sk.to_pem() cannot create the same pem file from SigningKey.from_pem(fstream.read(), hashlib.sha256)

[Jiu-hong]

The pem file

-----BEGIN EC PRIVATE KEY-----
MC4CAQEEIIX0Wk/h+GvE8RkARl4qZp+J4Ex1hjG/ZCi7mVov37teoAcGBSuBBAAK
-----END EC PRIVATE KEY-----

My code

    with open(fpath) as fstream:
        sk = SigningKey.from_pem(fstream.read(), hashlib.sha256)
        file = sk.to_pem()
        print(file)

This is the generates pem file

-----BEGIN EC PRIVATE KEY-----
MHQCAQEEIIX0Wk/h+GvE8RkARl4qZp+J4Ex1hjG/ZCi7mVov37teoAcGBSuBBAAKoUQDQgAEs+tq\n5A4hqUNrlWqoo69bczY0DPxuwDXbeuxqT/HNoi9L38c8MzsSEearJzvLBrC5d6Dt/3x16vji/xAw\nONnEKQ==
-----END EC PRIVATE KEY-----

which isn't the same as the original pem file.

Can you help advise how to generate the same file ?
Thank you.

[tomato42]

specify that you want to use compressed point encoding:

python-ecdsa/src/ecdsa/keys.py

Lines 1173 to 1203 in 2a6593d

	def to_pem(
	self,
	point_encoding="uncompressed",
	format="ssleay",
	curve_parameters_encoding=None,
	):
	"""
	Convert the private key to the :term:`PEM` format.
	See :func:`~SigningKey.from_pem` method for format description.
	Only the named curve format is supported.
	The public key will be included in generated string.
	The PEM header will specify ``BEGIN EC PRIVATE KEY`` or
	``BEGIN PRIVATE KEY``, depending on the desired format.
	:param str point_encoding: format to use for encoding public point
	:param str format: either ``ssleay`` (default) or ``pkcs8``
	:param str curve_parameters_encoding: format of encoded curve
	parameters, default depends on the curve, if the curve has
	an associated OID, ``named_curve`` format will be used,
	if no OID is associated with the curve, the fallback of
	``explicit`` parameters will be used.
	:return: PEM encoded private key
	:rtype: bytes
	.. warning:: The PEM is encoded to US-ASCII, it needs to be
	re-encoded if the system is incompatible (e.g. uses UTF-16)
	"""