text: package org.bouncycastle.crypto.parsers;
  
  import java.io.IOException;
  import java.io.InputStream;
  
  import org.bouncycastle.crypto.KeyParser;
  import org.bouncycastle.crypto.params.AsymmetricKeyParameter;
  import org.bouncycastle.crypto.params.ECDomainParameters;
  import org.bouncycastle.crypto.params.ECPublicKeyParameters;
  
  public class ECIESPublicKeyParser
      implements KeyParser
  {
      private ECDomainParameters ecParams;
  
      public ECIESPublicKeyParser(ECDomainParameters ecParams)
      {
          this.ecParams = ecParams;
      }
  
      public AsymmetricKeyParameter readKey(InputStream stream)
          throws IOException
      {
          byte[] V;
          int    first = stream.read();
  
          // Decode the public ephemeral key
          switch (first)
          {
          case 0x00: // infinity
              throw new IOException("Sender's public key invalid.");
  
          case 0x02: // compressed
          case 0x03: // Byte length calculated as in ECPoint.getEncoded();
              V = new byte[1 + (ecParams.getCurve().getFieldSize()+7)/8];
              break;
  
          case 0x04: // uncompressed or
          case 0x06: // hybrid
          case 0x07: // Byte length calculated as in ECPoint.getEncoded();
              V = new byte[1 + 2*((ecParams.getCurve().getFieldSize()+7)/8)];
              break;
  
          default:
              throw new IOException("Sender's public key has invalid point encoding 0x" + Integer.toString(first, 16));
          }
  
          V[0] = (byte)first;
          stream.read(V, 1, V.length - 1);
  
          return new ECPublicKeyParameters(ecParams.getCurve().decodePoint(V), ecParams);
      }
  }
  