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package org.spongycastle.crypto.generators;
import org.spongycastle.crypto.KeyGenerationParameters;
import org.spongycastle.crypto.params.DESedeParameters;
public class DESedeKeyGenerator
extends DESKeyGenerator
{
/**
* initialise the key generator - if strength is set to zero
* the key generated will be 192 bits in size, otherwise
* strength can be 128 or 192 (or 112 or 168 if you don't count
* parity bits), depending on whether you wish to do 2-key or 3-key
* triple DES.
*
* @param param the parameters to be used for key generation
*/
public void init(
KeyGenerationParameters param)
{
this.random = param.getRandom();
this.strength = (param.getStrength() + 7) / 8;
if (strength == 0 || strength == (168 / 8))
{
strength = DESedeParameters.DES_EDE_KEY_LENGTH;
}
else if (strength == (112 / 8))
{
strength = 2 * DESedeParameters.DES_KEY_LENGTH;
}
else if (strength != DESedeParameters.DES_EDE_KEY_LENGTH
&& strength != (2 * DESedeParameters.DES_KEY_LENGTH))
{
throw new IllegalArgumentException("DESede key must be "
+ (DESedeParameters.DES_EDE_KEY_LENGTH * 8) + " or "
+ (2 * 8 * DESedeParameters.DES_KEY_LENGTH)
+ " bits long.");
}
}
public byte[] generateKey()
{
byte[] newKey = new byte[strength];
do
{
random.nextBytes(newKey);
DESedeParameters.setOddParity(newKey);
}
while (DESedeParameters.isWeakKey(newKey, 0, newKey.length));
return newKey;
}
}
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