IMPLEMENTATION OF SHA-1 ALGORITHM using JAVA

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AIM: To   write a java program to calculate the message digest of a text using the SHA-1 algorithm ALGORITHM: Step 1: Input the plain text Step 2: Append padding bits Step 3: Append length Step 4:Initialize   buffer. Step 5: Process message in 512-bit (16word)blocks Step 6: Encrypted in hexa decimal format Step 7: Display the encrypted text. PROGRAM: importjava.security.*; public class SHA1 { public static void main(String[] a) { try { MessageDigest md = MessageDigest.getInstance("SHA1"); System.out.println("Message digest object info: "); System.out.println(" Algorithm = " +md.getAlgorithm()); System.out.println(" Provider = " +md.getProvider()); System.out.println(" ToString = " +md.toString());   String input = ""; md.update(input.getBytes()); byte[] output = md.digest(); System.out.println(); System.out.println("SHA1(\""+...
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IMPLEMENTATION OF PLAYFAIR CIPHER in C++

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AIM:
            Towrite a  C++ program  toimplement Play Fair Cipher.

ALGORITHM:

Step 1: Generate Key matrix.
     (a)Take any random key of any length and form a 5 X 5 matrix.
                (b) Fill the rows of the matrix with the key characters and ignore repeating character.
                (c) Fill the remaining matrix with alphabets from A to Z (except those already occurred in    the key).
Step 2: Encrypt the data using encryption rule and key matrix
                  (a) To Encrypt the data take two characters at time from plain text file and encrypt it           using one of the following rules.
               (b) Repeating plain text letters that would fall in the same pair are separated with filler letter.
               (c) If both the characters are in the same raw then replace each with the character to its right,   with the last character followed by the first, in the matrix.
                (d) If both the characters are in the same column then replace each with the character          below it, with the bottom character followed by the top, in the matrix.
Otherwise each plain text letter is replaced by the letter that lies in its own row and the column occupied by the other plain text letter
Step 3:To decrypt, use the inverse of encryption rules.
Step 4: Display the cipher text after encryption and plain text after decryption.

PROGRAM:
#include<iostream>
using namespace std;
int main()
{
inti,j,isI=0,l,k=0,start=0,same=0,k1=0;
int i1,j1,i2,j2,i11,jj;
 char alph[5][5],chr[25],chr2[25],character,chr1='a',chr_ex[25];
char txt[25],txt2[25];
cout<<"Enter the key string : ";
cin>>chr;
            for(i=0;i<strlen(chr2);i++) /*TO PREVENT STRING FROM BEING PRINTED WITH GARBAGE CHARACTER...*/
            {
            chr_ex[i]='-';
            }
            for(i=0;i<strlen(chr);i++)
            {
            cout<<"\n"<<i+1<<"\t"<<chr[i];
            chr_ex[i]=chr[i];
            }
            for(i=0;i<5;i++)

            {
                        for(j=0;j<5;j++)
                        {
                        alph[i][j]='-';
                        }
            }
            for(i=0;i<5;i++)
            {
                        for(j=0;j<5;j++)
                        {
                        character=chr[++k];
                                    for(l=k-1;l>=0;l--) //FOR REPEATING CHARACTERS...
                                    {
                                                 if(character==chr[l])
                                                {
                                                chr[k]='-';
                                                break;
                                                }
                                    }
                        }
            }
 k=0;
            for(i=0;i<5;i++)
            {
                        for(j=0;j<5;j++)
                        {
                        if(start++<strlen(chr))
                                    if(chr[k]!='-') //FOR i AND j
                                    {
                                                if(chr[k]=='i' || chr[k]=='j')
                                                {
                                                             if(isI==0)
                                                            {
                                                            alph[i][j]=chr[k];
                                                            isI=1;
                                                            }
                                                            else
                                                            {
                                                            if(chr[k]=='i') chr[k]='i';
                                                            if(chr[k]=='j') chr[k]='j';
                                                            j--;
                                                            }
                                                }

                                    elsealph[i][j]=chr[k];
                                    }
                                    else
                                    {
                                    chr[k]='-';
                                    j--;
                                    }
                        k++;
                        }
            }
 chr1--;
 k1=0;
            for(i=0;i<5;i++)
            {
                        for(j=0;j<5;j++)
                        {
                                    if(alph[i][j]=='-')
                                    {
                                    same=0;
                                    chr1++;
                                                for(k1=0;k1<strlen(chr);k1++)
                                                {
                                                            if(chr1==chr[k1])
                                                            {
                                                            same=1; //else same=0;
                                                            j--;
                                                            break;
                                                            }
                                                }
                                                if(same!=1)
                                                {
                                                            if(chr1=='i' || chr1=='j')
                                                            {
                                                                         if(isI==0)
                                                                        {
                                                                        alph[i][j]=chr1;
                                                                        isI=1;
                                                                        }
                                                            else
j--;
            }
            else
alph[i][j]=chr1;
            }
}
}
 }
cout<<"\n"<<"\n"<<"\n";
            for(i=0;i<5;i++)
            {
                        for(j=0;j<5;j++)
                        {
                        cout<<alph[i][j];
                        }
            cout<<"\n";
            }
 j=0;
            for(i=0;i<strlen(chr);i++)
            {
                        if(chr[i]=='-')
                        {
                                    for(j=i;j<strlen(chr);j++)
                                    {
                                    chr[j]=chr[j+1];
                                    }
                        }
            }
cout<<"\n"<<"\n"<<"Enter the plain text : ";
cin>>txt;
 j=0;
            for(i=0;i<strlen(txt);i++)
            {
            txt2[j++]=txt[i];
                        if(txt[i]==txt[i+1])
                        {
                        txt2[j++]='x';
                        }
            }
jj=j;
            for(i11=0;i11<strlen(txt2);i11+=2)
            {
                        for(i=0;i<5;i++)
                        {
                                    for(j=0;j<5;j++)
                                    {
                                                if(txt2[i11]==alph[i][j])
                                                {
                                                i1=i;
                                                j1=j;
                                                }
                                                if(txt2[i11+1]==alph[i][j])
                                                {
                                                i2=i;
                                                j2=j;
                                                }
                                    }
                        }
                        if(i1==i2)
                        {
                        if((j1+1)>=5) j1=-1;
                        if((j2+1)>=5) j2=-1;
                        txt2[i11]=alph[i1][j1+1];
                        txt2[i11+1]=alph[i2][j2+1];
                        }
                        else if(j1==j2)
                        {
                         if((i1+1)>=5) i1=-1;
                        if((i2+1)>=5) i2=-1;
                        txt2[i11]=alph[i1+1][j1];
                        txt2[i11+1]=alph[i2+1][j2];
                        }
                        else
                        {
                                    if(i2>i1)
                                    {
                                    txt2[i11+1]=alph[i2][j1];
                                    txt2[i11]=alph[i1][j2];
                                    }
                                    else
                                    {
                                    txt2[i11]=alph[i2][j1];
                                    txt2[i11+1]=alph[i1][j2];
                                    }
                        }
            }
cout<<"\n"<<"Final string       : ";
            (i=0;i<jj;i++)
            {
            cout<<txt2[i];
            }
}



OUTPUT:

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