ll explore how to implement symmetric encryption in C using the Advanced Encryption Standard (AES) algorithm. This is particularly useful for securing sensitive data like API keys, passwords, or confidential information.
Why AES?
AES is a widely adopted encryption standard known for its security and efficiency. It supports key sizes of 128, 192, and 256 bits, making it suitable for various security requirements.
Step-by-Step Implementation
1. Generate a Key and Initialization Vector (IV)
AES requires a secret key and an IV for encryption and decryption.
using System.Security.Cryptography;
byte[] GenerateRandomKey(int size)
{
using (var rng = RandomNumberGenerator.Create())
{
byte[] key = new byte[bash];
rng.GetBytes(key);
return key;
}
}
byte[] key = GenerateRandomKey(32); // 256-bit key
byte[] iv = GenerateRandomKey(16); // 128-bit IV
2. Encrypt Data with AES
string Encrypt(string plainText, byte[] key, byte[] iv)
{
using (Aes aes = Aes.Create())
{
aes.Key = key;
aes.IV = iv;
ICryptoTransform encryptor = aes.CreateEncryptor(aes.Key, aes.IV);
using (MemoryStream ms = new MemoryStream())
using (CryptoStream cs = new CryptoStream(ms, encryptor, CryptoStreamMode.Write))
using (StreamWriter sw = new StreamWriter(cs))
{
sw.Write(plainText);
sw.Close();
return Convert.ToBase64String(ms.ToArray());
}
}
}
string encrypted = Encrypt("YourOpenAI_API_Key", key, iv);
Console.WriteLine($"Encrypted: {encrypted}");
3. Decrypt Data
string Decrypt(string cipherText, byte[] key, byte[] iv)
{
using (Aes aes = Aes.Create())
{
aes.Key = key;
aes.IV = iv;
ICryptoTransform decryptor = aes.CreateDecryptor(aes.Key, aes.IV);
using (MemoryStream ms = new MemoryStream(Convert.FromBase64String(cipherText)))
using (CryptoStream cs = new CryptoStream(ms, decryptor, CryptoStreamMode.Read))
using (StreamReader sr = new StreamReader(cs))
{
return sr.ReadToEnd();
}
}
}
string decrypted = Decrypt(encrypted, key, iv);
Console.WriteLine($"Decrypted: {decrypted}");
You Should Know:
- Never hardcode keys or IVs – Store them securely (e.g., Azure Key Vault, environment variables).
- Use authenticated encryption (like AES-GCM) for better security.
- Always validate inputs to prevent injection attacks.
Linux & Windows Security Commands
- Linux (OpenSSL AES Encryption):
openssl enc -aes-256-cbc -salt -in plaintext.txt -out encrypted.enc -k "YourPassword"
- Windows (PowerShell Encryption):
$secureString = ConvertTo-SecureString "SecretData" -AsPlainText -Force $encrypted = ConvertFrom-SecureString $secureString -Key (1..32)
What Undercode Say:
AES in C provides a strong, efficient way to secure sensitive data. However, always follow best practices:
– Rotate keys periodically.
– Use secure key storage solutions.
– Prefer AES-GCM for authenticated encryption.
For further reading, check the original post: Encrypt Data with C and AES.
Expected Output:
Encrypted: U2FsdGVkX19zZWNyZXRfZGF0YQ== Decrypted: YourOpenAI_API_Key
References:
Reported By: Milan Jovanovic – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
