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ASN.1 Format

Description​

ASN.1 (Abstract Syntax Notation One) is a standard interface description language for defining data structures. It's widely used in telecommunications and cryptography. ASN.1 data can be encoded in various formats, with DER (Distinguished Encoding Rules) being common.

File Extensions​

  • .asn1 - ASN.1 files
  • .der - DER-encoded ASN.1 files (alias)

Implementation Details​

Reading​

The ASN.1 implementation:

  • Uses pyasn1 library for decoding
  • Parses DER-encoded ASN.1 data
  • Converts ASN.1 structures to Python dictionaries
  • Handles sequences and other ASN.1 types

Writing​

Writing support:

  • Encodes Python dictionaries to ASN.1 format
  • Writes DER-encoded ASN.1 data
  • Note: Simplified conversion, real ASN.1 encoding requires schema

Key Features​

  • Standard format: ITU-T and ISO standard
  • Telecommunications: Widely used in telecom
  • Cryptography: Used in certificates and keys
  • Binary format: DER encoding is binary
  • Schema-based: Typically requires ASN.1 schema

Usage​

from iterable import open_iterable

# Basic reading
with open_iterable('data.der') as source:
    for row in source:
        print(row)

# Writing
with open_iterable('output.der', mode='w') as dest:
    dest.write({'field1': 'value1', 'field2': 123})

Parameters​

No specific parameters required.

Limitations​

  1. pyasn1 dependency: Requires pyasn1 package
  2. Schema complexity: Real ASN.1 encoding requires schema
  3. Binary format: Not human-readable
  4. Simplified conversion: Current implementation is simplified
  5. DER encoding: Primarily supports DER encoding

Compression Support​

ASN.1 files can be compressed with all supported codecs:

  • GZip (.der.gz)
  • BZip2 (.der.bz2)
  • LZMA (.der.xz)
  • LZ4 (.der.lz4)
  • ZIP (.der.zip)
  • Brotli (.der.br)
  • ZStandard (.der.zst)

Use Cases​

  • Telecommunications: Telecom protocol data
  • Cryptography: Certificates, keys, and cryptographic data
  • Standards compliance: When ASN.1 is required by standards
  • X.509 certificates: Certificate encoding

Error Handling​

  • Missing dependency: optional libraries raise ImportError with an install hint (pip install 'iterabledata[<extra>]' when an extra exists).
  • Write mode: read-only formats raise WriteNotSupportedError or ValueError when opened with mode="w".
  • Bad or unsupported input: may raise ValueError, OSError, or library-specific errors.
  • See Troubleshooting for decoding, detection, and engine issues.