> I Sent: Monday, 14 January, 2013 16:56

> For ECDH key agreement, each party should generate (or have) a 
> keypair, and send the public key to the other party (or provide it 
> some other way such as publication in a directory). There are 
> several possible representations of a public key, but the one 
> used by OpenSSL by default is one octet 04 plus the x coordinate 
> of the point which for P-256 is 32 octets. The x coordinate (and 
> also y in other representation) is practically random bits which 
> can easily include an octet of 00, or other sometimes-special 
> octets like 0D, 0A, 1A, etc. You must send it (and store it, 
> if static) by means that preserve all binary values; in some 
> situations this means encoding, escaping, etc.
> 
Sorry, brainfade.
The default format, with 04, is uncompressed (both x and y) 
so for P-256 that's 1+64 = 65 octets.

(It is still correct that it can include any octet values.)

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