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gchq / CyberChef

The Cyber Swiss Army Knife - a web app for encryption, encoding, compression and data analysis
https://gchq.github.io/CyberChef
Apache License 2.0
28.66k stars 3.22k forks source link

Add 'Wrap Input in SEQUENCE' to Parse ASN.1 hex string #1883

Open learn-more opened 1 month ago

learn-more commented 1 month ago

This will parse extra tags concatenated to the first tag.

For example, the following ASN.1 encoded public key consists of multiple top-level tags:

300d06092a864886f70d010101050003818d0030818902818100d88280e8d619027d1f85183925a2652be1bfd405d3bce6363baaf04c6c5bb6e7aa3c734555b2f1bdea9742ed9a340a15d4a95cf54025ddd907c132b2756cc4cabba3fe56277143aa63f5303e9328e5faf1093bf3b74d4e39f75c495ab8c11dd3b28afe70309542cbfe2b518b5a3c3af9224f90b202a7539c4f34e7ab04b27b6f0203010001

Without the option: image

With the option enabled: image

learn-more commented 1 month ago

Another solution would be to overload the substr function, capturing the last accessed offset by the library, and re-start parsing from that, or to search if there is a 'length' function inside the library that can be used, and re-start parsing after that.