233 lines
10 KiB
Markdown
233 lines
10 KiB
Markdown
# asn1crypto
|
|
|
|
A fast, pure Python library for parsing and serializing ASN.1 structures.
|
|
|
|
- [Features](#features)
|
|
- [Why Another Python ASN.1 Library?](#why-another-python-asn1-library)
|
|
- [Related Crypto Libraries](#related-crypto-libraries)
|
|
- [Current Release](#current-release)
|
|
- [Dependencies](#dependencies)
|
|
- [Installation](#installation)
|
|
- [License](#license)
|
|
- [Documentation](#documentation)
|
|
- [Continuous Integration](#continuous-integration)
|
|
- [Testing](#testing)
|
|
- [Development](#development)
|
|
|
|
[](https://travis-ci.org/wbond/asn1crypto)
|
|
[](https://ci.appveyor.com/project/wbond/asn1crypto)
|
|
[](https://circleci.com/gh/wbond/asn1crypto)
|
|
[](https://codecov.io/gh/wbond/asn1crypto)
|
|
[](https://pypi.python.org/pypi/asn1crypto)
|
|
|
|
## Features
|
|
|
|
In addition to an ASN.1 BER/DER decoder and DER serializer, the project includes
|
|
a bunch of ASN.1 structures for use with various common cryptography standards:
|
|
|
|
| Standard | Module | Source |
|
|
| ---------------------- | ------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------- |
|
|
| X.509 | [`asn1crypto.x509`](asn1crypto/x509.py) | [RFC 5280](https://tools.ietf.org/html/rfc5280) |
|
|
| CRL | [`asn1crypto.crl`](asn1crypto/crl.py) | [RFC 5280](https://tools.ietf.org/html/rfc5280) |
|
|
| CSR | [`asn1crypto.csr`](asn1crypto/csr.py) | [RFC 2986](https://tools.ietf.org/html/rfc2986), [RFC 2985](https://tools.ietf.org/html/rfc2985) |
|
|
| OCSP | [`asn1crypto.ocsp`](asn1crypto/ocsp.py) | [RFC 6960](https://tools.ietf.org/html/rfc6960) |
|
|
| PKCS#12 | [`asn1crypto.pkcs12`](asn1crypto/pkcs12.py) | [RFC 7292](https://tools.ietf.org/html/rfc7292) |
|
|
| PKCS#8 | [`asn1crypto.keys`](asn1crypto/keys.py) | [RFC 5208](https://tools.ietf.org/html/rfc5208) |
|
|
| PKCS#1 v2.1 (RSA keys) | [`asn1crypto.keys`](asn1crypto/keys.py) | [RFC 3447](https://tools.ietf.org/html/rfc3447) |
|
|
| DSA keys | [`asn1crypto.keys`](asn1crypto/keys.py) | [RFC 3279](https://tools.ietf.org/html/rfc3279) |
|
|
| Elliptic curve keys | [`asn1crypto.keys`](asn1crypto/keys.py) | [SECG SEC1 V2](http://www.secg.org/sec1-v2.pdf) |
|
|
| PKCS#3 v1.4 | [`asn1crypto.algos`](asn1crypto/algos.py) | [PKCS#3 v1.4](ftp://ftp.rsasecurity.com/pub/pkcs/ascii/pkcs-3.asc) |
|
|
| PKCS#5 v2.1 | [`asn1crypto.algos`](asn1crypto/algos.py) | [PKCS#5 v2.1](http://www.emc.com/collateral/white-papers/h11302-pkcs5v2-1-password-based-cryptography-standard-wp.pdf) |
|
|
| CMS (and PKCS#7) | [`asn1crypto.cms`](asn1crypto/cms.py) | [RFC 5652](https://tools.ietf.org/html/rfc5652), [RFC 2315](https://tools.ietf.org/html/rfc2315) |
|
|
| TSP | [`asn1crypto.tsp`](asn1crypto/tsp.py) | [RFC 3161](https://tools.ietf.org/html/rfc3161) |
|
|
| PDF signatures | [`asn1crypto.pdf`](asn1crypto/pdf.py) | [PDF 1.7](http://wwwimages.adobe.com/content/dam/Adobe/en/devnet/pdf/pdfs/PDF32000_2008.pdf) |
