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--- ic:labs:04 [2022/10/23 16:55]
razvan.smadu [SPN 2 (3p)]
+++ ic:labs:04 [2023/10/09 23:21] (current)
razvan.smadu
@@ Line 3: / Line 3: @@
 Prezentarea PowerPoint pentru acest laborator poate fi găsită [[https://drive.google.com/file/d/1mjbkxFqYNB-lRRXGAhsdh1vK9nwbnDuS/view?usp=sharing|aici]].
+Puteți lucra acest laborator folosind platforma Google Colab, accesând [[https://colab.research.google.com/github/ACS-IC-labs/IC-labs/blob/main/labs/lab04/lab4.ipynb
+|acest]] link.
+<hidden>
+<spoiler Click pentru a vedea utils.py>
 <file python utils.py>
 import base64
+from typing import Generator
-# CONVERSION FUNCTIONS
-def _chunks(string, chunk_size):
-    for i in range(0, len(string), chunk_size):
-        yield string[i:i+chunk_size]
-# THIS ONE IS NEW
+def _pad(data: str, size: int) -> str:
-def byte_2_bin(bval):
+    reminder = len(data) % size
-    """
+    if reminder != 0:
-      Transform a byte (8-bit) value into a bitstring
+        data = "0" * (size - reminder) + data
+    return data
+def _chunks(data: str, chunk_size: int) -> Generator[str, None, None]:
+    data = _pad(data, chunk_size)
+    for i in range(0, len(data), chunk_size):
+        yield data[i : i + chunk_size]
+def _hex(data: int) -> str:
+    return format(data, "02x")
+# Conversion functions
+def byte_2_bin(bval: int) -> str:
+    """Converts a byte value to a binary string.
+    Args:
+        bval (int):
+            The byte value to be converted. It should be an integer between
+and 255.
+    Returns:
+        str: The binary string representation of the byte value, where each bit
+        is encoded as a character. The result has a fixed length of 8 characters
+        and is padded with leading zeros if necessary.
+    Examples:
+        >>> byte_2_bin(72)
+        '01001000'
+        >>> byte_2_bin(66)
+        '01000010'
     """
     return bin(bval)[2:].zfill(8)
-def _hex(x):
-    return format(x, '02x')
-def hex_2_bin(data):
+def hex_2_bin(data: str) -> str:
-    return ''.join(f'{int(x, 16):08b}' for x in _chunks(data, 2))
+    """Converts a hexadecimal string to a binary representation.
-def str_2_bin(data):
+    Args:
-    return ''.join(f'{ord(c):08b}' for c in data)
+        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).
-def bin_2_hex(data):
+    Returns:
-    return ''.join(f'{int(b, 2):02x}' for b in _chunks(data, 8))
+        str: The binary representation of the hexadecimal string, where each
+            pair of hexadecimal digits is encoded as an 8-bit binary number.
-def str_2_hex(data):
+    Examples:
-    return ''.join(f'{ord(c):02x}' for c in data)
+        >>> hex_2_bin("01abcd")
+        '000000011010101111001101'
+        >>> hex_2_bin("0a")
+        '00001010'
+    """
+    return "".join(f"{int(x, 16):08b}" for x in _chunks(data, 2))
-def bin_2_str(data):
-    return ''.join(chr(int(b, 2)) for b in _chunks(data, 8))
-def hex_2_str(data):
+def bin_2_hex(data: str) -> str:
-    return ''.join(chr(int(x, 16)) for x in _chunks(data, 2))
+    """Converts a binary string to a hexadecimal representation.
-# XOR FUNCTIONS
+    Args:
-def strxor(a, b):  # xor two strings, trims the longer input
+        data (str): The binary string to be converted. It should have a multiple
-    return ''.join(chr(ord(x) ^ ord(y)) for (x, y) in zip(a, b))
+            of 8 characters and only contain valid binary digits (0 or 1).
-def bitxor(a, b):  # xor two bit-strings, trims the longer input
+    Returns:
-    return ''.join(str(int(x) ^ int(y)) for (x, y) in zip(a, b))
+        str: The hexadecimal representation of the binary string, where each
+            group of 8 binary digits is encoded as a pair of hexadecimal digits.
-def hexxor(a, b):  # xor two hex-strings, trims the longer input
+    Examples:
-    return ''.join(_hex(int(x, 16) ^ int(y, 16)) for (x, y) in zip(_chunks(a, 2), _chunks(b, 2)))
+        >>> bin_2_hex("000000011010101111001101")
+        '01abcd'
+        >>> bin_2_hex("00001010")
+        '0a'
+    """
+    return "".join(f"{int(b, 2):02x}" for b in _chunks(data, 8))
-# BASE64 FUNCTIONS
-def b64decode(data):
-    return bytes_to_string(base64.b64decode(string_to_bytes(data)))
-def b64encode(data):
+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 bytes_to_string(bytes_data):
-    return bytes_data.decode()  # default utf-8
-def string_to_bytes(string_data):
+def b64decode(data: str) -> str:
-    return string_data.encode()  # default utf-8
+    """Decodes a base64 encoded string.
