File: //var/opt/nydus/ops/asn1crypto/__pycache__/parser.cpython-39.pyc
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Functions for parsing and dumping using the ASN.1 DER encoding. Exports the
following items:
- emit()
- parse()
- peek()
Other type classes are defined that help compose the types listed above.
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Constructs a byte string of an ASN.1 DER-encoded value
This is typically not useful. Instead, use one of the standard classes from
asn1crypto.core, or construct a new class with specific fields, and call the
.dump() method.
:param class_:
An integer ASN.1 class value: 0 (universal), 1 (application),
2 (context), 3 (private)
:param method:
An integer ASN.1 method value: 0 (primitive), 1 (constructed)
:param tag:
An integer ASN.1 tag value
:param contents:
A byte string of the encoded byte contents
:return:
A byte string of the ASN.1 DER value (header and contents)
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Parses a byte string of ASN.1 BER/DER-encoded data.
This is typically not useful. Instead, use one of the standard classes from
asn1crypto.core, or construct a new class with specific fields, and call the
.load() class method.
:param contents:
A byte string of BER/DER-encoded data
:param strict:
A boolean indicating if trailing data should be forbidden - if so, a
ValueError will be raised when trailing data exists
:raises:
ValueError - when the contents do not contain an ASN.1 header or are truncated in some way
TypeError - when contents is not a byte string
:return:
A 6-element tuple:
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- 2: integer tag
- 3: byte string header
- 4: byte string content
- 5: byte string trailer
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Parses a byte string of ASN.1 BER/DER-encoded data to find the length
This is typically used to look into an encoded value to see how long the
next chunk of ASN.1-encoded data is. Primarily it is useful when a
value is a concatenation of multiple values.
:param contents:
A byte string of BER/DER-encoded data
:raises:
ValueError - when the contents do not contain an ASN.1 header or are truncated in some way
TypeError - when contents is not a byte string
:return:
An integer with the number of bytes occupied by the ASN.1 value
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Parses a byte string into component parts
:param encoded_data:
A byte string that contains BER-encoded data
:param data_len:
The integer length of the encoded data
:param pointer:
The index in the byte string to parse from
:param lengths_only:
A boolean to cause the call to return a 2-element tuple of the integer
number of bytes in the header and the integer number of bytes in the
contents. Internal use only.
:param depth:
The recursion depth when evaluating indefinite-length encoding.
:return:
A 2-element tuple:
- 0: A tuple of (class_, method, tag, header, content, trailer)
- 1: An integer indicating how many bytes were consumed
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