it is not necessary to use or to implement all of the data types and other features of ASN.1; you can implement only the features that you are using. Since DER uses the same framing for all data types, it is possible to skip past any fields that you do not care about (although in some cases you will still need to check its type, to determine whether or not an optional field is present; fortunately the type can be checked easily, even if it is not a type you implement).

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morshu9001 4 hours ago | parent [-]

Yes but I don't want to worry about what parts of the spec are implemented on each end. If you removed all the unnecessary stuff and formed a new standard, it'd basically be protobuf.

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zzo38computer 4 hours ago | parent [-]

I do not agree. Which parts are necessary depends on the application; there is not one good way to do for everyone (and Protobuf is too limited). You will need to implement the parts specific to your schema/application on each end, and if the format does not have the data types that you want then you must add them in a more messy way (especially when using JSON).

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morshu9001 4 hours ago | parent [-]

In what ASN1 application is protobuf spec too limited? I've used protobuf for tons of different things, it's always felt right. Though I understand certain encodings of ASN1 can have better performance for specific things.

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zzo38computer 3 hours ago | parent [-]

Numbers bigger than 64-bits, character sets other than Unicode (and ASCII), OIDs, etc.

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morshu9001 an hour ago | parent [-]

These are only scalars that you'd encode into bytes. I guess it's slightly annoying that both ends have to agree on how to serialize rather than protobuf itself doing it, but it's not a big enough problem.

Also I don't see special ASN1 support for non-Unicode string encodings, only subsets of Unicode like ascii or printable ascii. It's a big can of worms once you bring in things like Latin-1.

	▲	zzo38computer 13 minutes ago \| parent [-]
		ASN.1 has support for ISO 2022 as well as ASCII and Unicode (ASCII is a subset of Unicode as well as a subset of ISO 2022). (My own nonstandard extensions add a few more (such as TRON character code and packed BCD), and the standard unrestricted character string type can be used if you really need arbitrary character sets.) (Unicode is not a very good character set, anyways.) Also, DER allows to indicate the type of data within the file (unless you are using implicit types). Protobuf has only a limited case of this (you cannot always identify the types), and it requires different framing for different types. However, DER uses the same framing for all types, and strings are not inherently limited to 2GB by the file format. Furthermore, there are other non-scalar types as well. In any of these cases, you do not have to use all of the types (nor do you need to implement all of the types); you only need to use the types that are applicable for your use. I will continue to use ASN.1; Protobuf is not good enough in my opinion.