Constant aes_kw::IV

pub const IV: [u8; 8];

Default Initial Value for AES-KW as defined in RFC3394 § 2.2.3.1.

https://datatracker.ietf.org/doc/html/rfc3394#section-2.2.3.1

The default initial value (IV) is defined to be the hexadecimal
constant:

    A[0] = IV = A6A6A6A6A6A6A6A6

The use of a constant as the IV supports a strong integrity check on
the key data during the period that it is wrapped.  If unwrapping
produces A[0] = A6A6A6A6A6A6A6A6, then the chance that the key data
is corrupt is 2^-64.  If unwrapping produces A[0] any other value,
then the unwrap must return an error and not return any key data.