/// <summary>
/// Update the
/// <see cref="encryptor"/>
/// : calculate counter and
/// <see cref="padding"/>
/// .
/// </summary>
/// <exception cref="System.IO.IOException"/>
private void UpdateEncryptor()
{
long counter = streamOffset / codec.GetCipherSuite().GetAlgorithmBlockSize();
padding = unchecked ((byte)(streamOffset % codec.GetCipherSuite().GetAlgorithmBlockSize
()));
inBuffer.Position(padding);
// Set proper position for input data.
codec.CalculateIV(initIV, counter, iv);
encryptor.Init(key, iv);
}
/// <summary>AES/CTR/NoPadding is required</summary>
public static void CheckCodec(CryptoCodec codec)
{
if (codec.GetCipherSuite() != CipherSuite.AesCtrNopadding)
{
throw new UnsupportedCodecException("AES/CTR/NoPadding is required");
}
}
/// <summary>Get crypto codec for specified algorithm/mode/padding.</summary>
/// <param name="conf">the configuration</param>
/// <param name="cipherSuite">algorithm/mode/padding</param>
/// <returns>
/// CryptoCodec the codec object. Null value will be returned if no
/// crypto codec classes with cipher suite configured.
/// </returns>
public static CryptoCodec GetInstance(Configuration conf, CipherSuite cipherSuite
)
{
IList <Type> klasses = GetCodecClasses(conf, cipherSuite);
if (klasses == null)
{
return(null);
}
CryptoCodec codec = null;
foreach (Type klass in klasses)
{
try
{
CryptoCodec c = ReflectionUtils.NewInstance(klass, conf);
if (c.GetCipherSuite().GetName().Equals(cipherSuite.GetName()))
{
if (codec == null)
{
PerformanceAdvisory.Log.Debug("Using crypto codec {}.", klass.FullName);
codec = c;
}
}
else
{
PerformanceAdvisory.Log.Debug("Crypto codec {} doesn't meet the cipher suite {}."
, klass.FullName, cipherSuite.GetName());
}
}
catch (Exception)
{
PerformanceAdvisory.Log.Debug("Crypto codec {} is not available.", klass.FullName
);
}
}
return(codec);
}
/// <summary>Check and floor buffer size</summary>
public static int CheckBufferSize(CryptoCodec codec, int bufferSize)
{
Preconditions.CheckArgument(bufferSize >= MinBufferSize, "Minimum value of buffer size is "
+ MinBufferSize + ".");
return(bufferSize - bufferSize % codec.GetCipherSuite().GetAlgorithmBlockSize());
}
private long GetCounter(long position)
{
return(position / codec.GetCipherSuite().GetAlgorithmBlockSize());
}
