src/eric7/Documentation/Source/eric7.Utilities.crypto.py3AES.html

<!DOCTYPE html>
<html><head>
<title>eric7.Utilities.crypto.py3AES</title>
<meta charset="UTF-8">
<link rel="stylesheet" href="styles.css">
</head>
<body>
<a NAME="top" ID="top"></a>
<h1>eric7.Utilities.crypto.py3AES</h1>

<p>
Module implementing classes for encryption according
Advanced Encryption Standard.
</p>
<h3>Global Attributes</h3>

<table>
<tr><td>None</td></tr>
</table>
<h3>Classes</h3>

<table>

<tr>
<td><a href="#AES">AES</a></td>
<td>Class implementing the Advanced Encryption Standard algorithm.</td>
</tr>
<tr>
<td><a href="#AESModeOfOperation">AESModeOfOperation</a></td>
<td>Class implementing the different AES mode of operations.</td>
</tr>
</table>
<h3>Functions</h3>

<table>

<tr>
<td><a href="#append_PKCS7_padding">append_PKCS7_padding</a></td>
<td>Function to pad the given data to a multiple of 16-bytes by PKCS7 padding.</td>
</tr>
<tr>
<td><a href="#decryptData">decryptData</a></td>
<td>Module function to decrypt the given data with the given key.</td>
</tr>
<tr>
<td><a href="#encryptData">encryptData</a></td>
<td>Module function to encrypt the given data with the given key.</td>
</tr>
<tr>
<td><a href="#strip_PKCS7_padding">strip_PKCS7_padding</a></td>
<td>Function to strip off PKCS7 padding.</td>
</tr>
</table>
<hr />
<hr />
<a NAME="AES" ID="AES"></a>
<h2>AES</h2>

<p>
    Class implementing the Advanced Encryption Standard algorithm.
</p>
<h3>Derived from</h3>
None
<h3>Class Attributes</h3>

<table>
<tr><td>KeySize</td></tr><tr><td>Rcon</td></tr><tr><td>rsbox</td></tr><tr><td>sbox</td></tr>
</table>
<h3>Class Methods</h3>

<table>
<tr><td>None</td></tr>
</table>
<h3>Methods</h3>

<table>

<tr>
<td><a href="#AES.__addRoundKey">__addRoundKey</a></td>
<td>Private method to add (XORs) the round key to the state.</td>
</tr>
<tr>
<td><a href="#AES.__aes_invMain">__aes_invMain</a></td>
<td>Private method to do the inverse AES encryption for one round.</td>
</tr>
<tr>
<td><a href="#AES.__aes_invRound">__aes_invRound</a></td>
<td>Private method to apply the 4 operations of the inverse round in sequence.</td>
</tr>
<tr>
<td><a href="#AES.__aes_main">__aes_main</a></td>
<td>Private method to do the AES encryption for one round.</td>
</tr>
<tr>
<td><a href="#AES.__aes_round">__aes_round</a></td>
<td>Private method to apply the 4 operations of the forward round in sequence.</td>
</tr>
<tr>
<td><a href="#AES.__core">__core</a></td>
<td>Private method performing the key schedule core operation.</td>
</tr>
<tr>
<td><a href="#AES.__createRoundKey">__createRoundKey</a></td>
<td>Private method to create a round key.</td>
</tr>
<tr>
<td><a href="#AES.__expandKey">__expandKey</a></td>
<td>Private method performing Rijndael's key expansion.</td>
</tr>
<tr>
<td><a href="#AES.__galois_multiplication">__galois_multiplication</a></td>
<td>Private method to perform a Galois multiplication of 8 bit characters a and b.</td>
</tr>
<tr>
<td><a href="#AES.__getRconValue">__getRconValue</a></td>
<td>Private method to retrieve a given Rcon value.</td>
</tr>
<tr>
<td><a href="#AES.__getSBoxInvert">__getSBoxInvert</a></td>
<td>Private method to retrieve a given Inverted S-Box value.</td>
</tr>
<tr>
<td><a href="#AES.__getSBoxValue">__getSBoxValue</a></td>
<td>Private method to retrieve a given S-Box value.</td>
</tr>
<tr>
<td><a href="#AES.__mixColumn">__mixColumn</a></td>
<td>Private method to perform a galois multiplication of 1 column the 4x4 matrix.</td>
</tr>
<tr>
<td><a href="#AES.__mixColumns">__mixColumns</a></td>
<td>Private method to perform a galois multiplication of the 4x4 matrix.</td>
</tr>
<tr>
<td><a href="#AES.__rotate">__rotate</a></td>
<td>Private method performing Rijndael's key schedule rotate operation.</td>
</tr>
<tr>
<td><a href="#AES.__shiftRow">__shiftRow</a></td>
<td>Private method to shift the bytes of a row to the left.</td>
</tr>
<tr>
<td><a href="#AES.__shiftRows">__shiftRows</a></td>
<td>Private method to iterate over the 4 rows and call __shiftRow() with that row.</td>
</tr>
<tr>
<td><a href="#AES.__subBytes">__subBytes</a></td>
<td>Private method to substitute all the values from the state with the value in the SBox using the state value as index for the SBox.</td>
</tr>
<tr>
<td><a href="#AES.decrypt">decrypt</a></td>
<td>Public method to decrypt a 128 bit input block against the given key of size specified.</td>
</tr>
<tr>
<td><a href="#AES.encrypt">encrypt</a></td>
<td>Public method to encrypt a 128 bit input block against the given key of size specified.</td>
</tr>
</table>
<h3>Static Methods</h3>

