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83 lines (68 loc) · 1.69 KB
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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 SecureRandom.GetNextBytes(random, strength);
}
}
}