API of the ‘gostcrypto.gostpbkdf’ module¶

Introduction¶

The module implementing the password-based key derivation function in accordance with R 50.1.111-2016. The module includes the R5011112016 and GOSTPBKDFError classes and the new function.

Functions¶

new(password, **kwargs)¶

Creates a new object for the password-based key derivation function and returns it.

import gostcrypto

password = b'password'
salt = b'salt'

pbkdf_obj = gostcrypto.gostpbkdf.new(password, salt=salt, counter=2000)

Arguments:

password - password that is a character string in Unicode UTF-8 encoding.

Keyword arguments:

salt - random value. If this argument is not passed to the function, the os.urandom function is used to generate this value with the length of the generated value of 32 bytes.
counter - number of iterations. The default value is 1000.

Return:

New object for the password-based key derivation function (as an instance of the R5011112016 class).

Exception:

GOSTPBKDFError(invalid password value’) - if the password value is incorrect.
GOSTPBKDFError(‘invalid salt value’) - if the salt value is incorrect.

Classes¶

R5011112016¶

Class that implementing the calculating the password-based key derivation function in accordance with R 50.1.111-2016.

Methods:¶

derive(dk_len)¶

Returns a derived key (as a byte object).

import gostcrypto

password = b'password'
salt = b'salt'

pbkdf_obj = gostcrypto.gostpbkdf.new(password, salt=salt, counter=2000)
pbkdf_result = pbkdf_obj.derive(32)

Arguments:

dk_len - Required length of the output sequence (in bytes).

Return:

The derived key (as a byte object).

Exception:

GOSTPBKDFError(‘invalid size of the derived key’) - in case of invalid size of the derived key.

hexderive(dk_len)¶

Returns a derived key (as a hexadecimal string).

import gostcrypto

password = b'password'
salt = b'salt'

pbkdf_obj = gostcrypto.gostpbkdf.new(password, salt=salt, counter=2000)
pbkdf_result = pbkdf_obj.hexderive(32)

Arguments:

dk_len - Required length of the output sequence (in bytes).

Return:

The derived key (as a hexadecimal string).

Exception:

GOSTPBKDFError(‘invalid size of the derived key’) - in case of invalid size of the derived key.

clear()¶

Сlears the password value.

import gostcrypto

password = b'password'
salt = b'salt'

pbkdf_obj = gostcrypto.gostpbkdf.new(password, salt=salt, counter=2000)
pbkdf_obj.clear()

Attributes:¶

salt¶

The byte object containing a random value (salt). Required when generating the salt value using os.urandom.

import gostcrypto

password = b'password'

pbkdf_obj = gostcrypto.gostpbkdf.new(password)
salt = pbkdf_obj.salt

GOSTPBKDFError¶

The class that implements exceptions.

import gostcrypto

password = b'password'
salt = b'salt'

try:
    pbkdf_obj = gostcrypto.gostpbkdf.new(password, salt=salt, counter=2000)
    pbkdf_result = pbkdf_obj.hexderive(32)
except gostcrypto.gostpbkdf.GOSTPBKDFError as err:
    print(err)
else:
    print(pbkdf_result)

Exception types:

invalid password value - if the password value is incorrect.
invalid salt value - if the salt value is incorrect.
invalid size of the derived key - if the size of the derived key is incorrect.

Example of use¶

import gostcrypto

password = b'password'
salt = b'salt'

pbkdf_obj = gostcrypto.gostpbkdf.new(password, salt=salt, counter=4096)
pbkdf_result = pbkdf_obj.derive(32)