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<header>
<h1 class="title">Module <code>cryptanalysis.spn</code></h1>
</header>
<section id="section-intro">
<p>The <code>spn</code> module implements the Substitution-Permutation Network (SPN) encryption algorithm.</p>
<p>SPN is a symmetric-key block cipher that operates on fixed-size blocks of plaintext and produces
corresponding blocks of ciphertext. It consists of several rounds of substitutions and permutations
and key additions applied to the input data.</p>
<p>Classes:
- SPN: Implementation of the SPN encryption algorithm.</p>
<p>Usage:
Initialize an instance of the <code><a title="cryptanalysis.spn.SPN" href="#cryptanalysis.spn.SPN">SPN</a></code> class with the required parameters, then use the provided methods
to perform encryption and decryption operations.</p>
<details class="source">
<summary>
<span>Expand source code</span>
</summary>
<pre><code class="python">"""
The `spn` module implements the Substitution-Permutation Network (SPN) encryption algorithm.
SPN is a symmetric-key block cipher that operates on fixed-size blocks of plaintext and produces
corresponding blocks of ciphertext. It consists of several rounds of substitutions and permutations
and key additions applied to the input data.
Classes:
- SPN: Implementation of the SPN encryption algorithm.
Usage:
Initialize an instance of the `SPN` class with the required parameters, then use the provided methods
to perform encryption and decryption operations.
"""
from math import log2
__all__ = ["rotate_left", "gen_pbox", "SPN"]
def rotate_left(val, shift, mod):
"""
Rotate the bits of the value to the left by the shift amount.
Parameters
----------
val : int
The value to be rotated.
shift : int
The number of places to shift the value to the left.
mod : int
The modulo to be applied on the result.
Returns
-------
int
The rotated value.
Notes
-----
The function rotates the bits of the value to the left by the shift amount,
wrapping the bits that overflow. The result is then masked by (1<<mod)-1
to only keep the mod number of least significant bits.
"""
shift = shift % mod
return (val << shift | val >> (mod - shift)) & ((1 << mod) - 1)
def gen_pbox(s, n):
"""
Generate a balanced permutation box for an SPN.
Parameters
----------
s : int
Number of bits per S-box.
n : int
Number of S-boxes.
Returns
-------
list of int
The generated P-box.
"""
return [(s * i + j) % (n * s) for j in range(s) for i in range(n)]
class SPN:
"""
Class representing the SPN (Substitution-Permutation Network) encryption algorithm.
Methods
-------
perm(inp)
Apply the P-box permutation on the input.
inv_perm(inp)
Apply the inverse P-box permutation on the input.
sub(inp)
Apply the S-box substitution on the input.
inv_sub(inp)
Apply the inverse S-box substitution on the input.
int_to_list(inp)
Convert a len(pbox)-sized integer to a list of S-box sized integers.
list_to_int(lst)
Convert a list of S-box sized integers to a len(pbox)-sized integer.
expand_key(key, rounds)
Derive round keys deterministically from the given key.
_enc_last_noperm(pt)
Encrypt plaintext using the SPN, where the last round doesn't contain the permute operation.
_enc_last_withperm(ct)
Encrypt plaintext using the SPN, where the last round contains the permute operation.
_dec_last_noperm(ct)
Decrypt ciphertext using the SPN, where the last round doesn't contain the permute operation.
_dec_last_withperm(ct)
Decrypt ciphertext using the SPN, where the last round contains the permute operation.
"""
def __init__(self, sbox, pbox, key, rounds, implementation=0):
"""
Initialize the SPN class with the provided parameters.
Parameters
----------
sbox : list of int
List of integers representing the S-box.
pbox : list of int
List of integers representing the P-box.
key : list of int or bytes or bytearray
List of integers, bytes, or bytearray representing the key.
LSB block_size bits will be used.
rounds : int
Number of rounds for the SPN.
implementation : int, optional
Implementation option. Default is 0.
0: Last round doesn't contain the permute operation.
1: Last round contains the permute operation.
