using Org.BouncyCastle.Math; using Org.BouncyCastle.Math.EC; using Org.BouncyCastle.Utilities; using System; using System.IO; namespace Org.BouncyCastle.Bcpg { public sealed class MPInteger : BcpgObject { private readonly BigInteger m_value; public BigInteger Value => m_value; public MPInteger(BcpgInputStream bcpgIn) { if (bcpgIn == null) throw new ArgumentNullException("bcpgIn"); bool validateLength = false; m_value = ReadMpi(bcpgIn, validateLength); } public MPInteger(BigInteger val) { if (val == null) throw new ArgumentNullException("val"); if (val.SignValue < 0) throw new ArgumentException("Values must be positive", "val"); m_value = val; } public override void Encode(BcpgOutputStream bcpgOut) { Encode(bcpgOut, m_value); } internal static void Encode(BcpgOutputStream bcpgOut, BigInteger n) { StreamUtilities.WriteUInt16BE(bcpgOut, (ushort)n.BitLength); BigIntegers.WriteUnsignedByteArray(bcpgOut, n); } internal unsafe static BigInteger ToMpiBigInteger(ECPoint point) { int encodedLength = point.GetEncodedLength(false); Span<byte> span; if (encodedLength <= 512) { int num = encodedLength; span = new Span<byte>(stackalloc byte[(int)(uint)num], num); } else span = new byte[encodedLength]; Span<byte> span2 = span; point.EncodeTo(false, span2); return new BigInteger(1, span2); } private unsafe static BigInteger ReadMpi(BcpgInputStream bcpgIn, bool validateLength) { int num = StreamUtilities.RequireUInt16BE(bcpgIn); int num2 = (num + 7) / 8; Span<byte> span; if (num2 <= 512) { int num3 = num2; span = new Span<byte>(stackalloc byte[(int)(uint)num3], num3); } else span = new byte[num2]; Span<byte> span2 = span; bcpgIn.ReadFully(span2); BigInteger bigInteger = new BigInteger(1, span2); if (validateLength && bigInteger.BitLength != num) throw new IOException("malformed MPI"); return bigInteger; } } }