A fast, pure Python library for parsing and serializing ASN.1 structures, including private keys, public keys, certificates, and various PKCS standards. Current version: 1.5.1. Release cadence: irregular, with the latest release on March 15, 2022. ([pypi.org](https://pypi.org/project/asn1crypto/?utm_source=openai))
Install & Compatibility
Where this runs
tested against v1.5.1 · pip install
no network on importno background threads
Install × environment matrix
Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux
muslpy 3.10–3.925 runs
installs and imports cleanly · install 0.0s · import 0.096s · 18.7MB
glibcpy 3.10–3.925 runs
installs and imports cleanly · install 1.7s · import 0.088s · 19MB
17MB installed
● package 17MB
Code
Verified usage
Verified import paths — ran on the pinned version, not inferred.
x509
✓ from asn1crypto import x509
Ensure correct import path to access X.509 certificate parsing and serialization.
A basic example demonstrating how to load, parse, and access details of an X.509 certificate using asn1crypto.
from asn1crypto import x509
# Load a certificate from a file
with open('certificate.pem', 'rb') as f:
cert_data = f.read()
# Parse the certificate
cert = x509.Certificate.load(cert_data)
# Access certificate details
print(cert.subject.native) # Print the subject of the certificate
print(cert.serial_number) # Print the serial number of the certificate
Debug
Known issues
breakingThe 'x509' module was introduced in version 0.22.0. Ensure your version is up-to-date to use this module.fixUpgrade to the latest version of asn1crypto.
affects: 0.22.0 and later
gotchaWhen parsing certificates, ensure the input data is in DER format. PEM format requires base64 decoding before parsing.fixConvert PEM to DER format before parsing or use appropriate methods to handle PEM format.
affects: All versions
breakingThe script failed because 'certificate.pem' was not found. Ensure the certificate file exists in the expected path.fixEnsure the 'certificate.pem' file is present in the working directory or provide the correct absolute/relative path to the file.
affects: All versions
breakingThe script failed because 'certificate.pem' was not found. Ensure the certificate file exists in the expected location and has the correct permissions.fixProvide the 'certificate.pem' file in the script's execution directory or update the file path in the script to point to the correct location of the certificate file.
affects: All versions
Errors
Common errors & fixes
ModuleNotFoundError: No module named 'asn1crypto'
The 'asn1crypto' package is not installed in the Python environment.
fixInstall the package using pip: 'pip install asn1crypto'.
ImportError: cannot import name 'core' from 'asn1crypto'
The 'core' module is not available in the 'asn1crypto' package, possibly due to an outdated version.
fixUpgrade to the latest version of 'asn1crypto' using pip: 'pip install --upgrade asn1crypto'.
AttributeError: module 'asn1crypto' has no attribute 'x509'
The 'x509' module is not present in the 'asn1crypto' package, likely due to an incorrect import statement.
fixEnsure the correct import statement: 'from asn1crypto import x509'.
TypeError: 'NoneType' object is not subscriptable
Attempting to access an element of a 'None' object, possibly due to a failed parsing operation.
fixCheck if the parsing operation returned 'None' and handle the error accordingly.
ValueError: Invalid ASN.1 tag
The input data contains an invalid ASN.1 tag, leading to a parsing error.
fixVerify the input data for correctness and ensure it conforms to the expected ASN.1 structure.
Audit
Dependencies
No dependency data recorded yet.