"""
self.sbox = sbox
self.pbox = pbox
self.sinv = [sbox.index(i) for i in range(len(sbox))]
self.pinv = [pbox.index(i) for i in range(len(pbox))]
self.block_size = len(pbox)
self.box_size = int(log2(len(sbox)))
self.num_sbox = len(pbox) // self.box_size
self.rounds = rounds
self.round_keys = self.expand_key(key, rounds)
if implementation == 0:
self.encrypt = self._enc_last_noperm
self.decrypt = self._dec_last_noperm
else:
self.encrypt = self._enc_last_withperm
self.decrypt = self._dec_last_withperm
def perm(self, inp: int) -> int:
"""
Apply the P-box permutation on the input.
Parameters
----------
inp : int
The input value to apply the P-box permutation on.
Returns
-------
int
The permuted value after applying the P-box.
"""
ct = 0
for i, v in enumerate(self.pbox):
ct |= (inp >> (self.block_size - 1 - i) & 1) << (
self.block_size - 1 - v)
return ct
def inv_perm(self, inp: int) -> int:
"""
Apply the inverse P-box permutation on the input.
Parameters
----------
inp : int
The input value to apply the inverse P-box permutation on.
Returns
-------
int
The permuted value after applying the inverse P-box.
"""
ct = 0
for i, v in enumerate(self.pinv):
ct |= (inp >> (self.block_size - 1 - i) & 1) << (
self.block_size - 1 - v)
return ct
def sub(self, inp: int) -> int:
"""
Apply the S-box substitution on the input.
Parameters
----------
inp : int
The input value to apply the S-box substitution on.
Returns
-------
int
The substituted value after applying the S-box.
"""
ct, bs = 0, self.box_size
for i in range(self.num_sbox):
ct |= self.sbox[(inp >> (i * bs)) & ((1 << bs) - 1)] << (bs * i)
return ct
def inv_sub(self, inp: int) -> int:
"""
Apply the inverse S-box substitution on the input.
Parameters
----------
inp : int
The input value to apply the inverse S-box substitution on.
Returns
-------
int
The substituted value after applying the inverse S-box.
"""
ct, bs = 0, self.box_size
for i in range(self.num_sbox):
ct |= self.sinv[(inp >> (i * bs)) & ((1 << bs) - 1)] << (bs * i)
return ct
def int_to_list(self, inp):
"""
Convert a len(pbox)-sized integer to a list of S-box sized integers.
Parameters
----------
inp : int
An integer representing a len(pbox)-sized input.
Returns
-------
list of int
A list of integers, each representing an S-box sized input.
"""
bs = self.box_size
return [(inp >> (i * bs)) & ((1 << bs) - 1)
for i in range(self.num_sbox - 1, -1, -1)]
def list_to_int(self, lst):
"""
Convert a list of S-box sized integers to a len(pbox)-sized integer.
Parameters
----------
lst : list of int
A list of integers, each representing an S-box sized input.
Returns
-------
int
An integer representing the combined input as a len(pbox)-sized integer.
"""
res = 0
for i, v in enumerate(lst[::-1]):
res |= v << (i * self.box_size)
return res
def expand_key(self, key, rounds):
"""
Derive round keys deterministically from the given key.
Parameters
----------
key : list of int or bytes or bytearray
A list of integers, bytes, or bytearray representing the key.
rounds : int
The number of rounds for the SPN.
Returns
-------
list of int
A list of integers representing the derived round keys.
"""
if isinstance(key, list):
key = self.list_to_int(key)
elif isinstance(key, (bytes, bytearray)):
key = int.from_bytes(key, 'big')
block_mask = (1 << self.block_size) - 1
key = key & block_mask
keys = [key]
for _ in range(rounds):
keys.append(self.sub(rotate_left(
keys[-1], self.box_size + 1, self.block_size)))
return keys
def _enc_last_noperm(self, pt: int) -> int:
"""
Encrypt plaintext using the SPN, where the last round doesn't contain the permute operation.
