International Journal for Research in Applied Science & Engineering Technology (IJRASET) ISSN: 2321-9653; IC Value: 45.98; SJ Impact Factor: 7.538 Volume 11 Issue III Mar 2023- Available at www.ijraset.com Each grid cell is a label with the number; it starts from 0 and reaches to n×n as following GA [11] scheme pattern. Assume a password, P and P=“ABCH ‘grid[1]’, ‘grid[2]’,…@D”. Each ‘grid[.]’ replaces with a set of pixels s×s, where ‘s×s’ is the patch of grid cell pixels. C. Password Setting In both schemes, a user can generate the graphical password by clicking on the sequence of objects at the CaRP image and by performing a double click on any object at the Captcha image, the user can find a window with n×n grid points for CODP scheme where he/she can draw a shape as a pattern by pen up or by a mouse. Pattern might be started from any points and end with at least 4 counts. The previous points will be considered as the end point if there is no further neighbor point is selected. Each point connects with a neighbor by the straight line. User can’t jump to the next point without choosing the current point. A user can reset, cancel or confirm the selected pattern. For example, a graphical password, P=“ABC@p<1>p<2>p<7>p<12>p<17>p<18>p<13>p <8>p<3 >DE”, with a particular sequence, the points p<·> are shown by white line in Fig 1. Similarly, for COSS scheme, user need to follow same steps as CODP scheme, only difference is the user need to click on the grid cells instead of drowning pattern. For example, P=“ABCH, ‘grid[1]’, ‘grid[2]’ ‘grid[3], ‘grid[4]’”, where H is the character which was selected to generate the grid cells window and, e.g., ‘grid [1]’ is obtained by click on the position at ‘1’ of grid cells window. D. Registration & Authentication 1) Registration: A Client ‘C’ accesses the Authentication Server ‘AS’ and requests ‘q’ to ‘AS’ and ‘AS’ responses to ‘C’ in terms of image. ‘C’ accepts the challenge and passed it by selecting the password ‘p’ and reproduced the password as it did in the previous attempts. After that, the password hashed (SHA-256) H(p, salt) corresponding to ‘C’, ‘AS’ will save the password associated with client record into the system. 2) Authentication: A client will repeat the same password but the ‘pʹ’ password will be compared with stored hash password ‘p’ if both hashed values are equal, the user will successfully access the system. IV. IMPLEMENTATION OF PROPOSED METHODS The scheme is implemented in C#.Net, framework and run at the Windows operating system. The application is associated with the SQL server 2012 Database. The user name, ID, selected password and other associated data are saved into the database at ‘AS’. For CS-AV image setting, input objects N set as 33, each object is rotated by 30° to -30° degree randomly and drawn on the grassy ground image. Each object covers individual quadratic area. The ground truth of each object is stored in a List. However, each object partially overlapped up to 3 pixels and this overlapped area, boundary, and corner of the object are marked as absent. To reduce the searching cost of click point at the image, the binary search mechanism is used, where clicked location on the image can be traced in (log2 ) computation cost, N is number of objects on Captcha image. For the next step; in CODP scheme, the pop-up window is generated with × , = 5 grid points. Each point assigned with a number starting from 1 to 25 and stored as ground truth. User can freely drag the mouse in 8 different directions while the selects points are concatenated into an array and sequence of selected points are assigned into a graphical password, P. For COSS scheme, instead of grid points, it bases on × = 100 grid cells, = 10 In this setting, at first, clicked object at CS-AV image is stored and zoomed with 200% then drawn as the backgroundof the pop-up image as is shown in Fig. 2, a character ‘H’ with a yellow color. Each cell label with the number, starting from1 to × and it contains × image patch. For each click on a grid cell of COSS scheme will contribute an ( × ) image patch into the graphical password. A. Password Strength To calculate effectiveness of graphical password, the entropy bits, log (Nr ) is calculated. For CODP, we use 6 minimum alphanumeric characters and 4 connected points from grid points window, the password strength can be measured as: = 58 (which 2 is a combination of 33 alphanumeric characters and 25 grid points), = 10, then entropy from equation (2) becomes: ‘G’, G log (5810 ) , = 10 × 5.86 = 58.6 bits. 2 For COSS scheme, N=133, where, 33 are alphanumeric characters and 100 are grid cells. The estimated entropy bits is: G log (13310) = 70.5 entropy bits, by using r=10. It comprises 6 alphanumeric characters and 4 grid cells. Each grid cell labelled with number, thus, it reach to 70.5 entropy bit. To overcome2 the graphical password space, each grid cell which is a patch of an image with a length of 20 × 20 pixels is used as part of password and for 4 grid cells, 4× 20 × 20 = 1600 pixels in total. If a user selects 4 grid cells in his/her ©IJRASET: All Rights are Reserved | SJ Impact Factor 7.538 | ISRA Journal Impact Factor 7.894 | 277