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POBadPaddingException in Android encrypt
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copied!<p>I am making an Android application and I want to encrypt a String before sending it to a DataBase, and encrytpion is correct. The problem happens when decrypting the String because I get a BadPaddingException and I have no idea where the problem is. Here is the code:</p> <pre><code>public final static String HEX = "36A52C8FB7DF9A3F"; public static String encrypt(String seed, String cleartext) throws Exception { byte[] rawKey = getRawKey(seed.getBytes()); byte[] result = encrypt(rawKey, cleartext.getBytes()); return toHex(result); } public static String decrypt(String seed, String encrypted) throws Exception { byte[] rawKey = getRawKey(seed.getBytes()); byte[] enc = toByte(encrypted); byte[] result = decrypt(rawKey, enc); return new String(result); } public static String toHex(String txt) { return toHex(txt.getBytes()); } public static String fromHex(String hex) { return new String(toByte(hex)); } public static byte[] toByte(String hexString) { int len = hexString.length()/2; byte[] result = new byte[len]; for (int i = 0; i < len; i++) result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16).byteValue(); return result; } public static String toHex(byte[] buf) { if (buf == null) return ""; StringBuffer result = new StringBuffer(2*buf.length); for (int i = 0; i < buf.length; i++) { appendHex(result, buf[i]); } return result.toString(); } private static byte[] getRawKey(byte[] seed) throws Exception { KeyGenerator kgen = KeyGenerator.getInstance("AES"); SecureRandom sr = SecureRandom.getInstance("SHA1PRNG"); sr.setSeed(seed); kgen.init(128, sr); // 192 and 256 bits may not be available SecretKey skey = kgen.generateKey(); byte[] raw = skey.getEncoded(); return raw; } 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; } private static void appendHex(StringBuffer sb, byte b) { sb.append(HEX.charAt((b>>4)&0x0f)).append(HEX.charAt(b&0x0f)); } </code></pre> <p>I encrypt and decrypt with this code:</p> <pre><code>String encrypted = encrypt(HEX, "some text"); String decrypted = decrypt(HEX, encrypted); </code></pre> <p>Can anyone help me please?</p> <p>Thank you very much!!</p> <p><strong>EDIT:</strong> Problem is not solved, but I have a bit more information. First of all, I encrypt in a Java project, and I decrypt in an Android project. I have tried to decrypt in the same Java project, and there is no problem, but if I try to decrypt in Android, it doesn't work. The problem is in method "getRawKey" (look at the kgen.generateKey() comment):</p> <p><strong>JAVA:</strong></p> <pre><code>private static byte[] getRawKey(byte[] seed) throws Exception { KeyGenerator kgen = KeyGenerator.getInstance("AES"); SecureRandom sr = SecureRandom.getInstance("SHA1PRNG"); sr.setSeed(seed); //Seed: [51, 54, 65, 53, 50, 67, 56, 70, 66, 55, 68, 70, 57, 65, 51, 70] kgen.init(128, sr); // 192 and 256 bits may not be available SecretKey skey = kgen.generateKey(); //skey.key = [-97, -52, 45, -95, -64, -58, 16, -20, 124, -50, -104, 58, 23, -75, 88, 94] byte[] raw = skey.getEncoded(); return raw; } </code></pre> <p><strong>ANDROID:</strong></p> <pre><code>private static byte[] getRawKey(byte[] seed) throws Exception { KeyGenerator kgen = KeyGenerator.getInstance("AES"); SecureRandom sr = SecureRandom.getInstance("SHA1PRNG"); sr.setSeed(seed); //Seed: [51, 54, 65, 53, 50, 67, 56, 70, 66, 55, 68, 70, 57, 65, 51, 70] kgen.init(128, sr); // 192 and 256 bits may not be available SecretKey skey = kgen.generateKey(); //skey.key = [-114, 32, 16, -52, -81, 125, -88, 88, -76, 20, -117, -11, 33, -61, 32, -91] byte[] raw = skey.getEncoded(); return raw; } </code></pre> <p>I am not a crypt expert, but how can be possible that with the same seed, I get a different key??</p>

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