krish07211/encryption-decryption-tool
0
1import streamlit as st2import numpy as np3import random4import string5 6# ---------------- Caesar Cipher ----------------7def caesar_encrypt(text, shift):8 result = ""9 for char in text:10 if char.isalpha():11 base = ord('A') if char.isupper() else ord('a')12 result += chr((ord(char) - base + shift) % 26 + base)13 else:14 result += char15 return result16 17def caesar_decrypt(text, shift):18 return caesar_encrypt(text, -shift)19 20 21# ---------------- Playfair Cipher ----------------22def generate_playfair_matrix(key):23 key = "".join(dict.fromkeys(key.upper().replace("J", "I")))24 alphabet = "ABCDEFGHIKLMNOPQRSTUVWXYZ"25 matrix = key + "".join([c for c in alphabet if c not in key])26 return np.array(list(matrix)).reshape(5,5)27 28def playfair_encrypt_pair(pair, matrix):29 pos = {matrix[i,j]: (i,j) for i in range(5) for j in range(5)}30 a, b = pair31 ra, ca = pos[a]; rb, cb = pos[b]32 if ra == rb: 33 return matrix[ra,(ca+1)%5] + matrix[rb,(cb+1)%5]34 elif ca == cb: 35 return matrix[(ra+1)%5,ca] + matrix[(rb+1)%5,cb]36 else: 37 return matrix[ra,cb] + matrix[rb,ca]38 39def playfair_decrypt_pair(pair, matrix):40 pos = {matrix[i,j]: (i,j) for i in range(5) for j in range(5)}41 a, b = pair42 ra, ca = pos[a]; rb, cb = pos[b]43 if ra == rb: 44 return matrix[ra,(ca-1)%5] + matrix[rb,(cb-1)%5]45 elif ca == cb: 46 return matrix[(ra-1)%5,ca] + matrix[(rb-1)%5,cb]47 else: 48 return matrix[ra,cb] + matrix[rb,ca]49 50def playfair_encrypt(text, key):51 if not key: return "Please enter a keyword"52 matrix = generate_playfair_matrix(key)53 text = "".join([c for c in text.upper().replace("J","I") if c.isalpha()])54 pairs = []55 i = 056 while i < len(text):57 a = text[i]58 if i+1 < len(text):59 b = text[i+1]60 if a == b:61 pairs.append((a,"X"))62 i += 163 else:64 pairs.append((a,b))65 i += 266 else:67 pairs.append((a,"X"))68 i += 169 return "".join(playfair_encrypt_pair(p,matrix) for p in pairs)70 71def playfair_decrypt(text, key):72 if not key: return "Please enter a keyword"73 matrix = generate_playfair_matrix(key)74 text = "".join([c for c in text.upper().replace("J","I") if c.isalpha()])75 if len(text) % 2 != 0: return "Invalid Ciphertext length"76 77 pairs = [(text[i], text[i+1]) for i in range(0, len(text), 2)]78 decrypted_text = "".join(playfair_decrypt_pair(p, matrix) for p in pairs)79 80 final_result = ""81 for i in range(len(decrypted_text)):82 if i > 0 and i < len(decrypted_text) - 1:83 if decrypted_text[i] == 'X' and decrypted_text[i-1] == decrypted_text[i+1]:84 continue # Skip the X85 final_result += decrypted_text[i]86 87 return final_result.rstrip('X')88 89 90# ---------------- Hill Cipher (Improved Math) ----------------91def modInverse(a, m):92 for x in range(1, m):93 if (((a % m) * (x % m)) % m == 1):94 return x95 return -196 97def mod_inverse_matrix(matrix, modulus=26):98 # For 2x2 matrix: [[a, b], [c, d]]99 a, b, c, d = matrix[0,0], matrix[0,1], matrix[1,0], matrix[1,1]100 det = (a*d - b*c) % modulus101 det_inv = modInverse(det, modulus)102 if det_inv == -1:103 return None104 # Adjugate matrix mod 26105 inv_matrix = np.array([[d, -b], [-c, a]]) * det_inv106 return inv_matrix % modulus107 108def hill_encrypt(text, key_matrix):109 text = "".join([c for c in text.upper() if c.isalpha()])110 while len(text) % 2 != 0:111 text += "X"112 result = ""113 for i in range(0, len(text), 2):114 vec = np.array([ord(text[i])-65, ord(text[i+1])-65])115 enc = np.dot(key_matrix, vec) % 26116 result += chr(int(enc[0])+65) + chr(int(enc[1])+65)117 return result118 119def hill_decrypt(cipher, key_matrix):120 inv_matrix = mod_inverse_matrix(key_matrix, 26)121 if inv_matrix is None: return "Matrix is not invertible!"122 cipher = "".join([c for c in cipher.upper() if c.isalpha()])123 result = ""124 for i in range(0, len(cipher), 2):125 vec = np.array([ord(cipher[i])-65, ord(cipher[i+1])-65])126 dec = np.dot(inv_matrix, vec) % 