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copied!<h2>Warning: This answer contains code you should not use as it is insecure (using SHA1PRNG for key derivation and using AES in ECB mode)</h2> <h2>Instead, use PBKDF2WithHmacSHA1 for key derivation and AES in CBC or GCM mode (GCM provides both privacy and integrity)</h2> <p>You could use functions like these:</p> <pre><code>private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception { SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES"); Cipher cipher = Cipher.getInstance("AES"); cipher.init(Cipher.ENCRYPT_MODE, skeySpec); byte[] encrypted = cipher.doFinal(clear); return encrypted; } private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception { SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES"); Cipher cipher = Cipher.getInstance("AES"); cipher.init(Cipher.DECRYPT_MODE, skeySpec); byte[] decrypted = cipher.doFinal(encrypted); return decrypted; } </code></pre> <p>And invoke them like this:</p> <pre><code>ByteArrayOutputStream baos = new ByteArrayOutputStream(); bm.compress(Bitmap.CompressFormat.PNG, 100, baos); // bm is the bitmap object byte[] b = baos.toByteArray(); byte[] keyStart = "this is a key".getBytes(); KeyGenerator kgen = KeyGenerator.getInstance("AES"); SecureRandom sr = SecureRandom.getInstance("SHA1PRNG"); sr.setSeed(keyStart); kgen.init(128, sr); // 192 and 256 bits may not be available SecretKey skey = kgen.generateKey(); byte[] key = skey.getEncoded(); // encrypt byte[] encryptedData = encrypt(key,b); // decrypt byte[] decryptedData = decrypt(key,encryptedData); </code></pre> <p>This should work, I use similar code in a project right now.</p>

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