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From: "Maciej S. Szmigiero" <mail@maciej.szmigiero.name>
To: Kamil Konieczny <k.konieczny@partner.samsung.com>
Cc: David Howells <dhowells@redhat.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
"David S. Miller" <davem@davemloft.net>,
Tom Lendacky <thomas.lendacky@amd.com>,
Gary Hook <gary.hook@amd.com>, James Morris <jmorris@namei.org>,
"Serge E. Hallyn" <serge@hallyn.com>,
keyrings@vger.kernel.org, linux-security-module@vger.kernel.org,
linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] X.509: unpack RSA signatureValue field from BIT STRING
Date: Tue, 17 Apr 2018 17:11:54 +0200 [thread overview]
Message-ID: <7497a6f6-b9fc-a249-a6c8-42ff2723aa4a@maciej.szmigiero.name> (raw)
In-Reply-To: <f29df54e-48e1-12e0-f2d2-fd8353cc445f@partner.samsung.com>
On 17.04.2018 17:07, Kamil Konieczny wrote:
>
>
> On 17.04.2018 15:39, Maciej S. Szmigiero wrote:
>> The signatureValue field of a X.509 certificate is encoded as a BIT STRING.
>> For RSA signatures this BIT STRING is of so-called primitive subtype, which
>> contains a u8 prefix indicating a count of unused bits in the encoding.
>>
>> We have to strip this prefix from signature data, just as we already do for
>> key data in x509_extract_key_data() function.
>>
>> This wasn't noticed earlier because this prefix byte is zero for RSA key
>> sizes divisible by 8. Since BIT STRING is a big-endian encoding adding zero
>> prefixes has no bearing on its value.
>>
>> The signature length, however was incorrect, which is a problem for RSA
>> implementations that need it to be exactly correct (like AMD CCP).
>>
>> Signed-off-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
>
> your e-mail address looks incorrect
>
> [...]
>
What's wrong with it?
Maciej
prev parent reply other threads:[~2018-04-17 15:12 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20180417134032epcas3p21dbb2d3a6d8650cd64e147d2ce89e6ea@epcas3p2.samsung.com>
2018-04-17 13:39 ` Maciej S. Szmigiero
2018-04-17 15:07 ` Kamil Konieczny
2018-04-17 15:11 ` Maciej S. Szmigiero [this message]
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