/// <summary>
/// De-envelope inner-wrapped duplication blob.
/// TODO: Move this to TpmPublic and make it fully general
/// </summary>
/// <param name="exportedPrivate"></param>
/// <param name="encAlg"></param>
/// <param name="encKey"></param>
/// <param name="nameAlg"></param>
/// <param name="name"></param>
/// <returns></returns>
public static Sensitive SensitiveFromDuplicateBlob(TpmPrivate exportedPrivate, SymDefObject encAlg, byte[] encKey, TpmAlgId nameAlg, byte[] name)
{
byte[] dupBlob = exportedPrivate.buffer;
byte[] sensNoLen;
using (SymmCipher c = Create(encAlg, encKey))
{
byte[] innerObject = c.CFBDecrypt(dupBlob);
byte[] innerIntegrity, sensitive;
KDF.Split(innerObject,
16 + CryptoLib.DigestSize(nameAlg) * 8,
out innerIntegrity,
8 * (innerObject.Length - CryptoLib.DigestSize(nameAlg) - 2),
out sensitive);
byte[] expectedInnerIntegrity = Marshaller.ToTpm2B(CryptoLib.HashData(nameAlg, sensitive, name));
if (!Globs.ArraysAreEqual(expectedInnerIntegrity, innerIntegrity))
{
throw new Exception("Bad inner integrity");
}
sensNoLen = Marshaller.Tpm2BToBuffer(sensitive);
}
var sens = Marshaller.FromTpmRepresentation <Sensitive>(sensNoLen);
return(sens);
}
public static byte[] Decrypt(SymDefObject symDef, byte[] key, byte[] iv, byte[] dataToDecrypt)
{
using (SymmCipher cipher = Create(symDef, key, iv))
{
return(cipher.CFBDecrypt(dataToDecrypt));
}
}
internal byte[] ParmEncrypt(byte[] parm, Direction inOrOut)
{
if (Symmetric == null)
{
throw new Exception("parameter encryption cipher not defined");
}
if (Symmetric.Algorithm == TpmAlgId.Null)
{
return(parm);
}
byte[] nonceNewer, nonceOlder;
if (inOrOut == Direction.Command)
{
nonceNewer = NonceCaller;
nonceOlder = NonceTpm;
}
else
{
nonceNewer = NonceTpm;
nonceOlder = NonceCaller;
}
byte[] encKey = (AuthHandle != null && AuthHandle.Auth != null) ?
SessionKey.Concat(AuthHandle.Auth).ToArray() : SessionKey;
if (Symmetric.Algorithm == TpmAlgId.Xor)
{
return(CryptoLib.KdfThenXor(AuthHash, encKey, nonceNewer, nonceOlder, parm));
}
int keySize = (Symmetric.KeyBits + 7) / 8,
blockSize = SymmCipher.GetBlockSize(Symmetric),
bytesRequired = keySize + blockSize;
byte[] keyInfo = KDF.KDFa(AuthHash, encKey, "CFB", nonceNewer, nonceOlder, (uint)(bytesRequired * 8));
var key = new byte[keySize];
Array.Copy(keyInfo, 0, key, 0, keySize);
var iv = new byte[blockSize];
Array.Copy(keyInfo, keySize, iv, 0, blockSize);
// Make a new SymmCipher from the key and IV and do the encryption.
using (SymmCipher s = SymmCipher.Create(Symmetric, key, iv))
{
return(inOrOut == Direction.Command ? s.CFBEncrypt(parm) : s.CFBDecrypt(parm));
}
}
