requests: SSL Error: bad handshake

Aha, ok, we got there.

api.smartsheet.com serves its TLS using what’s known as a “cross-signed certificate”. This was used because Verisign, the CA for api.smartsheet.com, originally used a 1024-bit root certificate. These were deprecated and replaced by stronger root certificates, but some older browsers and systems may not have received updates, so sites like api.smartsheet.com serve a root certificate that is signed by the 1024-bit root.

That’s not normally a problem, except:

• certifi removed the weak 1024-bit roots
• OpenSSL older than 1.0.2 sucks at building cert chains, and so fails to correctly validate the cross-signed root.

You can solve this in two ways. The first, better but more drastic way, is to upgrade your OpenSSL to 1.0.2 or later. This is hard to do on Centos, I’m afraid. The less good but more effective way is to get the output of running python -c "import certifi; print certifi.old_where()" and then set the REQUESTS_CA_BUNDLE environment variable to the printed path.

@pensnarik Can you try running pip install -U requests[security] in your environment and then try again?

Yup, so the server is wrong.

This is a really common problem with TLS. A TLS certificate validation is performed by first building a certificate chain that takes us from a certificate the server can prove it has the private key for (the “leaf”) to a certificate we trust (the “root”). For OpenSSL there is an additional rule: the root must be self-signed.

In most cases, this chain is more than two steps long: that is, the leaf is not signed by the root, but is instead signed by a so-called intermediate certificate. That intermediate may itself be signed by the root, but may also be signed by other intermediates, until we eventually reach an intermediate that was signed by a root.

For example, for https://python-hyper.org, the chain is as follows:

1. python-hyper.org, the “leaf”, which I applied for and had issued
2. Let’s Encrypt Authority X3, an intermediate certificate used by the Let’s Encrypt project
3. DST Root CA X3, the root certificate that my web browser (and Requests) trusts

The correct chain for the site you’re accessing should be:

1. infoproducts.alcatel-lucent.com, the leaf
2. Entrust Certification Authority - L1K, the intermediate certificate which issued the leaf
3. Entrust Root Certification Authority - G2, the root certificate that issued the intermediate

For your use case, Requests ships with certificate number 3 in its trust database as a trusted root. However, your server is only sending certificate number 1. Requests cannot go from certificate 1 to certificate 3 without having certificate 2, and the server isn’t sending it. Most browsers ship with commonly-used intermediate certs, or can maintain caches of them, but Requests cannot do that, so it has no way of getting hold of certificate 2. Without certificate 2, validation must fail.

Properly-configured TLS servers send the leaf certificate and all of the necessary intermediaries. This is to ensure that clients that have never seen the intermediaries and that cannot dynamically fetch them are still able to validate the chain. As a comparison, check out the output of a command like yours run against python-hyper.org:

% openssl s_client -connect python-hyper.org:443 -showcerts -servername "python-hyper.org"
CONNECTED(00000003)
depth=1 /C=US/O=Let's Encrypt/CN=Let's Encrypt Authority X3
verify error:num=20:unable to get local issuer certificate
verify return:0
---
Certificate chain
 0 s:/CN=python-hyper.org
   i:/C=US/O=Let's Encrypt/CN=Let's Encrypt Authority X3
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
 1 s:/C=US/O=Let's Encrypt/CN=Let's Encrypt Authority X3
   i:/O=Digital Signature Trust Co./CN=DST Root CA X3
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
---
Server certificate
subject=/CN=python-hyper.org
issuer=/C=US/O=Let's Encrypt/CN=Let's Encrypt Authority X3
---
No client certificate CA names sent
---
SSL handshake has read 2638 bytes and written 451 bytes
---
New, TLSv1/SSLv3, Cipher is AES256-SHA
Server public key is 2048 bit
Secure Renegotiation IS supported
Compression: NONE
Expansion: NONE
SSL-Session:
    Protocol  : TLSv1
    Cipher    : AES256-SHA
    Session-ID: BBDF2CA65B2142C1F0C416B28C4FDF8FD5118ED4D5FF8802789D0B54C6309469
    Session-ID-ctx: 
    Master-Key: BD9B8B97EC439248CC5849EBF4B2ED18E0A73472EB8D86FE6F038C4E6944AFD8A163D80D47A3A3B28A6237A44C1B31CE
    Key-Arg   : None
    Start Time: 1483447980
    Timeout   : 300 (sec)
    Verify return code: 0 (ok)
---

Note that the server sent two certificates in my case, whereas in yours it only sent one.

This is the error. Please reconfigure your server to send all the relevant intermediaries as well as the leaf.

While I’m here, I should note that running Qualys SSL Labs against your server would also have told you about this problem. =)

Downgrading certifi from 2015.11.20.1 to 2015.4.28 fixes the problem!

@sProject You would need to resolve both of those warnings before we can determine if you have a new problem. If you got requests from pip, run pip install pyopenssl pyasn1 ndg-httpsclient. If you got Requests from your system provider, you should install those three packages from there.

@Lukasa Thanks ! sudo pip install -U requests[security] worked for me.

GoDaddy is serving an incomplete certificate chain to you. That means we’re missing one of the intermediate certificates and can’t build up a trust chain. Either you’ll need to add the missing intermediary certificate to the certifi trust store or you’ll need to contact GoDaddy and tell them to sort their mess out.

Argh, the smartsheet SDK overrides that environment variable by explicitly using certifi.

New plan. Right at the start after you import smartsheet, before you do anything else, can you add the following lines?

import smartsheet.session
import certifi
smartsheet.session._TRUSTED_CERT_FILE = certifi.old_where()

That should hopefully help. You shouldn’t need the environment variable with this approach.