init method
Initialize the decryptor.
Implementation
@override
void init(CipherParameters params) {
var akparams = params as AsymmetricKeyParameter<AsymmetricKey>;
var k = akparams.key as ECAsymmetricKey;
if (k is! ECPrivateKey) {
throw ArgumentError('ECPrivateKey is required for decryption.');
}
_key = k;
}