On 10 mei 2012, at 18:59, "Dr. Stephen Henson" <[email protected]> wrote:
> On Thu, May 10, 2012, Dirk-Willem van Gulik wrote:
>
>> int nid1 = OBJ_create("1.3.6.1.4.1.2692.99.1", "geoLat",
>> "Latitude(WGS84) of device calculating CSR");
>> ASN1_OBJECT* obj1 = OBJ_nid2obj(nid1);
>>
>> ASN1_INTEGER * data1 = ASN1_INTEGER_new();
>> ASN1_INTEGER_set(data1, 100);
>>
>> sk_X509_EXTENSION_push(exts, X509_EXTENSION_create_by_OBJ(NULL, obj1,
>> 0, data1));
>>
>> I see this return also an OCTED STRING:
>>
>> 352:d=6 hl=2 l= 14 cons: SEQUENCE
>> 354:d=7 hl=2 l= 9 prim: OBJECT
>> :1.3.6.1.4.1.2692.99.1
>> 365:d=7 hl=2 l= 1 prim: OCTET STRING :d
>>
>> Where am I going wrong ? Specifically I'd like to embed a very small image
>> (containing a hard to forge noise pattern) and a few arbitrary IEEE floating
>> point number in the CSR (i.e. in the part that gets signed by the pub-key of
>> the CSR requester).
>
> Although the parser tolerates it you shouldn't place arbitrary data in an X509
> extension, you should instead place the encoding of the extension.
>
> So you'd use i2d_ASN1_OCTET_STRING or i2d_ASN1_INTEGER to generate the
> encoding and use that as the content of the extension OCTET STRING.
Thanks - but I think I am being a bit dim. If I understand it right - you mean
the following:
1) create the integer and populate it:
ASN1_INTEGER * int1 = ASN1_INTEGER_new();
ASN1_INTEGER_set(int1, 100);
2) figure out the length it would take when converted from internal into
der/asn1 wire encoding:
int n = i2d_ASN1_INTEGER(int1,NULL);
3) Ensure we have the needed space for that:
ASN1_OCTET_STRING data1;
data1.data = malloc(n);
data1.length = n;
4) Fill out the ASN1 string by translating it again - this time into the
buffer.
unsigned char * p =M_ASN1_STRING_data(&data1);
i2d_ASN1_INTEGER(int1,&p);
5) add to the extension stack.
sk_X509_EXTENSION_push(exts, X509_EXTENSION_create_by_OBJ(NULL, obj1,
0, &data1));
Nets me
365:d=7 hl=2 l= 3 prim: OCTET STRING [HEX DUMP]:020164
which looks close (02 type == integer, 01 length, number 100) -- but is
obviously not right as it is seen as an octed string still.
Where am I going wrong this time ?! :)
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