Sanitary

Sanitary is a simple utility that can remove/mask sensitive information, such as PII, from any data structure. It also includes a Structlog-compatible processor to clean up structured log messages.

It will automatically mask information marked as sensitive. By default, the masked data is replaced by a generic string, which can be configured to use a hashing function instead.

Installation

Sanitizer needs to be installed like any other Python package:

> pip install sanitary

Base Usage

The first step is to instantiate a Sanitizer object:

>>> from sanitary import Sanitizer
>>> sanitizer = Sanitizer(keys={"foo", "bar"})
>>> sanitizer.sanitize({"foo": 123, "bar": "abc", "baz": "boom"})
{"foo": "********", "bar": "********", "baz": "boom"}

Configuration

The Sanitizer class accepts the following arguments:

• keys: An iterator of key names that will be searched for recursively. Any of these keys will have its value replaced by the replacement value.
• patterns: An iterator of regular expression patterns that will be used to search the textual values. A value that matches any of the patterns will be entirely replaced by the message value.
• replacement: Can be any of the following types of values:
  1. A plain text, which will simply replace the sensitive value.
  2. A callable which takes a string as its single argument and returns another string, which will replace the value.
  3. A callable which takes a bytes object as its single argument and returns a "hash object"; this allows using the hashlib functions to mask the data.
• message: The textual message which will replace the value that matches any of the defined patterns.

Data Hashing

If the replacement argument is a callable, the value of a corresponding sensitive key will be replaced with the return value of the callable (or its hexdigest). This way, the sanitized data can still be tracked (e.g. an email address will always have the same hash value) without exposing the actual value.

>>> import hashlib
>>> from sanitary import Sanitizer
>>> sanitizer = Sanitizer(keys={"password", "email"}, replacement=hashlib.sha256)
>>> sanitizer.sanitize({"event": "clean password", "password": "blabla", "foo": {"Email": "test@example.com"}})
{
    'event': 'clean password',
    'password': 'ccadd99b16cd3d200c22d6db45d8b6630ef3d936767127347ec8a76ab992c2ea',
    'foo': {'Email': '973dfe463ec85785f5f95af5ba3906eedb2d931c24e69824a89ea65dba4e813b'}
}
>>>

Sensitive Text Values

Sanitizer can also clean up any text values that match specific regular expression patterns; any such value is completely replaced with a hardcoded warning message.

>>> from sanitary import Sanitizer
>>> sanitizer = Sanitizer(patterns={r"""'Authentication':"""})
>>> sanitizer.sanitize("'Authentication': 1234")
"#### WARNING: Message replaced due to sensitive pattern: 'Authentication':"
>>> sanitizer.sanitize({"example": "'Authentication': 1234"})
{'example': "#### WARNING: Message replaced due to sensitive pattern: 'Authentication':"}
>>>

Structlog Processor

The special subclass, StructlogSanitizer, is provided to enable sanitizing the logging context managed by the structlog library. It needs to be instantiated and added to the list of configured processors:

import hashlib
import structlog
from sanitary import StructlogSanitizer

structlog.configure(
    processors=[
        StructlogSanitizer(keys={"foo", "bar", "baz"}, replacement=hashlib.sha256), 
        structlog.processors.JSONRenderer()
    ],
    logger_factory=structlog.stdlib.LoggerFactory(),
)