假设我们要使用带加密密钥3的铁路围栏密码解密消息“daxsarineaistestsmoy”。请显示您如何继续操作的步骤。
信息安全,Cryptography密码学
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1条回答 默认 最新
- 游一游走一走 2022-10-18 16:34关注
drtiansexamissoeasy
# Python3 program to illustrate # Rail Fence Cipher Encryption # and Decryption # function to encrypt a message def encryptRailFence(text, key): # create the matrix to cipher # plain text key = rows , # length(text) = columns # filling the rail matrix # to distinguish filled # spaces from blank ones rail = [['\n' for i in range(len(text))] for j in range(key)] # to find the direction dir_down = False row, col = 0, 0 for i in range(len(text)): # check the direction of flow # reverse the direction if we've just # filled the top or bottom rail if (row == 0) or (row == key - 1): dir_down = not dir_down # fill the corresponding alphabet rail[row][col] = text[i] col += 1 # find the next row using # direction flag if dir_down: row += 1 else: row -= 1 # now we can construct the cipher # using the rail matrix result = [] for i in range(key): for j in range(len(text)): if rail[i][j] != '\n': result.append(rail[i][j]) return("" . join(result)) # This function receives cipher-text # and key and returns the original # text after decryption def decryptRailFence(cipher, key): # create the matrix to cipher # plain text key = rows , # length(text) = columns # filling the rail matrix to # distinguish filled spaces # from blank ones rail = [['\n' for i in range(len(cipher))] for j in range(key)] # to find the direction dir_down = None row, col = 0, 0 # mark the places with '*' for i in range(len(cipher)): if row == 0: dir_down = True if row == key - 1: dir_down = False # place the marker rail[row][col] = '*' col += 1 # find the next row # using direction flag if dir_down: row += 1 else: row -= 1 # now we can construct the # fill the rail matrix index = 0 for i in range(key): for j in range(len(cipher)): if ((rail[i][j] == '*') and (index < len(cipher))): rail[i][j] = cipher[index] index += 1 # now read the matrix in # zig-zag manner to construct # the resultant text result = [] row, col = 0, 0 for i in range(len(cipher)): # check the direction of flow if row == 0: dir_down = True if row == key-1: dir_down = False # place the marker if (rail[row][col] != '*'): result.append(rail[row][col]) col += 1 # find the next row using # direction flag if dir_down: row += 1 else: row -= 1 return("".join(result)) # Driver code if __name__ == "__main__": print(decryptRailFence("daxsarineaisestsmoy", 3))
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