openssl verify question

[Jan Just Keijser]

Hi,

On 12/06/21 22:20, Gaardiolor wrote:
> Hello,
>
> My openssl-1.0.2k-21.0.1.el7_9.x86_64 verify fails with HSM-signed 
> certificates. The HSM is causing other issues and is likely 
> misbehaving, I think this is a HSM bug. I'm sure I'm using the correct 
> server.crt and rootca.crt.
>
> $ openssl verify -CAfile rootca.crt server.crt
> server.crt: C <snip>
> error 7 at 0 depth lookup:certificate signature failure
> 139734096439184:error:0D0680A8:asn1 encoding 
> routines:ASN1_CHECK_TLEN:wrong tag:tasn_dec.c:1239:
> 139734096439184:error:0D07803A:asn1 encoding 
> routines:ASN1_ITEM_EX_D2I:nested asn1 error:tasn_dec.c:405:Type=X509_SIG
> 139734096439184:error:0D0C5006:asn1 encoding 
> routines:ASN1_item_verify:EVP lib:a_verify.c:249:
>
just wondering: why and how are you using an HSM to verify a certificate 
(without including a private key) ?  is the certificate stored only on 
the HSM?  is it possible to get it off the HSM?

Also, how are you connecting the HSM to OpenSSL? via opensc-pkcs11 ?  
you should have an openssl.cnf file somewhere for this.

HTH,

JJK



> I tried doing the verification manually like so:
>
> Extracting the 'to be signed' part of the server.crt:
> openssl asn1parse -in server.crt -strparse 4 -out server.tbs
>
> sha256 that:
> cat server.tbs | openssl sha256 -binary > server.tbs.sha256
>
> Extracting the signature from the server.crt:
> openssl asn1parse -in server.crt -strparse 569 -out server.sig
>
> Extracting the public key from rootca.crt:
> openssl x509 -in rootca.crt -noout -pubkey > rootca.pub
>
> Decrypting the signature:
> openssl rsautl -inkey rootca.pub -pubin -in server.sig -out 
> server.sig.decrypted
>
> Comparing server.tbs.sha256 and server.sig.decrypted .
>
> When I compare those, they are exactly the same. But that's the thing, 
> I think server.sig.decrypted should be prepended with a sha256 
> designator 30 31 30 0d 06 09 60 86 48 01 65 03 04 02 01 05 00 04 20, 
> which is missing. I do see this designator with working certificates. 
> I suspect this is the problem.
>
> Is that designator mandatory and likely the cause of my issue ? 
> https://datatracker.ietf.org/doc/html/rfc5280#section-4.1.1.2 suggests 
> it's mandatory.. but I'm not sure if I'm looking at the right section.
>
> Thanks.