copy method
Copies the private key.
Implementation
@override
RsaKeyPairData copy() {
if (hasBeenDestroyed) {
throw StateError('Key has been destroyed');
}
return RsaKeyPairData(
n: n,
e: e,
d: d,
p: p,
q: q,
dp: dp,
dq: dq,
qi: qi,
);
}