openssl-users Digest, Vol 88, Issue 18
Edward Tsang
etsang at splunk.com
Mon Mar 14 19:47:26 UTC 2022
I was hoping to tolerate some error "for now" and flag it and continue the
whole process (complete the handshake and treat the ssl connection as
"pass").
So for my case long res = SSL_get_verify_result( sslCtx ) from caller
should return X509_V_OK.
I guess I need to explicitly set X509_STORE_CTX_set_error(ctx, X509_V_OK)
before return 1 in the example if I need caller SSL_get_verify_result to
return
X509_V_OK?
On Mon, Mar 14, 2022 at 12:38 PM <openssl-users-request at openssl.org> wrote:
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> Today's Topics:
>
> 1. Re: DSA signatures in OpenSSL 3.0 (Richard Dymond)
> 2. Re: DSA signatures in OpenSSL 3.0 (Tomas Mraz)
> 3. Re: DSA signatures in OpenSSL 3.0 (Richard Dymond)
> 4. Question about examples in openssl doc
> X509_STORE_CTX_verify_cb (Edward Tsang)
> 5. Re: Question about examples in openssl doc
> X509_STORE_CTX_verify_cb (Viktor Dukhovni)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 14 Mar 2022 09:02:18 -0300
> From: Richard Dymond <rjdymond at gmail.com>
> To: openssl-users at openssl.org
> Subject: Re: DSA signatures in OpenSSL 3.0
> Message-ID:
> <CANVKdYAFQkS8wXADdpD334V=JHp_Bamvm8s=
> pX2tYRLNygppTg at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> On Mon, 14 Mar 2022 at 04:52, Tomas Mraz <tomas at openssl.org> wrote:
>
> > The DSA_SIG_* functions are not deprecated including the i2d and d2i
> > functions. So you can use d2i_DSA_SIG to decode the DER produced by the
> > EVP_DigestSign() and then obtain the r and s values from the DSA_SIG.
> >
>
> Thank you, that works! For some reason it had escaped my notice that the
> DSA_SIG_* functions are not deprecated.
>
> By the way, the reason I need to get the 'r' and 's' values from the DSA
> signature is that I am encoding them one after the other as 160-bit
> unsigned integers, in network byte order, as required by SSH and described
> in section 6.6 of RFC 4253 (dss_signature_blob)[1]. To do this encoding I
> am calling BN_bn2bin() twice to write 'r' followed by 's' at the
> appropriate locations in a 40-byte buffer. By any chance, does OpenSSL 3.0
> provide any support for encoding a DSA signature like this from a DSA_SIG
> (i.e. without having to extract 'r' and 's' first and then use
> BN_bn2bin())?
>
> Richard
>
> [1] https://datatracker.ietf.org/doc/html/rfc4253#section-6.6
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> ------------------------------
>
> Message: 2
> Date: Mon, 14 Mar 2022 15:03:01 +0100
> From: Tomas Mraz <tomas at openssl.org>
> To: Richard Dymond <rjdymond at gmail.com>
> Cc: openssl-users <openssl-users at openssl.org>
> Subject: Re: DSA signatures in OpenSSL 3.0
> Message-ID:
> <40bda5bc7e776522c25d94037a7b0808c140e774.camel at openssl.org>
> Content-Type: text/plain; charset="UTF-8"
>
> On Mon, 2022-03-14 at 08:58 -0300, Richard Dymond wrote:
> > On Mon, 14 Mar 2022 at 04:52, Tomas Mraz <tomas at openssl.org> wrote:
> > > The DSA_SIG_* functions are not deprecated including the i2d and
> > > d2i
> > > functions. So you can use d2i_DSA_SIG to decode the DER produced by
> > > the
> > > EVP_DigestSign() and then obtain the r and s values from the
> > > DSA_SIG.
> > >
> >
> >
> > Thank you, that works! For some reason it had escaped my notice that
> > that the DSA_SIG_* functions are not deprecated.
> >
> > By the way, the reason I need to get the 'r' and 's' values from the
> > DSA signature is that I am encoding them one after the other as 160-
> > bit unsigned integers, in network byte order, as required by SSH and
> > described in section 6.6 of RFC 4253 (dss_signature_blob)[1]. To do
> > this encoding I am calling BN_bn2bin() twice to write 'r' followed by
> > 's' at the appropriate locations in a 40-byte buffer. By any chance,
> > does OpenSSL 3.0 provide any support for encoding a DSA signature
> > like this from a DSA_SIG (i.e. without having to extract 'r' and 's'
> > first and then use BN_bn2bin())?
>
> No, there is no such function. However there is not much overhead in
> doing the two BN_bn2bin calls (should those be BN_bn2binpad actually?)
> once you already have a DSA_SIG object.
