I have an Android application that communicates with another java application. For the data encryption i use the javax.crypto library to encrypt and decrypt the data with a pre-shared key.
According to this question it's possible to get the source code from an APK file. So if somebody is able to read the source code of my application, he's also able to read/manipulate the encrypted data.
It's probably true, so is there a way to prevent this (additional measures, other security method)? Don't know if it have extra value but here is my encryption code:
private static String IV = "AAAAAAAAAAAAAAAA";
private static String ENCRYPTION_KEY = "0123456789abcdef";
Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
SecretKeySpec key = new SecretKeySpec(ENCRYPTION_KEY.getBytes("UTF-8"), "AES");
cipher.init(Cipher.ENCRYPT_MODE, key,new IvParameterSpec(IV.getBytes("UTF-8")));
return cipher.doFinal(input.getBytes("UTF-8"));
EDIT:
Communication is send and recieving by NFC. My main issue is, if someone has the key he's able to read and write (abused) information to the other side (the NFC reader)
The pre-shared key is not safe!
For someone with just little java reverse engineering skills it is a job of five minutes to decompile your APK file and extracting the key. Once this has been done your crypto is effectively useless.
The standard approach to fix this is to use a key agreement algorithm. You can for example use the Diffie-Hellman key exchange to quickly and secure generate a common secret between two devices: Wikipedia on Diffie-Hellman
Build a hash from the generated common secret and use this as your AES encryption key for this session is a lot more secure and doesn't take much work.
If NFC is your transport layer you need bidirectional data exchanges for Diffie-Hellman to work. Therefore Android Beam will not be usable for you. You can however do bidirectinal data-transfer using host based card emulation on one phone and reader/writer mode on the other.
Using encryption when transmitting data over NFC is a good idea by the way, also the communication range is limited to some few centimeters, you can still sniff the communication from a few meters distance. NFC doesn't do any encryption for you.
A last word of warning: Cryptography is hard to do in practice. Before you send out anything of value over a cryptographic link please make sure that you have a good understanding of what you do. I recommend reading this book which is a good and practical introduction of cryptography: Bruce Schneider - Cryptography Engineering
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What will be the most secure way in java to Pass username and password encrypted between 2 backend systems written in Java behind the vpn?
The goal will be that if the username and password encrypted being captured by someone, it could never be decrypted.
Theoritically speaking, asymmetric encryption tools are used for transporting confidential data. Every node/client will has a pair of keys that one of them is private and only known by itself, and the other one is public and should be known by everbody that wants to send confidential data to that particular node. The thing is, if a payload data is encrypted with the public key of the client X, it can only be decrypted with the private key of the client X.
Protocols like SSL, TLS, etc. are some widely used implementations of that concept.
assuming you can control both servers in an un-monitored manner(or at least not monitored by the intruder) and could implement any code on both servers then:
you can write your own made up protocol and its encryption algorithms on both systems and use it to share your data between your two systems.
this way the intruder would have no clue what the captured data even is or how to interpret them.
since you said 'Never be decrypted' your protocol could use an encryption key which is already defined on both servers and is not exchanged between them(over a handshake for example) and could use an encryption algorithm which doesn't store any encryption key validation in the transmitted data(like padding or hash etc) and of course shouldn't exchange the encryption algorithm.
it is worth noting that ssl/tls or any other protocol which expose their encryption algorithm and exchange encryption keys used are bad ideas to reach your goal since these protocols are prone to be deciphered if certain portions of their traffic are captured.
The SHA (Secure Hash Algorithm) is one of the popular cryptographic hash functions. A cryptographic hash can be used to make a signature for a text or a data file.
The SHA-256 algorithm generates an almost-unique, fixed-size 256-bit (32-byte) hash. This is a one-way function, so the result cannot be decrypted back to the original value.
Currently, SHA-2 hashing is widely used as it is being considered as the most secure hashing algorithm in the cryptographic arena.
A few library like Guava or Apache commons codec provide the functions.
In your case, I suggest you send the Username in clear text, but send the password use the SHA encrypted, since it cannot be decrypted, in another backend system, you have save the enrypted String somewhere safe like Database, when the password send over, you just need to see the encrypted string match.
This is nice tutorial article talk about SHA in java:
https://www.baeldung.com/sha-256-hashing-java
I am developing a FTP tool using symmetric key + RSA. I want to send my secret key to the server over dataoutputstream.How can I do this? I tried following,
Client:
SecretKey secretKey = en_de_cryptor.returnSecretKey();
String encodedKey = Base64.encode(secretKey.getEncoded());
dout.writeUTF(secretKey.toString());
Server:
String secretKey = din.readUTF();
byte[] decodedKey = Base64.decode(secretKey);
But I couldn't get the decode key. How can I solve this and get the secret key at server side.
As most other people have pointed out you have a problem which you are sending the most important part of an asymmetric key in clear text where the secret key can be intercepted. Sure you could encrypt the key, but that introduces other encryption problems to solve. If you use symmetric encryption algorithm to encrypt the key you have a key agreement problem to solve. How will each side agree on a key in a secure manner so that a 3rd party can't intercept it?
At some level you are re-solving problems SSL has already solved. Why not just use it? Also SSL has been battle tested and security experts have gone over it for 25 years. To develop your own version means you may fall into similar pitfalls that have already been encountered by SSL developers.