<table>
<tr><td>None</td></tr>
</table>

<a NAME="AES.__addRoundKey" ID="AES.__addRoundKey"></a>
<h4>AES.__addRoundKey</h4>
<b>__addRoundKey</b>(<i>state, roundKey</i>)

<p>
        Private method to add (XORs) the round key to the state.
</p>
<dl>

<dt><i>state</i></dt>
<dd>
state to be changed (bytearray)
</dd>
<dt><i>roundKey</i></dt>
<dd>
key to be used for the modification (bytearray)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
modified state (bytearray)
</dd>
</dl>
<a NAME="AES.__aes_invMain" ID="AES.__aes_invMain"></a>
<h4>AES.__aes_invMain</h4>
<b>__aes_invMain</b>(<i>state, expandedKey, nbrRounds</i>)

<p>
        Private method to do the inverse AES encryption for one round.
</p>
<p>
        Perform the initial operations, the standard round, and the
        final operations of the inverse AES, creating a round key for
        each round.
</p>
<dl>

<dt><i>state</i></dt>
<dd>
state to be worked on (bytearray)
</dd>
<dt><i>expandedKey</i></dt>
<dd>
expanded key to be used (bytearray)
</dd>
<dt><i>nbrRounds</i></dt>
<dd>
number of rounds to be done (integer)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
modified state (bytearray)
</dd>
</dl>
<a NAME="AES.__aes_invRound" ID="AES.__aes_invRound"></a>
<h4>AES.__aes_invRound</h4>
<b>__aes_invRound</b>(<i>state, roundKey</i>)

<p>
        Private method to apply the 4 operations of the inverse round in
        sequence.
</p>
<dl>

<dt><i>state</i></dt>
<dd>
state to be worked on (bytearray)
</dd>
<dt><i>roundKey</i></dt>
<dd>
round key to be used (bytearray)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
modified state (bytearray)
</dd>
</dl>
<a NAME="AES.__aes_main" ID="AES.__aes_main"></a>
<h4>AES.__aes_main</h4>
<b>__aes_main</b>(<i>state, expandedKey, nbrRounds</i>)

<p>
        Private method to do the AES encryption for one round.
</p>
<p>
        Perform the initial operations, the standard round, and the
        final operations of the forward AES, creating a round key for
        each round.
</p>
<dl>

