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--- ic:labs:01 [2022/10/03 15:28]
razvan.smadu
+++ ic:labs:01 [2025/02/23 13:24] (current)
razvan.smadu [Laboratorul 01 - Introducere]
@@ Line 1: / Line 1: @@
 ===== Laboratorul 01 - Introducere =====
+Puteți lucra acest laborator folosind și platforma Google Colab, accesând [[https://colab.research.google.com/github/ACS-IC-labs/IC-labs/blob/main/labs/lab01/lab1.ipynb|acest]] link, cu excepția exercițiului bonus. Un scurt tutorial pentru utilizarea platformei poate fi găsit [[https://docs.google.com/document/d/1Dcnyv9wTfWJx8CEgnR6OgLbHAO7XD1BXGjwOAMAEmlc/edit|aici]].
 ==== Python3 Crash Course ====
-Tutorialul poate fi găsit [[ic:resurse:python|aici]].
+Tutorialul poate fi găsit [[ic:resurse:python|aici]]. La laboratoare vom folosi Python 3.10 sau mai nou.
 ==== Codificare vs Criptare ====
@@ Line 24: / Line 26: @@
   * Binar (01010101)
   * Hexazecimal [0-9a-fA-F]
-  * Base64 [a-zA-Z0-9] împreună cu '+' și '/'. În general, Base64 se termină cu '=' sau '==' reprezentând padding. Este foarte folosit în web deoarece HTTP este un protocol de transfer text.
+  * Base64 [a-zA-Z0-9] împreună cu '+' și '/'. În general, base64 se termină cu '=' sau '==' reprezentând padding. Este foarte folosit în web deoarece HTTP este un protocol de transfer text.
 Mai jos găsiți câteva funcții utile pentru conversii și operații de XOR pentru date de diferite formate:
+<spoiler Click pentru a vedea utils.py>
 <file python utils.py>
 import base64
+from typing import Generator
-# CONVERSION FUNCTIONS
-def _chunks(string, chunk_size):
+def _pad(data: str, size: int) -> str:
-    for i in range(0, len(string), chunk_size):
+    reminder = len(data) % size
-        yield string[i:i+chunk_size]
+    if reminder != 0:
+        data = "0" * (size - reminder) + data
-def _hex(x):
+    return data
-    return format(x, '02x')
-def hex_2_bin(data):
+def _chunks(data: str, chunk_size: int) -> Generator[str, None, None]:
-    return ''.join(f'{int(x, 16):08b}' for x in _chunks(data, 2))
+    data = _pad(data, chunk_size)
+    for i in range(0, len(data), chunk_size):
-def str_2_bin(data):
+        yield data[i : i + chunk_size]
-    return ''.join(f'{ord(c):08b}' for c in data)
-def bin_2_hex(data):
+def _hex(data: int) -> str:
-    return ''.join(f'{int(b, 2):02x}' for b in _chunks(data, 8))
+    return format(data, "02x")
-def str_2_hex(data):
-    return ''.join(f'{ord(c):02x}' for c in data)
+# Conversion functions
-def bin_2_str(data):
-    return ''.join(chr(int(b, 2)) for b in _chunks(data, 8))
+def hex_2_bin(data: str) -> str:
+    """Converts a hexadecimal string to a binary representation.
-def hex_2_str(data):
-    return ''.join(chr(int(x, 16)) for x in _chunks(data, 2))
+    Args:
+        data (str): The hexadecimal string to be converted. It should have an
-# XOR FUNCTIONS
+            even number of characters and only contain valid hexadecimal digits
+            (0-9, A-F, a-f).
-def strxor(a, b):  # xor two strings, trims the longer input
-    return ''.join(chr(ord(x) ^ ord(y)) for (x, y) in zip(a, b))
+    Returns:
+        str: The binary representation of the hexadecimal string, where each
-def bitxor(a, b):  # xor two bit-strings, trims the longer input
+            pair of hexadecimal digits is encoded as an 8-bit binary number.
