tree 625218efa68bf781541b18e9b07d08b6b90b2726
parent f01de145bd5fdb2e843bab427f45a566d358b225
author David Horstmann <david.horstmann@arm.com> 1676461693 +0000
committer David Horstmann <david.horstmann@arm.com> 1676462547 +0000

Disallow overlong encoding when parsing OIDs

OID subidentifiers are encoded as follow. For every byte:
* The top bit is 1 if there is another byte to come, 0 if this is the
last byte.
* The other 7 bits form 7 bits of the number. These groups of 7 are
concatenated together in big-endian order.

Overlong encodings are explicitly disallowed by the BER/DER/X690
specification. For example, the number 1 cannot be encoded as:

0x80 0x80 0x01

It must be encoded as:

0x01

Enforce this in Mbed TLS' OID DER-to-string parser.

Signed-off-by: David Horstmann <david.horstmann@arm.com>