Parameters
----------
pt : int
The plaintext input to be encrypted.
Returns
-------
int
The ciphertext after encryption.
"""
ct = pt ^ self.round_keys[0]
for round_key in self.round_keys[1:-1]:
ct = self.sub(ct)
ct = self.perm(ct)
ct ^= round_key
ct = self.sub(ct)
return ct ^ self.round_keys[-1]
def _enc_last_withperm(self, ct: int) -> int:
"""
Encrypt plaintext using the SPN, where the last round contains the permute operation.
Note, the last permutation provides no additional security.
Parameters
----------
ct : int
The plaintext input to be encrypted.
Returns
-------
int
The ciphertext after encryption.
"""
for round_key in self.round_keys[:-1]:
ct ^= round_key
ct = self.sub(ct)
ct = self.perm(ct)
return ct ^ self.round_keys[-1]
def _dec_last_noperm(self, ct: int) -> int:
"""
Decrypt ciphertext using the SPN, where the last round doesn't contain the permute operation.
Parameters
----------
ct : int
The ciphertext input to be decrypted.
Returns
-------
int
The plaintext after decryption.
"""
ct = ct ^ self.round_keys[-1]
ct = self.inv_sub(ct)
for rk in self.round_keys[-2:0:-1]:
ct ^= rk
ct = self.inv_perm(ct)
ct = self.inv_sub(ct)
return ct ^ self.round_keys[0]
def _dec_last_withperm(self, ct: int) -> int:
"""
Decrypt ciphertext using the SPN, where the last round contains the permute operation.
Parameters
----------
ct : int
The ciphertext input to be decrypted.
Returns
-------
int
The plaintext after decryption.
"""
ct = ct ^ self.round_keys[-1]
for rk in self.round_keys[-2::-1]:
ct = self.inv_perm(ct)
ct = self.inv_sub(ct)
ct ^= rk
return ct</code></pre>
</details>
</section>
<section>
</section>
<section>
</section>
<section>
<h2 class="section-title" id="header-functions">Functions</h2>
<dl>
<dt id="cryptanalysis.spn.gen_pbox"><code class="name flex">
<span>def <span class="ident">gen_pbox</span></span>(<span>s, n)</span>
</code></dt>
<dd>
<div class="desc"><p>Generate a balanced permutation box for an SPN.</p>
<h2 id="parameters">Parameters</h2>
<dl>
<dt><strong><code>s</code></strong> : <code>int</code></dt>
<dd>Number of bits per S-box.</dd>
<dt><strong><code>n</code></strong> : <code>int</code></dt>
<dd>Number of S-boxes.</dd>
</dl>
<h2 id="returns">Returns</h2>
<dl>
<dt><code>list</code> of <code>int</code></dt>
<dd>The generated P-box.</dd>
</dl></div>
<details class="source">
<summary>
<span>Expand source code</span>
</summary>
<pre><code class="python">def gen_pbox(s, n):
"""
Generate a balanced permutation box for an SPN.
Parameters
----------
s : int
Number of bits per S-box.
n : int
Number of S-boxes.
Returns
-------
list of int
The generated P-box.
"""
return [(s * i + j) % (n * s) for j in range(s) for i in range(n)]</code></pre>
</details>
</dd>
<dt id="cryptanalysis.spn.rotate_left"><code class="name flex">
<span>def <span class="ident">rotate_left</span></span>(<span>val, shift, mod)</span>
</code></dt>
<dd>
<div class="desc"><p>Rotate the bits of the value to the left by the shift amount.</p>
<h2 id="parameters">Parameters</h2>
<dl>
<dt><strong><code>val</code></strong> : <code>int</code></dt>
<dd>The value to be rotated.</dd>
<dt><strong><code>shift</code></strong> : <code>int</code></dt>
<dd>The number of places to shift the value to the left.</dd>
<dt><strong><code>mod</code></strong> : <code>int</code></dt>
<dd>The modulo to be applied on the result.</dd>
</dl>
<h2 id="returns">Returns</h2>
<dl>
<dt><code>int</code></dt>
<dd>The rotated value.</dd>
</dl>
<h2 id="notes">Notes</h2>
<p>The function rotates the bits of the value to the left by the shift amount,
wrapping the bits that overflow. The result is then masked by (1<<mod)-1
to only keep the mod number of least significant bits.</p></div>
<details class="source">
<summary>
<span>Expand source code</span>
</summary>
<pre><code class="python">def rotate_left(val, shift, mod):
"""
Rotate the bits of the value to the left by the shift amount.
