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- ASN1
- ====
- Abstract Syntax Notation One (or ASN1) is a standard by ITU-T and ISO/IEC
- and used as a description language for defining data structure in
- an independent manner.
- Any data described in ASN1 notation can be serialized (or encoded) and
- de-serialized (or decoded) with well-defined encoding rules.
- A combination of ASN1 compiler and ASN1 decoder library function will
- provide a function interface for parsing encoded binary into specific
- data structure:
- 1) define data structure in a text file (*.asn1)
- 2) define "action" routines for specific "tags" defined in (1)
- 3) generate bytecode as a C file (*.asn1.[ch]) from *.asn1 file
- with ASN1 compiler (tools/asn1_compiler)
- 4) call a ASN1 decoder (asn1_ber_decoder()) with bytecode and data
- Usage of ASN1 compiler
- ----------------------
- asn1_compiler [-v] [-d] <grammar-file> <c-file> <hdr-file>
- <grammar-file>: ASN1 input file
- <c-file>: generated C file
- <hdr-file>: generated include file
- Usage of ASN1 decoder
- ---------------------
- int asn1_ber_decoder(const struct asn1_decoder *decoder, void *context,
- const unsigned char *data, size_t datalen);
- @decoder: bytecode binary
- @context: context for decoder
- @data: data to be parsed
- @datalen: size of data
- As of writing this, ASN1 compiler and decoder are used to implement
- X509 certificate parser, pcks7 message parser and RSA public key parser
- for UEFI secure boot.
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