From 79bb71732b568d6901b522aed9cb86885d7e8f12 Mon Sep 17 00:00:00 2001
From: mnjx <111888944+mnjx@users.noreply.github.com>
Date: Tue, 14 Feb 2023 20:44:42 +0100
Subject: [PATCH] Added cipher programs

---
 caesar-cipher-bruteforce.c |  60 ++++++++++++++++++
 caesar-cipher.c            |  39 ++++++++++++
 polyalphabetic-cipher.c    | 127 +++++++++++++++++++++++++++++++++++++
 vernam-cipher.c            |  46 ++++++++++++++
 4 files changed, 272 insertions(+)
 create mode 100644 caesar-cipher-bruteforce.c
 create mode 100644 caesar-cipher.c
 create mode 100644 polyalphabetic-cipher.c
 create mode 100644 vernam-cipher.c

diff --git a/caesar-cipher-bruteforce.c b/caesar-cipher-bruteforce.c
new file mode 100644
index 0000000..325f1fe
--- /dev/null
+++ b/caesar-cipher-bruteforce.c
@@ -0,0 +1,60 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+void encode(char message[]) {
+    char alphabet[52] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};
+
+    for (int k = 1; k < 26; k++) {
+        for (int i = 0; i < strlen(message); i++) {
+            for (int j = 0; j < 26; j++) {
+                if (alphabet[j] == message[i]) {
+                    message[i] = alphabet[j+k];
+                    break;
+                }
+            }
+        }
+        printf("\nEncoded with shift %d: %s\n", k, message);
+    }
+}
+
+void decode(char message[]) {
+    char alphabet[52] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};
+
+    for (int k = 1; k < 26; k++) {
+        for (int i = 0; i < strlen(message); i++) {
+            for (int j = 26; j < 52; j++) {
+                if (alphabet[j] == message[i]) {
+                    message[i] = alphabet[j-k];
+                    break;
+                }
+            }
+        }
+        printf("\nDecoded with shift %d: %s\n", k, message);
+    }
+}
+
+int main() {
+    char ar[1000];
+    printf("Enter the message\n");
+    scanf("%[^\n]", &ar);
+    
+    int option = -1;
+    printf("Encode or decode? 0 or 1\n");
+    scanf("%d", &option);
+
+    while (option == 0 || option == 1) {
+        switch (option) {
+            case 0:
+                encode(ar);
+                option = -1;
+                break;
+            case 1:
+                decode(ar);
+                option = -1;
+                break;
+            default:
+                printf("Please enter a valid number.\n");
+        }
+    }
+}
\ No newline at end of file
diff --git a/caesar-cipher.c b/caesar-cipher.c
new file mode 100644
index 0000000..462fbc7
--- /dev/null
+++ b/caesar-cipher.c
@@ -0,0 +1,39 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+void encode(char message[], int shift) {
+    char alphabet[52] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};
+
+    for (int i = 0; i < strlen(message); i++) {
+        for (int j = 0; j < 26; j++) {
+            if (alphabet[j] == message[i]) {
+                message[i] = alphabet[j+shift];
+                break;
+            }
+        }
+    }
+}
+
+void decode(char message[], int shift) {
+    char alphabet[52] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};
+
+    for (int i = 0; i < strlen(message); i++) {
+        for (int j = 26; j < 52; j++) {
+            if (alphabet[j] == message[i]) {
+                message[i] = alphabet[j-shift];
+                break;
+            }
+        }
+    }
+}
+
+int main() {
+    char ar[1000];
+    scanf("%[^\n]", &ar);
+    encode(ar, 25);
+    printf("Encoded: %s\n", ar);
+
+    decode(ar, 25);
+    printf("\nDecoded: %s\n", ar);
+}
\ No newline at end of file
diff --git a/polyalphabetic-cipher.c b/polyalphabetic-cipher.c
new file mode 100644
index 0000000..706af87
--- /dev/null
+++ b/polyalphabetic-cipher.c
@@ -0,0 +1,127 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+void encode(char message[], char code_char[]) {
+    char alphabet[52] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};
+    int code[strlen(code_char)];
+
+    for (int i = 0; i < strlen(code_char); i++) {
+        for (int j = 0; j < 26; j++) {
+            if (alphabet[j] == code_char[i] && code_char[i] != ' ' && code_char[i] != ',' && code_char[i] != '.') code[i] = j+1;
+        }
+    }
+
+    // for (int i = 0; i < strlen(code_char); i++) printf("%d ", code[i]); printf("\n");
+
+    for (int i = 0, k = 0; i < strlen(message); i++) {
+        for (int j = 0; j < 26; j++) {
+            if (alphabet[j] == message[i]) {
+                if (k >= strlen(code_char)) k = 0;
+                if (1 <= code[k] && code[k] <= 26) {
+                    // printf("%c = ", message[i]);
+                    message[i] = alphabet[j+code[k]];
+                    // printf("%c\n", message[i]);  
+                    k++;
