Security- decrypting in java "BadPaddingException" -

i'm encrypting strings , writing them text file. in order decrypt content, i'm reading file , print decrypted data. when tested code 1 string value, encrypted , decrypted fine; however, when added more strings encrypt, encryption worked fine decryption gave me exception "javax.crypto.badpaddingexception: given final block not padded "

this code. please help!

// these initialized in main secretkey key = keygenerator.getinstance("des").generatekey();             algorithmparameterspec paramspec = new ivparameterspec(iv);             ecipher = cipher.getinstance("des/cbc/pkcs5padding");             dcipher = cipher.getinstance("des/cbc/pkcs5padding");             ecipher.init(cipher.encrypt_mode, key, paramspec);             dcipher.init(cipher.decrypt_mode, key, paramspec); // catches ..  // take string , file have encrypted strings private static void encrypt(string s, outputstream os) throws illegalblocksizeexception, badpaddingexception {         try {             byte[] buf = s.getbytes();             byte[] b = ecipher.dofinal(buf);             os.write(b); // write new line after writing each encrypted value , avoid overwriting             os.write(system.getproperty("line.separator").getbytes());              os.flush();             os.close();         }     catch (ioexception e) {         system.out.println("i/o error:" + e.getmessage());     } } // take file has of encryptions private static void decrypt(inputstream is) throws illegalblocksizeexception, badpaddingexception {     try {         byte[] buf = new byte[is.available()];         is.read(buf);         byte[] decrypted = dcipher.dofinal(buf);  // cause of problem!!!!         system.out.println(new string (decrypted));         is.close();     }     catch (ioexception e) {         system.out.println("i/o error:" + e.getmessage());     } 

when encrypting, you're writing encrypted data output file adding newline, when decrypting, seem reading entire contents of file , decrypting it, include newline character attempt decrypt if part of ciphertext, causing padding exception. you're attempting decrypt of separately written strings using single decrypt call, whereas need decrypted individually.

i suggest converting encrypted data base64 before writing output file , appending newline. when decrypting, read line, convert base64 byte[] , decrypt, repeat each line in input.