A New Design of Algorithm for Enhancing Security in Bluetooth Communication with Triple DES
Bluetooth technology is an emerging wireless networking standard, which is based on chip that provides short-range wireless frequency hopping communication. Now, Bluetooth technology is mainly applied to the communication between mobile terminal devices, such as palm computers, mobile phones, laptops and so on. However, the phenomenon of data-leaking frequently arises in using the Bluetooth technology for data transfer. To enhance the security of data transmission in Bluetooth communication, a hybrid encryption algorithm based on DES and RSA is proposed. The currently used encryption algorithm employed by the Bluetooth to protect the confidentiality of data during transport between two or more devices is a 128-bit symmetric stream cipher called E0. The proposed hybrid encryption algorithm, instead of the E0 encryption, DES algorithm is used for data transmission because of its higher efficiency in block encryption, and RSA algorithm is used for the encryption of the key of the DES because of its management advantages in key cipher. Under the dual protection with the DES algorithm and the RSA algorithm, the data transmission in the Bluetooth system will be more secure. This project is extended with triple des in place of des to enhance more security.
Draw backs of old algorithm:
a. The weakness of E0 stream cipher algorithm
b. Limited resources capacity of linear feedback shift registers LFSR
c. Low credibility of PIN
d. Address Spoofing
First of all, two large distinct prime numbers p and q must be generated. The product of these, we call n is a component of the public key. It must be large enough such that the numbers p and q cannot be extracted from it – 512 bits at least i.e. numbers greater than 10154. We then generate the encryption key e which must be co-prime to the number m = ϕ(n) = (p − 1)(q − 1). We then create the decryption key d such that demodm = 1. We now have both the public and private keys.
Cipher text(C) = M^e mod (n).
Plain text (M) = C^d mod (n).
Process of encryption:
During the process of sending encrypted information, the random number generator uses 64-bit DES session key only once, it encrypt the plaintext to produce cipher text. On the other hand, the sender get debit’s public key from public key management center, and then using RSA to encrypt session key. Finally, the combination of the session key from RSA encryption and the cipher text from DES encryption are sent out.
1) Bluetooth packet plaintext M is divided into 64-bit plaintext Mi (i=1,2,…,n)).
2) Crypts Mi for 16 cycles by 64-bit key K ,and Mi will turn into a 64-bit cipher text Ci (i = 1,2, … n), then all the Ci (i = 1,2 , … n) are combined into cipher text C. The second, RSA algorithm encrypts the key of DES algorithm.
3) Obtain RSA public key of receiver B from the key server, or other sources.
4) Make DES 64-bit session key K for RSA encryption by public key eB that obtains from recipient, then a session key encrypted information CK is formed.
5) Composite Cipher text message C from the use of DES encryption, and session key CK from RSA encryption, we can get the hybrid CM for transmission.
Process of decryption:
The decryption of hybrid encryption algorithm is as follows. The first, the receiver B divide received cipher text CM into two parts, one is cipher text CK from the RSA algorithm encryption, and the other is cipher text C from the DES algorithm encryption. The second, the receiver B decrypt cipher text CK by their own private key dB, receive the key K which belongs DES algorithm, then decrypt the cipher text C to the original M by key K. Figure is a decryption of hybrid encryption algorithm.
Proposed hybrid algorithm with Triple Des:
The Triple Data Encryption Algorithm (TDEA) is made available for use by Federal agencies within the context of a total security program consisting of physical security procedures, good information management practices, and computer system/network access controls.
Triple DES uses a “key bundle” which comprises three DES keys, K1, K2 and K3, each of 56 bits (excluding parity bits).
The encryption algorithm is:
Ciphertext = EK3 (DK2 (EK1 (plaintext)))
I.e., DES encrypts with K1, DES decrypt with K2, then DES encrypt with K3.
Decryption is the reverse:
Plaintext = DK1 (EK2 (DK3(cipher text)))
i.e., decrypt with K3, encrypt with K2, and then decrypt with K1.Each triple encryption encrypts one block of 64 bits of data.
In each case the middle operation is the reverse of the first and last. Using standard DES encryption, TDES encrypts data three times and uses a different key for at least one of the three passes. The DES “modes of operation” may also be used with triple-DES. This 192-bit (24 characters) cipher uses three separate 64-bit keys and encrypts data using the DES algorithm three times. While anything less than that can be considered reasonably secure only the 192 bit (24 characters) encryption can provide true security. One variation that takes a single 192 bit (24 characters) key and then: encrypts data using first 64 bits (eight characters), decrypts same data using second 64 bits (eight characters), and encrypts same data using the last 64 bits (eight characters). For some time, it has been a common practice to protect and transport a key for DES encryption with triple-DES. This means that the plaintext is, in effect, encrypted three times. A number of modes of TDES have been proposed:
• DES-EEE3: Three DES encryptions with three different keys.
• DES-EDE3: Three DES operations in the sequence encrypt-decrypt-encrypt with three different keys.
• DES-EEE2 and DES-EDE2: Same as the previous formats except that the first and third operations use the same key.
In this paper this hybrid encryption algorithm is proposed with triple des algorithm in the place of des algorithm. In triple des here we using 3 keys to encrypt the data, so the key strength becomes stronger, the data will be more secure.
The advantages of hybrid encryption algorithm:
Using RSA algorithm and the DES key for data transmission, so it is no need to transfer DES key secretly before communication.
Management of RSA key is the same as RS situation, only keep one decryption key secret.
Using RSA to send keys, so it can also use for digital signature.
The speed of encryption and decryption is the same as DES. In other words, the time-consuming RSA just do with DES keys.
This project leads to very useful to implement hybrid algorithms in Bluetooth communication technology. With the help of many algorithms like idea, aes, md5 and rsa, we can implement many hybrid algorithms for Bluetooth communication to enhance more security. This triple des and rsa hybrid algorithm further extended with triple des and triple rsa to enhance more security.
Bluetooth technology is a new technology, which will change our transmission method. As communication networks, it uses wireless channel for the transmission medium. Compared to the fixed network Bluetooth network is more vulnerable to be attacked. Currently, stream cipher E0 used in Bluetooth standard has many shortcomings, while the DES and RSA hybrid encryption algorithm is relatively more secure and easier to achieve, thus ensures data transmission between the Bluetooth device safety and real-time. As long as we protect the key that encrypt original, and the security of entire file will be guaranteed. Because of the dual protection of DES algorithm and RSA algorithm, the data in transit is safe.