$4$ Task $2$: Encryption using Different Ciphers and Modes

In this task, we will play with various encryption algorithms and modes. You can use the following openssl enc command to encrypt$/$decrypt a file. To see the manuals, you can type man openssl and man enc.Please replace the ciphertype with a specific cipher type, such as $-$aes$-128-$cbc$,-$bf$-$cbc$,-$aes$-128-$cfb$,$ etc. In this task, you should try at least $3$ different ciphers. You can find the meaning of the command$-$line options and all the supported cipher types by typing "man enc". We include some common options for the openssl enc command in the following:$5$ Task $3$: Encryption Mode $-$ ECB vs$.$ CBCThe file pic$\_$original.bmp is included in the Labsetup.zip file, and it is a simple picture. We would like to encrypt this picture, so people without the encryption keys cannot know what is in the picture. Please encrypt the file using the ECB $($Electronic Code Book$)$ and CBC $($Cipher Block Chaining$)$ modes, and then do the following:

Let us treat the encrypted picture as a picture, and use a picture viewing software to display it$.$ However, For the $.$bmp file, the first $54$ bytes contain the header information about the picture, we have to set it correctly, so the encrypted file can be treated as a legitimate $.$ bmp file. We will replace the header of the encrypted picture with that of the original picture. We can use the bless hex editor tool $($already installed on our VM$)$ to directly modify binary files. We can also use the following commands to get the header from $p1.$bmp$,$ the data from $p2.$ bmp $($from offset $55$ to the end of the file$),$ and then combine the header and data together into a new file.

SEED Labs $-$ Secret$-$Key Encryption Lab

$5$Display the encrypted picture using a picture viewing program $($we have installed an image viewer program called eog on our VM$).$ Can you derive any useful information about the original picture from the encrypted picture? Please explain your observations.

Select a picture of your choice, repeat the experiment above, and report your observations.