private static KeySizes[] FindSupportedKeySizes(SafeCspHandle csp, out int defaultKeySize)
{
if (s_supportedKeySizes == null)
{
List <KeySizes> list = new List <KeySizes>();
int num = 0;
for (CapiNative.PROV_ENUMALGS prov_enumalgs = CapiNative.GetProviderParameterStruct <CapiNative.PROV_ENUMALGS>(csp, CapiNative.ProviderParameter.EnumerateAlgorithms, CapiNative.ProviderParameterFlags.RestartEnumeration); prov_enumalgs.aiAlgId != CapiNative.AlgorithmId.None; prov_enumalgs = CapiNative.GetProviderParameterStruct <CapiNative.PROV_ENUMALGS>(csp, CapiNative.ProviderParameter.EnumerateAlgorithms, CapiNative.ProviderParameterFlags.None))
{
switch (prov_enumalgs.aiAlgId)
{
case CapiNative.AlgorithmId.Aes128:
list.Add(new KeySizes(0x80, 0x80, 0));
if (0x80 > num)
{
num = 0x80;
}
break;
case CapiNative.AlgorithmId.Aes192:
list.Add(new KeySizes(0xc0, 0xc0, 0));
if (0xc0 > num)
{
num = 0xc0;
}
break;
case CapiNative.AlgorithmId.Aes256:
list.Add(new KeySizes(0x100, 0x100, 0));
if (0x100 > num)
{
num = 0x100;
}
break;
}
}
s_supportedKeySizes = list.ToArray();
s_defaultKeySize = num;
}
defaultKeySize = s_defaultKeySize;
return(s_supportedKeySizes);
}
private static KeySizes[] FindSupportedKeySizes(SafeCspHandle csp, out int defaultKeySize)
{
Contract.Requires(csp != null);
Contract.Ensures(Contract.Result <KeySizes[]>() != null);
// If this platform has any supported algorithm sizes, then the default key size should be set to a
// reasonable value.
Contract.Ensures(Contract.Result <KeySizes[]>().Length == 0 ||
(Contract.ValueAtReturn <int>(out defaultKeySize) > 0 && Contract.ValueAtReturn <int>(out defaultKeySize) % 8 == 0));
if (s_supportedKeySizes == null)
{
List <KeySizes> keySizes = new List <KeySizes>();
int maxKeySize = 0;
//
// Enumerate the CSP's supported algorithms to see what key sizes it supports for AES
//
CapiNative.PROV_ENUMALGS algorithm =
CapiNative.GetProviderParameterStruct <CapiNative.PROV_ENUMALGS>(csp,
CapiNative.ProviderParameter.EnumerateAlgorithms,
CapiNative.ProviderParameterFlags.RestartEnumeration);
// Translate between CAPI AES algorithm IDs and supported key sizes
while (algorithm.aiAlgId != CapiNative.AlgorithmId.None)
{
switch (algorithm.aiAlgId)
{
case CapiNative.AlgorithmId.Aes128:
keySizes.Add(new KeySizes(128, 128, 0));
if (128 > maxKeySize)
{
maxKeySize = 128;
}
break;
case CapiNative.AlgorithmId.Aes192:
keySizes.Add(new KeySizes(192, 192, 0));
if (192 > maxKeySize)
{
maxKeySize = 192;
}
break;
case CapiNative.AlgorithmId.Aes256:
keySizes.Add(new KeySizes(256, 256, 0));
if (256 > maxKeySize)
{
maxKeySize = 256;
}
break;
default:
break;
}
algorithm = CapiNative.GetProviderParameterStruct <CapiNative.PROV_ENUMALGS>(csp,
CapiNative.ProviderParameter.EnumerateAlgorithms,
CapiNative.ProviderParameterFlags.None);
}
s_supportedKeySizes = keySizes.ToArray();
s_defaultKeySize = maxKeySize;
}
defaultKeySize = s_defaultKeySize;
return(s_supportedKeySizes);
}
