diff --git a/Crypto/src/crypto/parameters/DHParameters.cs b/Crypto/src/crypto/parameters/DHParameters.cs
new file mode 100644
index 000000000..a0544e73b
--- /dev/null
+++ b/Crypto/src/crypto/parameters/DHParameters.cs
@@ -0,0 +1,184 @@
+using System;
+
+using Org.BouncyCastle.Math;
+using Org.BouncyCastle.Utilities;
+
+namespace Org.BouncyCastle.Crypto.Parameters
+{
+ public class DHParameters
+ : ICipherParameters
+ {
+ private const int DefaultMinimumLength = 160;
+
+ private readonly BigInteger p, g, q, j;
+ private readonly int m, l;
+ private readonly DHValidationParameters validation;
+
+ private static int GetDefaultMParam(
+ int lParam)
+ {
+ if (lParam == 0)
+ return DefaultMinimumLength;
+
+ return System.Math.Min(lParam, DefaultMinimumLength);
+ }
+
+ public DHParameters(
+ BigInteger p,
+ BigInteger g)
+ : this(p, g, null, 0)
+ {
+ }
+
+ public DHParameters(
+ BigInteger p,
+ BigInteger g,
+ BigInteger q)
+ : this(p, g, q, 0)
+ {
+ }
+
+ public DHParameters(
+ BigInteger p,
+ BigInteger g,
+ BigInteger q,
+ int l)
+ : this(p, g, q, GetDefaultMParam(l), l, null, null)
+ {
+ }
+
+ public DHParameters(
+ BigInteger p,
+ BigInteger g,
+ BigInteger q,
+ int m,
+ int l)
+ : this(p, g, q, m, l, null, null)
+ {
+ }
+
+ public DHParameters(
+ BigInteger p,
+ BigInteger g,
+ BigInteger q,
+ BigInteger j,
+ DHValidationParameters validation)
+ : this(p, g, q, DefaultMinimumLength, 0, j, validation)
+ {
+ }
+
+ public DHParameters(
+ BigInteger p,
+ BigInteger g,
+ BigInteger q,
+ int m,
+ int l,
+ BigInteger j,
+ DHValidationParameters validation)
+ {
+ if (p == null)
+ throw new ArgumentNullException("p");
+ if (g == null)
+ throw new ArgumentNullException("g");
+ if (!p.TestBit(0))
+ throw new ArgumentException("field must be an odd prime", "p");
+ if (g.CompareTo(BigInteger.Two) < 0
+ || g.CompareTo(p.Subtract(BigInteger.Two)) > 0)
+ throw new ArgumentException("generator must in the range [2, p - 2]", "g");
+ if (q != null && q.BitLength >= p.BitLength)
+ throw new ArgumentException("q too big to be a factor of (p-1)", "q");
+ if (m >= p.BitLength)
+ throw new ArgumentException("m value must be < bitlength of p", "m");
+ if (l != 0)
+ {
+ if (l >= p.BitLength)
+ throw new ArgumentException("when l value specified, it must be less than bitlength(p)", "l");
+ if (l < m)
+ throw new ArgumentException("when l value specified, it may not be less than m value", "l");
+ }
+ if (j != null && j.CompareTo(BigInteger.Two) < 0)
+ throw new ArgumentException("subgroup factor must be >= 2", "j");
+
+ // TODO If q, j both provided, validate p = jq + 1 ?
+
+ this.p = p;
+ this.g = g;
+ this.q = q;
+ this.m = m;
+ this.l = l;
+ this.j = j;
+ this.validation = validation;
+ }
+
+ public BigInteger P
+ {
+ get { return p; }
+ }
+
+ public BigInteger G
+ {
+ get { return g; }
+ }
+
+ public BigInteger Q
+ {
+ get { return q; }
+ }
+
+ public BigInteger J
+ {
+ get { return j; }
+ }
+
+ /// <summary>The minimum bitlength of the private value.</summary>
+ public int M
+ {
+ get { return m; }
+ }
+
+ /// <summary>The bitlength of the private value.</summary>
+ public int L
+ {
+ get { return l; }
+ }
+
+ public DHValidationParameters ValidationParameters
+ {
+ get { return validation; }
+ }
+
+ public override bool Equals(
+ object obj)
+ {
+ if (obj == this)
+ return true;
+
+ DHParameters other = obj as DHParameters;
+
+ if (other == null)
+ return false;
+
+ return Equals(other);
+ }
+
+ protected bool Equals(
+ DHParameters other)
+ {
+ return p.Equals(other.p)
+ && g.Equals(other.g)
+ && Platform.Equals(q, other.q);
+ }
+
+ public override int GetHashCode()
+ {
+ int hc = p.GetHashCode() ^ g.GetHashCode();
+
+ if (q != null)
+ {
+ hc ^= q.GetHashCode();
+ }
+
+ return hc;
+ }
+ }
+}
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