Parameters
----------
val : int
The value to be rotated.
shift : int
The number of places to shift the value to the left.
mod : int
The modulo to be applied on the result.
Returns
-------
int
The rotated value.
Notes
-----
The function rotates the bits of the value to the left by the shift amount,
wrapping the bits that overflow. The result is then masked by (1<<mod)-1
to only keep the mod number of least significant bits.
"""
shift = shift % mod
return (val << shift | val >> (mod - shift)) & ((1 << mod) - 1)</code></pre>
</details>
</dd>
</dl>
</section>
<section>
<h2 class="section-title" id="header-classes">Classes</h2>
<dl>
<dt id="cryptanalysis.spn.SPN"><code class="flex name class">
<span>class <span class="ident">SPN</span></span>
<span>(</span><span>sbox, pbox, key, rounds, implementation=0)</span>
</code></dt>
<dd>
<div class="desc"><p>Class representing the SPN (Substitution-Permutation Network) encryption algorithm.</p>
<h2 id="methods">Methods</h2>
<p>perm(inp)
Apply the P-box permutation on the input.
inv_perm(inp)
Apply the inverse P-box permutation on the input.
sub(inp)
Apply the S-box substitution on the input.
inv_sub(inp)
Apply the inverse S-box substitution on the input.
int_to_list(inp)
Convert a len(pbox)-sized integer to a list of S-box sized integers.
list_to_int(lst)
Convert a list of S-box sized integers to a len(pbox)-sized integer.
expand_key(key, rounds)
Derive round keys deterministically from the given key.
_enc_last_noperm(pt)
Encrypt plaintext using the SPN, where the last round doesn't contain the permute operation.
_enc_last_withperm(ct)
Encrypt plaintext using the SPN, where the last round contains the permute operation.
_dec_last_noperm(ct)
Decrypt ciphertext using the SPN, where the last round doesn't contain the permute operation.
_dec_last_withperm(ct)
Decrypt ciphertext using the SPN, where the last round contains the permute operation.</p>
<p>Initialize the SPN class with the provided parameters.</p>
<h2 id="parameters">Parameters</h2>
<dl>
<dt><strong><code>sbox</code></strong> : <code>list</code> of <code>int</code></dt>
<dd>List of integers representing the S-box.</dd>
<dt><strong><code>pbox</code></strong> : <code>list</code> of <code>int</code></dt>
<dd>List of integers representing the P-box.</dd>
<dt><strong><code>key</code></strong> : <code>list</code> of <code>int</code> or <code>bytes</code> or <code>bytearray</code></dt>
<dd>List of integers, bytes, or bytearray representing the key.
LSB block_size bits will be used.</dd>
<dt><strong><code>rounds</code></strong> : <code>int</code></dt>
<dd>Number of rounds for the SPN.</dd>
<dt><strong><code>implementation</code></strong> : <code>int</code>, optional</dt>
<dd>Implementation option. Default is 0.
0: Last round doesn't contain the permute operation.
1: Last round contains the permute operation.</dd>
</dl></div>
<details class="source">
<summary>
<span>Expand source code</span>
</summary>
<pre><code class="python">class SPN:
"""
Class representing the SPN (Substitution-Permutation Network) encryption algorithm.
