how to use gnutls_privkey_import_ext

Carolin Latze latze at
Sun Jun 10 21:15:35 CEST 2012

On 06/10/2012 08:45 PM, Nikos Mavrogiannopoulos wrote:
> On 06/10/2012 07:36 PM, Carolin Latze wrote:
>> I am sorry, but this still causes me some troubles.
>> As far as I understand it, the hash in PKCS#1 is:
>> bytes 00 - 14: algorithm identifier + some more bytes
>> bytes 15 - 20: the hash
>> So I thought it might be sufficient do define a new gnutls_datum_t vdata
>> with
>> =&raw_data->data[15]
>> vdata.size = raw_data->size-15
> Why do you do that? You're not supposed to interpret that data, just
> sign it using raw RSA. You should treat it the same way you treated the
> MD5+SHA1 combo in TLS 1.0.
Hm. I cannot send more than 20 bytes to the TPM sign function, so I 
would need to encrypt. As far as I remember the TLS 1.2 RFC, the goal 
was to have 20 bytes and be able to use standard signature functions 
instead of encryption as it was in TLS <1.2. So maybe other 
cryptographic modules are able to handle the complete PKCS#1 structure, 
but unfortunately, the TPM is not.

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