<dt><i>state</i></dt>
<dd>
state to be worked on (bytearray)
</dd>
<dt><i>expandedKey</i></dt>
<dd>
expanded key to be used (bytearray)
</dd>
<dt><i>nbrRounds</i></dt>
<dd>
number of rounds to be done (integer)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
modified state (bytearray)
</dd>
</dl>
<a NAME="AES.__aes_round" ID="AES.__aes_round"></a>
<h4>AES.__aes_round</h4>
<b>__aes_round</b>(<i>state, roundKey</i>)

<p>
        Private method to apply the 4 operations of the forward round in
        sequence.
</p>
<dl>

<dt><i>state</i></dt>
<dd>
state to be worked on (bytearray)
</dd>
<dt><i>roundKey</i></dt>
<dd>
round key to be used (bytearray)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
modified state (bytearray)
</dd>
</dl>
<a NAME="AES.__core" ID="AES.__core"></a>
<h4>AES.__core</h4>
<b>__core</b>(<i>data, iteration</i>)

<p>
        Private method performing the key schedule core operation.
</p>
<dl>

<dt><i>data</i></dt>
<dd>
data to operate on (bytearray)
</dd>
<dt><i>iteration</i></dt>
<dd>
iteration counter (integer)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
modified data (bytearray)
</dd>
</dl>
<a NAME="AES.__createRoundKey" ID="AES.__createRoundKey"></a>
<h4>AES.__createRoundKey</h4>
<b>__createRoundKey</b>(<i>expandedKey, roundKeyPointer</i>)

<p>
        Private method to create a round key.
</p>
<dl>

<dt><i>expandedKey</i></dt>
<dd>
expanded key to be used (bytearray)
</dd>
<dt><i>roundKeyPointer</i></dt>
<dd>
position within the expanded key (integer)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
round key (bytearray)
</dd>
</dl>
<a NAME="AES.__expandKey" ID="AES.__expandKey"></a>
<h4>AES.__expandKey</h4>
<b>__expandKey</b>(<i>key, size, expandedKeySize</i>)

<p>
        Private method performing Rijndael's key expansion.
</p>
<p>
        Expands a 128, 192 or 256 bit key into a 176, 208 or 240 bit key.
</p>
<dl>

<dt><i>key</i></dt>
<dd>
key to be expanded (bytes or bytearray)
</dd>
<dt><i>size</i></dt>
<dd>
size of the key in bytes (16, 24 or 32)
</dd>
<dt><i>expandedKeySize</i></dt>
<dd>
size of the expanded key (integer)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
expanded key (bytearray)
</dd>
</dl>
<a NAME="AES.__galois_multiplication" ID="AES.__galois_multiplication"></a>
<h4>AES.__galois_multiplication</h4>
<b>__galois_multiplication</b>(<i>a, b</i>)

<p>
        Private method to perform a Galois multiplication of 8 bit characters
        a and b.
</p>
<dl>

<dt><i>a</i></dt>
<dd>
first factor (byte)
</dd>
<dt><i>b</i></dt>
<dd>
second factor (byte)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
result (byte)
</dd>
</dl>
<a NAME="AES.__getRconValue" ID="AES.__getRconValue"></a>
<h4>AES.__getRconValue</h4>
<b>__getRconValue</b>(<i>num</i>)

<p>
        Private method to retrieve a given Rcon value.
</p>
<dl>

<dt><i>num</i></dt>
<dd>
position of the value (integer)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
Rcon value (integer)
</dd>
</dl>
<a NAME="AES.__getSBoxInvert" ID="AES.__getSBoxInvert"></a>
<h4>AES.__getSBoxInvert</h4>
<b>__getSBoxInvert</b>(<i>num</i>)

<p>
        Private method to retrieve a given Inverted S-Box value.
</p>
<dl>

<dt><i>num</i></dt>
<dd>
position of the value (integer)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
value of the Inverted S-Box (integer)
</dd>
</dl>
<a NAME="AES.__getSBoxValue" ID="AES.__getSBoxValue"></a>
<h4>AES.__getSBoxValue</h4>
<b>__getSBoxValue</b>(<i>num</i>)

