Secure Web Services: REST over HTTPS vs SOAP + WS-Security. Which is better?

REST security is transport dependent while SOAP security is not.

REST inherits security measures from the underlying transport while SOAP defines its own via WS-Security.

When we talk about REST, over HTTP - all security measures applied HTTP are inherited and this is known as transport level security.

Transport level security, secures your message only while its on the wire - as soon as it leaves the wire, the message is no more secured.

But, with WS-Security, its message level security - even though the message leaves the transport channel it will be still protected. Also - with message level security you can partly encrypt the message [not the entire message, but only the parts you want] - but with transport level security you can't do it.

WS-Security has measures for authentication, integrity, confidentiality and non-repudiation while SSL doesn't support non repudiation [with 2-legged OAuth it does].

In performance-wise SSL is very much faster than WS-Security.

Thanks...

HTTPS secures the transmission of the message over the network and provides some assurance to the client about the identity of the server. This is what's important to your bank or online stock broker. Their interest in authenticating the client is not in the identity of the computer, but in your identity. So card numbers, user names, passwords etc. are used to authenticate you. Some precautions are then usually taken to ensure that submissions haven't been tampered with, but on the whole whatever happens over in the session is regarded as having been initiated by you.

WS-Security offers confidentiality and integrity protection from the creation of the message to it's consumption. So instead of ensuring that the content of the communications can only be read by the right server it ensures that it can only be read by the right process on the server. Instead of assuming that all the communications in the securely initiated session are from the authenticated user each one has to be signed.

There's an amusing explanation involving naked motorcyclists here:

https://docs.microsoft.com/archive/blogs/vbertocci/end-to-end-security-or-why-you-shouldnt-drive-your-motorcycle-naked

So WS-Security offers more protection than HTTPS would, and SOAP offers a richer API than REST. My opinion is that unless you really need the additional features or protection you should skip the overhead of SOAP and WS-Security. I know it's a bit of a cop-out but the decisions about how much protection is actually justified (not just what would be cool to build) need to be made by those who know the problem intimately.