+    Args:
+        data (str): The base64 encoded string to be decoded. It should only
+            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>
+<note tip>
 In acest laborator veti avea niste exercitii ce folosesc PRFs, PRPs si DES. Puteti sa va uitati in cursul de  [[https://drive.google.com/file/d/1Fjybv6k5QudRB1bkAi5shVUGlUyTO_0U/view?usp=sharing|aici]] ca sa va aduceti aminte lucrurile de baza.
+</note>
 ==== Exercițiul 1 (4p) ====
@@ Line 99: / Line 372: @@
 <note tip>
 Puteți porni de la urmatorul schelet de cod:
-</note>
+<spoiler Click pentru a vedea spn1.py>
 <code python spn1.py>
+from typing import List
 from utils import *
+# fmt: off
 # Rijndael S-box
 sbox = [0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67,
@@ Line 155: / Line 431: @@
 x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55,
 x21, 0x0c, 0x7d]
+# fmt: on
-def permute4(s):
-    """
-      Perform a permutatation by shifting all bits 4 positions right.
-      The input is assumed to be a 16-bit bitstring
-    """
-    ps = ''
-    ps = ps + s[12:16]
-    ps = ps + s[0:12]
-    return ps
-def permute_inv4(s):
+def permute4(s: str) -> str:
-    """
+    """Perform a permutatation by shifting all bits 4 positions right.
-      Perform the inverse of permute4
-      The input is assumed to be a 16-bit bitstring
-    """
-    ps = ''
-    ps = ps + s[4:16]
-    ps = ps + s[0:4]
-    return ps
+    Args:
+        s (str): The input is assumed to be a 16-bit bitstring.
-def spn_1r_reduced_2s(k, x):
+    Raises:
+        TypeError: Expected input to be a string.
+        ValueError: Expected input to have length 16.
+    Returns:
+        str: The permuted string by shifting all bits 4 positions right.
     """
-      Performs an encryption with a substitution-permutation network.
+    if not isinstance(s, str):
-      Key k = {k1, k2}, total of 16 bits (2 x 8 bits)
+        raise TypeError(
-      Input x = {x1, x2}, total of 16 bits (2 x 8 bits)
+            f"Invalid type for the input. Expected `str`, but got `{type(s)}`."
-      Both k and x are assumed to be bitstrings.
+        )
+    if len(s) != 16:
+        raise ValueError(
+            f"Invalit input length. Expected to be 16, but got {len(s)}."
+        )
+    return s[12:16] + s[0:12]
+def permute_inv4(s: str) -> str:
+    """Perform the inverse of permute4.
+    Args:
+        s (str): The input is assumed to be a 16-bit bitstring.
+    Raises:
+        TypeError: Expected input to be a string.
+        ValueError: Expected input to have length 16.
-      Return:
+    Returns:
-      a 16-bit bitstring containing the encryption y = {y1, y2}
+        str: The permuted string by shifting all bits 4 positions left.
     """
+    if not isinstance(s, str):
+        raise TypeError(
+            f"Invalid type for the input. Expected `str`, but got `{type(s)}`."
+        )
+    if len(s) != 16:
+        raise ValueError(
+            f"Invalit input length. Expected to be 16, but got {len(s)}."
+        )
+    return s[4:16] + s[0:4]
+def spn_1r_reduced_2s(k: str, x: str) -> str:
+    """Performs an encryption with a substitution-permutation network.
+    Args:
+        k (str): Key k = {k1, k2}, total of 16 bits (2 x 8 bits). Assumed to be
+            bitstring.
+        x (str): Input x = {x1, x2}, total of 16 bits (2 x 8 bits). Assumed to
+            be bitstring.
+    Returns:
+        str: a 16-bit bitstring containing the encryption y = {y1, y2}
+    """
     # Split input and key
-    x1 = x[0:8]
+    x1, x2 = x[0:8], x[8:16]
-    x2 = x[8:16]
+    k1, k2 = k[0:8], k[8:16]
-    k1 = k[0:8]
-    k2 = k[8:16]
     # Apply S-box
@@ Line 212: / Line 516: @@
-def spn_1r_full_2s(k, x):
+def spn_1r_full_2s(k: str, x: str) -> str:
-    """
+    """Performs an encryption with a substitution-permutation network.
-      Performs an encryption with a substitution-permutation network.
-      Key k = {k1, k2, k3, k4}, total of 32 bits (4 x 8 bits)
-      Input x = {x1, x2}, total of 16 bits (2 x 8 bits)
-      Both k and x are assumed to be bitstrings.
-      Return:
+    Args:
-      a 16-bit bitstring containing the encryption y = {y1, y2}
+        k (str): Key k = {k1, k2, k3, k4}, total of 32 bits (4 x 8 bits).
-    """
+            Assumed to be bitstring.
+        x (str): Input x = {x1, x2}, total of 16 bits (2 x 8 bits).
