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Uuid.cs
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Uuid.cs
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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.Security.Cryptography;
namespace Microsoft.DotNet.Cli.Utils
{
public class Uuid
{
/// <summary>
/// Generate a Version 5 (SHA1 Name Based) Guid from a name.
/// </summary>
/// <param name="name">The name to use for generating the GUID.</param>
/// <returns>A generated <see cref="GUID"/>.</returns>
public static Guid Create(string name)
{
// Any fixed GUID will do for a namespace.
Guid namespaceId = new Guid("28F1468D-672B-489A-8E0C-7C5B3030630C");
using (SHA1 hasher = SHA1.Create())
{
var nameBytes = System.Text.Encoding.UTF8.GetBytes(name ?? string.Empty);
var namespaceBytes = namespaceId.ToByteArray();
SwapGuidByteOrder(namespaceBytes);
var streamToHash = new byte[namespaceBytes.Length + nameBytes.Length];
Array.Copy(namespaceBytes, streamToHash, namespaceBytes.Length);
Array.Copy(nameBytes, 0, streamToHash, namespaceBytes.Length, nameBytes.Length);
var hashResult = hasher.ComputeHash(streamToHash);
var res = new byte[16];
Array.Copy(hashResult, res, res.Length);
unchecked { res[6] = (byte)(0x50 | (res[6] & 0x0F)); }
unchecked { res[8] = (byte)(0x40 | (res[8] & 0x3F)); }
SwapGuidByteOrder(res);
return new Guid(res);
}
}
// Do a byte order swap, .NET GUIDs store multi byte components in little
// endian.
private static void SwapGuidByteOrder(byte[] b)
{
Swap(b, 0, 3);
Swap(b, 1, 2);
Swap(b, 5, 6);
Swap(b, 7, 8);
}
private static void Swap(byte[] b, int x, int y)
{
byte t = b[x];
b[x] = b[y];
b[y] = t;
}
}
}