+                } else {
+                    k++;
+                    if (1 <= code[k] && code[k] <= 26) {
+                        // printf("%c = ", message[i]);
+                        message[i] = alphabet[j+code[k]];
+                        // printf("%c\n", message[i]);  
+                        k++;
+                    } else {
+                        k++;
+                        if (1 <= code[k] && code[k] <= 26) {
+                            // printf("%c = ", message[i]);
+                            message[i] = alphabet[j+code[k]];
+                            // printf("%c\n", message[i]);  
+                            k++;
+                        }
+                    }
+                }
+                break;
+            }
+        }
+    }
+
+    printf("Encoded with repeating shifts ");
+    for (int i = 0; i < strlen(code_char); i++) {
+        if (1 <= code[i] && code[i] <= 26) printf("%d ", code[i]);
+    }
+    printf(": %s\n", message);
+}
+
+void decode(char message[], char code_char[]) {
+    char alphabet[52] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};
+    int code[strlen(code_char)];
+
+    for (int i = 0; i < strlen(code_char); i++) {
+        for (int j = 0; j < 26; j++) {
+            if (alphabet[j] == code_char[i] && code_char[i] != ' ' && code_char[i] != ',' && code_char[i] != '.') code[i] = j+1;
+        }
+    }
+
+    // for (int i = 0; i < strlen(code_char); i++) printf("%d ", code[i]); printf("\n");
+
+    for (int i = 0, k = 0; i < strlen(message); i++) {
+        for (int j = 26; j < 52; j++) {
+            if (alphabet[j] == message[i]) {
+                if (k >= strlen(code_char)) k = 0;
+                if (1 <= code[k] && code[k] <= 26) {
+                    // printf("%c = ", message[i]);
+                    message[i] = alphabet[j-code[k]];
+                    // printf("%c\n", message[i]);  
+                    k++;
+                } else {
+                    k++;
+                    if (1 <= code[k] && code[k] <= 26) {
+                        // printf("%c = ", message[i]);
+                        message[i] = alphabet[j-code[k]];
+                        // printf("%c\n", message[i]);  
+                        k++;
+                    } else {
+                        k++;
+                        if (1 <= code[k] && code[k] <= 26) {
+                            // printf("%c = ", message[i]);
+                            message[i] = alphabet[j-code[k]];
+                            // printf("%c\n", message[i]);  
+                            k++;
+                        }
+                    }
+                }
+                break;
+            }
+        }
+    }
+
+    printf("Encoded with repeating shifts ");
+    for (int i = 0; i < strlen(code_char); i++) {
+        if (1 <= code[i] && code[i] <= 26) printf("%d ", code[i]);
+    }
+    printf(": %s\n", message);
+}
+
+int main() {
+    char ar[1000];
+    char code[1000];
+    char option_char;
+    printf("Enter the message\n");
+    scanf("%[^\n]", &ar);
+    
+    int option = -1;
+    printf("Encode or decode? 0 or 1 and the code word/sentence\n");
+
+    scanf("%d %[^\n]", &option, &code);
+
+    switch (option) {
+        case 0:
+            encode(ar, code);
+            option = -1;
+            break;
+        case 1:
+            decode(ar, code);
+            option = -1;
+            break;
+    }
+}
\ No newline at end of file
diff --git a/vernam-cipher.c b/vernam-cipher.c
new file mode 100644
index 0000000..f83e215
--- /dev/null
+++ b/vernam-cipher.c
@@ -0,0 +1,46 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+void encode(char message[]) {
+    char origin[strlen(message)];
+    for (int i = 0; i < strlen(message); i++) {
+        origin[i] = message[i];
+    }
+    char alphabet[52] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};
+    int shifts[strlen(message)];
+    for (int i = 0; i < strlen(message); i++) {
+        shifts[i] = 0;
+    }
+    int k;
+
+    for (int i = 0; i < strlen(message); i++) {
+        for (int j = 0; j < 26; j++) {
+            if (alphabet[j] == message[i]) {
+                k = rand() % 27 + 1;
+                shifts[i] = k;
+                message[i] = alphabet[j+k];                
+                break;
+            }
+        }
+    }
+    printf("Encoded: %s\n", message);
+    // for (int i = 0; i < strlen(message); i++) {
+    //     printf("%d %c; ", shifts[i], origin[i]);
+    // }
+    // printf("\n");
+}
+
+// void decode(char message[]); (uplne to nejde...)
+
+int main() {
+    srand(time(NULL));
+    
+    char ar[1000];
+
+    printf("Enter the message\n");
+    scanf("%[^\n]", &ar);
+    
+    encode(ar);
+}
\ No newline at end of file