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This article will provide a step-by-step guide on how to write a Python program to encrypt and decrypt a message using the Caesar Cipher algorithm and the Rail Fence algorithm. The Caesar Cipher algorithm is a substitution cipher that shifts the letters of a message by a certain number of places in the alphabet. The Rail Fence algorithm is a transposition cipher that rearranges the letters of a message in a zig-zag pattern. Both algorithms are simple to implement and can be used to encrypt and decrypt messages.<\/p>\n
# Caesar Cipher Algorithm<\/p>\n
# Encryption
\ndef encrypt(text,s):
\n result = “” <\/p>\n
# traverse text
\n for i in range(len(text)):
\n char = text[i] <\/p>\n
# Encrypt uppercase characters
\n if (char.isupper()):
\n result += chr((ord(char) + s-65) % 26 + 65) <\/p>\n
# Encrypt lowercase characters
\n else:
\n result += chr((ord(char) + s – 97) % 26 + 97) <\/p>\n
return result <\/p>\n
# Decryption
\ndef decrypt(text,s):
\n result = “” <\/p>\n
# traverse text
\n for i in range(len(text)):
\n char = text[i] <\/p>\n
# Decrypt uppercase characters
\n if (char.isupper()):
\n result += chr((ord(char) – s-65) % 26 + 65) <\/p>\n
# Decrypt lowercase characters
\n else:
\n result += chr((ord(char) – s – 97) % 26 + 97) <\/p>\n
return result <\/p>\n
# Driver code
\ntext = “ATTACKATONCE”
\ns = 4<\/p>\n
# Encrypt the string
\nprint (“Text : ” + text)
\nprint (“Shift : ” + str(s))
\nprint (“Cipher: ” + encrypt(text,s)) <\/p>\n
# Decrypt the string
\nprint (“Text : ” + encrypt(text,s))
\nprint (“Shift : ” + str(s))
\nprint (“Plain : ” + decrypt(encrypt(text,s),s)) <\/p>\n
# Rail Fence Algorithm<\/p>\n
# Encryption
\ndef encryptRailFence(text, key):
\n\trail = [[‘\\n’ for i in range(len(text))]
\n\t\t\t\tfor j in range(key)] <\/p>\n
\t# to find the direction
\n\tdir_down = False
\n\trow, col = 0, 0<\/p>\n
\tfor i in range(len(text)): <\/p>\n
\t\t# check the direction of flow
\n\t\t# reverse the direction if we’ve just
\n\t\t# filled the top or bottom rail
\n\t\tif (row == 0) or (row == key – 1):
\n\t\t\tdir_down = not dir_down <\/p>\n
\t\t# fill the corresponding alphabet
\n\t\trail[row][col] = text[i]
\n\t\tcol += 1<\/p>\n
\t\t# find the next row using direction flag
\n\t\tif dir_down:
\n\t\t\trow += 1
\n\t\telse:
\n\t\t\trow -= 1
\n\t# now we can construct the cipher
\n\t# using the rail matrix
\n\tresult = []
\n\tfor i in range(key):
\n\t\tfor j in range(len(text)):
\n\t\t\tif rail[i][j] != ‘\\n’:
\n\t\t\t\tresult.append(rail[i][j])
\n\treturn(“” . join(result)) <\/p>\n
# Decryption
\ndef decryptRailFence(cipher, key): <\/p>\n
\t# create the matrix to fill
\n\t# in the rail fence pattern
\n\trail = [[‘\\n’ for i in range(len(cipher))]
\n\t\t\t\tfor j in range(key)] <\/p>\n
\t# to find the direction
\n\tdir_down = None
\n\trow, col = 0, 0<\/p>\n
\t# mark the places with ‘*’
\n\tfor i in range(len(cipher)):
\n\t\tif row == 0:
\n\t\t\tdir_down = True
\n\t\tif row == key – 1:
\n\t\t\tdir_down = False<\/p>\n
\t\t# place the marker
\n\t\trail[row][col] = ‘*’
\n\t\tcol += 1<\/p>\n
\t\t# find the next row
\n\t\t# using direction flag
\n\t\tif dir_down:
\n\t\t\trow += 1
\n\t\telse:
\n\t\t\trow -= 1<\/p>\n
\t# now we can construct the
\n\t# fill the rail matrix
\n\tindex = 0
\n\tfor i in range(key):
\n\t\tfor j in range(len(cipher)):
\n\t\t\tif ((rail[i][j] == ‘*’) and
\n\t\t\t(index < len(cipher))): \n\t\t\t\trail[i][j] = cipher[index] \n\t\t\t\tindex += 1\n\t\n\t# now read the matrix in \n\t# zig-zag manner to construct \n\t# the resultant text \n\tresult = [] \n\trow, col = 0, 0\n\tfor i in range(len(cipher)): \n\t\t\n\t\t# check the direction of flow \n\t\tif row == 0: \n\t\t\tdir_down = True\n\t\tif row == key-1: \n\t\t\tdir_down = False\n\t\t\n\t\t# place the marker \n\t\tif (rail[row][col] != '*'): \n\t\t\tresult.append(rail[row][col]) \n\t\t\tcol += 1\n\t\t\t\n\t\t# find the next row using \n\t\t# direction flag \n\t\tif dir_down: \n\t\t\trow += 1\n\t\telse: \n\t\t\trow -= 1\n\treturn(\"\" . join(result)) \n\n# Driver Code \ntext = \"ATTACKATONCE\"\nkey = 3\n\n# Encrypt the string \nprint (\"Text : \" + text) \nprint (\"Shift : \" + str(key)) \nprint (\"Cipher: \" + encryptRailFence(text,key)) \n \n# Decrypt the string \nprint (\"Text : \" + encryptRailFence(text,key)) \nprint (\"Shift : \" + str(key)) \nprint (\"Plain : \" + decryptRailFence(encryptRailFence(text,key),key)) <\/p>\n
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Write a python program to encrypt and decrypt the message using caesar cipher alogorithm and rail fence algorithm [closed]<\/p>\n
Encrypting and decrypting messages is an important part of modern communication. There are many different algorithms that can be used to encrypt and decrypt messages, such as the Caesar Cipher algorithm and the Rail Fence algorithm. In this article, we will discuss how to use these two algorithms to encrypt and decrypt messages.<\/p>\n
The Caesar Cipher algorithm is a substitution cipher that uses a single key to encrypt and decrypt messages. It works by shifting each letter of the plaintext message by a certain number of places in the alphabet. For example, if the key is 3, then the letter A would be shifted to the letter D, the letter B would be shifted to the letter E, and so on. To decrypt the message, the same key is used to shift the letters back to their original positions.<\/p>\n
The Rail Fence algorithm is a transposition cipher that uses a single key to encrypt and decrypt messages. It works by writing the plaintext message in a zigzag pattern, with each letter being written in a different row. For example, if the key is 3, then the message would be written in three rows, with the first letter being written in the first row, the second letter being written in the second row, and so on. To decrypt the message, the same key is used to read the message in the same zigzag pattern.<\/p>\n
Encrypting and decrypting messages using the Caesar Cipher algorithm and the Rail Fence algorithm is a simple and effective way to protect sensitive information. Both algorithms are easy to use and can be used to encrypt and decrypt messages quickly and securely.<\/p>\n","protected":false},"excerpt":{"rendered":"