java - Security: Write javax.mail.Message to File with Encryption -

i have 'javax.mail.message' object should written file system. use javax.mail (com.sun.mail) version 1.5.5

javax.mail.message message = buildmessage(...); message.writeto(new fileoutputstream("message.plain")); 

now message written file. how can encrypt & decrypt file? post example below, code fails.

my example code:

static byte[] salt = new byte[8]; static {     securerandom random = new securerandom();     random.nextbytes(salt); }  public final void test() throws exception {     message message = buildtestmessage(...);      secretkey secret = encode(message, new fileoutputstream("test.encrypted"), "01234567".tochararray());     message message2 = decode(new fileinputstream("test.encrypted"), "01234567".tochararray());      // out sth. from@domain <--> null     system.out.println(message.getfrom()[0] + " <--> " + message2.getfrom());  }  private message decode(         inputstream mailfileinputstream, char[] password) throws nosuchalgorithmexception, nosuchpaddingexception,         invalidkeyexception, messagingexception, ioexception, invalidkeyspecexception {     /* derive key, given password , salt. */     secretkeyfactory factory = secretkeyfactory.getinstance("pbewithhmacsha256andaes_128");     keyspec spec = new pbekeyspec(password, salt, 65536, 256);     secretkey tmp = factory.generatesecret(spec);     secretkey secret = new secretkeyspec(tmp.getencoded(), "pbewithhmacsha256andaes_128");      cipher cipher = cipher.getinstance("pbewithhmacsha256andaes_128");     cipher.init(cipher.decrypt_mode, secret);             inputstream = new cipherinputstream(mailfileinputstream, cipher);     properties props = new properties();     session session = session.getdefaultinstance(props, null);      message message = new mimemessage(session, );     return message; }  static secretkey encode(         message message,         fileoutputstream out,         char[] password) throws exception {      /* derive key, given password , salt. */     secretkeyfactory factory = secretkeyfactory.getinstance("pbewithhmacsha256andaes_128");     keyspec spec = new pbekeyspec(password, salt, 65536, 256);     secretkey tmp = factory.generatesecret(spec);     secretkey secret = new secretkeyspec(tmp.getencoded(), "pbewithhmacsha256andaes_128");      cipher cipher  = cipher.getinstance("pbewithhmacsha256andaes_128");     cipher.init(cipher.encrypt_mode, secret);      outputstream cos = new cipheroutputstream(out, cipher);     message.writeto(cos);     cos.close();      return secret; } 

additional: upvote question , mark answer accepted. have question ban , no open questions left or no attention questions!

