added submission for gangus

gangus-assign1/caesar-cipher.txt

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+SBWKRQ

gangus-assign1/caesar-plain.txt

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+PYTHON

gangus-assign1/crypto.py

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+"""
+Assignment 1: Cryptography
+Course: CS 92SI
+Name: GEOFFREY ANGUS
+Date: 10/7/2015
+
+Replace this with a description of the program.
+"""
+
+def encrypt_caesar(plaintext):
+    """
+    Encrypts plaintext using a Caesar cipher.
+    Add more implementation details here.
+    """
+
+    ciphertext = []
+    for letter in plaintext:
+        ciphertext.append(chr(((ord(letter) - 62) % 26) + 65))
+    outputString = ''.join(ciphertext)
+
+    # plaintext:
+    # PYTHON
+    # ciphertext:
+    # SBWKRQ
+
+    return outputString
+
+
+def decrypt_caesar(ciphertext):
+    """
+    Decrypts a ciphertext using a Caesar cipher.
+    Add more implementation details here.
+    """
+
+    plaintext = []
+    for letter in ciphertext:
+        plaintext.append(chr(((ord(letter) + 36) % 26) + 65))
+    outputString = ''.join(plaintext)
+    return outputString
+
+
+def encrypt_vigenere(plaintext, keyword):
+    """
+    Encrypts plaintext using a Vigenere cipher with a keyword.
+    Add more implementation details here.
+    """
+    key = []
+    index = 0
+
+    ciphertext = []
+    for i in range(len(plaintext)):
+        index = i % len(keyword)
+        key = keyword[index]
+        ciphertext.append(chr((ord(plaintext[i])+ord(key)) % 26 + 65))
+    outputString = ''.join(ciphertext)
+
+    # plaintext:
+    # ATTACKATDAWN
+    # key:
+    # LEMONLEMONLE
+    # ciphertext:
+    # LXFOPVEFRNHR
+    return outputString
+
+
+def decrypt_vigenere(ciphertext, keyword):
+    """
+    Decrypts ciphertext using a Vigenere cipher with a keyword.
+    Add more implementation details here.
+    """
+    key = []
+    index = 0
+
+    plaintext = []
+    for i in range(len(ciphertext)):
+        index = i % len(keyword)
+        key = keyword[index]
+        plaintext.append(chr((ord(ciphertext[i])-ord(key)) % 26 + 65))
+    outputString = ''.join(plaintext)
+
+    return outputString
+
+def encrypt_railfence(plaintext, num_rails):
+    """
+    Encrypts plaintext using a railfence cipher.
+    Add more implementation details here.
+    """
+    level = 0
+    direction = -1
+
+    cipherlist = [[] for _ in range(num_rails)]
+    for letter in plaintext:
+        cipherlist[level].append(letter)
+        if level > num_rails - 2:
+            direction = -direction
+        elif level < 1:
+            direction = -direction
+        level = level + direction
+
+    ciphertext = []
+    for i in cipherlist:
+        ciphertext.append(''.join(i))
+
+    outputString = ''.join(ciphertext)
+
+    # plaintext:
+    # WEAREDISCOVEREDFLEEATONCE
+    # num_rails:
+    # 3
+    # ciphertext:
+    # WECRLTEERDSOEEFEAOCAIVDEN
+
+    return outputString
+
+
+def decrypt_railfence(ciphertext, num_rails):
+    """
+    Encrypts plaintext using a railfence cipher.
+    Add more implementation details here.
+    """
+
+    spacing = num_rails + num_rails - 2
+    segmentLength = num_rails - 1
+    numSegments = len(ciphertext) // segmentLength
+    numRepetition = len(ciphertext) // spacing
+    numLeftover = len(ciphertext) % segmentLength
+
+    isAscending = numSegments % 2
+
+    plainlist = [[] for _ in range(spacing)]
+
+    if isAscending:
+        numsFromEnd = len(ciphertext) - numRepetition - 1
+    else:
+        numsFromEnd = len(ciphertext) - numRepetition
+
+    plainlist[spacing - 1] = ciphertext[numsFromEnd:]
+
+    i = 0
+    count = 0
+    plainbucket = 0
+    leftOverlist = []
+    for j in range(spacing - 1):
+        if (i < numsFromEnd - numRepetition):
+            plainlist[j] = ciphertext[i:i + numRepetition + 1]
+        else:
+            plainlist[j] = ciphertext[i:numsFromEnd]
+        if i + numRepetition + 1 < numsFromEnd - 1:
+            i += numRepetition + 1
+        else:
+            i += 1
+        if (numLeftover > 0):
+            leftOverlist += ciphertext[i]
+            numLeftover -= 1
+    mergeMid = plainlist[1] + plainlist[2]
+    plainlist = [plainlist[0],mergeMid,plainlist[3]]
+    i = 0
+    plaintext = [None] * (len(ciphertext))
+    for level in range(spacing):
+        if (level == 0 or level == segmentLength):
+            plaintext[level::spacing] = plainlist[level]
+        else:
+            plaintext[level::spacing] = mergeMid[i // 2::2]
+        i += 1
+    return ''.join(plaintext)
+
+
+    # i = 0
+    # segmentLength = num_rails - 1
+    # numSegments = len(ciphertext) // segmentLength
+    # numLeftover = len(ciphertext) % segmentLength
+    # isAscending = numSegments % 2
+    # count = 0
+    # segment = 0
+    # plainList = [None] * len(ciphertext)
+    # for letters in ciphertext:
+    #     offset = count % segmentLength * 2
+    #     if offset == 0:
+    #         plainList[offset::spacing] = ciphertext[segment:segment + numSegments//2]