-    return ''.join(str(int(x) ^ int(y)) for (x, y) in zip(a, b))
+    Examples:
-def hexxor(a, b):  # xor two hex-strings, trims the longer input
+        >>> hex_2_bin("01abcd")
-    return ''.join(_hex(int(x, 16) ^ int(y, 16)) for (x, y) in zip(_chunks(a, 2), _chunks(b, 2)))
+        '000000011010101111001101'
+        >>> hex_2_bin("0a")
-# BASE64 FUNCTIONS
+        '00001010'
+    """
-def b64decode(data):
+    return "".join(f"{int(x, 16):08b}" for x in _chunks(data, 2))
-    return bytes_to_string(base64.b64decode(string_to_bytes(data)))
-def b64encode(data):
+def bin_2_hex(data: str) -> str:
+    """Converts a binary string to a hexadecimal representation.
+    Args:
+        data (str): The binary string to be converted. It should have a multiple
+            of 8 characters and only contain valid binary digits (0 or 1).
+    Returns:
+        str: The hexadecimal representation of the binary string, where each
+            group of 8 binary digits is encoded as a pair of hexadecimal digits.
+    Examples:
+        >>> bin_2_hex("000000011010101111001101")
+        '01abcd'
+        >>> bin_2_hex("00001010")
+        '0a'
+    """
+    return "".join(f"{int(b, 2):02x}" for b in _chunks(data, 8))
+def str_2_bin(data: str) -> str:
+    """Converts a string to a binary representation.
+    Args:
+        data (str): The string to be converted.
+    Returns:
+        str: The binary representation of the string, where each character is
+            encoded as an 8-bit binary number.
+    Examples:
+        >>> str_2_bin("Hello")
+        '0100100001100101011011000110110001101111'
+        >>> str_2_bin("IC")
+        '0100100101000011'
+    """
+    return "".join(f"{ord(c):08b}" for c in data)
+def bin_2_str(data: str) -> str:
+    """Converts a binary string to a string.
+    Args:
+        data (str): The binary string to be converted. It should have a multiple
+            of 8 characters and only contain valid binary digits (0 or 1).
+    Returns:
+        str: The string representation of the binary string, where each group
+            of 8 binary digits is decoded as a character.
+    Examples:
+        >>> bin_2_str("0100100001100101011011000110110001101111")
+        'Hello'
+        >>> bin_2_str("0100100101000011")
+        'IC'
+    """
+    return "".join(chr(int(b, 2)) for b in _chunks(data, 8))
+def str_2_hex(data: str) -> str:
+    """Converts a string to a hexadecimal representation.
+    Args:
+        data (str): The string to be converted.
+    Returns:
+        str: The hexadecimal representation of the string, where each character
+            is encoded as a pair of hexadecimal digits.
+    Examples:
+        >>> str_2_hex("Hello")
+        '48656c6c6f'
+        >>> str_2_hex("IC")
+        '4943'
+    """
+    return "".join(f"{ord(c):02x}" for c in data)
+def hex_2_str(data: str) -> str:
+    """Converts a hexadecimal string to a string.
+    Args:
+        data (str): The hexadecimal string to be converted. It should have an
+            even number of characters and only contain valid hexadecimal digits
+            (0-9, A-F, a-f).
+    Returns:
+        str: The string representation of the hexadecimal string, where each
+            pair of hexadecimal digits is decoded as a character.
+    Examples:
+        >>> hex_2_str("48656c6c6f")
+        'Hello'
+        >>> hex_2_str("4943")
+        'IC'
+    """
+    return "".join(chr(int(x, 16)) for x in _chunks(data, 2))
+# XOR functions
+def strxor(operand_1: str, operand_2: str) -> str:
+    """Performs a bitwise exclusive OR (XOR) operation on two strings.
+    Args:
+        operand_1 (str): The first string to be XORed.
+        operand_2 (str): The second string to be XORed.
