# Create a matrix message1

message1<-matrix(c("A","T","T","A","C","K"," ","T","H","E"," ",
                   "C","A","S","T","L","E"," ","A","T"," ",
                   "D","A","W","N"),nrow=5,byrow=T)

# Display m
message1


# Generate the ciphertext

 ciphertext1<-c(0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)

for(i in 1:5)
{
  ciphertext1[i]<-message1[6-i,5]
}

for(i in 6:10)
{
  ciphertext1[i]<-message1[i-5,4]
}

for(i in 11:15)
{
  ciphertext1[i]<-message1[16-i,3]
}

for(i in 16:20)
{
  ciphertext1[i]<-message1[i-15,2]
}


for(i in 21:25)
{
  ciphertext1[i]<-message1[26-i,1]
}


# Display ciphertext1

ciphertext1



# Generate an appropriate matrix message2

message2<-matrix(c("A","T","T","A","C","K"," ","T","H","E"," ",
                   "C","A","S","T","L","E"," ","A","T"," ",
                   "D","A","W","N"," "," "),nrow=3,byrow=T)
message2



#generate ciphertext2 ------ read by columns 

ciphertext2<-c(0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)

for(i in 1:9)        #columns indice
{
    for(j in 1:3)    #row indice
    {
      ciphertext2[3*(i-1)+j]=message2[j,i]
    }
  
}

# display ciphertext2
ciphertext2



#generate ciphertext3 ------ read it diagonally up and down from the bottom right corner

ciphertext3<-c(0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)

k<-1    # k is the indice of vector ciphertext3   
m<-3     
n<-9    # start from (3,9)


for(i in 1:11)       #loop for 3+9-1 times, 第i条对角线上元素坐标和等于13-i 
{
   if(i%%2==0)         #对角线执行序号为偶数，向下走。 奇数向上走
   {    
      while(m<=3&n>=1)        #把这条线走完
      {
        ciphertext3[k]<-message2[m,n]      #m=3,n=6时,
        k<-k+1     
        m<-m+1   
        n<-n-1
      }
    

     if(m>3)  
     {
       m=3
       n=12-i-m
     }
     if(m==3&n==0)
     {
       m<-1
       n=1
     }
     
   }

  
   else
   {
     while(m>=1&n<=9)
     {  ciphertext3[k]<-message2[m,n]
        k<-k+1     
        m<-m-1   
        n<-n+1                #m=1,n=9时,加减完m=0,n=10, 本应该m=1,n=8
     }
     
     if(n>9&m==2)   #向上走的边界
     {
      m<-2
      n<-9
     }
     if(n>9&m==0)
     {
       m<-1
       n<-8
     }
 
     if(n<9&m<1)
     {
       m<-1
       n<-12-i
     }
     
     
   }
}


message2
ciphertext3



#Which of the two matrices, message1 or message2 do you think produces the most secure encryption methods? 

# In my opinion, message2 produces the most secure encryption methods
# because message2 is 3*9 matrix,we get more elements to make up the password