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- <html>
- <title>
- PyASN1 reference manual
- </title>
- <head>
- </head>
- <body>
- <center>
- <table width=60%>
- <tr>
- <td>
- <h3>
- PyASN1 reference manual
- </h3>
- <p align=right>
- <i>written by <a href=mailto:ilya@glas.net>Ilya Etingof</a>, 2011-2012</i>
- </p>
- <p>
- Free and open-source pyasn1 library makes it easier for programmers and
- network engineers to develop, debug and experiment with ASN.1-based protocols
- using Python programming language as a tool.
- </p>
- <p>
- Abstract Syntax Notation One
- (<a href=http://en.wikipedia.org/wiki/Abstract_Syntax_Notation_1x>ASN.1</a>)
- is a set of
- <a href=http://www.itu.int/ITU-T/studygroups/com17/languages/X.680-X.693-0207w.zip>
- ITU standards</a> concered with provisioning instrumentation for developing
- data exchange protocols in a robust, clear and interoperabable way for
- various IT systems and applications. Most of the efforts are targeting the
- following areas:
- <ul>
- <li>Data structures: the standard introduces a collection of basic data types
- (similar to integers, bits, strings, arrays and records in a programming
- language) that can be used for defining complex, possibly nested data
- structures representing domain-specific data units.
- <li>Serialization protocols: domain-specific data units expressed in ASN.1
- types could be converted into a series of octets for storage or transmission
- over the wire and then recovered back into their structured form on the
- receiving end. This process is immune to various hardware and software
- related dependencies.
- <li>Data description language: could be used to describe particular set of
- domain-specific data structures and their relationships. Such a description
- could be passed to an ASN.1 compiler for automated generation of program
- code that represents ASN.1 data structures in language-native environment
- and handles data serialization issues.
- </ul>
- </p>
- <p>
- This tutorial and algorithms, implemented by pyasn1 library, are
- largely based on the information read in the book
- <a href="http://www.oss.com/asn1/dubuisson.html">
- ASN.1 - Communication between heterogeneous systems</a>
- by Olivier Dubuisson. Another relevant resource is
- <a href=ftp://ftp.rsasecurity.com/pub/pkcs/ascii/layman.asc>
- A Layman's Guide to a Subset of ASN.1, BER, and DER</a> by Burton S. Kaliski.
- It's advised to refer to these books for more in-depth knowledge on the
- subject of ASN.1.
- </p>
- <p>
- As of this writing, pyasn1 library implements most of standard ASN.1 data
- structures in a rather detailed and feature-rich manner. Another highly
- important capability of the library is its data serialization facilities.
- The last component of the standard - ASN.1 compiler is planned for
- implementation in the future.
- </p>
- </p>
- The pyasn1 library was designed to follow the pre-1995 ASN.1 specification
- (also known as X.208). Later, post 1995, revision (X.680) introduced
- significant changes most of which have not yet been supported by pyasn1.
- </p>
- <h3>
- Table of contents
- </h3>
- <p>
- <ul>
- <li><a href="scalar.html">1. Data model for ASN.1 types</a>
- <li><a href="scalar.html#1.1">1.1 Scalar types</a>
- <li><a href="scalar.html#1.1.1">1.1.1 Boolean type</a>
- <li><a href="scalar.html#1.1.2">1.1.2 Null type</a>
- <li><a href="scalar.html#1.1.3">1.1.3 Integer type</a>
- <li><a href="scalar.html#1.1.4">1.1.4 Enumerated type</a>
- <li><a href="scalar.html#1.1.5">1.1.5 Real type</a>
- <li><a href="scalar.html#1.1.6">1.1.6 Bit string type</a>
- <li><a href="scalar.html#1.1.7">1.1.7 OctetString type</a>
- <li><a href="scalar.html#1.1.8">1.1.8 ObjectIdentifier type</a>
- <li><a href="scalar.html#1.1.9">1.1.9 Character string types</a>
- <li><a href="scalar.html#1.1.10">1.1.10 Useful types</a>
- <li><a href="tagging.html">1.2 Tagging</a>
- <li><a href="constructed.html">1.3 Constructed types</a>
- <li><a href="constructed.html#1.3.1">1.3.1 Sequence and Set types</a>
- <li><a href="constructed.html#1.3.2">1.3.2 SequenceOf and SetOf types</a>
- <li><a href="constructed.html#1.3.3">1.3.3 Choice type</a>
- <li><a href="constructed.html#1.3.4">1.3.4 Any type</a>
- <li><a href="constraints.html">1.4 Subtype constraints</a>
- <li><a href="constraints.html#1.4.1">1.4.1 Single value constraint</a>
- <li><a href="constraints.html#1.4.2">1.4.2 Value range constraint</a>
- <li><a href="constraints.html#1.4.3">1.4.3 Size constraint</a>
- <li><a href="constraints.html#1.4.4">1.4.4 Alphabet constraint</a>
- <li><a href="constraints.html#1.4.5">1.4.5 Constraint combinations</a>
- <li><a href="constraints.html#1.5">1.5 Types relationships</a>
- <li><a href="codecs.html">2. Codecs</a>
- <li><a href="codecs.html#2.1">2.1 Encoders</a>
- <li><a href="codecs.html#2.2">2.2 Decoders</a>
- <li><a href="codecs.html#2.2.1">2.2.1 Decoding untagged types</a>
- <li><a href="codecs.html#2.2.2">2.2.2 Ignoring unknown types</a>
- </ul>
- <p>
- Although pyasn1 software is almost a decade old and used in many production
- environments, it still may have bugs and non-implemented pieces. Anyone
- who happens to run into such defect is welcome to complain to
- <a href=mailto:pyasn1-users@lists.sourceforge.net>pyasn1 mailing list</a>
- or better yet fix the issue and send
- <a href=mailto:ilya@glas.net>me</a> the patch.
- </p>
- <p>
- Typically, pyasn1 is used for building arbitrary protocol support into
- various applications. This involves manual translation of ASN.1 data
- structures into their pyasn1 implementations. To save time and effort,
- data structures for some of the popular protocols are pre-programmed
- and kept for further re-use in form of the
- <a href=http://sourceforge.net/projects/pyasn1/files/pyasn1-modules/>
- pyasn1-modules package</a>. For instance, many structures for PKI (X.509,
- PKCS#*, CRMF, OCSP), LDAP and SNMP are present.
- Applications authors are advised to import and use relevant modules
- from that package whenever needed protocol structures are already
- there. New protocol modules contributions are welcome.
- </p>
- <p>
- And finally, the latest pyasn1 package revision is available for free
- download from
- <a href=http://sourceforge.net/projects/pyasn1/>project home</a> and
- also from the
- <a href=http://pypi.python.org/pypi>Python package repository</a>.
- </p>
- <hr>
- </td>
- </tr>
- </table>
- </center>
- </body>
- </html>
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