Hybrid Hiding Encryption Algorithm (HHEA)

1. Hybrid Hiding Encryption Algorithm (HHEA) K.V.Bhargavi 2001HS12557

2. Outline • Basic Idea • Encryption Process • Algorithm • Decryption Process • Key Length • Algorithm Analysis • Conclusion

3. Basic operations include inserting part of the plain text bits into a cover to hide it from recognition. hiding in a random bit string. The name “Hybrid” is derived from the fact that the features of the algorithm are inherited from data hiding techniques or Steganography. Basic Idea

4. Basic Idea • Based on hiding a number of bits from plain text message (M) into a random vector (V) of bits. • No conventional substitution and translation operations on the plain text characters are used. • Locations of the hidden bits are determined by a “key” (K).

5. Encryption • A Key Matrix KLX2 • Every character from the message is replaced by a binary value. • An eight-bit octet is generated randomly and set in a temporary vector V, called hiding vector. • The bits in the vector V from position K[1,1] to position K[1,2] are replaced by bits from the secret message. • Resulting vector is stored in a file. • Repeat the above steps till the end of the file. • Sent to Receiver.

6. Algorithm • Input:M[Plain Text Message], KLX2[Key Array] where K[i,j] € {0,1,2,3,4,5,6,7} for i=0,1…L;L>=16 j=1,2 Output: Encrypted File • First, in a plain text file, each character is sequentially replaced by its binary value.

7. Algorithm i:=0 m:=first digit in M file While(m!=EOF) i=i mod L Random vector (of 8 bits) Generation for j=K[i,1] to K[i,2] if (m ≠ EOF) then do V[j] = m m := next m in M file end do next j Save V in output file i:= i+1 end while

8. Decryption • Read an octet from the Encrypted Binary Plain text Message (EBPM) file. • Set in a temporary vector V. • From V, bits are extracted from position K[1,1] to position K[1,2] and set in a Binary Plain text Message (BPM) file. • Repeat the above steps till the end of EBPM file.

9. Key Length • The probability of replacing a string of bits whose length ranges from 1 to 8 bit in the generated octet is 1/64. • If the key length is 16 there are 6416=7.9x1028 possible keys. • Assume that a supercomputer working in parallel is able to try 1012 attempts per second, it will take 2.5x109 years to find the secret message.

10. Algorithm Analysis • Worst case occurs when replacing only one bit from message M to the vector V leading to the “linear complexity”. • Key length can be varied from 16 to any “larger value” depending on the security level required. • The whole process can be repeated any number of times using the “same” key.

11. Comparison Results

12. Conclusion • Higher degrees of data security can be obtained by repeating the process on the resulting ciphered file. • Using more than one round of encryption cycles. • The number of rounds should be agreed upon by sender and receiver before transmission begins.

13. Thanks