Is TLS_AES_256_GCM_SHA384 secure?

What is the RFC for HTTPS?

HTTP provides a standard set of HTTP methods (GET, POST.) and a standard set of headers: HTTP Method / Header. HTTP header: Accept: application/json. HTTP response: Content-Type: application/json. HEAD. HTTP header/method/headers are conveyed in requests and responses. HTTPS is HTTP over Secure Socket. It's the subset of HTTP that supports things like TLS (HTTP over Transport Layer Security) and its successor Hypertext Transfer Protocol Secure (HTTPS).

Why is it called HTTPS? HTTPS is a protocol extension (a kind if service), analogous to HTTPs. It provides a sort of over the top authentication and encryption.

The name originated in Twilio Hosted Voice where a request for a call over SSL is labeled with HTTPS in the same way that SIP requests are labeled with the protocol SIP. The prefix was later adopted by various groups with the growing needs for more security. Transport Layer Security (TLS). HTTP is built in layers but the core of the protocol is not as trivial as you might think at first. It has a few key properties.

We can make a GET request to any host (unrestricted). We can make a POST request to any host (unrestricted). We can make a PUT request for a host-restricted resource (unrestricted). We can make a DELETE request for a host-restricted resource (unrestricted). All requests must be sent with a connection header. As such, HTTP requires a connection to be setup before the message could be sent. HTTP does not have a concept of a single connection and is global where multiple requests can be sent at once.

Is TLS_AES_256_GCM_SHA384 secure?

Do I really want to?

When should one use TLSAES256GCMSHA384 compared to TLSAES256CBCSHA384? I want to use the TLSAES256GCMSHA384 to avoid man-in-the-middle attacks. I am not particularly worried about the length of the key (keeping it secret) or whether people intercept the data (I will be using HTTPS on a router). As such, I intend on keying a 256-bit key.

Does this key size offer any security benefit? Would specifying GCM mode even improve the situation? I am having trouble conceptualizing the difference between GCM mode and CBC mode. In CBC mode, should I be using a random IV (should that be 256 bits?) or a static IV that I control? (In that case, why is it that the default is to use 256-bit of IV?) Following consideration: I can fit around 256 random bits in a 16-byte AES blocksize. I assume this is good enough? 200 bit of IV is sufficient as long as it is random. How can I generate something random? What are the security considerations of trying to encrypt a 256-bit IV in CBC mode? You should, like most people, worry about the non-secret parameters leaking information. (As a worst case, imagine it actually happened for an Internet-sized set of ciphertext-plaintext pairs that are publicly known; this would be a huge loss of public confidence in TLS security in general.)
With this attack in mind, you should avoid built-in non-secret settings for key size and padding, and avoid using the standard block cipher pgp/gcrypt (as used in OpenPGP.) When your application is very sensitive to leakage, then you do need stronger security (like GCM).

Therefore: What are the security considerations of trying to encrypt a 256-bit IV in CBC mode?

Which ciphers should be disabled?

Which ones are currently disabled?

It's very hard to know which ciphers are stronger than which, and which are weaker than the others. (Note that future standards may weaken the 128-bit ciphers. But by the standards of today, the AES ciphers will always be as secure as they are.)
The cipher that you are most likely to encounter insecure is RSA-IDEIf you need to implement a secure protocol, you need to choose a different cipher. From what I can tell: RSA-AES256 (and AES256) are the only full TLS ciphers that are vulnerable (and that's not necessarily a bad thing). AES-256, DES-EDE3 and RC4 are somewhat vulnerable, might be exploitable if implementation-specific improvements are implemented. It's still safe to use them as long as you use a secure key preparation and implementation. As a note of caution, remember DES should never be used for authentication (unless you're working on a system that doesn't have AES-256).

On most platforms you can't enable rc4, NW2 in CBC mode is a default cipher on most systems so usually it's not gominally that useful to turn it off. On older platforms and something like an embedded system you might do with it, otherwise use AES-256 where available.

What is RFC 5246?

The Internet Engineering Task Force (IETF) is a standards-setting body that develops Internet standards such as IPv6, IPv4, Transmission Control Protocol (TCP), IP Security (IPsec), Key Management Internet Protocol (KMIP) and many others. The IETF is responsible for current versions of these protocols, but it also defines new versions of these protocols.

Where can I read the RFCs? It is possible to get hold of copies of the RFCs in a variety of ways. The main way to obtain RFCs is via the IETF's Web site (ie. Once you have found the RFC you are interested in, you need to choose a format that suits you.

Can the RFC be read online? It is possible to read the RFC online at (you will need a Web browser to do this). When you read the RFC you will see that there are a number of ways of viewing the text of the RFC.

There are a number of ways to read the RFC document online. Online RFCs. You can read the current version of the RFC online. If you are interested in a particular RFC then you need to locate the appropriate web site. If you are interested in reading the RFC online, then you need to go to

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