diff --git a/ciphers/porta_cipher.py b/ciphers/porta_cipher.py
new file mode 100644
index 000000000..a8e794159
--- /dev/null
+++ b/ciphers/porta_cipher.py
@@ -0,0 +1,110 @@
+alphabet = {
+    "A": ("ABCDEFGHIJKLM", "NOPQRSTUVWXYZ"),
+    "B": ("ABCDEFGHIJKLM", "NOPQRSTUVWXYZ"),
+    "C": ("ABCDEFGHIJKLM", "ZNOPQRSTUVWXY"),
+    "D": ("ABCDEFGHIJKLM", "ZNOPQRSTUVWXY"),
+    "E": ("ABCDEFGHIJKLM", "YZNOPQRSTUVWX"),
+    "F": ("ABCDEFGHIJKLM", "YZNOPQRSTUVWX"),
+    "G": ("ABCDEFGHIJKLM", "XYZNOPQRSTUVW"),
+    "H": ("ABCDEFGHIJKLM", "XYZNOPQRSTUVW"),
+    "I": ("ABCDEFGHIJKLM", "WXYZNOPQRSTUV"),
+    "J": ("ABCDEFGHIJKLM", "WXYZNOPQRSTUV"),
+    "K": ("ABCDEFGHIJKLM", "VWXYZNOPQRSTU"),
+    "L": ("ABCDEFGHIJKLM", "VWXYZNOPQRSTU"),
+    "M": ("ABCDEFGHIJKLM", "UVWXYZNOPQRST"),
+    "N": ("ABCDEFGHIJKLM", "UVWXYZNOPQRST"),
+    "O": ("ABCDEFGHIJKLM", "TUVWXYZNOPQRS"),
+    "P": ("ABCDEFGHIJKLM", "TUVWXYZNOPQRS"),
+    "Q": ("ABCDEFGHIJKLM", "STUVWXYZNOPQR"),
+    "R": ("ABCDEFGHIJKLM", "STUVWXYZNOPQR"),
+    "S": ("ABCDEFGHIJKLM", "RSTUVWXYZNOPQ"),
+    "T": ("ABCDEFGHIJKLM", "RSTUVWXYZNOPQ"),
+    "U": ("ABCDEFGHIJKLM", "QRSTUVWXYZNOP"),
+    "V": ("ABCDEFGHIJKLM", "QRSTUVWXYZNOP"),
+    "W": ("ABCDEFGHIJKLM", "PQRSTUVWXYZNO"),
+    "X": ("ABCDEFGHIJKLM", "PQRSTUVWXYZNO"),
+    "Y": ("ABCDEFGHIJKLM", "OPQRSTUVWXYZN"),
+    "Z": ("ABCDEFGHIJKLM", "OPQRSTUVWXYZN"),
+}
+
+
+def generate_table(key):
+    """
+    >>> generate_table('marvin')  # doctest: +NORMALIZE_WHITESPACE
+    [('ABCDEFGHIJKLM', 'UVWXYZNOPQRST'), ('ABCDEFGHIJKLM', 'NOPQRSTUVWXYZ'),
+     ('ABCDEFGHIJKLM', 'STUVWXYZNOPQR'), ('ABCDEFGHIJKLM', 'QRSTUVWXYZNOP'),
+     ('ABCDEFGHIJKLM', 'WXYZNOPQRSTUV'), ('ABCDEFGHIJKLM', 'UVWXYZNOPQRST')]
+    """
+    return [alphabet[char] for char in key.upper()]
+
+
+def encrypt(key, words):
+    """
+    >>> encrypt('marvin', 'jessica')
+    'QRACRWU'
+    """
+    cipher = ""
+    count = 0
+    table = generate_table(key)
+    for char in words.upper():
+        cipher += get_opponent(table[count], char)
+        count = (count + 1) % len(table)
+    return cipher
+
+
+def decrypt(key, words):
+    """
+    >>> decrypt('marvin', 'QRACRWU')
+    'JESSICA'
+    """
+    return encrypt(key, words)
+
+
+def get_position(table, char):
+    """
+    >>> table = [
+    ...     ('ABCDEFGHIJKLM', 'UVWXYZNOPQRST'), ('ABCDEFGHIJKLM', 'NOPQRSTUVWXYZ'),
+    ...     ('ABCDEFGHIJKLM', 'STUVWXYZNOPQR'), ('ABCDEFGHIJKLM', 'QRSTUVWXYZNOP'),
+    ...     ('ABCDEFGHIJKLM', 'WXYZNOPQRSTUV'), ('ABCDEFGHIJKLM', 'UVWXYZNOPQRST')]
+    >>> get_position(table, 'A')
+    (None, None)
+    """
+    if char in table[0]:
+        row = 0
+    else:
+        row = 1 if char in table[1] else -1
+    return (None, None) if row == -1 else (row, table[row].index(char))
+
+
+def get_opponent(table, char):
+    """
+    >>> table = [
+    ...     ('ABCDEFGHIJKLM', 'UVWXYZNOPQRST'), ('ABCDEFGHIJKLM', 'NOPQRSTUVWXYZ'),
+    ...     ('ABCDEFGHIJKLM', 'STUVWXYZNOPQR'), ('ABCDEFGHIJKLM', 'QRSTUVWXYZNOP'),
+    ...     ('ABCDEFGHIJKLM', 'WXYZNOPQRSTUV'), ('ABCDEFGHIJKLM', 'UVWXYZNOPQRST')]
+    >>> get_opponent(table, 'A')
+    'A'
+    """
+    row, col = get_position(table, char.upper())
+    if row == 1:
+        return table[0][col]
+    else:
+        return table[1][col] if row == 0 else char
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()  # Fist ensure that all our tests are passing...
+    """
+    ENTER KEY: marvin
+    ENTER TEXT TO ENCRYPT: jessica
+    ENCRYPTED: QRACRWU
+    DECRYPTED WITH KEY: JESSICA
+    """
+    key = input("ENTER KEY: ").strip()
+    text = input("ENTER TEXT TO ENCRYPT: ").strip()
+    cipher_text = encrypt(key, text)
+
+    print(f"ENCRYPTED: {cipher_text}")
+    print(f"DECRYPTED WITH KEY: {decrypt(key, cipher_text)}")