Size for ECC keys have changed from 256 to 255

[Baptiste Beauplat]

Hi,

I noticed that the key size reported by gpg --with-colons for ECC keys
(ed25519) have changed from 256 to 255.

For instance, on my key I previously got:

$gpg --with-colons -k lyknode at cilg.org | grep pub | cut -d : -f 3
256

While now the result is:

$gpg --with-colons -k lyknode at cilg.org | grep pub | cut -d : -f 3
255

I was wondering if that's a bug, since from what I understand (certainly
way to little) the public key size of ed25519 is fixed at 256 and the
value 255 is only used in the prime number calculation (2^255 - 19).

Note: The changed comes from the following commit in libgcrypt:

https://dev.gnupg.org/rCdb7b2c591004868abedbc2c19d3bb2efebf8529d

Best,

-- 
Baptiste Beauplat - lyknode
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