Re: Add ECDSA signature R and S to X509 structure

[William Roberts]

This thread actually has some code on it for doing this:

https://www.mail-archive.com/openssl-users@openssl.org/msg86672.html

Bill

On Mon, Aug 26, 2019 at 9:46 AM Ken Goldman  wrote:
>
> On 8/17/2019 5:35 AM, Billy Brumley wrote:
> > Hey Ken,
> >
> >> I have an ECDSA signature supplied to me as R and S byte arrays and
> >> lengths (from an HSM).
> >>
> >> How do I add them to the X509 structure?
> >>
> >> Is there an API, a set of calls, or do you have any hints?
> >
> > You might be looking for ECDSA_SIG_set0:
> >
> > https://www.openssl.org/docs/man1.1.0/man3/ECDSA_SIG_set0.html
> >
> > You might find some snippets in ecdsatest.c.
> >
> > Hope it helps,
>
> I think so.  This seems to work.  Does it make sense? Is there a better way?
>
> - convert R and S, bin to bignum
> - use ECDSA_SIG_set0 to create an ECDSA_SIG
> - use i2d to convert the ECDSA_SIG to DER
> - memcpy the DER into X509->signature->data
>
>

Re: Add ECDSA signature R and S to X509 structure

[Ken Goldman]

On 8/17/2019 5:35 AM, Billy Brumley wrote:

Hey Ken,


I have an ECDSA signature supplied to me as R and S byte arrays and
lengths (from an HSM).

How do I add them to the X509 structure?

Is there an API, a set of calls, or do you have any hints?


You might be looking for ECDSA_SIG_set0:

https://www.openssl.org/docs/man1.1.0/man3/ECDSA_SIG_set0.html

You might find some snippets in ecdsatest.c.

Hope it helps,


I think so.  This seems to work.  Does it make sense? Is there a better way?

- convert R and S, bin to bignum
- use ECDSA_SIG_set0 to create an ECDSA_SIG
- use i2d to convert the ECDSA_SIG to DER
- memcpy the DER into X509->signature->data

Re: Add ECDSA signature R and S to X509 structure

[Billy Brumley]

Hey Ken,

> I have an ECDSA signature supplied to me as R and S byte arrays and
> lengths (from an HSM).
>
> How do I add them to the X509 structure?
>
> Is there an API, a set of calls, or do you have any hints?

You might be looking for ECDSA_SIG_set0:

https://www.openssl.org/docs/man1.1.0/man3/ECDSA_SIG_set0.html

You might find some snippets in ecdsatest.c.

Hope it helps,

BBB

Add ECDSA signature R and S to X509 structure

[Ken Goldman]

I have an ECDSA signature supplied to me as R and S byte arrays and 
lengths (from an HSM).


How do I add them to the X509 structure?

Is there an API, a set of calls, or do you have any hints?

~~

For RSA, I simply filled in the ASN1_BIT_STRING length, data, and flags, 
but an RSA signature is a simply BIT_STRING.


For ECDSA, the BIT_STRING is a SEQUENCE of two INTEGERs.

I could construct the SEQUENCE DER manually and then add it as with RSA, 
but that seems like a hack.  Is there a better way?


Is there a better way for RSA?  I suspect that peering inside the 
ASN1_BIT_STRING will break for openssl 1.1.