<p>
        Private method to retrieve a given S-Box value.
</p>
<dl>

<dt><i>num</i></dt>
<dd>
position of the value (integer)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
value of the S-Box (integer)
</dd>
</dl>
<a NAME="AES.__mixColumn" ID="AES.__mixColumn"></a>
<h4>AES.__mixColumn</h4>
<b>__mixColumn</b>(<i>column, isInv</i>)

<p>
        Private method to perform a galois multiplication of 1 column the
        4x4 matrix.
</p>
<dl>

<dt><i>column</i></dt>
<dd>
column to be worked on (bytearray)
</dd>
<dt><i>isInv</i></dt>
<dd>
flag indicating an inverse operation (boolean)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
modified column (bytearray)
</dd>
</dl>
<a NAME="AES.__mixColumns" ID="AES.__mixColumns"></a>
<h4>AES.__mixColumns</h4>
<b>__mixColumns</b>(<i>state, isInv</i>)

<p>
        Private method to perform a galois multiplication of the 4x4 matrix.
</p>
<dl>

<dt><i>state</i></dt>
<dd>
state to be worked on (bytearray)
</dd>
<dt><i>isInv</i></dt>
<dd>
flag indicating an inverse operation (boolean)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
modified state (bytearray)
</dd>
</dl>
<a NAME="AES.__rotate" ID="AES.__rotate"></a>
<h4>AES.__rotate</h4>
<b>__rotate</b>(<i>data</i>)

<p>
        Private method performing Rijndael's key schedule rotate operation.
</p>
<p>
        Rotate the data word eight bits to the left: eg,
        rotate(1d2c3a4f) == 2c3a4f1d.
</p>
<dl>

<dt><i>data</i></dt>
<dd>
data of size 4 (bytearray)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
rotated data (bytearray)
</dd>
</dl>
<a NAME="AES.__shiftRow" ID="AES.__shiftRow"></a>
<h4>AES.__shiftRow</h4>
<b>__shiftRow</b>(<i>state, statePointer, nbr, isInv</i>)

<p>
        Private method to shift the bytes of a row to the left.
</p>
<dl>

<dt><i>state</i></dt>
<dd>
state to be worked on (bytearray)
</dd>
<dt><i>statePointer</i></dt>
<dd>
index into the state (integer)
</dd>
<dt><i>nbr</i></dt>
<dd>
number of positions to shift (integer)
</dd>
<dt><i>isInv</i></dt>
<dd>
flag indicating an inverse operation (boolean)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
modified state (bytearray)
</dd>
</dl>
<a NAME="AES.__shiftRows" ID="AES.__shiftRows"></a>
<h4>AES.__shiftRows</h4>
<b>__shiftRows</b>(<i>state, isInv</i>)

<p>
        Private method to iterate over the 4 rows and call __shiftRow() with
        that row.
</p>
<dl>

<dt><i>state</i></dt>
<dd>
state to be worked on (bytearray)
</dd>
<dt><i>isInv</i></dt>
<dd>
flag indicating an inverse operation (boolean)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
modified state (bytearray)
</dd>
</dl>
<a NAME="AES.__subBytes" ID="AES.__subBytes"></a>
<h4>AES.__subBytes</h4>
<b>__subBytes</b>(<i>state, isInv</i>)

<p>
        Private method to substitute all the values from the state with the
        value in the SBox using the state value as index for the SBox.
</p>
<dl>

<dt><i>state</i></dt>
<dd>
state to be worked on (bytearray)
</dd>
<dt><i>isInv</i></dt>
<dd>
flag indicating an inverse operation (boolean)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
modified state (bytearray)
</dd>
</dl>
<a NAME="AES.decrypt" ID="AES.decrypt"></a>
<h4>AES.decrypt</h4>
<b>decrypt</b>(<i>iput, key, size</i>)

<p>
        Public method to decrypt a 128 bit input block against the given key
        of size specified.
</p>
<dl>

<dt><i>iput</i></dt>
<dd>
input data (bytearray)
</dd>
<dt><i>key</i></dt>
<dd>
key to be used (bytes or bytearray)
</dd>
<dt><i>size</i></dt>
<dd>
key size (16, 24 or 32)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
decrypted data (bytes)
</dd>
</dl>
<dl>

