diff options
Diffstat (limited to 'lib/src/main/java/com/trilead/ssh2/crypto/dh/DhGroupExchange.java')
-rw-r--r-- | lib/src/main/java/com/trilead/ssh2/crypto/dh/DhGroupExchange.java | 113 |
1 files changed, 113 insertions, 0 deletions
diff --git a/lib/src/main/java/com/trilead/ssh2/crypto/dh/DhGroupExchange.java b/lib/src/main/java/com/trilead/ssh2/crypto/dh/DhGroupExchange.java new file mode 100644 index 0000000..8e798ee --- /dev/null +++ b/lib/src/main/java/com/trilead/ssh2/crypto/dh/DhGroupExchange.java @@ -0,0 +1,113 @@ +
+package com.trilead.ssh2.crypto.dh;
+
+import java.math.BigInteger;
+import java.security.SecureRandom;
+
+import com.trilead.ssh2.DHGexParameters;
+import com.trilead.ssh2.crypto.digest.HashForSSH2Types;
+
+
+/**
+ * DhGroupExchange.
+ *
+ * @author Christian Plattner, plattner@trilead.com
+ * @version $Id: DhGroupExchange.java,v 1.1 2007/10/15 12:49:57 cplattne Exp $
+ */
+public class DhGroupExchange
+{
+ /* Given by the standard */
+
+ private BigInteger p;
+ private BigInteger g;
+
+ /* Client public and private */
+
+ private BigInteger e;
+ private BigInteger x;
+
+ /* Server public */
+
+ private BigInteger f;
+
+ /* Shared secret */
+
+ private BigInteger k;
+
+ public DhGroupExchange(BigInteger p, BigInteger g)
+ {
+ this.p = p;
+ this.g = g;
+ }
+
+ public void init(SecureRandom rnd)
+ {
+ k = null;
+
+ x = new BigInteger(p.bitLength() - 1, rnd);
+ e = g.modPow(x, p);
+ }
+
+ /**
+ * @return Returns the e.
+ */
+ public BigInteger getE()
+ {
+ if (e == null)
+ throw new IllegalStateException("Not initialized!");
+
+ return e;
+ }
+
+ /**
+ * @return Returns the shared secret k.
+ */
+ public BigInteger getK()
+ {
+ if (k == null)
+ throw new IllegalStateException("Shared secret not yet known, need f first!");
+
+ return k;
+ }
+
+ /**
+ * Sets f and calculates the shared secret.
+ */
+ public void setF(BigInteger f)
+ {
+ if (e == null)
+ throw new IllegalStateException("Not initialized!");
+
+ BigInteger zero = BigInteger.valueOf(0);
+
+ if (zero.compareTo(f) >= 0 || p.compareTo(f) <= 0)
+ throw new IllegalArgumentException("Invalid f specified!");
+
+ this.f = f;
+ this.k = f.modPow(x, p);
+ }
+
+ public byte[] calculateH(byte[] clientversion, byte[] serverversion, byte[] clientKexPayload,
+ byte[] serverKexPayload, byte[] hostKey, DHGexParameters para)
+ {
+ HashForSSH2Types hash = new HashForSSH2Types("SHA1");
+
+ hash.updateByteString(clientversion);
+ hash.updateByteString(serverversion);
+ hash.updateByteString(clientKexPayload);
+ hash.updateByteString(serverKexPayload);
+ hash.updateByteString(hostKey);
+ if (para.getMin_group_len() > 0)
+ hash.updateUINT32(para.getMin_group_len());
+ hash.updateUINT32(para.getPref_group_len());
+ if (para.getMax_group_len() > 0)
+ hash.updateUINT32(para.getMax_group_len());
+ hash.updateBigInt(p);
+ hash.updateBigInt(g);
+ hash.updateBigInt(e);
+ hash.updateBigInt(f);
+ hash.updateBigInt(k);
+
+ return hash.getDigest();
+ }
+}
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