#  Trifid Relationships by ANCHISES

#  to accompany Trifid article in Jan-Feb 2008 Computer Column









#.....paste ciphertext and crib here....

 



T="PP#TNPAUF"   #ciphertext must begin at start of a period

C="aininitss"   #crib must be lowercase.

                          #if crib begins part way through period, it must be

                          # preceded by dots. So if crib 'hello' starts in fifth

                          # letter of period 9, C="....hello"

                        

len_cipher=len(T)

len_crib=len(C)



period=9    #  insert period here



def make_arrays(T,C,len_cipher,len_crib):

    #.....remove spaces......

    t=-1

    for j in range (len_crib):

        if C[j] != ' ':

            t+=1

            pt[t] = C[j]      

    



    t=-1

    for j in range (len_cipher):

        if T[j] != ' ':

            t+=1

            ct[t] = T[j]

            if (T[j]=='#'):

                ct[t]='['

    len_cipher=t+1

    return(pt,ct,len_cipher)



def make_ribbons(pt,ct,len_cipher):

    nob=len_cipher/period

    #.......make rib_p[]........

    print"period=",period,"len_cipher=",len_cipher,"nob=",nob

    #...full periods....

    t=-1

    for j in range(nob):

        for m in range(0,3,1):

            for k in range(period):

                t=t+1

                if(pt[(j*period)+k]=='.'):

                    rib_p[t]=-1;

                else:

                    x=ord(pt[(j*period)+k])-97+(30*m)

                    rib_p[t]=x

     #.... part period at end...

    tail=len_cipher-(nob*period)

     

    for m in range(3):

        for j in range(tail):

            x=ord(pt[(nob*period)+j])-97+(30*m)

            t=t+1; rib_p[t]=x

                 

    len_r=t+1             

#.....make rib_c[]...................

  #...full periods....  

    t=-1

    for j in range(nob):

        for k in range(period):

              for m in range(3):

                  t=t+1

                  x=ord(ct[j*period+k])-65+(30*m)

                  rib_c[t]=x

  #...part period at end.....

    tail=len_cipher-(nob*period)

    for j in range(tail):

        for m in range (3):

            x=ord(ct[nob*period+j]) - 65 +(30*m)

            t=t+1;  rib_c[t]=x



    return(rib_p,rib_c,len_r)





    



#.......START............



pt=['.']*500; ct=[0]*1000 

rib_p=[0]*500; rib_c=[0]*500

line=[None]*20      #make array line[20][50]

index=['A']*27

for x in range(20):

    line[x]=[None]*50

len_line=[0]*30

grid=[None]*3

for row in range(3):

    grid[row]=[None]*27 #grid[3][27]

len_r=0







pt,ct,len_cipher=make_arrays(T,C,len_cipher,len_crib)  #make plain & cipher arrays, pt[] & ct[]



rib_p,rib_c,len_r=make_ribbons(pt,ct,len_cipher)   #make plain and cipher ribbons, rib_p[] & rib_c[]



print "pt[]: ",

for j in range (len_cipher):

    print pt[j],

print       

print "ct[]: ", 

for j in range (len_cipher):

    print ct[j],

print

print"Plain ribbon from crib:"

for j in range(3*len_cipher):

        print rib_p[j],

print

print"Cipher ribbon from ciphertext:"             

for j in range(3*len_cipher):

    print rib_c[j],

print;print

print  "length of ribbon= ",len_r

print



#...make lines.....

nol=-1; 

for m in range(30):   len_line[m]=0;

for pos in range(len_r):

    

    if(rib_c[pos]==-1 or rib_p[pos]==-1):

        continue  #skip if no letter in ribbon

    nol+=1                    # start a new line

    line[nol][0]=rib_p[pos]   # enter 1st plain-cipher pair

    line[nol][1]=rib_c[pos]

    len_line[nol]=2

    rib_p[pos]=-1; rib_c[pos]=-1

    present=1

    while present>0:  # add all other pairs to row where one matches

        present=0

        

        for p in range (pos+1,len_r):  #..search rest of ribbon for match 

            if(rib_c[p]==-1 or rib_p[p]==-1):  continue  #skip if ribbon empty

            flag=0

            for k in range(len_line[nol]):

               if(rib_p[p]==line[nol][k]):

                   flag=1                 # match found to crib part

                   break

            for k in range(len_line[nol]):

                if(rib_c[p]==line[nol][k]):

                   flag+=10                # match found to cipher part

                   break

            if(flag==1):          # where match found, add part to line

                line[nol][len_line[nol]]=rib_c[p]

                len_line[nol]+=1

                present=1

            if(flag==10):

                line[nol][len_line[nol]]=rib_p[p]

                len_line[nol]+=1

                present=1

            if(flag>0):

                rib_p[p]=-1;

                rib_c[p]=-1  # delete parts from ribbons         

nol+=1           

 





print "number of lines = ", nol



for p in range(nol):

    print chr(97+p),"  ",

    for q in range(len_line[p]):

        print line[p][q],

    print

    

for row in range(3): #initialise grid[][]

    for col in range(27):

        grid[row][col]=-1

        

for row in range(nol): #put discovered parts into grid

    for col in range(len_line[row]):

        x=line[row][col]

        while(x>29):

            x=x%30

        y=line[row][col]/30

        grid[y][x]=row

#find out how many letters have all 3 parts

t=-1

for col in range(27):

     flag=0

     for m in range(3):

         if(grid[m][col]>-1): flag+=1

     if(flag==3):

         t+=1

         index[t]=col

len_index=t+1



print

print"Here are relationships from the placed crib:"

for m in range(len_index):

     print chr(index[m]+65),

print

for row in range(3):

    for col in range(len_index):

        print chr(97+grid[row][index[col]]),

    print

print