Input length must be multiple of 16 when decrypting with padded cipher

Question

I have a server and client socket program  a server send a encrypted message to client  i e   the server side code    cipher2   Cipher getInstance  AES     secretKeySpec   new SecretKeySpec decryptedText   AES    cipher2 init Cipher ENCRYPT MODE  secretKeySpec   feedback    Your answer is wrong  getBytes    cipher2 doFinal feedback   dos writeInt feedback length   dos write feedback     the client side code   int result len   0  result len   din readInt                byte   result Bytes   new byte result len   din readFully result Bytes   cipher2   Cipher getInstance  AES    cipher2 init Cipher DECRYPT MODE  aesKey                byte   encrypt   cipher2 doFinal result Bytes     Exception throw at byte   encrypt   cipher2 doFinal result Bytes    javax crypto IllegalBlockSizeException  Input length must be multiple of 16 when decrypting with padded cipher     at com sun crypto provider CipherCore doFinal CipherCore java 750      at com sun crypto provider CipherCore doFinal CipherCore java 676      at com sun crypto provider AESCipher engineDoFinal AESCipher java 313      at javax crypto Cipher doFinal Cipher java 2086    what is the problem

User · Answer

Have a look at this answer  Encrypt and decrypt with AES and Base64 encoding

User · Answer

This is a very old question  but my answer may help someone     In the encrypt method  don t forget to encode your string to Base64 In the decrypt method  don t forget to decode your string to Base64   Below is the working code      import java util Arrays      import java util Base64       import javax crypto Cipher      import javax crypto SecretKey      import javax crypto spec SecretKeySpec       public class EncryptionDecryptionUtil        public static String encrypt final String secret  final String data              byte   decodedKey   Base64 getDecoder   decode secret            try               Cipher cipher   Cipher getInstance  AES                   rebuild key using SecretKeySpec             SecretKey originalKey   new SecretKeySpec Arrays copyOf decodedKey  16    AES                cipher init Cipher ENCRYPT MODE  originalKey               byte   cipherText   cipher doFinal data getBytes  UTF-8                 return Base64 getEncoder   encodeToString cipherText             catch  Exception e                throw new RuntimeException                       Error occured while encrypting data   e                         public static String decrypt final String secret              final String encryptedString              byte   decodedKey   Base64 getDecoder   decode secret            try               Cipher cipher   Cipher getInstance  AES                   rebuild key using SecretKeySpec             SecretKey originalKey   new SecretKeySpec Arrays copyOf decodedKey  16    AES                cipher init Cipher DECRYPT MODE  originalKey               byte   cipherText   cipher doFinal Base64 getDecoder   decode encryptedString                return new String cipherText             catch  Exception e                throw new RuntimeException                       Error occured while decrypting data   e                         public static void main String   args             String data    This is not easy as you think           String key    ---------------------------------           String encrypted   encrypt key  data           System out println encrypted           System out println decrypt key  encrypted                  For Generating Key you can use below class      import java security NoSuchAlgorithmException  import java security SecureRandom  import java util Base64   import javax crypto KeyGenerator  import javax crypto SecretKey   public class SecretKeyGenerator        public static void main String   args  throws NoSuchAlgorithmException            KeyGenerator keyGenerator   KeyGenerator getInstance  AES             SecureRandom secureRandom   new SecureRandom            int keyBitSize   256          keyGenerator init keyBitSize  secureRandom            SecretKey secretKey   keyGenerator generateKey      System out println Base64 getEncoder   encodeToString secretKey getEncoded

User · Answer

I know this message is old and was a long time ago - but i also had problem with  with the exact same error   the problem I had was relates to the fact the encrypted text was converted to String and to byte   when trying to DECRYPT it       private Key getAesKey   throws Exception       return new SecretKeySpec Arrays copyOf key getBytes  UTF-8    16    AES       private Cipher getMutual   throws Exception       Cipher cipher   Cipher getInstance  AES        return cipher    cipher doFinal pass getBytes        public byte   getEncryptedPass String pass  throws Exception       Cipher cipher   getMutual        cipher init Cipher ENCRYPT MODE  getAesKey         byte   encrypted   cipher doFinal pass getBytes  UTF-8         return encrypted      public String getDecryptedPass byte   encrypted  throws Exception       Cipher cipher   getMutual        cipher init Cipher DECRYPT MODE  getAesKey         String realPass   new String cipher doFinal encrypted        return realPass

User · Answer

Had a similar issue  But it is important to understand the root cause and it may vary for different use cases   Scenario 1 You are trying to decrypt a value which was not encoded correctly in the first place   byte   encryptedBytes   Base64 decodeBase64 encryptedBase64String     If the String is misconfigured for certain reason or has not been encoded correctly  you would see the error   Input length must be multiple of 16 when decrypting with padded cipher   Scenario 2 Now if by any chance you are using this encoded string in url  trying to pass in the base64Encoded value in url  it will fail  You should do URLEncoding and then pass in the token  it will work   Scenario 3 When integrating with one of the vendors  we found that we had to do encryption of Base64 using URLEncoder but then we need not decode it because it was done internally by the Vendor

[java] Input length must be multiple of 16 when decrypting with padded cipher

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