ASP.NET MVC 5 external authentication with Twitter's new policy - ssl

Question

I have been trying this authentication method for the last 3 days without any success, I am totally new to the field MVC and Identity. I required to do an external authentication for my site with Facebook, Microsoft and Twitter, so I am using Identity 2.0 with MVC 5.
Facebook and Microsoft are already done, but I have trouble doing the same for twitter, because they change their authentication policy last December, so now I require an HTTPS site (which is not the problem) with a Twitter SSL certificate (I have problems with this one).
I am using IIS Express to run my website in development mode.
I already created my app on twitter's developer site, I got my API key, API Secret, Access Token and Access Secret.
I already change my Startup.Auth.cs, to uncomment app.UseTwitterAuthentication with my consumerKey (ApiKey) and consumerSecret (ApiSecret). But when I run my site and try to sign-in with Twitter I keep receiving this error: the remote certificate is invalid according to the validation procedure.
See these discussion issues:
https://dev.twitter.com/discussions/24239
https://dev.twitter.com/docs/security/using-ssl
Reading a little bit about this issue, I know require a Twitter SSL certificate, which I got, but cannot figure out how to use it.
Please, I am desperate and I need a solution to this problem, can anyone enlighten me on how to make this work with VS 2013 and IIS Express? I have no idea what to do.

Answer 1

... now I require an HTTPS site (which is not the problem) with a Twitter SSL certificate (I have problems with this one)
According to Twitter is updating its SSL certificates for api.twitter.com, the signing root is changing to VeriSign Class 3 Public Primary Certification Authority - G5.
It appears it has already changed:
$ openssl s_client -connect api.twitter.com:443
CONNECTED(00000003)
depth=1 C = US, O = "VeriSign, Inc.", OU = VeriSign Trust Network, OU = Terms of use at https://www.verisign.com/rpa (c)10, CN = VeriSign Class 3 Secure Server CA - G3
verify error:num=20:unable to get local issuer certificate
verify return:0
---
Certificate chain
0 s:/C=US/ST=California/L=San Francisco/O=Twitter, Inc./OU=Twitter Security/CN=api.twitter.com
i:/C=US/O=VeriSign, Inc./OU=VeriSign Trust Network/OU=Terms of use at https://www.verisign.com/rpa (c)10/CN=VeriSign Class 3 Secure Server CA - G3
1 s:/C=US/O=VeriSign, Inc./OU=VeriSign Trust Network/OU=Terms of use at https://www.verisign.com/rpa (c)10/CN=VeriSign Class 3 Secure Server CA - G3
i:/C=US/O=VeriSign, Inc./OU=VeriSign Trust Network/OU=(c) 2006 VeriSign, Inc. - For authorized use only/CN=VeriSign Class 3 Public Primary Certification Authority - G5
...
Go to Download Verisign Root Certificates and download VeriSign Class 3 Primary CA - G5. It has thumbprint 4e b6 d5 78 49 9b 1c cf 5f 58 1e ad 56 be 3d 9b 67 44 a5 e5.
After downloading the certificate, import it into the Computer's Root Certificate Authority Store. For instuctions, see Manage Trusted Root Certificates on TechNet. Be sure to follow Adding certificates to the Trusted Root Certification Authorities store for a local computer. You want the local computer, and you want Trusted Root Certification Authorities store.
Once you use the downloaded certificate as a trust anchor, the chain will verify. Notice the -CAfile option, and the Verify return code: 0 (ok) at the end:
$ openssl s_client -connect api.twitter.com:443 -CAfile VeriSign-Class\ 3-Public-Primary-Certification-Authority-G5.pem
CONNECTED(00000003)
depth=2 C = US, O = "VeriSign, Inc.", OU = VeriSign Trust Network, OU = "(c) 2006 VeriSign, Inc. - For authorized use only", CN = VeriSign Class 3 Public Primary Certification Authority - G5
verify return:1
depth=1 C = US, O = "VeriSign, Inc.", OU = VeriSign Trust Network, OU = Terms of use at https://www.verisign.com/rpa (c)10, CN = VeriSign Class 3 Secure Server CA - G3
verify return:1
depth=0 C = US, ST = California, L = San Francisco, O = "Twitter, Inc.", OU = Twitter Security, CN = api.twitter.com
verify return:1
---
Certificate chain
0 s:/C=US/ST=California/L=San Francisco/O=Twitter, Inc./OU=Twitter Security/CN=api.twitter.com
i:/C=US/O=VeriSign, Inc./OU=VeriSign Trust Network/OU=Terms of use at https://www.verisign.com/rpa (c)10/CN=VeriSign Class 3 Secure Server CA - G3
1 s:/C=US/O=VeriSign, Inc./OU=VeriSign Trust Network/OU=Terms of use at https://www.verisign.com/rpa (c)10/CN=VeriSign Class 3 Secure Server CA - G3
i:/C=US/O=VeriSign, Inc./OU=VeriSign Trust Network/OU=(c) 2006 VeriSign, Inc. - For authorized use only/CN=VeriSign Class 3 Public Primary Certification Authority - G5
---
...
Start Time: 1407206791
Timeout : 300 (sec)
Verify return code: 0 (ok)