Thanks Jakob,
Callback is a possibility but the limitation is that this callback does not
have access to the filename (which can change for every client) to load all
pem files. Also I do not want to read the file every time in call back.
I was ablt to prototype my idea by recreating the SSL object from context
and use it for SSL_Connect and SSL_accept.
But unfortunately client is sending a fatal unexpected_message alert to
server immediately after client hello.
here is the ssl dump:
New TCP connection #1: localhost.localdomain(10289) <->
localhost.localdomain(23037)
1 1 0.0001 (0.0001) C>SV3.1(67) Handshake
ClientHello
Version 3.1
random[32]=
4e d8 a4 ee fd 9e be ec 58 1b 3e 16 fd a6 b2 e9
a5 fe 65 34 79 e4 65 03 81 d4 f2 b7 7a a8 ac 55
cipher suites
TLS_DHE_RSA_WITH_AES_256_CBC_SHA
TLS_DHE_DSS_WITH_AES_256_CBC_SHA
TLS_RSA_WITH_AES_256_CBC_SHA
TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA
TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA
TLS_RSA_WITH_3DES_EDE_CBC_SHA
TLS_DHE_RSA_WITH_AES_128_CBC_SHA
TLS_DHE_DSS_WITH_AES_128_CBC_SHA
TLS_RSA_WITH_AES_128_CBC_SHA
TLS_RSA_WITH_IDEA_CBC_SHA
TLS_RSA_WITH_RC4_128_SHA
TLS_RSA_WITH_RC4_128_MD5
compression methods
NULL
1 2 0.0005 (0.0003) S>CV3.1(74) Handshake
ServerHello
Version 3.1
random[32]=
4e d8 a4 ee a5 b1 69 b8 9a a1 e4 01 07 96 e4 a1
31 dc 7d b7 e3 01 48 4e d1 f1 21 c6 58 4e 74 ff
session_id[32]=
81 98 54 07 4c 14 b2 37 d6 13 05 26 05 5f bc dd
46 5c d6 aa 9e ee 20 22 3e 13 7b 98 13 d0 30 ee
cipherSuite TLS_RSA_WITH_3DES_EDE_CBC_SHA
compressionMethod NULL
1 3 0.0005 (0.0000) S>CV3.1(1278) Handshake
Certificate
1 4 0.0005 (0.0000) S>CV3.1(160) Handshake
CertificateRequest
certificate_types rsa_sign
certificate_types dss_sign
certificate_types unknown value
certificate_authority
30 81 8d 31 0b 30 09 06 03 55 04 06 13 02 55 53
31 0b 30 09 06 03 55 04 08 13 02 43 61 31 11 30
0f 06 03 55 04 07 13 08 53 61 6e 20 4a 6f 73 65
31 1b 30 19 06 03 55 04 0a 13 12 50 61 79 50 61
30 1e 06 09 2a 86 48 86 f7 0d 01 09 01 16 11 70
76 6f 69 63 75 40 70 61 79 70 61 6c 2e 63 6f 6d
ServerHelloDone
1 5 0.0008 (0.0003) C>SV3.1(2) Alert
level fatal
value unknown_ca
1 6 0.0130 (0.0121) C>SV3.1(67) Handshake
ClientHello
Version 3.1
random[32]=
4e d8 a4 ee 61 a7 5b 6c 64 89 61 fb cf 0a a2 85
65 04 40 47 23 0d 62 35 b4 59 b5 bb 2e b7 a8 22
cipher suites
TLS_DHE_RSA_WITH_AES_256_CBC_SHA
TLS_DHE_DSS_WITH_AES_256_CBC_SHA
TLS_RSA_WITH_AES_256_CBC_SHA
TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA
TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA
TLS_RSA_WITH_3DES_EDE_CBC_SHA
TLS_DHE_RSA_WITH_AES_128_CBC_SHA
TLS_DHE_DSS_WITH_AES_128_CBC_SHA
TLS_RSA_WITH_AES_128_CBC_SHA
TLS_RSA_WITH_IDEA_CBC_SHA
TLS_RSA_WITH_RC4_128_SHA
TLS_RSA_WITH_RC4_128_MD5
compression methods
NULL
*1 7 0.0130 (0.0000) C>SV3.1(2) Alert*
* level fatal*
* value unexpected_message*
1 0.0130 (0.0000) C>S TCP FIN
1 8 0.0131 (0.0001) S>CV3.1(74) Handshake
ServerHello
Version 3.1
random[32]=
4e d8 a4 ee 42 58 23 7f 51 e4 c1 10 b6 9d f0 7e
25 bd 8a 95 3c e2 dd 0e 4d 3e 61 38 33 2b a9 58
session_id[32]=
5b ca 68 de 2f 18 cb 03 df 8b 23 b9 b0 19 87 7e
02 72 f7 bb e2 a5 21 6a 7e c8 a8 38 12 83 d8 fe
cipherSuite TLS_RSA_WITH_3DES_EDE_CBC_SHA
compressionMethod NULL
