Attributes and Conversions

Contents

• Attributes and Conversions
  • Conversions

This module contains a wrapper around the key attributes and the template struct generation to make it possible to create templates in python and easily convert them into templates in C.

pycryptoki.attributes.KEY_TRANSFORMS CK_ATTRIBUTE Types mapped to Python->C transformation functions

pycryptoki.attributes.ret_type(c_type)

Decorator to set a returned C Type so we can determine what type to use for an AutoCArray

Parameters:c_type – Default return-type of the transform function.

pycryptoki.attributes.to_long(val, reverse=False)

Convert a integer/long value to a pValue, ulValueLen tuple

Parameters:

• val – Value to convert
• reverse – Whether to convert from C -> Python

Returns:

(ctypes.c_void_p ptr to ctypes.c_ulong, ctypes.c_ulong

size of long value)

pycryptoki.attributes.to_bool(val, reverse=False)

Convert a boolean-ish value to a pValue, ulValueLen tuple.

Parameters:

• val – Value to convert
• reverse – Whether to convert from C -> Python

Returns:

(ctypes.c_void_p ptr to pycryptoki.cryptoki.CK_BBOOL,

ctypes.c_ulong size of bool value)

pycryptoki.attributes.to_char_array(val, reverse=False)

Convert the given string or list of string values into a char array.

This is slightly different than to_byte_array, which has different assumptions as to the format of the input.

Parameters:

• val – Value to convert
• reverse – Whether to convert from C -> Python

Returns:

(ctypes.c_void_p ptr to pycryptoki.cryptoki.CK_CHAR array,

ctypes.c_ulong size of array)

pycryptoki.attributes.to_ck_date(val, reverse=False)

Transform a date string, date dictionary, or date object into a PKCS11 readable form (YYYYMMDD)

Parameters:

• val – Value to convert
• reverse – Whether to convert from C -> Python

Returns:

(ctypes.c_void_p ptr to pycryptoki.cryptoki.CK_CHAR array,

ctypes.c_ulong size of array)

pycryptoki.attributes.to_pka_key_status(val, reverse=False)

Transform a Per Key Authorization Key Status object into a PKCS11 readable byte string

Parameters:

• val – Value to convert
• reverse – Whether to convert from C -> Python

Returns:

(ctypes.c_void_p ptr to pycryptoki.cryptoki.CK_KEY_STATUS object,

ctypes.c_ulong size of array)

pycryptoki.attributes.to_byte_array(val, reverse=False)

Converts an arbitrarily sized integer, list, or byte array into a byte array.

It’ll zero-pad the bit length so it’s a multiple of 8, then convert the int to binary, split the binary string into sections of 8, then place each section into a slot in a ctypes.c_ubyte array (converting to small int).

Parameters:

• val – Value to convert
• reverse – Whether to convert from C -> Python

Returns:

(ctypes.c_void_p ptr to pycryptoki.cryptoki.CK_BYTE array,

ctypes.c_ulong size of array)

pycryptoki.attributes.to_sub_attributes(val, reverse=False)

Convert to another Attributes class & return the struct.

Parameters:

• val – Value to convert
• reverse – Whether to convert from C -> Python

Returns:

(ctypes.c_void_p ptr to pycryptoki.cryptoki.CK_ATTRIBUTE array,

ctypes.c_ulong size of array)

class pycryptoki.attributes.Attributes(*args, **kwargs)

Python container for handling PKCS11 Attributes.

Provides get_c_struct(), that would returns a list of C Structs, each with the following structure:

class CK_ATTRIBUTE(Structure):
    '''
    Defines type, value and length of an attribute:

    c_ulong type;
    c_void_p pValue;
    c_ulong ulValueLen;
    '''
    pass

This list of structs can be used with C_GetAttributeValue() to get the length of the value that will be placed in pValue (will be set to ulValueLen), or if you already know the length required you can ‘blank fill’ pValue for direct use.

You can also provide new transformations in the form of a dictionary that will be preferred to the KEY_TRANSFORMS dictionary. This is passed in only as a keyword argument:

transform = {1L: lambda x: return x**2}`
attrs = Attributes({...}, new_transforms=transform)
# attrs.get_c_struct will use the lambda expression in the transform dictionary
# for key 1L

get_c_struct()

Build an array of CK_ATTRIBUTE Structs & return it.

Returns:CK_ATTRIBUTE array

static from_c_struct(c_struct)

Build out a dictionary from a c_struct.

Parameters:c_struct – Pointer to an array of CK_ATTRIBUTE structs Returns:dict

pycryptoki.attributes.c_struct_to_python(c_struct)

Converts a C struct to a python dictionary.

Parameters:c_struct – The c struct to convert into a dictionary in python Returns:Returns a python dictionary which represents the C struct passed in

pycryptoki.attributes.convert_c_ubyte_array_to_string(byte_array)

Converts a ctypes unsigned byte array into a string.

Parameters:byte_array –

Conversions

Provide low-level conversions between common data types.

The from_xyz functions should all return an iterator over a list of integers, representing the individual bytes in the passed-in value.

The to_xyz functions take in an iterable of integers and convert it to the specified type.

Example 1

Convert a raw bytestring to hex

raw_bytes = from_bytestring(b"Some test data")
assert raw_bytes = [83, 111, 109, 101, 32, 116, 101, 115, 116, 32, 100, 97, 116, 97]

hex_data = to_hex(from_bytestring(b"Some test data"))
assert hex_data == b'536f6d6520746573742064617461'

Example 2

Convert hex data to a raw bytestring

bytestring_data = to_bytestring(from_hex(b'536f6d6520746573742064617461'))
assert bytestring_data == b"Some test data"

raw_bytes = list(from_hex(b'536f6d6520746573742064617461'))
assert raw_bytes == [83, 111, 109, 101, 32, 116, 101, 115, 116, 32, 100, 97, 116, 97]

pycryptoki.conversions.from_bytestring(ascii_)

Convert an iterable of strings into an iterable of integers.

Note

For bytestrings on python3, this does effectively nothing, since iterating over a bytestring in python 3 will return integers.

Parameters:ascii – String to convert Returns:iterator

pycryptoki.conversions.to_bytestring(ascii_)

Convert an iterable of integers into a bytestring.

Parameters:ascii (iterable) – Iterable of integers Returns:bytestring

pycryptoki.conversions.from_bin(bin_)

Convert a string-representation of binary into a list of integers.

Parameters:bin (str) – String representation of binary data (ex: “10110111”) Returns:iterator over integers

pycryptoki.conversions.to_bin(ascii_)

Convert an iterable of integers to a binary representation.

Parameters:ascii (iterable) – iterable of integers Returns:bytestring of the binary values

pycryptoki.conversions.from_hex(hex_)

Convert a hexademical string to an iterable of integers.

Parameters:hex (str) – Hex string Returns:Iterator

pycryptoki.conversions.to_hex(ints)

Convert an iterable of integers to a hexadecimal string.

Parameters:ints (iterable) – Iterable of integers Returns:bytestring representing the hex data.