Add files via upload

enc and decry using caser ciper without key.c

@@ -0,0 +1,57 @@
+// Progam for encryption and decryption using Caesar cipher technique without key //
+#include <stdio.h>
+#include <conio.h>
+#include <string.h>
+void main()
+{
+	char plain[50];
+	char cipher[50];
+	char c;
+	int key = 3,i,j;
+	clrscr();
+	printf("Enter Plain Text =");
+	gets(plain);
+
+	// Encryption Logic
+	for(i=0; i<strlen(plain); i++);
+	{
+		if(plain[i]>='A' && plain[i]<='Z')
+		{
+			cipher[i]=((plain[i]-65+key) % 26)+65;
+			printf("%c",cipher[i]);
+		}
+		else if(plain[i]>='a' && plain[i]<='z')
+		{
+			cipher[i]=((plain[i]-97+key) % 26)+97;
+			printf("%c",cipher[i]);
+		}
+		else
+		{
+			cipher[i] = plain[i];
+			printf("%c",plain[i]);
+		}
+	}
+	printf("\n\n");
+
+	// Decryption Logic
+	printf("Decryption is =");
+	for(i=0;i<strlen(plain);i++)
+	{
+		if(cipher[i]>='A' && cipher[i]<='Z')
+		{
+			plain[i]=((cipher[i]-65-key) % 26)+65;
+			printf("%c",plain[i]);
+		}
+		else if(plain[i]>='a' && plain[i]<='z')
+		{
+			plain[i]=((cipher[i]-97-key) % 26)+97;
+			printf("%c",plain[i]); 
+		}
+		else
+		{
+			cipher[i] = plain[i];
+			printf("%c",cipher[i]);
+		}
+	}
+getch();	
+}

enc and decry using columnar transpostion.c

@@ -0,0 +1,106 @@
+// Encryption and Decryption using columnar transposition //
+
+#include<stdio.h>
+#include<conio.h>
+void main()
+{
+    char pt[60];
+    char newpt[60] = {"\0"};
+    char et[60] = {"\0"};
+    char newet[60] = {"\0"};
+    char dt[60] = {"\0"};
+    char mat[12][5];
+    int row, column = 5, len, i, j, newlen, k = 0, m;
+    clrscr();
+    printf("\n\nEnter Plain Text:");
+    gets(pt);
+
+    len = strlen(pt);
+    for(i=0; i<len; i++)
+    {
+        if(pt[i] != 32)
+        30
+        {
+            newlen = strlen(newpt);
+            newpt[newlen] = pt[i];
+        }
+    }
+    // Getting Size of Row //
+    newlen - strlen(newpt);
+    row = newlen/column;
+    if(newlen % column > 0)
+    row = row + 1;
+
+    // Create matrix from plaintext //
+    printf("\nColumner Matrix is:");
+    for(i = 0; i < row; i++)
+    {
+        for(j = 0; j < column; j++)
+        {
+            if(k < newlen)
+            {
+                mat[i][j] = newpt[k];
+                printf("%2c",newpt[k]);
+                k++;
+            }else{
+                mat[i][j] = 32;
+        }
+    }
+    printf("\n");
+}
+// Encryption Code //
+k = 0;
+for(m = 0; m < column; m += 2)
+{
+    for(i = 0; i < row; i++)
+    {
+        et[k] = mat[i][m];
+        k++;
+    }
+}
+for(m = 1; m < column; m += 2)
+{
+    for(i = 0; i < row; i++)  
+    {
+        et[k] = mat[i][m];
+        k++;        
+    }  
+    31
+}
+
+// Blank space Remove Code //
+newlen = strlen(et);
+for(i = 0; i < newlen; i++)
+{
+    if(et[i] != 32)
+    {
+        len = strlen(newet);
+        newet[len] = et[i];
+    }
+}
+printf("\n\nEncrypted Text Is: %s", newet);
+
+// Decryption Code //
+k = 0;
+for(i = 0; i < row; i++)
+{
+    m = i;
+    for(j = 0; j < column; j++)
+    {
+        if(j%2 == 0)
+        {
+            dt[k] = et[m];
+            m = m + (row * 3);
+            k++;
+
+        }
+        else{
+            dt[k] = et[m];
+            m = m - (row * 2);
+            k++;
+        }
+    }
+}
+printf("\n\n Decrypted Text Is: %s", dt);
+getch();
+}

