FileCrypter Developed by: Under the Guidance Ms.S.Maheswari, M.C.A. T.Prabaharan D.Suresh Kumar Under the Guidance Ms.S.Maheswari, M.C.A. Dept. of B.C.A.

Hardware Configuration FileCrypter Hardware Configuration Pentium Processor P4 256 MB RAM 5 MB of HDD space

Software Configuration FileCrypter Software Configuration Windows XP SP-2 Visual Basic 6 ADO Library

FileCrypter Abstract The System 'FileCrypter' uses cryptography technique. System enables user to Encrypt or Decrypt data/text based on a KEY. Encryption & Decryption are done based on Rijndael Algorithm.

The System Consists of Two Modules. FileCrypter System Details The System Consists of Two Modules. Encryption Module Decryption Module

FileCrypter Encryption Module: Three steps are enclosed in this module. KeyExpansion Initial Round Rounds

FileCrypter 1) Key Expansion: This process involves getting of Round Keys. Round keys are keys generated by Key Cycle process of Rijndael Algorithm. Key Cycle process takes keys entered by user as its input.

FileCrypter 2) Initial Expansion: Each byte is combined with round keys. Bitwise XOR operation is used to combine the byte. This process is so called ADD ROUND KEY, since addition of round key to data takes place.

FileCrypter 3) Rounds Here three steps of process take place to ENCRYPT. Sub Bytes- a linear substitution where each byte is replaced by verifying look up table. Shift Rows- each row of state is shifted at a sequence. Mix Column- operation on column, combing some bytes in each column.

FileCrypter Decryption Module: The decryption process involves three steps. Decryption is just a reverse process of encryption. It involves Key Expansion, Reverse Rounding and Key decomposition.

FileCrypter 1) Key Expansion: 2) Reverse Rounding: Same as Key Expansion that done in Encryption, (i.e.) Rounding Keys. 2) Reverse Rounding: Based on key value the subtraction of bytes from each column. Then rearranging of Rows in the data matrix takes place.

FileCrypter Finally, referring look-up table substitution performed. 3) Key Decomposition: The Key Decomposition is the process of removing added Round Key from the data matrix. This is the process of retrieval of original data in the system.

FileCrypter Data Flow Diagram Level 0 PF-Plain File PF/PT PT-Plain Text CF-Cipher File CT-Cipher Text PF/PT SYSTEM Key - Flow of Encryption CF/CT - Flow of Decryption Level 0

FileCrypter Module 1:Encryption Level 1 PT/PF KEY FS KE AR SB SR MC AR PT- Plain Text PF- Plain File FS- Form State KE- Key Expansion AR-Add Round off SB- Sub Byte SR- Shift Row MC- Mix Column CT- Cipher Text CP- Cipher File FS KE AR SB SR MC AR Level 1 CT/CF