+    Returns:
+        str: The result of the XOR operation on the two strings, where each
+            character is encoded as an 8-bit binary number. The result has
+            the same length as the shorter input string.
+    Examples:
+        >>> strxor("Hello", "IC")
+        '\\x01&'
+        >>> strxor("secret", "key")
+        '\\x18\\x00\\x1a'
+    """
+    return "".join(chr(ord(x) ^ ord(y)) for (x, y) in zip(operand_1, operand_2))
+def bitxor(operand_1: str, operand_2: str) -> str:
+    """Performs a bitwise exclusive OR (XOR) operation on two bit-strings.
+    Args:
+        operand_1 (str): The first bit-string to be XORed. It should only
+            contain valid binary digits (0 or 1).
+        operand_2 (str): The second bit-string to be XORed. It should only
+            contain valid binary digits (0 or 1).
+    Returns:
+        str: The result of the XOR operation on the two bit-strings, where each
+            bit is encoded as a character. The result has the same length as
+            the shorter input bit-string.
+    Examples:
+        >>> bitxor("01001000", "01000010")
+        '00001010'
+        >>> bitxor("10101010", "00110011")
+        '10011001'
+    """
+    return "".join(str(int(x) ^ int(y)) for (x, y) in zip(operand_1, operand_2))
+def hexxor(operand_1: str, operand_2: str) -> str:
+    """Performs a bitwise exclusive OR (XOR) operation on two hexadecimal
+    strings.
+    Args:
+        operand_1 (str): The first hexadecimal string to be XORed. It should
+            have an even number of characters and only contain valid hexadecimal
+            digits (0-9, A-F, a-f).
+        operand_2 (str): The second hexadecimal string to be XORed. It should
+            have an even number of characters and only contain valid
+            digits (0-9, A-F, a-f).
+    Returns:
+        str: The result of the XOR operation on the two hexadecimal strings,
+            where each pair of hexadecimal digits is encoded as a pair of
+            hexadecimal digits. The result has the same length as the shorter
+            input hexadecimal string.
+    Examples:
+        >>> hexxor("48656c6c6f", "42696e67")
+        '0a0c020b'
+        >>> hexxor("736563726574", "6b6579")
+        '18001a'
+    """
+    return "".join(
+        _hex(int(x, 16) ^ int(y, 16))
+        for (x, y) in zip(_chunks(operand_1, 2), _chunks(operand_2, 2))
+    )
+# Python3 'bytes' functions
+def bytes_to_string(bytes_data: bytearray | bytes) -> str:
+    """Converts a byte array or a byte string to a string.
+    Args:
+        bytes_data (bytearray | bytes): The byte array or the byte string to be
+            converted. It should be encoded in Latin-1 format.
+    Returns:
+        str: The string representation of the byte array or the byte string,
+            decoded using Latin-1 encoding.
+    Examples:
+        >>> bytes_to_string(b'Hello')
+        'Hello'
+        >>> bytes_to_string(bytearray(b'IC'))
+        'IC'
+    """
+    return bytes_data.decode(encoding="raw_unicode_escape")
+def string_to_bytes(string_data: str) -> bytes:
+    """Converts a string to a byte string.
+    Args:
+        string_data (str): The string to be converted.
+    Returns:
+        bytes: The byte string representation of the string, encoded using
+        Latin-1 encoding.
+    Examples:
+        >>> string_to_bytes('Hello')
+        b'Hello'
+        >>> string_to_bytes('IC')
+        b'IC'
+    """
+    return string_data.encode(encoding="raw_unicode_escape")
+# Base64 functions
+def b64encode(data: str) -> str:
+    """Encodes a string to base64.
+    Parameters:
+        data (str): The string to be encoded.
+    Returns:
+        str: The base64 encoded string, using Latin-1 encoding.
+    Examples:
+        >>> b64encode("Hello")
+        'SGVsbG8='
+        >>> b64encode("IC")
+        'SUM='
+    """
     return bytes_to_string(base64.b64encode(string_to_bytes(data)))
-# PYTHON3 'BYTES' FUNCTIONS
+def b64decode(data: str) -> str:
-def bytes_to_string(bytes_data):
+    """Decodes a base64 encoded string.
