https://www.ssllabs.com/ssltest/analyze.html?d=ssl.safaribooksonline.com Protocols TLS 1.2 No TLS 1.1 No TLS 1.0 Yes SSL 3 No SSL 2 No Cipher Suites (sorted by strength; the server has no preference) TLS_RSA_WITH_RC4_128_SHA (0x5) WEAK 128 Also, it appears to support the insecure client-initiated renegotiation (i.e. MITM is possible).

I e-mailed Safari about this, and I got the following response from a member of their Technical Support: > Our engineers are currently preparing for the switch to supporting the AES-256 cipher and we hope > to have this ready sometime next month. Thank you for taking the time to let us know about this, > I was unaware of the planned deprecation of RC4 in Firefox 39 but fortunately we should be ahead > of that release. Sounds like a decent plan!

TLS 1.0 through TLS 1.2 and modern cipher suites are all supported now.