But, if you must re-implement you are going to need to change your algorithm. The most secure way to protect the private key is to never send it over the network in the first place. Asymmetric encryption allows you to trade messages between the client and server without the key agreement problem symmetric algorithms have.
Here's an algorithm that will get around the key agreement problem:
Have the server generate an asymmetric key. Two options:
Generate an asymmetric key one time (ie at server startup) and all connections use the same key.
Generate an asymmetric key for each client when they connect making it more secure.
When the client connects transfer the server's public key to the client
The client will generate a secret key for a symmetric algorithm (How do you pick the algorithm? SSL solved this too).
Client encrypts this secret key using the server's public key
The client transfers the encrypted secret key to the server.
The server decrypts the message using its private key to obtain the symmetric secret key.
Now the server and client can exchange any encrypted message using symmetric encryption and a 3rd party can't listen in.
While even if you did this you still are open to man in the middle attacks where a 3rd party listener could trick the client and server to send unencrypted data through the 3rd party as the client trades messages with the client and server. Just a simple example of how implementing this stuff yourself could lead to you creating something less secure than just using SSL.
If you do send encrypted payloads around you'll want to ditch DataInputStream and go with straight binary streams so you don't need to convert binary payloads to UTF strings with Base64Encoding.
omg, don't do that! base64 doesn't give you any security. use encryption, not encoding
you send secretKey.toString (which is not encoded) instead of encodedKey
I've read about the Adobe CryptoSupport that is now in CQ5.5+, which is meant to provide a utility for encrypting and decrypting data, for example, to store API keys in the JCR more securely.
The JavaDocs or the general Adobe documentation give no details on its implementation, just stating that:
Note that this method and the decrypt(byte[]) method provide full
round trip support:
decrypt(encrypt(plainText)).equals(plainText) == true
Please note,
that calling this method twice on the same plainText does not return
the same cipher text:
encrypt(plainText).equals(encrypt(plainText)) == false
This is reasonably useful, but what it doesn't tell me is how these ciphers are enncrypted to begin with. I've tried encrypting on one CQ instance & decrypting on another, but this doesn't seem to work.
To use this feature with confidence, I'd like to know on what CQ bases its encrypted.
There are two main concerns I have:
How do I know that the service is salted (think that's the correct term) based on something secure? Or if it needs to be configured, how do I do that? (i.e. does it use the equivalent level of security OOTB as a log-in of 'admin/admin'!)
If the encryption is environment specific, does this mean that I cannot encrypt data & then transfer across between servers?
Bundle description in the Felix console states that
The Crypto Support bundle provides a CryptoSupport services which
allows applications to encrypt and decrypt binary and String data.
Encryption is based on the symmetric AES/CBC/PKCS5Padding (AES
algorithm, CBC mode with PKCS5 padding) from the RSA JSafe libary.
Key is randomly generated during the first start of the Adobe Granite Crypto Support bundle and then saved as /etc/key/master property. It is per-instance by design and I don't think it's a good idea to move this key between CQ installations. Actually, Adobe says it's a good idea to move key between author and publish instances.
Answering your questions:
you don't need to worry about configuring the service as it's done automatically during the first bundle activation,
you can move encrypted data from one instance to another as long as you also move the key.
I am currently making an app that will need to save sensitive data in J2ME, either in RMS or using LWUIT's storage class. (For example username and password)
How secure is such an implementation, and what are the steps to take in order to make sure the data is secure and not vulnerable to theft?
RMS is not encrypted - an attacker can easily read off any data. You'll need to encrypt the data - I recommend the Bouncycastle AES provider, but the Java AES provider also works (although it isn't as efficient, and you'll need to enable 256-bit keys on it). See the accepted answer to this question for some example code, I don't recommend changing anything in the code without asking StackOverflow or another good Q&A site first (it's very easy to incorrectly use encryption libraries); the code uses the Java crypto provider, to use the Bouncycastle provider use Cipher.getInstance("AES/CBC/PKCS7Padding", new BouncyCastleProvider()) after you import the Bouncycastle library. Important to note is that the code generates a Keyspec spec from a char[] password - the user will need to enter this password at least once per session in order for you to decrypt the data (you can't store the password on the device, that would defeat the purpose of encrypting the data). Also important is that you'll need to use the same IV (initialization vector) in the encryption and decryption phases; this IV should be unique to each record that you're encrypting (e.g. when you encrypt foo.txt then use a different IV than when you encrypt bar.txt), but it does not need to be secret (you can store it in plaintext alongside the encrypted file). As an added precaution, wipe the char[] password when you're done with it.
My requirement is to find best algorithm use to secure data sent using XML over network. This is important data which is to be exchanged between third parties.
I know about DES which is quite outdated these days. MD5 appeared as another option but this does not allow decryption to get data back(please correct me if I am wrong)
What other options do we have to accomplish above task and which is best and most standard way to do it?
Tried out AES, it uses common key for encryption and decryption. Other option I explored was RSA, which has two keys public and private, for encryption and decryption.
Not able to decide about better approach of above two.
You can use Advanced Encryption Standard(AES).The differences between AES and DES
There's a W3C standard for this, it's called XML Encryption Syntax and Processing, which uses a cipher like a DES/3DES-CBC symmetric key cipher.