-    return bytes_data.decode()  # default utf-8
+    Args:
-def string_to_bytes(string_data):
+        data (str): The base64 encoded string to be decoded. It should only
-    return string_data.encode()  # default utf-8
+            contain valid base64 characters (A-Z, a-z, 0-9, +, /, =).
+    Returns:
+        str: The decoded string, using Latin-1 encoding.
+    Examples:
+        >>> b64decode("SGVsbG8=")
+        'Hello'
+        >>> b64decode("SUM=")
+        'IC'
+    """
+    return bytes_to_string(base64.b64decode(string_to_bytes(data)))
 </file>
+</spoiler>
 == Bytes în Python ==
@@ Line 92: / Line 342: @@
 text1 = "Ana are mere"
 text2 = b"Ana are mere"
-type(text1) # <class 'str'>
+print(type(text1))  # <class 'str'>
-type(text2) # <class 'bytes'>
+print(type(text2))  # <class 'bytes'>
 </code>
@@ Line 118: / Line 368: @@
 ==== Hail, Caesar! ====
-Unul dintre cele mai cunoscute și mai simple scheme de criptare este [[https://en.wikipedia.org/wiki/Caesar_cipher|Cifrul lui Cezar]]. Ideea de baza este de a transforma fiecare litera din plaintext prin deplasarea la stânga a poziției literei curente cu trei poziții. Cu alte cuvinte, A devine D, B devine E, C devine F, și așa mai departe. Operația de criptare a unei litere $m$ este definită prin relația $Enc(m) = (m + 3)\ mod\ 26 $. Analog, pentru a decripta un text, trebuie să facem deplasarea la dreapta cu 3 poziții. Deci, operația de decriptare pentru fiecare literă $c$ dintr-un ciphertext este dată de relația $Dec(c) = (c - 3)\ mod\ 26$.
+Unul dintre cele mai cunoscute și mai simple scheme de criptare este [[https://en.wikipedia.org/wiki/Caesar_cipher|Cifrul lui Cezar]]. Ideea de bază este de a transforma fiecare literă din plaintext prin deplasarea la stânga a poziției literei curente cu trei poziții. Cu alte cuvinte, A devine D, B devine E, C devine F, și așa mai departe. Operația de criptare a unei litere $m$ este definită prin relația $Enc(m) = (m + 3)\ mod\ 26 $. Analog, pentru a decripta un text, trebuie să facem deplasarea la dreapta cu 3 poziții. Deci, operația de decriptare pentru fiecare literă $c$ dintr-un ciphertext este dată de relația $Dec(c) = (c - 3)\ mod\ 26$.
 === Criptarea unei litere ===
@@ Line 125: / Line 375: @@
 <code python>
-alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
-def caesar_enc(letter):
-    if letter < 'A' or letter > 'Z':
-        print("Invalid letter")
+def caesar_enc(letter: str) -> str:
-        return
+    if not "A" <= letter <= "Z":
-    else:
+        raise ValueError("Invalid letter")
-        return alphabet[(ord(letter) - ord('A') + 3) % len(alphabet)]
+    return ALPHABET[(ord(letter) - ord("A") + 3) % len(ALPHABET)]
 </code>
@@ Line 150: / Line 400: @@
 Testați următoarele comenzi în consolă:
 <code python>
->>> print(alphabet)
+>>> print(ALPHABET)
->>> len(alphabet)
+>>> len(ALPHABET)
->>> alphabet[0]
+>>> ALPHABET[0]
->>> ord('A')
+>>> ord("A")
->>> ord('D') - ord('A')
+>>> ord("D") - ord("A")
 >>> 26 % 26
 >>> 28 % 26
@@ Line 162: / Line 412: @@
 Testați funcția de criptare pe câteva exemple:
 <code>
->>> caesar_enc('D')
+>>> caesar_enc("D")
->>> caesar_enc('Z')
+>>> caesar_enc("Z")
->>> caesar_enc('B')
+>>> caesar_enc("B")
 </code>
