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From:   David Howells <dhowells@redhat.com>
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To:     Vitaly Chikunov <vt@altlinux.org>
Cc:     dhowells@redhat.com, Stephan Mueller <smueller@chronox.de>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Mimi Zohar <zohar@linux.vnet.ibm.com>,
        Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
        linux-integrity@vger.kernel.org, keyrings@vger.kernel.org,
        linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 4/4] crypto: Add EC-RDSA algorithm
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Date:   Wed, 16 Jan 2019 16:15:20 +0000
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Vitaly Chikunov <vt@altlinux.org> wrote:

> > Regarding your comment (2), I am not sure I understand. Why do you say that 
> > the DER format cannot be parsed by the kernel's ASN.1 parser? For example, 
> 
> It can, but DER is stricter than BER. For example, in DER 'OCTET STRING'
> length field should be encoded in just one byte if it's smaller than
> 128, in BER it could be encoded in multiple encodings. This does not
> seem like a big deal, though. With BER decoder an improperly DER-encoded
> certificate could be successfully parsed.

Whilst that is true, I don't think it's that big a deal.  DER is a subset of
BER, so a BER decoder ought to be able to parse it.  Note that X.509 is
supposed to be DER, but we use a BER decoder for that too.

David