1 files changed, 83 insertions, 0 deletions
diff --git a/Crypto/src/crypto/CipherKeyGenerator.cs b/Crypto/src/crypto/CipherKeyGenerator.cs
new file mode 100644
index 000000000..5d00d34dd
--- /dev/null
+++ b/Crypto/src/crypto/CipherKeyGenerator.cs
@@ -0,0 +1,83 @@
+using System;
+
+using Org.BouncyCastle.Security;
+
+namespace Org.BouncyCastle.Crypto
+{
+ /**
+ * The base class for symmetric, or secret, cipher key generators.
+ */
+ public class CipherKeyGenerator
+ {
+ protected internal SecureRandom random;
+ protected internal int strength;
+ private bool uninitialised = true;
+ private int defaultStrength;
+
+ public CipherKeyGenerator()
+ {
+ }
+
+ internal CipherKeyGenerator(
+ int defaultStrength)
+ {
+ if (defaultStrength < 1)
+ throw new ArgumentException("strength must be a positive value", "defaultStrength");
+
+ this.defaultStrength = defaultStrength;
+ }
+
+ public int DefaultStrength
+ {
+ get { return defaultStrength; }
+ }
+
+ /**
+ * initialise the key generator.
+ *
+ * @param param the parameters to be used for key generation
+ */
+ public void Init(
+ KeyGenerationParameters parameters)
+ {
+ if (parameters == null)
+ throw new ArgumentNullException("parameters");
+
+ this.uninitialised = false;
+
+ engineInit(parameters);
+ }
+
+ protected virtual void engineInit(
+ KeyGenerationParameters parameters)
+ {
+ this.random = parameters.Random;
+ this.strength = (parameters.Strength + 7) / 8;
+ }
+
+ /**
+ * Generate a secret key.
+ *
+ * @return a byte array containing the key value.
+ */
+ public byte[] GenerateKey()
+ {
+ if (uninitialised)
+ {
+ if (defaultStrength < 1)
+ throw new InvalidOperationException("Generator has not been initialised");
+
+ uninitialised = false;
+
+ engineInit(new KeyGenerationParameters(new SecureRandom(), defaultStrength));
+ }
+
+ return engineGenerateKey();
+ }
+
+ protected virtual byte[] engineGenerateKey()
+ {
+ return random.GenerateSeed(strength);
+ }
+ }
+}
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