import java.io.bytearrayinputstream; import java.io.bytearrayoutputstream; import java.io.ioexception; import java.io.inputstream; import java.security.invalidalgorithmparameterexception; import java.security.invalidkeyexception; import java.security.nosuchalgorithmexception; import java.security.securerandom; import java.security.spec.invalidkeyspecexception; import java.security.spec.keyspec; import java.util.base64; import java.util.date; import java.util.optional;  import javax.crypto.badpaddingexception; import javax.crypto.cipher; import javax.crypto.illegalblocksizeexception; import javax.crypto.nosuchpaddingexception; import javax.crypto.secretkey; import javax.crypto.secretkeyfactory; import javax.crypto.spec.ivparameterspec; import javax.crypto.spec.pbekeyspec; import javax.crypto.spec.secretkeyspec; import javax.mail.message; import javax.mail.messagingexception; import javax.mail.multipart; import javax.mail.session; import javax.mail.internet.internetaddress; import javax.mail.internet.mimebodypart; import javax.mail.internet.mimemessage; import javax.mail.internet.mimemultipart;  public class stackoverflow {      private static final int keysize = 128;     static byte[] saltforthisrun = new byte[8];     static {         securerandom random = new securerandom();         random.nextbytes(saltforthisrun);     }      public static void main(             string[] args) throws exception {         message message = buildtestmessage("from@null.org", new string[] { "to@null.org", "to2@null.org" },                 "subject needed here", optional.of("this text"), optional.empty());          char[] password = "password".tochararray();         string encryptedmsg = encrypt(password, saltforthisrun, message);         system.out.println("encryptedmsg: " + encryptedmsg);         message message2 = decrypt(password, saltforthisrun, encryptedmsg);          // out sth. from@domain <--> null         system.out.println(message.getfrom()[0] + " <--> " + message2.getfrom()[0]);      }      private static message decrypt(             char[] password,             byte[] salt,             string base64ciphertext) throws encryptionexception {         try {             secretkey secretkey = generatekey(password, salt, keysize);             byte[] initializationvector = createinitializationvector(keysize);              cipher aescipherfordecryption = cipher.getinstance("aes/cbc/pkcs5padding");              aescipherfordecryption.init(cipher.decrypt_mode, secretkey, new ivparameterspec(initializationvector));             byte[] decryptedbyteciphertext = base64.getdecoder().decode(base64ciphertext);             byte[] bytedecryptedmessage = aescipherfordecryption.dofinal(decryptedbyteciphertext);             return createmessagefrombytes(bytedecryptedmessage);         } catch (illegalstateexception | invalidkeyexception | invalidalgorithmparameterexception                 | nosuchalgorithmexception | nosuchpaddingexception | invalidkeyspecexception                 | illegalblocksizeexception | badpaddingexception | messagingexception e) {             throw new encryptionexception(string.format("unable enrypt message due to: %s", e.getmessage()), e);         }     }      /**      *       * @param password      * @param salt      * @param message      * @param chararray      * @return base64 encoded ciphertext      * @throws encryptionexception      *             if sth. goes wrong      */     private static string encrypt(             char[] password,             byte[] salt,             message message) throws encryptionexception {         try {             /**              * step 1. generate aes key password , salt              *               */             secretkey secretkey = generatekey(password, salt, keysize);             system.out.println(secretkey.getencoded().length);              /**              * step 2. generate initialization vector (iv)              * a. use securerandom generate random bits              * size of iv matches blocksize of cipher (e.g. 128 bits aes)              * b. construct appropriate ivparameterspec object data pass cipher's init() method              */             byte[] initializationvector = createinitializationvector(keysize);              /**              * step 3. create cipher specifying following parameters              * a. algorithm name - here aes              * b. mode - here cbc mode              * c. padding - e.g. pkcs7 or pkcs5              *               * must specify mode explicitly jce providers default ecb mode!!              */             cipher aescipherforencryption = cipher.getinstance("aes/cbc/pkcs5padding");              /**              * step 4. initialize cipher encryption              */             aescipherforencryption.init(cipher.encrypt_mode, secretkey, new ivparameterspec(initializationvector));              /**              * step 5. encrypt data              * a. declare / initialize data. here data of type string              * b. convert input text bytes              * c. encrypt bytes using dofinal method              */             byte[] byteciphertext = updatecipherwithmessage(aescipherforencryption, message);             return new string(base64.getencoder().encode(byteciphertext));          } catch (illegalblocksizeexception | badpaddingexception | ioexception | messagingexception                 | invalidkeyexception | invalidalgorithmparameterexception | nosuchalgorithmexception                 | nosuchpaddingexception | invalidkeyspecexception e) {             throw new encryptionexception(string.format("unable enrypt message due to: %s", e.getmessage()), e);         }      }      private static mimemessage createmessagefrombytes(             byte[] decodedbytes) throws messagingexception {         inputstream = new bytearrayinputstream(decodedbytes);         session session = null;         return new mimemessage(session, is);     }      private static byte[] updatecipherwithmessage(             cipher cipher,             message message) throws ioexception, messagingexception, illegalblocksizeexception, badpaddingexception {         bytearrayoutputstream os = new bytearrayoutputstream();         try {             message.writeto(os);             return cipher.dofinal(os.tobytearray());         } {             os.close();         }     }      private static byte[] createinitializationvector(             int keylength) {         // save iv bytes or send in plaintext encrypted data can decrypt data later         byte[] iv = new byte[keylength / 8];          securerandom prng = new securerandom();         prng.nextbytes(iv);         return iv;     }      private static secretkey generatekey(             char[] password,             byte[] salt,             int keysize) throws invalidkeyspecexception, nosuchalgorithmexception {         int niterations = 65536;         secretkeyfactory factory = secretkeyfactory.getinstance("pbkdf2withhmacsha1");         keyspec spec = new pbekeyspec(password, salt, niterations, keysize);         secretkey tmp = factory.generatesecret(spec);         return new secretkeyspec(tmp.getencoded(), "aes");     }      private static message buildtestmessage(             string from,             string[] to,             string subject,             optional<string> text,             optional<string> html) throws exception {         string replyto = from;         session session = null;         message message = new mimemessage(session);         multipart multipart = new mimemultipart("alternative");          try {              if (text.ispresent()) {                 mimebodypart textpart = new mimebodypart();                 textpart.settext(text.get(), "utf-8");                 multipart.addbodypart(textpart);             }             if (html.ispresent()) {                 mimebodypart htmlpart = new mimebodypart();                 htmlpart.setcontent(html, "text/html; charset=utf-8");                 multipart.addbodypart(htmlpart);             }              message.setcontent(multipart);              if (from != null) {                 message.setfrom(new internetaddress(from));             } else                 message.setfrom();              if (replyto != null)                 message.setreplyto(new internetaddress[] { new internetaddress(replyto) });             else                 message.setreplyto(new internetaddress[] { new internetaddress(from) });              internetaddress[] toaddresses = new internetaddress[to.length];             (int = 0; < toaddresses.length; i++) {                 toaddresses[i] = new internetaddress(to[i]);             }             message.setrecipients(message.recipienttype.to, toaddresses);             message.setsubject(subject);             message.setsentdate(new date());              return message;          } catch (exception e) {             e.printstacktrace();             system.out.println("exception: " + e.getmessage());             throw e;          }      }  }