And I seem to recall that one bit is for compact representation.
That is, is y positive or negative. With p256, you have to transmit
x and y or deal with the compact representation patent.
On 09/04/2018 08:00 AM, Kyle Hamilton
wrote:
Probably because the definition of X25519 requires
that bits 0, 1, and 2 of the first byte of the private key are
set to 0 before being used, and OpenSSL counts the number of
bits including the highest-order set bit. (Really, there's an
additional 2 bits that are also set to known values: bit 6 of
the last byte is set, and bit 7 of the last byte is cleared. In
my view, this actually reduces the necessary brute-force search
space from 256 bits to 251 bits. However, literally any 32-byte
string can be used as a public key. Apparently, djb views this
as sufficient to call it a 256-bit strength function.)
-Kyle H
Hi,
When using openssl with X25519, why it shows the server temp
key as 253 bits?
Example:
---
No client certificate CA names sent
Peer signing digest: SHA256
Peer signature type: RSA
Server Temp Key: X25519, 253 bits
---
I thought Curve25519 is using 256 bit keys.
Why 253 instead of 256?
with regards,
Saravanan
--
openssl-users mailing list
To unsubscribe: https://mta.openssl.org/mailman/listinfo/openssl-users
|
--
openssl-users mailing list
To unsubscribe: https://mta.openssl.org/mailman/listinfo/openssl-users
