/// <summary>
/// Return the hash function block size in bytes
/// </summary>
/// <param name="hashAlg"></param>
/// <returns></returns>
public static ushort BlockSize(TpmAlgId hashAlg)
{
return((ushort)CryptoLib.BlockSize(hashAlg));
}
CreateSensitiveComposite(TpmPublic pub,
ref byte[] keyData,
out IPublicIdUnion publicId)
{
ISensitiveCompositeUnion newSens = null;
publicId = null;
if (pub.type == TpmAlgId.Rsa)
{
if (keyData != null)
{
Globs.Throw <ArgumentException>("Cannot specify key data for an RSA key");
return(null);
}
var newKeyPair = new RawRsa((pub.parameters as RsaParms).keyBits);
// Put the key bits into the required structure envelopes
newSens = new Tpm2bPrivateKeyRsa(newKeyPair.Private);
publicId = new Tpm2bPublicKeyRsa(newKeyPair.Public);
}
else if (pub.type == TpmAlgId.Symcipher)
{
var symDef = (SymDefObject)pub.parameters;
if (symDef.Algorithm != TpmAlgId.Aes)
{
Globs.Throw <ArgumentException>("Unsupported symmetric algorithm");
return(null);
}
int keySize = (symDef.KeyBits + 7) / 8;
if (keyData == null)
{
keyData = Globs.GetRandomBytes(keySize);
}
else if (keyData.Length != keySize)
{
keyData = Globs.CopyData(keyData);
}
else
{
Globs.Throw <ArgumentException>("Wrong symmetric key length");
return(null);
}
newSens = new Tpm2bSymKey(keyData);
}
else if (pub.type == TpmAlgId.Keyedhash)
{
var scheme = (pub.parameters as KeyedhashParms).scheme;
TpmAlgId hashAlg = scheme is SchemeHash ? (scheme as SchemeHash).hashAlg
: scheme is SchemeXor ? (scheme as SchemeXor).hashAlg
: pub.nameAlg;
var digestSize = CryptoLib.DigestSize(hashAlg);
if (keyData == null)
{
keyData = Globs.GetRandomBytes(digestSize);
}
else if (keyData.Length <= CryptoLib.BlockSize(hashAlg))
{
keyData = Globs.CopyData(keyData);
}
else
{
Globs.Throw <ArgumentException>("HMAC key is too big");
return(null);
}
newSens = new Tpm2bSensitiveData(keyData);
}
else
{
Globs.Throw <ArgumentException>("Unsupported key type");
}
return(newSens);
}
