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Use hash/hmac one shots in NTLM #70857

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merged 2 commits into from
Jun 17, 2022
Merged

Use hash/hmac one shots in NTLM #70857

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902128a
Use hash/hmac one shots in NTLM
vcsjones Jun 16, 2022
3556f0b
Code review feedback.
vcsjones Jun 17, 2022
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31 changes: 10 additions & 21 deletions src/libraries/Common/src/System/Net/NTAuthentication.Managed.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -444,14 +444,10 @@ private static void makeNtlm2Hash(string domain, string userName, ReadOnlySpan<c
{
Encoding.Unicode.GetBytes(password, pwBytes);
MD4.HashData(pwBytes, pwHash);

using (var hmac = IncrementalHash.CreateHMAC(HashAlgorithmName.MD5, pwHash))
{
// strangely, user is upper case, domain is not.
byte[] blob = Encoding.Unicode.GetBytes(string.Concat(userName.ToUpperInvariant(), domain));
hmac.AppendData(blob);
hmac.GetHashAndReset(hash);
}
// strangely, user is upper case, domain is not.
byte[] blob = Encoding.Unicode.GetBytes(string.Concat(userName.ToUpperInvariant(), domain));
int written = HMACMD5.HashData(pwHash, blob, hash);
Debug.Assert(written == HMACMD5.HashSizeInBytes);
}
finally
{
Expand Down Expand Up @@ -502,16 +498,12 @@ private unsafe void WriteChannelBindingHash(Span<byte> hashBuffer)
{
IntPtr cbtData = _channelBinding.DangerousGetHandle();
int cbtDataSize = _channelBinding.Size;

using (var md5 = IncrementalHash.CreateHash(HashAlgorithmName.MD5))
{
md5.AppendData(new Span<byte>((void *)cbtData, cbtDataSize));
md5.GetHashAndReset(hashBuffer);
}
int written = MD5.HashData(new Span<byte>((void*)cbtData, cbtDataSize), hashBuffer);
Debug.Assert(written == MD5.HashSizeInBytes);
}
else
{
hashBuffer.Fill(0);
hashBuffer.Clear();
}
}

Expand Down Expand Up @@ -716,12 +708,9 @@ private static byte[] DeriveKey(ReadOnlySpan<byte> exportedSessionKey, ReadOnlyS
Debug.Assert(flags.HasFlag(Flags.NegotiateSign) && flags.HasFlag(Flags.NegotiateKeyExchange));

// Derive session base key
Span<byte> sessionBaseKey = stackalloc byte[16];
using (var hmacSessionKey = IncrementalHash.CreateHMAC(HashAlgorithmName.MD5, ntlm2hash))
{
hmacSessionKey.AppendData(responseAsSpan.Slice(response.NtChallengeResponse.PayloadOffset, 16));
hmacSessionKey.GetHashAndReset(sessionBaseKey);
}
Span<byte> sessionBaseKey = stackalloc byte[HMACMD5.HashSizeInBytes];
int sessionKeyWritten = HMACMD5.HashData(ntlm2hash, responseAsSpan.Slice(response.NtChallengeResponse.PayloadOffset, 16), sessionBaseKey);
Debug.Assert(sessionKeyWritten == HMACMD5.HashSizeInBytes);

// Encrypt exportedSessionKey with sessionBaseKey
using (RC4 rc4 = new RC4(sessionBaseKey))
Expand Down