RFR 8171279: Support X25519 and X448 in TLS 1.3

[Xuelei Fan]

I asked the question in a previous email.  The key size for x25529 is 
fixed, right?

If it is not right, stop here and tell me that it is not right.  Keep 
reading if it is right.

OK, as the key size for x25519 is fixed, when you know the algorithm is 
x25519, you know the key size.  Does it sound right to you?

If it is not right, stop here and tell me that it is not right. 
Otherwise, keep reading.

 From the name you know the key size, when you create a 
NamedParameterSpec object for "x25519", you know the name and key size 
from the object, right?

Let's look at the x25519 case at first.  If we figure it out, we then 
can look into the x488.

Thanks,
Xuelei

On 9/6/2018 1:43 PM, Adam Petcher wrote:
> On 9/6/2018 3:19 PM, Xuelei Fan wrote:
> 
>> I think I suggested to use NamedParameterSpec, which is a public API.
>>
>>    NamedParameterSpec -> name "x25519"
>>        -> key size is the key size of x25519.
>>
>> Please let me know if the logic is wrong.
> 
> It's that last arrow that I still don't get. How does this code figure 
> out that "X25519" -> 255 and "X448" -> 448? Perhaps you can reply with 
> some code to illustrate how you think this should work.
> 
> 
>