Proposal for Complex AES Security using Key Generator and Text Permutation

Advanced Encryption Standard (AES) is a symmetric-key encryption each of these ciphers has a 128-bit block size, with key sizes of 128, 192 and 256 bits. The AES cipher is specified as a number of repetitions of transformation rounds that convert the input plaintext into the final output of ciphertext. Each round consists of several processing steps, including one that depends on the encryption key[1,2]. This research proposes a technique intended to make the Advanced Encryption Standard (AES) more safe and secure. Through the generation of random key, and permutation key sites in each round, instead of the process of expanding key locations in addition to the proposed permutation the plaintext before entering the encryption and inverse permutation for resulting ciphertext

Rijndael with a larger block size have additional columns in the state).Most AES calculations are done in a special finite field The AES cipher is specified as a number of repetitions of transformation rounds that convert the input plaintext into the final output of ciphertext.Each round consists of several processing steps, including one that depends on the encryption key.A set of reverse rounds are applied to transform cipher text back into the original plaintext using the same encryption key [3][4][5][6][7].

Description of the algorithm, see figure (1)
1. Key Expansion-round keys are derived from the cipher key using Rijndael key schedule 2. Initial Round • AddRoundKey-each byte of the state is combined with the round key using bitwise xor 3. Rounds • SubBytes-a non-linear substitution step where each byte is replaced with another according to a lookup table.

THE PROPOSAL SYSTEM DESIGN
In the proposed research, the aim is to strengthen (AES) algorithm.Where the proposal consists of two parts the first generation of random key.Where the user of the algorithm determines the length of the key 128-bit and all four bits number is hexadecimal or 32 number hexadecimal, and so if the length of the key 192-bit or 256-bit is equivalent to 48 or 62, No. hexadecimal, and then do permutation positions the key using a matrix consisting of 32 No. hexadecimal dimensions (4 X 8), represent the key length if 128-bit .Repeated a number of permutation rounds if the number of bits of a 128-bit repeated 10 times in each round so that the key to this allowance for the expansion of the key .
The other part includes the process of permutation or switching positions on the original text so that the matrix of either 128-bit dimensions are (8x16) or converted to hexadecimal system and its dimensions are (4 x 8) and then enter the encryption operations in the future be the same operations with the inverse matrix permutation.see figure (

THE IMPLEMENTATION OF THE PROPOSAL SYSTEM
The implementation of the proposal done by using javascript run the implementation and vb6 to Description of Work Map the operations as mentioned in previous sections, the proposal aim to strength the AES algorithm in figure (6) consists of five functions, first function to choose a key length 128, 192 or 256-bit and then move to the second function to generate a key the third function is to convert the key generator to hexadecimal Fourth function is the work of the key permutation and permutation to the text of the original entrance Then complete the operations as the encryption algorithm AES, But on the other side the same for the key generation process with the use of inverse permutation key and cipher text .In figure (6) implementation function to choose a key length 128, 192 or 256-bit to generator.In figure (7) implementation to key generation by used randomize and convert to hexadecimal.In figure (8) implementation initial array permutation key and plaintext.In figure (9) implementation array of inverse initial permutation key and cipher text.In figure (10) the full implementation of the proposal through the application of an example of generating a random key number and convert the hexadecimal system and permutation the key and the original text and then enter the other operations in the algorithm (AES)

CONCLUSIONS
By studying the AES algorithms and analysis it is work, this research present some modification on it.By implementing the proposed modified AES there is some point concluded these are: PDF created with pdfFactory Pro trial version www.pdffactory.com1.The encryption of AES has some thing danger, that it is an algorithm depend on symmetric key, so if the key is discovered that will destroy the AES security.2. from previous point, the research propose key generation method aim to reduce the danger of symmetric keys by taking short key and from it the overall key will be generated, so this short key only will be known previously by sender and receiver.3. AES depend on key expansion, and this expansion is static method.in this research the dependency on a proposed key generation preserve the randomness by permutation in each round.4. AES without secure dealing with plaintext, so this research aim to enter the plaintext in the security process.That by applying initial permutations on the plaintext and finally applying the inverse permutations on resulted ciphertext.PDF created with pdfFactory Pro trial version www.pdffactory.comPDF created with pdfFactory Pro trial version www.pdffactory.com

Figure ( 3 )
Figure (3): This form displays the overall process of AES decryption.

Figure ( 5
Figure (5): The implementation steps for proposed modifications on AES.

Figure ( 9 ):
Figure (9): Form of generating initial permutation arrays applying on key and cipher text 5)PDF created with pdfFactory Pro trial version www.pdffactory.com