+            Assumed to be bitstring.
+    Returns:
+        str: a 16-bit bitstring containing the encryption y = {y1, y2}
+    """
     # Split input and key
-    x1 = x[0:8]
+    x1, x2 = x[0:8], x[8:16]
-    x2 = x[8:16]
+    k1, k2, k3, k4 = k[0:8], k[8:16], k[16:24], k[24:32]
-    k1 = k[0:8]
-    k2 = k[8:16]
-    k3 = k[16:24]
-    k4 = k[24:32]
     # Apply S-box
@@ Line 250: / Line 551: @@
     y2 = bitxor(po2, k4)
-    return y1+y2
+    return y1 + y2
-def main():
+def main() -> None:
     # Run reduced 2-byte SPN
-    msg = 'Hi'
+    msg = "Hi"
-    key = '??'  # Find this
+    key = "??"  # Find the key that should replace ??
-    xs = str_2_bin(msg)
     ks = str_2_bin(key)
+    # TODO 1: Find the key in the reduced 2-byte SPN
+    xs = str_2_bin(msg)
     ys = spn_1r_reduced_2s(ks, xs)
-    print('Two y halves of reduced SPN: ' + ys[0:8] + ' (hex: ' + bin_2_hex(
+    print(
-        ys[0:8]) + '), ' + ys[8:16] + ' (hex: ' + bin_2_hex(ys[8:16]) + ')')
+        "Two y halves of reduced SPN:"
+        f" {ys[0:8]} (hex: {bin_2_hex(ys[0:8])}),"
+        f" {ys[8:16]} (hex: {bin_2_hex(ys[8:16])})"
+    )
     # Run full 2-byte SPN
-    msg = 'Om'
+    msg = "Om"
-    key = '????'  # Find this
+    key = "????"  # Find the key that should replace ????
-    xs = str_2_bin(msg)
     ks = str_2_bin(key)
+    # TODO 2: Find the key in the full 2-byte SPN
+    xs = str_2_bin(msg)
     ys = spn_1r_full_2s(ks, xs)
-    print('Two y halves of full SPN (2 bytes): ' + ys[0:8] + ' (hex: ' + bin_2_hex(
+    print(
-        ys[0:8]) + '), ' + ys[8:16] + ' (hex: ' + bin_2_hex(ys[8:16]) + ')')
+        "Two y halves of full SPN (2 bytes):"
+        f" {ys[0:8]} (hex: {bin_2_hex(ys[0:8])}),"
+        f" {ys[8:16]} (hex: {bin_2_hex(ys[8:16])})"
+    )
 if __name__ == "__main__":
     main()
 </code>
+</spoiler>
+</note>
 ==== SPN 2 (3p) ====
@@ Line 287: / Line 606: @@
 <note tip>O să trebuiască să faceți căutare brute-force.</note>
-==== SPN 3 (Bonus) ====
+==== SPN 3 - Bonus (2p) ====
-In acest exercitiu vom folosi un bloc mai mare. In acest SPN sunt introdusi 4 octeti x=[x1 || x2 || x3 || x4], iar cheia folosita contine 8 octeti k=[k1 || k2 || k3 || k4 || k5 || k6 || k7 || k8] ca in figura:
+În acest exercițiu vom folosi un bloc mai mare. În acest SPN sunt introduși 4 octeți x=[x1 || x2 || x3 || x4], iar cheia folosită conține 8 octeți k=[k1 || k2 || k3 || k4 || k5 || k6 || k7 || k8] ca în figură:
 {{:sasc:laboratoare:spn_1r_full_4s.png|}}
-Ca si in SPN-ul precedent, permutarea roteste toti octetii la dreapta cu 4 biti.
+Ca și în SPN-ul precedent, permutarea rotește toți octeții la dreapta cu 4 biți.
-  - Gasiti cheia stiind urmatoarele perechi mesaj/ciphertext: ('Omul', 0xddcf7bc7), ('stea', 0x96d58b43), ('luna', 0x9c3f2303)
+  - Găsiți cheia știind următoarele perechi mesaj/ciphertext: ('Omul', 0xddcf7bc7), ('stea', 0x96d58b43), ('luna', 0x9c3f2303)
 <note tip>
-De data aceasta nu se poate executa o cautare brute-force pe toti octetii de XOR. Incercati sa atacati cate un S-box pe rand. Ganditi-va ce biti sunt afectati de fiecare S-box pentru a construi un atac eficient. Ce se intampla daca faceti brute force pe k5 si k6? Puteti sa aflati k1?
+De data aceasta nu se poate executa o cautare brute-force pe toți octeții de XOR. Încercați să atacați câte un S-box pe rând. Gandiți-vă ce biți sunt afectați de fiecare S-box pentru a construi un atac eficient. Ce se întâmplă dacă faceți brute force pe k5 și k6? Puteți să aflați k1?
 </note>
+</hidden>

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ic/labs/04.1666533303.txt.gz · Last modified: 2022/10/23 16:55 by razvan.smadu

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