enc and decry using hill cipher.c

@@ -0,0 +1,120 @@
+// Program for Encryption and Decryption using Hill Cipher technique //
+
+#include<stdio.h>
+#include<conio.h>
+#include<string.h>
+void main()
+{
+    char ptext[20] = "\0", newptext[20] = "\0", etext[20] = "\0", newetext[20] = "\0",
+    dtext[20] = "\0", newdtext[20] = "\0", abcd[26] = "abcdefghijklmnopqrstuvwxyz";
+
+    int b[20], c[20], newmod[20], mod[20], mat[3][3], a[9];
+    int A, i, j ,len ,len1 ,oldlen , sum = 0 , k = 0, x, y, div, DIV, m , n = 0;
+    clrscr();
+
+    // Enter Plain Text //
+    printf("Enter the plain text:");
+    gets(ptext);
+
+    // Remove Blank Space //
+    oldlen = strlen(ptext);
+    for(k = 0; k < oldlen; k++)
+    {
+        if(ptext[k] != 32)
+        {
+            len1 = strlen(newptext);
+            newptext[len1] = ptext[k];
+        }
+    }
+
+    // Add Two Fake or Dummy Character for Grouping of 3 Character //
+    oldlen = strlen(newptext);
+    newptext[oldlen] = 'x';
+    newptext[oldlen + 1] = 'x';
+    len = strlen(newptext);
+
+    // Enter Values of Matrix //
+    printf("\n Enter values of 3 X 3 array:\n");
+    for(i = 0; i < 3; i++)
+    {
+        for(j = 0; j < 3; j++)
+        {
+            scanf("%d",&mat[i][j]);
+        }
+    }
+
+    // Encryption Start here //
+    for(m = 1; m <= len; m++)
+    {
+        if(m % 3 == 0)
+        {
+            for(i = n; i < n+3; i++)
+            {
+                for(j = 0; j < 26; j++) // It will get index of plaintext
+                {
+                    if(newptext[i] == abcd[j]);
+                    {
+                        b[i % 3] = j;
+                        break;
+                    }
+                }
+            }
+            for(i = 0; i < 3; i++)
+            {
+                for(j = 0; j < 3; j++)
+                {
+                    sum = sum + (b[j] * mat[i][j]);
+                }
+                mod[i] = sum % 26;
+                sum = 0;
+            }
+            // Creating Text From Modulied Matrix //
+            for(i = n; i < n +3; i++)
+            {
+                for(j = 0; j < 26; j++)
+                {
+                    if(mod[i % 3] == j)
+                    {
+                        etext[i] = abcd[j];
+                        break;
+                    }
+                }
+            }
+            n = n + 3;
+        }
+    }
+    // Remove Extra Character From End of etext //
+    for(i = 0; i < oldlen; i++){
+        newetext[i] = etext[i];
+    }
+    // Print Encrypted Text //
+    printf("\n Encrypted Text is :");
+    puts(newetext);
+
+    // Inverse of matrix for decryption //
+    A = (mat[0][0] * (mat[1][1] * mat[2][2] - mat[2][1] * mat[1][2])) - (mat[0][1] * (mat[1][0]
+    * mat[2][2] - mat[2][0] * mat[1][2])) + (mat[0][2] * (mat[1][0] * mat[2][1] - mat[2][0] * mat[1][1]));
+
+    div = A/26;
+    if(div < 0)
+    {
+        DIV = div - 1;
+    }
+    else{
+        DIV = div;
+    }
+    A = A-26 * DIV;
+    printf("\n Value of a is %d\n\n",A);
+    for(x = 1; x < 1000; x++)
+    {
+        if(y * 26 == A*x-1)
+        {
+            goto xy;
+        }
+    }
+    xy:    
+    printf("\n x = %d y = %d \n\n",x,y);
+    a[0] = (mat[1][1] * mat[2][2] - mat[2][1] * mat[1][2]);
+    a[3] = -(mat[1][0] * mat[2][2] - mat[2][0] * mat[1][2]);
+    a[6] = (mat[1][0] * mat[2][1] - mat[2][0] * mat[1][1]);
+}

enc and decry using vigener cipher.c

@@ -0,0 +1,90 @@
+// Progam for Encryption and Decryption using Vigener Cipher technique //
+
+#include <stdio.h>
+#include <conio.h>
+#include <string.h>
+void main()
+{
+	char str[100];
+	char cstr[100];
+	char code[5] = "SSPC",c;
+	char cap_code[5] = "SSPC";
+	int indexcode = 0, ascii;
+	int i,j,number,a,b, len = 0;
+	clrscr();
+	printf("\n\n\t\tEnter Plain Text = ");
+	gets(str);
+	i = strlen(str);
+	len = strlen(code) - 1;
+	for(j = 0; j < i; j++)
+	{
+		if(str[j] != '')
+		{
+			ascii = (int)str[j];
+			if(ascii >= 65 && ascii <=90)
+			{
+				int index = indexcode % len;
+				cstr[j] = code[index];
+			}
+			indexcode++;
+		}
+		else
+			cstr[j] = '';
+	}
+	cstr[j] = '\0';
+	printf("\n\n\t\tKey Code = ");
+	puts(cstr)
+	for(j = 0; j < i; j++)
+	{
+		ascii = (int)str[j];
+		if(str[j] != '')
+		{
+			if(ascii >= 65 && ascii <= 90)
+			{
+				a = (int)str[j] % 65;
+				b = (int)cstr[j] % 65;
+				number = (a + b) % 26;
+				number = number + 97;								
+			}
+			else if(ascii >= 97 && ascii <= 122)
+			{
+				a = (int)str[j] % 97;
+				b = (int)cstr[j] % 97;
+				number = (a + b) % 26;
+				number = number + 97;							
+			}
+			str[j] = (char) number;
+		}
+		else str[j] = '';
+	}
+	str[j] = '\0';
+	printf("\n\n\t\tEncrypted Text = ");
+	puts(str);
+	for(j = 0; j++)
+	{
+		ascii = (int)str[j];
+		if(str[j] != '')
+		{
+			if(ascii >= 65 && ascii <= 90)
+			{
+				a = (int)str[j] % 65;
+				b = (int)cstr[j] % 65;
+				number = (a + b) % 26;
+				number = number + 97;								
+			}
+			else if(ascii >= 97 && ascii <= 122)
+			{
+				a = (int)str[j] % 97;
+				b = (int)cstr[j] % 97;
+				number = (a + b) % 26;
+				number = number + 97;							
+			}
+			str[j] = (char) number;
+		}
+		else str[j] = '';
+	}
+	str[j] = '\0';
+	printf("\n\n\t\tPlain Text = ");
+	puts(str);
+	getch();	 
+}