@@ Line 178: / Line 428: @@
 <code Python>
-def caesar_enc_string(plaintext):
+def caesar_enc_string(plaintext: str) -> str:
-    ciphertext = ''
+    ciphertext = ""
     for letter in plaintext:
-        ciphertext = ciphertext + caesar_enc(letter)
+        ciphertext += caesar_enc(letter)
     return ciphertext
 </code>
@@ Line 189: / Line 439: @@
 <code Python>
 shell$ python -i caesar.py # run the script in interactive mode
->>> test = 'HELLO'
+>>> test = "HELLO"
->>> test += 'WORLD'
+>>> test += "WORLD"
 >>> caesar_enc_string(test)
 </code>
@@ Line 198: / Line 448: @@
 <file Python test_caesar.py>
-alphabet='ABCDEFGHIJKLMNOPQRSTUVWXYZ'
+ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
-def caesar_enc(letter):
-    if letter < 'A' or letter > 'Z':
-        print('Invalid letter')
-        return
-    else:
-        return alphabet[(ord(letter) - ord('A') + 3) % len(alphabet)]
-def caesar_enc_string(plaintext):
+def caesar_enc(letter: str) -> str:
-    ciphertext = ''
+    if not 'A' <= letter <= 'Z':
+        raise ValueError('Invalid letter')
+    return ALPHABET[(ord(letter) - ord('A') + 3) % len(ALPHABET)]
+def caesar_enc_string(plaintext: str) -> str:
+    ciphertext = ""
     for letter in plaintext:
-        ciphertext = ciphertext + caesar_enc(letter)
+        ciphertext += caesar_enc(letter)
     return ciphertext
-def main():
-    m = 'BINEATIVENIT'
+def main() -> None:
+    m = "BINEATIVENIT"
     c = caesar_enc_string(m)
     print(c)
 if __name__ == "__main__":
     main()
@@ Line 241: / Line 493: @@
 <code Python>
-def caesar_enc(letter, k = 3):
+def caesar_enc(letter: str, k: int = 3) -> str:
-    if letter < 'A' or letter > 'Z':
+    if not "A" <= letter <= "Z":
-        print('Invalid letter')
+        raise ValueError("Invalid letter")
-        return None
+    return ALPHABET[(ord(letter) - ord("A") + k) % len(ALPHABET)]
-    else:
-        return alphabet[(ord(letter) - ord('A') + k) % len(alphabet)]
-def caesar_enc_string(plaintext, k = 3):
-    ciphertext = ''
+def caesar_enc_string(plaintext: str, k: int = 3) -> str:
+    ciphertext = ""
     for letter in plaintext:
-        ciphertext = ciphertext + caesar_enc(letter, k)
+        ciphertext += caesar_enc(letter, k)
     return ciphertext
 </code>
@@ Line 259: / Line 510: @@
 <code Python>
 shell$ python -i caesar.py
->>> caesar_enc_string('HELLO')       # use the default value for k
+>>> caesar_enc_string("HELLO")       # use the default value for k
->>> caesar_enc_string('HELLO', 0)    # pass the key as a positional argument
+>>> caesar_enc_string("HELLO", 0)    # pass the key as a positional argument
->>> caesar_enc_string('HELLO', k=1)  # pass the key as a keyword (named) argument
+>>> caesar_enc_string("HELLO", k=1)  # pass the key as a keyword (named) argument
 </code>
@@ Line 320: / Line 571: @@
 python mtp.py <ciphertexts filename>  # OR python3 mtp.py <ciphertexts filename>
 </code>
+<note info>
+`<ciphertexts filename>` trebuie să conțină cele 10 texte cifrate de mai sus.
+</note>
 <note info>

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ic/labs/01.1664800094.txt.gz · Last modified: 2022/10/03 15:28 by razvan.smadu

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