|
|
|
|
## Why Another Python ASN.1 Library?
|
|
|
|
Python has long had the [pyasn1](https://pypi.python.org/pypi/pyasn1) and
|
|
[pyasn1_modules](https://pypi.python.org/pypi/pyasn1-modules) available for
|
|
parsing and serializing ASN.1 structures. While the project does include a
|
|
comprehensive set of tools for parsing and serializing, the performance of the
|
|
library can be very poor, especially when dealing with bit fields and parsing
|
|
large structures such as CRLs.
|
|
|
|
After spending extensive time using *pyasn1*, the following issues were
|
|
identified:
|
|
|
|
1. Poor performance
|
|
2. Verbose, non-pythonic API
|
|
3. Out-dated and incomplete definitions in *pyasn1-modules*
|
|
4. No simple way to map data to native Python data structures
|
|
5. No mechanism for overridden universal ASN.1 types
|
|
|
|
The *pyasn1* API is largely method driven, and uses extensive configuration
|
|
objects and lowerCamelCase names. There were no consistent options for
|
|
converting types of native Python data structures. Since the project supports
|
|
out-dated versions of Python, many newer language features are unavailable
|
|
for use.
|
|
|
|
Time was spent trying to profile issues with the performance, however the
|
|
architecture made it hard to pin down the primary source of the poor
|
|
performance. Attempts were made to improve performance by utilizing unreleased
|
|
patches and delaying parsing using the `Any` type. Even with such changes, the
|
|
performance was still unacceptably slow.
|
|
|
|
Finally, a number of structures in the cryptographic space use universal data
|
|
types such as `BitString` and `OctetString`, but interpret the data as other
|
|
types. For instance, signatures are really byte strings, but are encoded as
|
|
`BitString`. Elliptic curve keys use both `BitString` and `OctetString` to
|
|
represent integers. Parsing these structures as the base universal types and
|
|
then re-interpreting them wastes computation.
|
|
|
|
*asn1crypto* uses the following techniques to improve performance, especially
|
|
when extracting one or two fields from large, complex structures:
|
|
|
|
- Delayed parsing of byte string values
|
|
- Persistence of original ASN.1 encoded data until a value is changed
|
|
- Lazy loading of child fields
|
|
- Utilization of high-level Python stdlib modules
|
|
|
|
While there is no extensive performance test suite, the
|
|
`CRLTests.test_parse_crl` test case was used to parse a 21MB CRL file on a
|
|
late 2013 rMBP. *asn1crypto* parsed the certificate serial numbers in just
|
|
under 8 seconds. With *pyasn1*, using definitions from *pyasn1-modules*, the
|
|
same parsing took over 4,100 seconds.
|
|
|
|
For smaller structures the performance difference can range from a few times
|
|
faster to an order of magnitude of more.
|
|
|
|
## Related Crypto Libraries
|
|
|
|
*asn1crypto* is part of the modularcrypto family of Python packages:
|
|
|
|
- [asn1crypto](https://github.com/wbond/asn1crypto)
|
|
- [oscrypto](https://github.com/wbond/oscrypto)
|
|
- [csrbuilder](https://github.com/wbond/csrbuilder)
|
|
- [certbuilder](https://github.com/wbond/certbuilder)
|
|
- [crlbuilder](https://github.com/wbond/crlbuilder)
|
|
- [ocspbuilder](https://github.com/wbond/ocspbuilder)
|
|
- [certvalidator](https://github.com/wbond/certvalidator)
|
|
|
|
## Current Release
|
|
|
|
0.24.0 - [changelog](changelog.md)
|
|
|
|
## Dependencies
|
|
|
|
Python 2.6, 2.7, 3.2, 3.3, 3.4, 3.5, 3.6 or pypy. *No third-party packages
|
|
required.*
|
|
|
|
## Installation
|
|
|
|
```bash
|
|
pip install asn1crypto
|
|
```
|
|
|
|
## License
|
|
|
|
*asn1crypto* is licensed under the terms of the MIT license. See the
|
|
[LICENSE](LICENSE) file for the exact license text.