>
> > Richard
> >
> > [1] https://datatracker.ietf.org/doc/html/rfc4253#section-6.6
>
> --
> Tom?? Mr?z, OpenSSL
>
>
>
>
> ------------------------------
>
> Message: 3
> Date: Mon, 14 Mar 2022 13:09:01 -0300
> From: Richard Dymond <rjdymond at gmail.com>
> To: Tomas Mraz <tomas at openssl.org>
> Cc: openssl-users <openssl-users at openssl.org>
> Subject: Re: DSA signatures in OpenSSL 3.0
> Message-ID:
> <
> CANVKdYAh2uH1n-UNwMNvb18hDwD8U2DhjjQj_PpvU7XJezRKzw at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> On Mon, 14 Mar 2022 at 11:03, Tomas Mraz <tomas at openssl.org> wrote:
>
> > On Mon, 2022-03-14 at 08:58 -0300, Richard Dymond wrote:
> > > By the way, the reason I need to get the 'r' and 's' values from the
> > > DSA signature is that I am encoding them one after the other as 160-
> > > bit unsigned integers, in network byte order, as required by SSH and
> > > described in section 6.6 of RFC 4253 (dss_signature_blob)[1]. To do
> > > this encoding I am calling BN_bn2bin() twice to write 'r' followed by
> > > 's' at the appropriate locations in a 40-byte buffer. By any chance,
> > > does OpenSSL 3.0 provide any support for encoding a DSA signature
> > > like this from a DSA_SIG (i.e. without having to extract 'r' and 's'
> > > first and then use BN_bn2bin())?
> >
> > No, there is no such function. However there is not much overhead in
> > doing the two BN_bn2bin calls (should those be BN_bn2binpad actually?)
> > once you already have a DSA_SIG object.
> >
>
> OK, I suppose that was hoping for too much. But thanks for the tip
> regarding BN_bn2binpad v. BN_bn2bin - that does simplify the code a little
> more.
>
> Richard
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> ------------------------------
>
> Message: 4
> Date: Mon, 14 Mar 2022 11:25:51 -0700
> From: Edward Tsang <etsang at splunk.com>
> To: openssl-users at openssl.org
> Subject: Question about examples in openssl doc
> X509_STORE_CTX_verify_cb
> Message-ID:
> <CACrfNRHerj3=
> hgX4Ls7DLRcAhvSd2iHrEhx5O2CqcLfkkCD-yw at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> link:
> https://www.openssl.org/docs/man1.1.1/man3/X509_STORE_CTX_verify_cb.html
>
> I am trying to figure out how this example works but it does not seem to
> bypass the (use the second example of X509_V_ERR_CERT_HAS_EXPIRED)
>
> However the caller code ll
> long res = SSL_get_verify_result( sslCtx ); still reports res NOT as
> X509_V_OK, which it should be oper the example since it is returning as 1.
>
> I don't think I need to use X509_STORE_CTX_set_error(ctx, X509_V_OK);
> before return 1 in the X509_STORE_CTX_verify_cb example.
> Or am I missing something?
> Thanjs
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> ------------------------------
>
> Message: 5
> Date: Mon, 14 Mar 2022 15:27:59 -0400
> From: Viktor Dukhovni <openssl-users at dukhovni.org>
> To: openssl-users at openssl.org
> Subject: Re: Question about examples in openssl doc
> X509_STORE_CTX_verify_cb
> Message-ID: <Yi+XP0ey1xVWM5kU at straasha.imrryr.org>
> Content-Type: text/plain; charset=us-ascii
>
> On Mon, Mar 14, 2022 at 11:25:51AM -0700, Edward Tsang via openssl-users
> wrote:
>
> > https://www.openssl.org/docs/man1.1.1/man3/X509_STORE_CTX_verify_cb.html
> >
> > I am trying to figure out how this example works but it does not seem to
> > bypass the (use the second example of X509_V_ERR_CERT_HAS_EXPIRED)
> >
> > However the caller code
> > long res = SSL_get_verify_result( sslCtx ); still reports res NOT as
> > X509_V_OK, which it should be oper the example since it is returning as
> 1.
>
> This is correct and expected. Returning "ok = 1" from the verify
> callback allows the handshake to continue, rather than be aborted,
> but it does not and should not mark the certificate as verified.
>
> > I don't think I need to use X509_STORE_CTX_set_error(ctx, X509_V_OK);
> > before return 1 in the X509_STORE_CTX_verify_cb example.
> > Or am I missing something?
>
> You're missing something. It is best to not suppress the error code,
> since this will also mean that resumed sessions are unaware of the
> error, ... Rather if you want to tolerate expired certificates record
> and admit that error both in the callback and after the handshake.
>
> --
> Viktor.
>
>
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> End of openssl-users Digest, Vol 88, Issue 18
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