Methods
-------
perm(inp)
Apply the P-box permutation on the input.
inv_perm(inp)
Apply the inverse P-box permutation on the input.
sub(inp)
Apply the S-box substitution on the input.
inv_sub(inp)
Apply the inverse S-box substitution on the input.
int_to_list(inp)
Convert a len(pbox)-sized integer to a list of S-box sized integers.
list_to_int(lst)
Convert a list of S-box sized integers to a len(pbox)-sized integer.
expand_key(key, rounds)
Derive round keys deterministically from the given key.
_enc_last_noperm(pt)
Encrypt plaintext using the SPN, where the last round doesn't contain the permute operation.
_enc_last_withperm(ct)
Encrypt plaintext using the SPN, where the last round contains the permute operation.
_dec_last_noperm(ct)
Decrypt ciphertext using the SPN, where the last round doesn't contain the permute operation.
_dec_last_withperm(ct)
Decrypt ciphertext using the SPN, where the last round contains the permute operation.
"""
def __init__(self, sbox, pbox, key, rounds, implementation=0):
"""
Initialize the SPN class with the provided parameters.
Parameters
----------
sbox : list of int
List of integers representing the S-box.
pbox : list of int
List of integers representing the P-box.
key : list of int or bytes or bytearray
List of integers, bytes, or bytearray representing the key.
LSB block_size bits will be used.
rounds : int
Number of rounds for the SPN.
implementation : int, optional
Implementation option. Default is 0.
0: Last round doesn't contain the permute operation.
1: Last round contains the permute operation.
"""
self.sbox = sbox
self.pbox = pbox
self.sinv = [sbox.index(i) for i in range(len(sbox))]
self.pinv = [pbox.index(i) for i in range(len(pbox))]
self.block_size = len(pbox)
self.box_size = int(log2(len(sbox)))
self.num_sbox = len(pbox) // self.box_size
self.rounds = rounds
self.round_keys = self.expand_key(key, rounds)
if implementation == 0:
self.encrypt = self._enc_last_noperm
self.decrypt = self._dec_last_noperm
else:
self.encrypt = self._enc_last_withperm
self.decrypt = self._dec_last_withperm
def perm(self, inp: int) -> int:
"""
Apply the P-box permutation on the input.
Parameters
----------
inp : int
The input value to apply the P-box permutation on.
Returns
-------
int
The permuted value after applying the P-box.
"""
ct = 0
for i, v in enumerate(self.pbox):
ct |= (inp >> (self.block_size - 1 - i) & 1) << (
self.block_size - 1 - v)
return ct
def inv_perm(self, inp: int) -> int:
"""
Apply the inverse P-box permutation on the input.
Parameters
----------
inp : int
The input value to apply the inverse P-box permutation on.
Returns
-------
int
The permuted value after applying the inverse P-box.
"""
ct = 0
for i, v in enumerate(self.pinv):
ct |= (inp >> (self.block_size - 1 - i) & 1) << (
self.block_size - 1 - v)
return ct
def sub(self, inp: int) -> int:
"""
Apply the S-box substitution on the input.
Parameters
----------
inp : int
The input value to apply the S-box substitution on.
Returns
-------
int
The substituted value after applying the S-box.
"""
ct, bs = 0, self.box_size
for i in range(self.num_sbox):
ct |= self.sbox[(inp >> (i * bs)) & ((1 << bs) - 1)] << (bs * i)
return ct
def inv_sub(self, inp: int) -> int:
"""
Apply the inverse S-box substitution on the input.
Parameters
----------
inp : int
The input value to apply the inverse S-box substitution on.
Returns
-------
int
The substituted value after applying the inverse S-box.
"""
ct, bs = 0, self.box_size
for i in range(self.num_sbox):
ct |= self.sinv[(inp >> (i * bs)) & ((1 << bs) - 1)] << (bs * i)
return ct
def int_to_list(self, inp):
"""
Convert a len(pbox)-sized integer to a list of S-box sized integers.
Parameters
----------
inp : int
An integer representing a len(pbox)-sized input.
Returns
-------
list of int
A list of integers, each representing an S-box sized input.