|
|
|
|
## Documentation
|
|
|
|
The documentation for *asn1crypto* is composed of tutorials on basic usage and
|
|
links to the source for the various pre-defined type classes.
|
|
|
|
### Tutorials
|
|
|
|
- [Universal Types with BER/DER Decoder and DER Encoder](docs/universal_types.md)
|
|
- [PEM Encoder and Decoder](docs/pem.md)
|
|
|
|
### Reference
|
|
|
|
- [Universal types](asn1crypto/core.py), `asn1crypto.core`
|
|
- [Digest, HMAC, signed digest and encryption algorithms](asn1crypto/algos.py), `asn1crypto.algos`
|
|
- [Private and public keys](asn1crypto/keys.py), `asn1crypto.keys`
|
|
- [X509 certificates](asn1crypto/x509.py), `asn1crypto.x509`
|
|
- [Certificate revocation lists (CRLs)](asn1crypto/crl.py), `asn1crypto.crl`
|
|
- [Online certificate status protocol (OCSP)](asn1crypto/ocsp.py), `asn1crypto.ocsp`
|
|
- [Certificate signing requests (CSRs)](asn1crypto/csr.py), `asn1crypto.csr`
|
|
- [Private key/certificate containers (PKCS#12)](asn1crypto/pkcs12.py), `asn1crypto.pkcs12`
|
|
- [Cryptographic message syntax (CMS, PKCS#7)](asn1crypto/cms.py), `asn1crypto.cms`
|
|
- [Time stamp protocol (TSP)](asn1crypto/tsp.py), `asn1crypto.tsp`
|
|
- [PDF signatures](asn1crypto/pdf.py), `asn1crypto.pdf`
|
|
|
|
## Continuous Integration
|
|
|
|
- [Windows](https://ci.appveyor.com/project/wbond/asn1crypto/history) via AppVeyor
|
|
- [OS X](https://circleci.com/gh/wbond/asn1crypto) via CircleCI
|
|
- [Linux](https://travis-ci.org/wbond/asn1crypto/builds) via Travis CI
|
|
- [Test Coverage](https://codecov.io/gh/wbond/asn1crypto/commits) via Codecov
|
|
|
|
## Testing
|
|
|
|
Tests are written using `unittest` and require no third-party packages:
|
|
|
|
```bash
|
|
python run.py tests
|
|
```
|
|
|
|
To run only some tests, pass a regular expression as a parameter to `tests`.
|
|
|
|
```bash
|
|
python run.py tests ocsp
|
|
```
|
|
|
|
## Development
|
|
|
|
To install the package used for linting, execute:
|
|
|
|
```bash
|
|
pip install --user -r requires/lint
|
|
```
|
|
|
|
The following command will run the linter:
|
|
|
|
```bash
|
|
python run.py lint
|
|
```
|
|
|
|
Support for code coverage can be installed via:
|
|
|
|
```bash
|
|
pip install --user -r requires/coverage
|
|
```
|
|
|
|
Coverage is measured by running:
|
|
|
|
```bash
|
|
python run.py coverage
|
|
```
|
|
|
|
To install the necessary packages for releasing a new version on PyPI, run:
|
|
|
|
```bash
|
|
pip install --user -r requires/release
|
|
```
|
|
|
|
Releases are created by:
|
|
|
|
- Making a git tag in [semver](http://semver.org/) format
|
|
- Running the command:
|
|
|
|
```bash
|
|
python run.py release
|
|
```
|
|
|
|
Existing releases can be found at https://pypi.python.org/pypi/asn1crypto.
|
|
|
|
## CI Tasks
|
|
|
|
A task named `deps` exists to ensure a modern version of `pip` is installed,
|
|
along with all necessary testing dependencies.
|
|
|
|
The `ci` task runs `lint` (if flake8 is available for the version of Python) and
|
|
`coverage` (or `tests` if coverage is not available for the version of Python).
|
|
If the current directory is a clean git working copy, the coverage data is
|
|
submitted to codecov.io.
|
|
|
|
```bash
|
|
python run.py deps
|
|
python run.py ci
|
|
```
|