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Use one shot pbkdf2 #31200

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Merged
7 commits merged into from
Mar 30, 2021
Merged

Use one shot pbkdf2 #31200

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f4587ca
Use one shot pbkdf2
HaoK Mar 24, 2021
d18c3e9
Update NetCorePbkdf2Provider.cs
HaoK Mar 24, 2021
17b6ec1
CR feedback
HaoK Mar 25, 2021
56d7f85
CR feedback
HaoK Mar 26, 2021
d54e81f
Fix
HaoK Mar 26, 2021
a3449e7
Just use GetBytes for now
HaoK Mar 29, 2021
265bc2b
Update NetCorePbkdf2Provider.cs
HaoK Mar 29, 2021
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11 changes: 6 additions & 5 deletions src/DataProtection/Cryptography.KeyDerivation/src/PBKDF2/NetCorePbkdf2Provider.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@

#if NETCOREAPP
using System;
using System.Buffers;
using System.Diagnostics;
using System.Security.Cryptography;
using System.Text;
Expand Down Expand Up @@ -54,11 +55,11 @@ private static byte[] DeriveKeyImpl(string password, byte[] salt, KeyDerivationP
throw new ArgumentOutOfRangeException();
}

var passwordBytes = Encoding.UTF8.GetBytes(password);
using (var rfc = new Rfc2898DeriveBytes(passwordBytes, salt, iterationCount, algorithmName))
{
return rfc.GetBytes(numBytesRequested);
}
var maxBytes = Encoding.UTF8.GetMaxByteCount(password.Length);
Span<byte> bytes = (maxBytes > 256) ? ArrayPool<byte>.Shared.Rent(maxBytes) : stackalloc byte[256];
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@pranavkm pranavkm Mar 26, 2021

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I'm not sure if this turns it in to an Oracle since stackalloc is faster than the ArrayPool. Also, I just recalled @GrabYourPitchforks recommending against using the shared array pool for crypto things.

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@HaoK HaoK Mar 29, 2021

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@pranavkm how do you feel about if we just do stackalloc for up to 256 and use the old alloc from GetBytes for crazy long passwords (which has to be extremely uncommon)

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@HaoK HaoK Mar 29, 2021

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Chatted with @pranavkm offline, we will put this into the bucket of spanification things to revisit in a separate PR,

var byteCount = Encoding.UTF8.GetBytes(password.AsSpan(), bytes);
bytes = bytes.Slice(0, byteCount);
return Rfc2898DeriveBytes.Pbkdf2(bytes, salt, iterationCount, algorithmName, numBytesRequested);
}
}
}
Expand Down