"""
bs = self.box_size
return [(inp >> (i * bs)) & ((1 << bs) - 1)
for i in range(self.num_sbox - 1, -1, -1)]
def list_to_int(self, lst):
"""
Convert a list of S-box sized integers to a len(pbox)-sized integer.
Parameters
----------
lst : list of int
A list of integers, each representing an S-box sized input.
Returns
-------
int
An integer representing the combined input as a len(pbox)-sized integer.
"""
res = 0
for i, v in enumerate(lst[::-1]):
res |= v << (i * self.box_size)
return res
def expand_key(self, key, rounds):
"""
Derive round keys deterministically from the given key.
Parameters
----------
key : list of int or bytes or bytearray
A list of integers, bytes, or bytearray representing the key.
rounds : int
The number of rounds for the SPN.
Returns
-------
list of int
A list of integers representing the derived round keys.
"""
if isinstance(key, list):
key = self.list_to_int(key)
elif isinstance(key, (bytes, bytearray)):
key = int.from_bytes(key, 'big')
block_mask = (1 << self.block_size) - 1
key = key & block_mask
keys = [key]
for _ in range(rounds):
keys.append(self.sub(rotate_left(
keys[-1], self.box_size + 1, self.block_size)))
return keys
def _enc_last_noperm(self, pt: int) -> int:
"""
Encrypt plaintext using the SPN, where the last round doesn't contain the permute operation.
Parameters
----------
pt : int
The plaintext input to be encrypted.
Returns
-------
int
The ciphertext after encryption.
"""
ct = pt ^ self.round_keys[0]
for round_key in self.round_keys[1:-1]:
ct = self.sub(ct)
ct = self.perm(ct)
ct ^= round_key
ct = self.sub(ct)
return ct ^ self.round_keys[-1]
def _enc_last_withperm(self, ct: int) -> int:
"""
Encrypt plaintext using the SPN, where the last round contains the permute operation.
Note, the last permutation provides no additional security.
Parameters
----------
ct : int
The plaintext input to be encrypted.
Returns
-------
int
The ciphertext after encryption.
"""
for round_key in self.round_keys[:-1]:
ct ^= round_key
ct = self.sub(ct)
ct = self.perm(ct)
return ct ^ self.round_keys[-1]
def _dec_last_noperm(self, ct: int) -> int:
"""
Decrypt ciphertext using the SPN, where the last round doesn't contain the permute operation.
Parameters
----------
ct : int
The ciphertext input to be decrypted.
Returns
-------
int
The plaintext after decryption.
"""
ct = ct ^ self.round_keys[-1]
ct = self.inv_sub(ct)
for rk in self.round_keys[-2:0:-1]:
ct ^= rk
ct = self.inv_perm(ct)
ct = self.inv_sub(ct)
return ct ^ self.round_keys[0]
def _dec_last_withperm(self, ct: int) -> int:
"""
Decrypt ciphertext using the SPN, where the last round contains the permute operation.
Parameters
----------
ct : int
The ciphertext input to be decrypted.
Returns
-------
int
The plaintext after decryption.
"""
ct = ct ^ self.round_keys[-1]
for rk in self.round_keys[-2::-1]:
ct = self.inv_perm(ct)
ct = self.inv_sub(ct)
ct ^= rk
return ct</code></pre>
</details>
<h3>Subclasses</h3>
<ul class="hlist">
<li><a title="cryptanalysis.cryptanalysis.Cryptanalysis" href="cryptanalysis.html#cryptanalysis.cryptanalysis.Cryptanalysis">Cryptanalysis</a></li>
</ul>
<h3>Methods</h3>
<dl>
<dt id="cryptanalysis.spn.SPN.expand_key"><code class="name flex">
<span>def <span class="ident">expand_key</span></span>(<span>self, key, rounds)</span>
</code></dt>
<dd>
<div class="desc"><p>Derive round keys deterministically from the given key.</p>
<h2 id="parameters">Parameters</h2>
<dl>
<dt><strong><code>key</code></strong> : <code>list</code> of <code>int</code> or <code>bytes</code> or <code>bytearray</code></dt>
<dd>A list of integers, bytes, or bytearray representing the key.</dd>
<dt><strong><code>rounds</code></strong> : <code>int</code></dt>
<dd>The number of rounds for the SPN.</dd>
</dl>
<h2 id="returns">Returns</h2>
<dl>
<dt><code>list</code> of <code>int</code></dt>
<dd>A list of integers representing the derived round keys.</dd>
</dl></div>
<details class="source">
<summary>
<span>Expand source code</span>
</summary>
<pre><code class="python">def expand_key(self, key, rounds):
"""
Derive round keys deterministically from the given key.
