diff --git a/Crypto/src/crypto/generators/BaseKdfBytesGenerator.cs b/Crypto/src/crypto/generators/BaseKdfBytesGenerator.cs
new file mode 100644
index 000000000..0366401d1
--- /dev/null
+++ b/Crypto/src/crypto/generators/BaseKdfBytesGenerator.cs
@@ -0,0 +1,141 @@
+using System;
+
+using Org.BouncyCastle.Crypto;
+using Org.BouncyCastle.Crypto.Parameters;
+
+namespace Org.BouncyCastle.Crypto.Generators
+{
+ /**
+ * Basic KDF generator for derived keys and ivs as defined by IEEE P1363a/ISO 18033
+ * <br/>
+ * This implementation is based on ISO 18033/P1363a.
+ */
+ public class BaseKdfBytesGenerator
+ : IDerivationFunction
+ {
+ private int counterStart;
+ private IDigest digest;
+ private byte[] shared;
+ private byte[] iv;
+
+ /**
+ * Construct a KDF Parameters generator.
+ *
+ * @param counterStart value of counter.
+ * @param digest the digest to be used as the source of derived keys.
+ */
+ protected BaseKdfBytesGenerator(
+ int counterStart,
+ IDigest digest)
+ {
+ this.counterStart = counterStart;
+ this.digest = digest;
+ }
+
+ public void Init(
+ IDerivationParameters parameters)
+ {
+ if (parameters is KdfParameters)
+ {
+ KdfParameters p = (KdfParameters)parameters;
+
+ shared = p.GetSharedSecret();
+ iv = p.GetIV();
+ }
+ else if (parameters is Iso18033KdfParameters)
+ {
+ Iso18033KdfParameters p = (Iso18033KdfParameters)parameters;
+
+ shared = p.GetSeed();
+ iv = null;
+ }
+ else
+ {
+ throw new ArgumentException("KDF parameters required for KDF Generator");
+ }
+ }
+
+ /**
+ * return the underlying digest.
+ */
+ public IDigest Digest
+ {
+ get
+ {
+ return digest;
+ }
+ }
+
+ /**
+ * fill len bytes of the output buffer with bytes generated from
+ * the derivation function.
+ *
+ * @throws ArgumentException if the size of the request will cause an overflow.
+ * @throws DataLengthException if the out buffer is too small.
+ */
+ public int GenerateBytes(
+ byte[] output,
+ int outOff,
+ int length)
+ {
+ if ((output.Length - length) < outOff)
+ {
+ throw new DataLengthException("output buffer too small");
+ }
+
+ long oBytes = length;
+ int outLen = digest.GetDigestSize();
+
+ //
+ // this is at odds with the standard implementation, the
+ // maximum value should be hBits * (2^32 - 1) where hBits
+ // is the digest output size in bits. We can't have an
+ // array with a long index at the moment...
+ //
+ if (oBytes > ((2L << 32) - 1))
+ {
+ throw new ArgumentException("Output length too large");
+ }
+
+ int cThreshold = (int)((oBytes + outLen - 1) / outLen);
+
+ byte[] dig = new byte[digest.GetDigestSize()];
+
+ int counter = counterStart;
+
+ for (int i = 0; i < cThreshold; i++)
+ {
+ digest.BlockUpdate(shared, 0, shared.Length);
+
+ digest.Update((byte)(counter >> 24));
+ digest.Update((byte)(counter >> 16));
+ digest.Update((byte)(counter >> 8));
+ digest.Update((byte)counter);
+
+ if (iv != null)
+ {
+ digest.BlockUpdate(iv, 0, iv.Length);
+ }
+
+ digest.DoFinal(dig, 0);
+
+ if (length > outLen)
+ {
+ Array.Copy(dig, 0, output, outOff, outLen);
+ outOff += outLen;
+ length -= outLen;
+ }
+ else
+ {
+ Array.Copy(dig, 0, output, outOff, length);
+ }
+
+ counter++;
+ }
+
+ digest.Reset();
+
+ return (int)oBytes;
+ }
+ }
+}
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