Hello Marek,

thanks for the hint.

> One workaround of this problem is to disable EDH ciphers, for example:
>
> $ openssl s_client -connect bshop.esprit.com:443 -cipher 'ALL:!EDH'


I tried this, but got exact the same error messages! Then I looked up the cipher
specs on http://www.openssl.org/docs/apps/ciphers.html and used -cipher
'ALL:!kEDH' and then I was able to connect. Where is the difference between
'ALL:!EDH' and 'ALL:!kEDH' (beside that one works and the other not) ?

Bye
Jan

Marek Marcola wrote:
> Hello,
>> it seems that there are some incompatibilities out there. For some hosts
>> establishing a SSL connection fails, when using openssl, but it succeeds when
>> using a browser. This in one example:
>>
>> F:\openssl>openssl.exe s_client -connect bshop.esprit.com:443
>> Loading 'screen' into random state - done
>> CONNECTED(00000778)
>> depth=1 /C=GB/O=Comodo Limited/OU=Comodo Trust Network/OU=Terms and Conditions of
>> use: http://www.comodo.net/repository/OU=(c)2002 Comodo Limited/CN=Comodo Class 3
>> Security Services CA
>> verify error:num=20:unable to get local issuer certificate
>> verify return:0
>> 3056:error:0407006A:rsa routines:RSA_padding_check_PKCS1_type_1:block type is not
>> 01:.\crypto\rsa\rsa_pk1.c:100:
>> 3056:error:04067072:rsa routines:RSA_EAY_PUBLIC_DECRYPTadding check failed:.\c
>> rypto\rsa\rsa_eay.c:580:
>> 3056:error:1408D07B:SSL routines:SSL3_GET_KEY_EXCHANGE:bad signature:.\ssl\s3_cl
>> nt.c:1189:
>>
>>
>> Can anybody explain it and give me a hint how I can connect with openssl to that
>> host? Maybe there is a compatibility switch?

> After looking at packet exchange I think that in ServerKeyExchange
> packet (which comes from bshop.esprit.com) there is bad signature
> of DHE parameters (Ys,p,g).
> In DHE server key exchange DH parameters are signed with server private
> key and client should check this signature to prevent man-in-the-middle
> attack. This looks like this parameters are signed with private key
> that is not compatible with certificate sent to client with Certificate
> packet.
> One workaround of this problem is to disable EDH ciphers, for example:
>
> $ openssl s_client -connect bshop.esprit.com:443 -cipher 'ALL:!EDH'
>
> Best regards,



--
Bye
Jan

jan@xn--schnellbcher-ncb.de
jan@abstiegsgespenst.de
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