Parameters
----------
key : list of int or bytes or bytearray
A list of integers, bytes, or bytearray representing the key.
rounds : int
The number of rounds for the SPN.
Returns
-------
list of int
A list of integers representing the derived round keys.
"""
if isinstance(key, list):
key = self.list_to_int(key)
elif isinstance(key, (bytes, bytearray)):
key = int.from_bytes(key, 'big')
block_mask = (1 << self.block_size) - 1
key = key & block_mask
keys = [key]
for _ in range(rounds):
keys.append(self.sub(rotate_left(
keys[-1], self.box_size + 1, self.block_size)))
return keys</code></pre>
</details>
</dd>
<dt id="cryptanalysis.spn.SPN.int_to_list"><code class="name flex">
<span>def <span class="ident">int_to_list</span></span>(<span>self, inp)</span>
</code></dt>
<dd>
<div class="desc"><p>Convert a len(pbox)-sized integer to a list of S-box sized integers.</p>
<h2 id="parameters">Parameters</h2>
<dl>
<dt><strong><code>inp</code></strong> : <code>int</code></dt>
<dd>An integer representing a len(pbox)-sized input.</dd>
</dl>
<h2 id="returns">Returns</h2>
<dl>
<dt><code>list</code> of <code>int</code></dt>
<dd>A list of integers, each representing an S-box sized input.</dd>
</dl></div>
<details class="source">
<summary>
<span>Expand source code</span>
</summary>
<pre><code class="python">def int_to_list(self, inp):
"""
Convert a len(pbox)-sized integer to a list of S-box sized integers.
Parameters
----------
inp : int
An integer representing a len(pbox)-sized input.
Returns
-------
list of int
A list of integers, each representing an S-box sized input.
"""
bs = self.box_size
return [(inp >> (i * bs)) & ((1 << bs) - 1)
for i in range(self.num_sbox - 1, -1, -1)]</code></pre>
</details>
</dd>
<dt id="cryptanalysis.spn.SPN.inv_perm"><code class="name flex">
<span>def <span class="ident">inv_perm</span></span>(<span>self, inp: int) ‑> int</span>
</code></dt>
<dd>
<div class="desc"><p>Apply the inverse P-box permutation on the input.</p>
<h2 id="parameters">Parameters</h2>
<dl>
<dt><strong><code>inp</code></strong> : <code>int</code></dt>
<dd>The input value to apply the inverse P-box permutation on.</dd>
</dl>
<h2 id="returns">Returns</h2>
<dl>
<dt><code>int</code></dt>
<dd>The permuted value after applying the inverse P-box.</dd>
</dl></div>
<details class="source">
<summary>
<span>Expand source code</span>
</summary>
<pre><code class="python">def inv_perm(self, inp: int) -> int:
"""
Apply the inverse P-box permutation on the input.
Parameters
----------
inp : int
The input value to apply the inverse P-box permutation on.
Returns
-------
int
The permuted value after applying the inverse P-box.
"""
ct = 0
for i, v in enumerate(self.pinv):
ct |= (inp >> (self.block_size - 1 - i) & 1) << (
self.block_size - 1 - v)
return ct</code></pre>
</details>
</dd>
<dt id="cryptanalysis.spn.SPN.inv_sub"><code class="name flex">
<span>def <span class="ident">inv_sub</span></span>(<span>self, inp: int) ‑> int</span>
</code></dt>