1 9 0.0131 (0.0000) S>CV3.1(1278) Handshake
Certificate
1 10 0.0131 (0.0000) S>CV3.1(160) Handshake
CertificateRequest
certificate_types rsa_sign
certificate_types dss_sign
certificate_types unknown value
certificate_authority
30 81 8d 31 0b 30 09 06 03 55 04 06 13 02 55 53
31 0b 30 09 06 03 55 04 08 13 02 43 61 31 11 30
0f 06 03 55 04 07 13 08 53 61 6e 20 4a 6f 73 65
0c 06 03 55 04 0b 13 05 49 6e 66 72 61 31 0f 30
0d 06 03 55 04 03 13 06 70 76 6f 69 63 75 31 20
30 1e 06 09 2a 86 48 86 f7 0d 01 09 01 16 11 70
76 6f 69 63 75 40 70 61 79 70 61 6c 2e 63 6f 6d
ServerHelloDone
Any help whatsoever to solve this will be highly appreciated.
Thanks,
handshak3
On Fri, Dec 2, 2011 at 3:42 AM, Jakob Bohm <[email protected]> wrote:
> On 12/1/2011 6:33 PM, Rohit Bansal wrote:
>
>> Hi,
>>
>> Let me start with a disclaimer that i am not very experienced with
>> openssl.
>>
>> I have a requirement. In an enterprise all clients and servers
>> communicate over ssl. the certs in client and server are self signed.
>> There is one client application which talks to 100+ different services.
>>
>> Currently the peer verification is done using a single file containing
>> all those self signed certs on client side.
>> if (!SSL_CTX_load_verify_**locations(context, trusted_certs_filename,
>> NULL))
>> fprintf(stderr,"SSL_CTX_load_**verify_locations failed (file:%s)",
>> _trusted_ca_certs_filename.**chars());
>>
>> // client always receives a certificate from the server, and if that
>> // certificate fails to verify, the handshake will be terminated
>> SSL_CTX_set_verify(context, SSL_VERIFY_PEER, NULL);
>>
>> As the pem file in question contains 100+ certs, ssl context
>> initialization takes a while. My task is to migrate that to using CA Path.I
>> have a solution but also want to build a fall back mechanism
>>
>> I want to fallback on initializing the context with the pem file in case
>> the cert verification fails with CA Path.
>>
>> At high level i see following to be done
>> - on client handle the reason code SSL_R_CERTIFICATE_VERIFY_**FAILED
>> from SSL_connect
>> - on server handle the reason code SSL_R_TLSV1_ALERT_UNKNOWN_CA from
>> SSL_accept
>> - change the ssl context to have pem file as verified certs on client
>> side.
>> - renegotiate ssl handshake over the same socket
>>
>> Does anybody of the users know of such implementation or its feasibility?
>> Please help me to give some ways to solve this issue
>>
>> Regards,
>> banro21
>>
> Here is another possibility:
>
> 1. Add your own verification callback, which should then be called when
> OpenSSL tries to
> verify that self-signed cert.
>
> 2. In your callback, manually try both verification methods before
> deciding if the result returned
> to the SSL code should be "valid" or "invalid".
>
> 3. The "Manual" code in the callback can presumably reuse the existing
> OpenSSL functions
> to do the verification, the point is that you get a chance to intercept
> the result before it
> reaches the SSL layer.
>
> This way you won't get into the whole "renegotiate on a failed connection"
> issue.
>
> ______________________________**______________________________**__________
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>
--
Rohit Bansal