+    #         segment += numSegments/2
+
+    #     else:
+    #         plainList[offset::spacing] = ciphertext[segment:segment + numSegments:2]
+    #         segment
+
+    #     count += 1
+
+def read_from_file(filename):
+    """
+    Reads and returns content from a file.
+    Add more implementation details here.
+    """
+    l = []
+    with open(filename) as f:
+        for line in f:
+            line = line.upper()
+            l.append(line)
+    str1 = ''.join(l)
+    return str1
+
+
+def write_to_file(filename, content):
+    with open(filename, 'w') as f:
+        f.write(content)
+
+
+def run_suite():
+    """
+    Runs a single iteration of the cryptography suite.
+
+    Asks the user for input text from a string or file, whether to encrypt
+    or decrypt, what tool to use, and where to show the output.
+    """
+    print("*Input*")
+    inputType = input('(F)ile or (S)tring? ').upper() # Obtain the user's desired input here
+    while not inputType or inputType[0] not in ['F','S']:
+        inputType = input('(F)ile or (S)tring? ').upper()
+    if inputType[0] == 'S':
+        inputString = input('Enter the string to encrypt: ').upper()
+    else:
+        inputString = read_from_file(input('Enter the file to encrypt: ')).upper()
+
+    inputString = ''.join([i for i in inputString if i.isalpha()])
+    print (inputString)
+
+
+    print("*Transform*")
+    inputType = input('(E)ncrypt or (D)ecrypt? ').upper() # Encrypt or decrypt the input
+    while not inputType or inputType[0] not in ['E','D']:
+        inputType = input('(E)ncrypt or (D)ecrypt? ').upper()
+
+    cipherType = input('(C)aesar, (V)igenere, or (R)ailfence? ').upper()
+    while not cipherType or cipherType[0] not in ['C','V','R']:
+        cipherType = input('(C)aesar, (V)igenere, or (R)ailfence? ').upper()
+    if cipherType[0] == 'C':
+        print("It's a Caesar cipher!")
+        if inputType[0] == 'E':
+            outputString = encrypt_caesar(inputString)
+        else:
+            outputString = decrypt_caesar(inputString)
+    elif cipherType[0] == 'V':
+        print("It's a Vigenere cipher!")
+        keyword = input('Passkey? ').upper()
+        if inputType[0] == 'E':
+            outputString = encrypt_vigenere(inputString, keyword)
+        else:
+            outputString = decrypt_vigenere(inputString, keyword)
+    else:
+        print("It's a Railfence cipher!")
+        railNum = int(input('Number of rails? '))
+        if inputType[0] == 'E':
+            outputString = encrypt_railfence(inputString, railNum)
+        else:
+            outputString = decrypt_railfence(inputString, railNum)        
+
+
+    # print('Encrypting' + + 'using' + + 'with' + 'key' + )
+
+    print("*Output*")
+    inputType = input('(F)ile or (S)tring? ').upper()  # Print or write the transformed output
+    while not inputType or inputType[0] not in ['F','S']:
+        inputType = input('(F)ile or (S)tring? ').upper()
+    if inputType[0] == 'S':
+        inputString = "Here it is!"
+        print (outputString)
+    else:
+        filename = input('Filename? ')
+        write_to_file(filename,outputString)
+        print ("Finished!")
+
+# Do not modify code beneath this point.
+def should_continue():
+    """
+    Asks the user whether they would like to continue.
+    Responses that begin with a `Y` return True. (case-insensitively)
+    Responses that begin with a `N` return False. (case-insensitively)
+    All other responses (including '') cause a reprompt.
+    """
+    choice = input("Again (Y/N)? ").upper()
+    while not choice or choice[0] not in ['Y', 'N']:
+        choice = input("Please enter either 'Y' or 'N'. Again (Y/N)? ").upper()
+    return choice[0] == 'Y'
+
+
+def main():
+    """Harness for the Cryptography Suite"""
+    print("Welcome to the Cryptography Suite!")
+    run_suite()
+    while should_continue():
+        run_suite()
+    print("Goodbye!")
+
+
+if __name__ == '__main__':
+    """This block is run if and only if the Python script is invoked from the
+    command line."""
+    main()

gangus-assign1/feedback.txt

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+Name: <YOUR NAME>
+1) How long did this assignment take you to complete?
+
+
+
+2) What has been the best part of the class so far?
+
+
+
+
+
+3) What can we do to make this class more enjoyable for you?
+
+
+
+
+
+4) What types of assignments would excite you in this class?
+
+
+
+
+

gangus-assign1/railfence-cipher.txt

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+WECRLTEERDSOEEFEAOCAIVDEN

gangus-assign1/railfence-plain.txt

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+WE ARE DISCOVERED. FLEE AT ONCE

gangus-assign1/secret_message.txt

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+KHOORZRUOG

gangus-assign1/test.txt

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+SBWKRQ

gangus-assign1/vigenere-cipher.txt

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+LXFOPVEFRNHR

gangus-assign1/vigenere-plain.txt

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+Attack At Dawn!