<dt>Raises <b>ValueError</b>:</dt>
<dd>
key size is invalid
</dd>
</dl>
<a NAME="AES.encrypt" ID="AES.encrypt"></a>
<h4>AES.encrypt</h4>
<b>encrypt</b>(<i>iput, key, size</i>)

<p>
        Public method to encrypt a 128 bit input block against the given key
        of size specified.
</p>
<dl>

<dt><i>iput</i></dt>
<dd>
input data (bytearray)
</dd>
<dt><i>key</i></dt>
<dd>
key to be used (bytes or bytearray)
</dd>
<dt><i>size</i></dt>
<dd>
key size (16, 24 or 32)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
encrypted data (bytes)
</dd>
</dl>
<dl>

<dt>Raises <b>ValueError</b>:</dt>
<dd>
key size is invalid
</dd>
</dl>
<div align="right"><a href="#top">Up</a></div>
<hr />
<hr />
<a NAME="AESModeOfOperation" ID="AESModeOfOperation"></a>
<h2>AESModeOfOperation</h2>

<p>
    Class implementing the different AES mode of operations.
</p>
<h3>Derived from</h3>
None
<h3>Class Attributes</h3>

<table>
<tr><td>ModeOfOperation</td></tr><tr><td>aes</td></tr>
</table>
<h3>Class Methods</h3>

<table>
<tr><td>None</td></tr>
</table>
<h3>Methods</h3>

<table>

<tr>
<td><a href="#AESModeOfOperation.__extractBytes">__extractBytes</a></td>
<td>Private method to extract a range of bytes from the input.</td>
</tr>
<tr>
<td><a href="#AESModeOfOperation.decrypt">decrypt</a></td>
<td>Public method to perform the decryption operation.</td>
</tr>
<tr>
<td><a href="#AESModeOfOperation.encrypt">encrypt</a></td>
<td>Public method to perform the encryption operation.</td>
</tr>
</table>
<h3>Static Methods</h3>

<table>
<tr><td>None</td></tr>
</table>

<a NAME="AESModeOfOperation.__extractBytes" ID="AESModeOfOperation.__extractBytes"></a>
<h4>AESModeOfOperation.__extractBytes</h4>
<b>__extractBytes</b>(<i>inputData, start, end, mode</i>)

<p>
        Private method to extract a range of bytes from the input.
</p>
<dl>

<dt><i>inputData</i></dt>
<dd>
input data (bytes)
</dd>
<dt><i>start</i></dt>
<dd>
start index (integer)
</dd>
<dt><i>end</i></dt>
<dd>
end index (integer)
</dd>
<dt><i>mode</i></dt>
<dd>
mode of operation (0, 1, 2)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
extracted bytes (bytearray)
</dd>
</dl>
<a NAME="AESModeOfOperation.decrypt" ID="AESModeOfOperation.decrypt"></a>
<h4>AESModeOfOperation.decrypt</h4>
<b>decrypt</b>(<i>cipherIn, originalsize, mode, key, size, IV</i>)

<p>
        Public method to perform the decryption operation.
</p>
<dl>

<dt><i>cipherIn</i></dt>
<dd>
data to be decrypted (bytes)
</dd>
<dt><i>originalsize</i></dt>
<dd>
unencrypted string length (required for CBC)
            (integer)
</dd>
<dt><i>mode</i></dt>
<dd>
mode of operation (0, 1 or 2)
</dd>
<dt><i>key</i></dt>
<dd>
key to be used (bytes)
</dd>
<dt><i>size</i></dt>
<dd>
length of the key (16, 24 or 32)
</dd>
<dt><i>IV</i></dt>
<dd>
initialisation vector (bytearray)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
decrypted data (bytes)
</dd>
</dl>
<dl>

<dt>Raises <b>ValueError</b>:</dt>
<dd>
key size is invalid or decrypted data is invalid
</dd>
</dl>
<a NAME="AESModeOfOperation.encrypt" ID="AESModeOfOperation.encrypt"></a>
<h4>AESModeOfOperation.encrypt</h4>
<b>encrypt</b>(<i>inputData, mode, key, size, IV</i>)

