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copied!<p>Got some help from <a href="http://oogifu.blogspot.com/2009/01/aes-in-java-and-c.html" rel="noreferrer">http://oogifu.blogspot.com/2009/01/aes-in-java-and-c.html</a>.</p> <p>Here is my Java class:</p> <pre><code>package com.neocodenetworks.smsfwd; import java.security.*; import javax.crypto.*; import javax.crypto.spec.*; import android.util.Log; public class Crypto { public static final String TAG = "smsfwd"; private static Cipher aesCipher; private static SecretKey secretKey; private static IvParameterSpec ivParameterSpec; private static String CIPHER_TRANSFORMATION = "AES/CBC/PKCS5Padding"; private static String CIPHER_ALGORITHM = "AES"; // Replace me with a 16-byte key, share between Java and C# private static byte[] rawSecretKey = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}; private static String MESSAGEDIGEST_ALGORITHM = "MD5"; public Crypto(String passphrase) { byte[] passwordKey = encodeDigest(passphrase); try { aesCipher = Cipher.getInstance(CIPHER_TRANSFORMATION); } catch (NoSuchAlgorithmException e) { Log.e(TAG, "No such algorithm " + CIPHER_ALGORITHM, e); } catch (NoSuchPaddingException e) { Log.e(TAG, "No such padding PKCS5", e); } secretKey = new SecretKeySpec(passwordKey, CIPHER_ALGORITHM); ivParameterSpec = new IvParameterSpec(rawSecretKey); } public String encryptAsBase64(byte[] clearData) { byte[] encryptedData = encrypt(clearData); return net.iharder.base64.Base64.encodeBytes(encryptedData); } public byte[] encrypt(byte[] clearData) { try { aesCipher.init(Cipher.ENCRYPT_MODE, secretKey, ivParameterSpec); } catch (InvalidKeyException e) { Log.e(TAG, "Invalid key", e); return null; } catch (InvalidAlgorithmParameterException e) { Log.e(TAG, "Invalid algorithm " + CIPHER_ALGORITHM, e); return null; } byte[] encryptedData; try { encryptedData = aesCipher.doFinal(clearData); } catch (IllegalBlockSizeException e) { Log.e(TAG, "Illegal block size", e); return null; } catch (BadPaddingException e) { Log.e(TAG, "Bad padding", e); return null; } return encryptedData; } private byte[] encodeDigest(String text) { MessageDigest digest; try { digest = MessageDigest.getInstance(MESSAGEDIGEST_ALGORITHM); return digest.digest(text.getBytes()); } catch (NoSuchAlgorithmException e) { Log.e(TAG, "No such algorithm " + MESSAGEDIGEST_ALGORITHM, e); } return null; } } </code></pre> <p>I used <a href="http://iharder.sourceforge.net/current/java/base64/" rel="noreferrer">http://iharder.sourceforge.net/current/java/base64/</a> for the base64 encoding.</p> <p>Here's my C# class:</p> <pre><code>using System; using System.Text; using System.Security.Cryptography; namespace smsfwdClient { public class Crypto { private ICryptoTransform rijndaelDecryptor; // Replace me with a 16-byte key, share between Java and C# private static byte[] rawSecretKey = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}; public Crypto(string passphrase) { byte[] passwordKey = encodeDigest(passphrase); RijndaelManaged rijndael = new RijndaelManaged(); rijndaelDecryptor = rijndael.CreateDecryptor(passwordKey, rawSecretKey); } public string Decrypt(byte[] encryptedData) { byte[] newClearData = rijndaelDecryptor.TransformFinalBlock(encryptedData, 0, encryptedData.Length); return Encoding.ASCII.GetString(newClearData); } public string DecryptFromBase64(string encryptedBase64) { return Decrypt(Convert.FromBase64String(encryptedBase64)); } private byte[] encodeDigest(string text) { MD5CryptoServiceProvider x = new System.Security.Cryptography.MD5CryptoServiceProvider(); byte[] data = Encoding.ASCII.GetBytes(text); return x.ComputeHash(data); } } } </code></pre> <p>I really hope this helps someone else!</p>

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