Système cryptagraphique AES GCM 256

app/src/main/java/lightcontainer/utils/AES_GCM.java

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+package lightcontainer.utils;
+
+import javax.crypto.Cipher;
+import javax.crypto.KeyGenerator;
+import javax.crypto.SecretKey;
+import javax.crypto.spec.GCMParameterSpec;
+import javax.crypto.spec.SecretKeySpec;
+import java.security.NoSuchAlgorithmException;
+import java.security.SecureRandom;
+import java.util.Base64;
+
+public class AES_GCM {
+    // Constants
+    public static final int AES_KEY_SIZE = 256;
+    public static final int GCM_IV_LENGTH = 16;
+    public static final int GCM_TAG_LENGTH = 16;
+
+    public static void main(String[] args) throws Exception
+    {
+        // Text pour test :
+        String plainText = "salut fils de pute";
+
+        String IV = generateIV();
+        String key = generateSecretKey();
+
+        System.out.println("Original Text : " + plainText);
+
+        byte[] cipherText = encrypt(plainText.getBytes(), key, IV);
+        System.out.println("Encrypted Text : " + Base64.getEncoder().encodeToString(cipherText));
+
+        String decryptedText = decrypt(cipherText, key, IV);
+        System.out.println("DeCrypted Text : " + decryptedText);
+    }
+
+    /**
+     * Decoder to decode base64 vector to byte vector.
+     * @param base64Vector A base64 encoded vector.
+     * @return Byte vector.
+     */
+    private static byte[] decodeBase64(String base64Vector) {
+        Base64.Decoder b64Decoder = Base64.getDecoder();
+        return b64Decoder.decode(base64Vector);
+    }
+
+    /**
+     * Encoder to encode vector to base64 string.
+     * @param rawVector A raw vector.
+     * @return A base64 encoded vector.
+     */
+    private static String encodeBase64(byte[] rawVector) {
+        Base64.Encoder b64Encoder = Base64.getEncoder();
+        return b64Encoder.encodeToString(rawVector);
+    }
+
+    /**
+     * Generate a secret key base64 encoded.
+     * @return New Secret key b64 encoded.
+     */
+    public static String generateSecretKey() throws NoSuchAlgorithmException {
+        KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
+        keyGenerator.init(AES_KEY_SIZE);
+        SecretKey key = keyGenerator.generateKey();
+        return encodeBase64(key.getEncoded());
+    }
+
+    /**
+     * Generate an IV (initialisation vector) base64 encoded.
+     * @return New generated IV b64 encoded.
+     */
+    public static String generateIV() {
+        byte[] IV = new byte[GCM_IV_LENGTH];
+        SecureRandom random = new SecureRandom();
+        random.nextBytes(IV);
+        return encodeBase64(IV);
+    }
+
+    /**
+     * Encrypt, with AES GCM.
+     * @param plainContent Content to encrypt.
+     * @param key Base64 encoded secret key.
+     * @param IV Base64 encoded vector.
+     * @return The encrypted cipherContent.
+     */
+    public static byte[] encrypt(byte[] plainContent, String key, String IV) throws Exception
+    {
+        // Get Cipher Instance
+        Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
+
+        // Create SecretKeySpec
+        SecretKeySpec keySpec = new SecretKeySpec(decodeBase64(key), "AES");
+
+        // Create GCMParameterSpec
+        GCMParameterSpec gcmParameterSpec = new GCMParameterSpec(GCM_TAG_LENGTH * 8, decodeBase64(IV));
+
+        // Initialize Cipher for ENCRYPT_MODE
+        cipher.init(Cipher.ENCRYPT_MODE, keySpec, gcmParameterSpec);
+
+        // Perform Encryption
+        return cipher.doFinal(plainContent);
+    }
+
+    /**
+     * Decrypt, with AES GCM.
+     * @param cipherContent The encrypted cipherContent
+     * @param key Base64 encoded secret key.
+     * @param IV Base64 encoded vector.
+     * @return The decrypted plainContent.
+     */
+        public static String decrypt(byte[] cipherContent, String key, String IV) throws Exception
+    {
+        // Get Cipher Instance
+        Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
+
+        // Create SecretKeySpec
+        SecretKeySpec keySpec = new SecretKeySpec(decodeBase64(key), "AES");
+
+        // Create GCMParameterSpec
+        GCMParameterSpec gcmParameterSpec = new GCMParameterSpec(GCM_TAG_LENGTH*8, decodeBase64(IV));
+
+        // Initialize Cipher for DECRYPT_MODE
+        cipher.init(Cipher.DECRYPT_MODE, keySpec, gcmParameterSpec);
+
+        // Perform Decryption
+        return new String(cipher.doFinal(cipherContent));
+    }
+}