writing | Leisure and joy
source ：Python technology 「ID: pythonall」
In the movie 《 Infernal Affairs 》 in , Liu Jianming （ Liu Dehua ） As an undercover of a gangster, Chen Yongren, an undercover of the police, was found in an operation （ Liang Chaowei decorated ） With inspector Huang （ Huang Qiusheng ） Communication by Morse code , After the emergency group SMS area " There's an inner ghost , Terminate the transaction " To avoid gang leaders being caught .
Through the moving picture, we can see that inspector Huang and Chen Yongren can complete the communication only by tapping their fingers , Isn't that amazing ？
The definition of Morse code is as follows ：
Morse code （ Morse code , English ：Morse code） It's a kind of time on and time off signal code , Express different letters in different order 、 Numbers and punctuation . It's by American Alfred · Will and Samuel · Morse is in 1836 The invention of .
Morse code is an early form of digital communication , It depends on a series of Point and row To transmit encoded information , It has five codes ：
spot （ · ）：1 （ read “ drop ” dit , Time takes up 1t ）
draw （—）：111 （ read “ Click ” dah , Time takes up 3t ）
A pause within a character （ Between the dot and the stroke ）：0 （ Time takes up 1t ）
Pause between characters ：000 （ Time takes up 3t ）
A pause between words ：0000000 （ Time takes up 7t ）
The length of the point （ That's the length of time above t） It determines the speed of sending messages .
Our English letters 、 The comparison of numbers and punctuation marks with Morse code is as follows ：
We're sending it now “M O R S E( Space ) C O D E” （morse code） The word , It can be seen from the table that , It should be like this
—— ——— ·—· ··· · / —·—· ——— —·· ·
The corresponding message should be as follows （ drop Indicates knocking ,▢ Indicates a pause ）
Drop by drop ▢ Drop by drop ▢▢▢ Drop by drop ▢ Drop by drop ▢ Drop by drop ▢▢▢ drop ▢ Drop by drop ▢ drop ▢▢▢ drop ▢ drop ▢ drop ▢▢▢ drop ▢▢▢▢▢▢▢ Drop by drop ▢ drop ▢ Drop by drop ▢ drop ▢▢▢ Drop by drop ▢ Drop by drop ▢ Drop by drop
Isn't it very interesting ？
use Python Realize the encryption and decryption of Morse password , It's very simple , Just put the comparison table in a dictionary , Split the plaintext when encrypting , Then take out the corresponding passwords from the dictionary and combine them together , Decryption is to find the corresponding plaintext through the ciphertext comparison table , Then put it together .
After we store the Morse code comparison table in a dictionary , That's true ：
MORSE_CODE_DICT = {
'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': '--..',
'1': '.----', '2': '..---', '3': '...--', '4': '....-', '5': '.....', '6': '-....',
'7': '--...', '8': '---..', '9': '----.', '0': '-----',
', ': '--..--', '.': '.-.-.-', '?': '..--..', '/': '-..-.', '-': '-....-',
'(': '-.--.', ')': '-.--.-'
}The process of encryption is the process of translating plaintext into ciphertext through the comparison table .
We read the plaintext one by one , If it's a letter 、 Numbers or punctuation marks go to the dictionary to find the corresponding password , Characters are separated by spaces , If it's a space between words , Just add two consecutive spaces , Separate words with .
The code of the encryption process is as follows ：
def encrypt(message):
cipher = ''
for letter in message:
if letter != ' ':
# Look up the dictionary and add the corresponding Morse password
# Morse passwords with spaces separating different characters
cipher += MORSE_CODE_DICT[letter] + ' '
else:
# 1 Spaces represent different characters
# 2 Different words
cipher += ' '
return cipherIn the case of decryption , We first add a space at the end of the string to be decoded , We extract characters from strings .
Once we get a space , We will extract the character sequence （ Or our Morse code ） Find the corresponding English characters in , And add it to the variable that will store the result .
Once we get 2 Consecutive spaces , We will add another space to the variable containing the decoded string .
The last space at the end of the string will help us identify the last sequence of Morse code characters .
The code of the decryption process is as follows ：
# A function that decrypts a string from moss to English
def decrypt(message):
# Add extra space at the end to access the last Morse password
message += ' '
decipher = ''
citext = ''
global i
for letter in message:
# Check the space
if letter != ' ':
i = 0
# In the case of spaces
citext += letter
# In the case of space
else:
# If i = 1 Represents a new character
i += 1
# If i = 2 Represents a new word
if i == 2:
# Add spaces to separate words
decipher += ' '
else:
# Use their values to access the key （ Encrypted reverse ）
decipher += list(MORSE_CODE_DICT.keys())[list(MORSE_CODE_DICT.values()).index(citext)]
citext = ''
return decipherLet's test the encryption algorithm first ：
message = "I LOVE YOU"
result = encrypt(message.upper())
print(result)The result of the operation is ：
.. .-.. --- ...- . -.-- --- ..-
You can check the mapping table to see if it is correct .
Test the decryption algorithm again ：
message = ".. .-.. --- ...- . -.-- --- ..-"
result = decrypt(message)
print(result)The result of the operation is ：
I LOVE YOU
The whole process of Morse cipher encryption and decryption is the operation of string , It's simpler . But think about the spies who decrypt manually by tapping or other means , It's still a little technically difficult . Install the encryption and decryption program 13 It's still very useful , Do you think? ？
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