26127 result += chr(int(dec[0])+65) + chr(int(dec[1])+65)128 129 # This line removes the padding 'X' at the very end130 return result.rstrip('X')131 132 133# ---------------- One-Time Pad ----------------134def generate_key(length):135 return ''.join(random.choice(string.ascii_uppercase) for _ in range(length))136 137def otp_encrypt(message, key):138 message = "".join([c for c in message.upper() if c.isalpha()])139 key = "".join([c for c in key.upper() if c.isalpha()])140 if len(key) < len(message): return "Key is too short!"141 result = ""142 for m,k in zip(message,key):143 result += chr(((ord(m)-65)+(ord(k)-65))%26 + 65)144 return result145 146def otp_decrypt(cipher, key):147 cipher = "".join([c for c in cipher.upper() if c.isalpha()])148 key = "".join([c for c in key.upper() if c.isalpha()])149 if len(key) < len(cipher): return "Key is too short!"150 result = ""151 for c,k in zip(cipher,key):152 result += chr(((ord(c)-65)-(ord(k)-65))%26 + 65)153 return result154 155 156# ---------------- Streamlit GUI ----------------157st.set_page_config(page_title="Cipher GUI", layout="wide")158st.title("🔐 Substitution Cipher GUI")159 160cipher_choice = st.sidebar.radio("Select Cipher:", 161 ["Caesar Cipher", "Playfair Cipher", "Hill Cipher", "One-Time Pad"])162 163col1, col2 = st.columns(2)164 165if cipher_choice == "Caesar Cipher":166 with col1:167 st.header("Encrypt")168 msg = st.text_area("Message to encrypt:", key="caesar_enc")169 shift = st.number_input("Shift:", min_value=0, max_value=25, value=3, key="caesar_enc_shift")170 if st.button("Encrypt", key="caesar_enc_btn"):171 st.success(caesar_encrypt(msg, shift))172 with col2:173 st.header("Decrypt")174 msg = st.text_area("Message to decrypt:", key="caesar_dec")175 shift = st.number_input("Shift:", min_value=0, max_value=25, value=3, key="caesar_dec_shift")176 if st.button("Decrypt", key="caesar_dec_btn"):177 st.success(caesar_decrypt(msg, shift))178 179elif cipher_choice == "Playfair Cipher":180 with col1:181 st.header("Encrypt")182 msg = st.text_area("Message to encrypt:", key="playfair_enc")183 key = st.text_input("Keyword:", key="playfair_key_enc")184 if st.button("Encrypt", key="playfair_enc_btn"):185 st.success(playfair_encrypt(msg, key))186 with col2:187 st.header("Decrypt")188 msg = st.text_area("Message to decrypt:", key="playfair_dec")189 key = st.text_input("Keyword:", key="playfair_key_dec")190 if st.button("Decrypt", key="playfair_dec_btn"):191 st.success(playfair_decrypt(msg, key))192 193elif cipher_choice == "Hill Cipher":194 with col1:195 st.header("Encrypt")196 msg = st.text_area("Message to encrypt:", key="hill_enc")197 st.write("Using fixed key matrix [[3,3],[2,5]]")198 key_matrix = np.array([[3,3],[2,5]])199 if st.button("Encrypt", key="hill_enc_btn"):200 st.success(hill_encrypt(msg, key_matrix))201 with col2:202 st.header("Decrypt")203 msg = st.text_area("Message to decrypt:", key="hill_dec")204 st.write("Using fixed key matrix [[3,3],[2,5]]")205 key_matrix = np.array([[3,3],[2,5]])206 if st.button("Decrypt", key="hill_dec_btn"):207 st.success(hill_decrypt(msg, key_matrix))208 209elif cipher_choice == "One-Time Pad":210 with col1:211 st.header("Encrypt")212 msg = st.text_area("Message to encrypt:", key="otp_enc")213 if st.button("Generate Key", key="otp_key_btn"):214 st.session_state['otp_key'] = generate_key(len(msg))215 st.info(f"Generated Key: {st.session_state['otp_key']}")216 217 current_key = st.session_state.get('otp_key', "")218 key = st.text_input("Key:", value=current_key, key="otp_key_enc")219 220 if st.button("Encrypt", key="otp_enc_btn"):221 st.success(otp_encrypt(msg, key))222 with col2:223 st.header("Decrypt")224 msg = st.text_area("Message to decrypt:", key="otp_dec")225 key = st.text_input("Key:", value=st.session_state.get('otp_key', ""), key="otp_key_dec")226 if st.button("Decrypt", key="otp_dec_btn"):227 st.success(otp_decrypt(msg, key))