<p>
        Public method to perform the encryption operation.
</p>
<dl>

<dt><i>inputData</i></dt>
<dd>
data to be encrypted (bytes)
</dd>
<dt><i>mode</i></dt>
<dd>
mode of operation (0, 1 or 2)
</dd>
<dt><i>key</i></dt>
<dd>
key to be used (bytes)
</dd>
<dt><i>size</i></dt>
<dd>
length of the key (16, 24 or 32)
</dd>
<dt><i>IV</i></dt>
<dd>
initialisation vector (bytearray)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
tuple with mode of operation, length of the input data and
            the encrypted data (integer, integer, bytes)
</dd>
</dl>
<dl>

<dt>Raises <b>ValueError</b>:</dt>
<dd>
key size is invalid or decrypted data is invalid
</dd>
</dl>
<div align="right"><a href="#top">Up</a></div>
<hr />
<hr />
<a NAME="append_PKCS7_padding" ID="append_PKCS7_padding"></a>
<h2>append_PKCS7_padding</h2>
<b>append_PKCS7_padding</b>(<i>b</i>)

<p>
    Function to pad the given data to a multiple of 16-bytes by PKCS7 padding.
</p>
<dl>

<dt><i>b</i></dt>
<dd>
data to be padded (bytes)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
padded data (bytes)
</dd>
</dl>
<div align="right"><a href="#top">Up</a></div>
<hr />
<hr />
<a NAME="decryptData" ID="decryptData"></a>
<h2>decryptData</h2>
<b>decryptData</b>(<i>key, data, mode=AESModeOfOperation.ModeOfOperation["CBC"]</i>)

<p>
    Module function to decrypt the given data with the given key.
</p>
<dl>

<dt><i>key</i></dt>
<dd>
key to be used for decryption (bytes)
</dd>
<dt><i>data</i></dt>
<dd>
data to be decrypted (with initialization vector prepended)
        (bytes)
</dd>
<dt><i>mode</i></dt>
<dd>
mode of operations (0, 1 or 2)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
decrypted data (bytes)
</dd>
</dl>
<dl>

<dt>Raises <b>ValueError</b>:</dt>
<dd>
raised to indicate an invalid key size
</dd>
</dl>
<div align="right"><a href="#top">Up</a></div>
<hr />
<hr />
<a NAME="encryptData" ID="encryptData"></a>
<h2>encryptData</h2>
<b>encryptData</b>(<i>key, data, mode=AESModeOfOperation.ModeOfOperation["CBC"]</i>)

<p>
    Module function to encrypt the given data with the given key.
</p>
<dl>

<dt><i>key</i></dt>
<dd>
key to be used for encryption (bytes)
</dd>
<dt><i>data</i></dt>
<dd>
data to be encrypted (bytes)
</dd>
<dt><i>mode</i></dt>
<dd>
mode of operations (0, 1 or 2)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
encrypted data prepended with the initialization vector (bytes)
</dd>
</dl>
<dl>

<dt>Raises <b>ValueError</b>:</dt>
<dd>
raised to indicate an invalid key size
</dd>
</dl>
<div align="right"><a href="#top">Up</a></div>
<hr />
<hr />
<a NAME="strip_PKCS7_padding" ID="strip_PKCS7_padding"></a>
<h2>strip_PKCS7_padding</h2>
<b>strip_PKCS7_padding</b>(<i>b</i>)

<p>
    Function to strip off PKCS7 padding.
</p>
<dl>

<dt><i>b</i></dt>
<dd>
data to be stripped (bytes)
</dd>
</dl>
<dl>
<dt>Return:</dt>
<dd>
stripped data (bytes)
</dd>
</dl>
<dl>

<dt>Raises <b>ValueError</b>:</dt>
<dd>
data padding is invalid
</dd>
</dl>
<div align="right"><a href="#top">Up</a></div>
<hr />
</body></html>