using Org.BouncyCastle.Utilities; using System; namespace Org.BouncyCastle.Asn1.Cms { public class GcmParameters : Asn1Encodable { private const int DefaultIcvLen = 12; private readonly Asn1OctetString m_nonce; private readonly int m_icvLen; public int IcvLen => m_icvLen; public static GcmParameters GetInstance(object obj) { if (obj == null) return null; GcmParameters gcmParameters = obj as GcmParameters; if (gcmParameters != null) return gcmParameters; return new GcmParameters(Asn1Sequence.GetInstance(obj)); } public static GcmParameters GetInstance(Asn1TaggedObject taggedObject, bool declaredExplicit) { return new GcmParameters(Asn1Sequence.GetInstance(taggedObject, declaredExplicit)); } public static GcmParameters GetTagged(Asn1TaggedObject taggedObject, bool declaredExplicit) { return new GcmParameters(Asn1Sequence.GetTagged(taggedObject, declaredExplicit)); } private GcmParameters(Asn1Sequence seq) { int count = seq.Count; int sequencePosition = 0; if (count < 1 || count > 2) throw new ArgumentException("Bad sequence size: " + count.ToString(), "seq"); m_nonce = Asn1OctetString.GetInstance(seq[sequencePosition++]); DerInteger derInteger = Asn1Utilities.ReadOptional(seq, ref sequencePosition, DerInteger.GetOptional); if (sequencePosition != count) throw new ArgumentException("Unexpected elements in sequence", "seq"); m_icvLen = (derInteger?.IntValueExact ?? 12); } public GcmParameters(byte[] nonce, int icvLen) { m_nonce = DerOctetString.FromContents(nonce); m_icvLen = icvLen; } public byte[] GetNonce() { return Arrays.Clone(m_nonce.GetOctets()); } public override Asn1Object ToAsn1Object() { if (m_icvLen != 12) return new DerSequence(m_nonce, new DerInteger(m_icvLen)); return new DerSequence(m_nonce); } } }