[Cryptography] encoding formats should not be committee'ized

Viktor Dukhovni cryptography at dukhovni.org
Wed Oct 2 10:46:05 EDT 2013


On Wed, Oct 02, 2013 at 09:09:05AM -0400, Phillip Hallam-Baker wrote:

> SMTP does not have nested structures or need
> them. A lot of application protocols do.

MIME: RFC 2045 - 2048, ...

A rather complex nested structure, and frankly rather more ambiguous
in practice than ASN.1.  For example, what is the meaning of:

	...
	Conent-Transfer-Encoding: base64
	Conent-Transfer-Encoding: 7-bit
	...

This type of ambiguity is not possible with ASN.1.  There are many
more edge cases in which the same MIME input is parsed very
differently by different implementations.  There are many more
interesting cases, but I shall not bore you with them here.

> Text encodings are easy to read but very difficult to specify
> boundaries in without ambiguity.

Yes, and not just boundaries.

-- 
	Viktor.


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