Bug Report - ReportLab not FIPS compliant, does not support FIPS by default

[Cooper]

Thank you reportlab contributers, for all the work you do.

The hashing algorithm is MD5 which is not FIPS compliant.  I had to monkey patch the hashlib to send all MD5 hashes to SHA256.

c = canvas.Canvas(packet, pagesize=page_size) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.11/site-packages/reportlab/pdfgen/canvas.py", line 305, in __init__ self._doc = pdfdoc.PDFDocument(compression=pageCompression, ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.11/site-packages/reportlab/pdfbase/pdfdoc.py", line 137, in __init__ sig = self.signature = md5() ^^^^^ _hashlib.UnsupportedDigestmodError: [digital envelope routines] unsupported

#Fixed by mokey patch (before report lab import)
# Define a wrapper function that calls hashlib.sha256 instead of hashlib.md5
def sha256_as_md5(*args, **kwargs):
    print("Warning: MD5 hash requested; using SHA256 as a FIPS-compliant replacement.")
    return hashlib.sha256(*args, **kwargs)


original_md5 = hashlib.md5
# Replace the hashlib.md5 with your wrapper function
hashlib.md5 = sha256_as_md5

[Zachary Rank]

I'm running into the same/similar problem with reportlab 4.0.9 on Python 3.9 on Red Hat 8. The call to the hashlib.md5() will not work on operating systems that are FIPS compliant. The fix is a simple one-liner to indicate that the usage of the md5 is not for security purposes.

Here is a stacktrace:

```

Traceback (most recent call last):
  ...
  File "venv/lib/python3.9/site-packages/reportlab/pdfbase/pdfdoc.py", line 137, in __init__

    sig = self.signature = md5()

Exception Type: ValueError
Exception Value: [digital envelope routines: EVP_DigestInit_ex] disabled for FIPS

```

Updating line 137 of reportlab/pdfbase/pdfdoc.py to be `sig = self.signature = md5(usedforsecurity=False)` should resolve the problem for everyone.