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#pragma warning disable CS1591
#nullable enable
using System;
using System.Collections.Generic;
using System.Text;
namespace MediaBrowser.Common.Cryptography
{
// Defined from this hash storage spec
// https://github.com/P-H-C/phc-string-format/blob/master/phc-sf-spec.md
// $<id>[$<param>=<value>(,<param>=<value>)*][$<salt>[$<hash>]]
// with one slight amendment to ease the transition, we're writing out the bytes in hex
// rather than making them a BASE64 string with stripped padding
public class PasswordHash
{
private readonly Dictionary<string, string> _parameters;
private readonly byte[] _salt;
private readonly byte[] _hash;
public PasswordHash(string id, byte[] hash)
: this(id, hash, Array.Empty<byte>())
{
}
public PasswordHash(string id, byte[] hash, byte[] salt)
: this(id, hash, salt, new Dictionary<string, string>())
{
}
public PasswordHash(string id, byte[] hash, byte[] salt, Dictionary<string, string> parameters)
{
if (id == null)
{
throw new ArgumentNullException(nameof(id));
}
if (id.Length == 0)
{
throw new ArgumentException("String can't be empty", nameof(id));
}
Id = id;
_hash = hash;
_salt = salt;
_parameters = parameters;
}
/// <summary>
/// Gets the symbolic name for the function used.
/// </summary>
/// <value>Returns the symbolic name for the function used.</value>
public string Id { get; }
/// <summary>
/// Gets the additional parameters used by the hash function.
/// </summary>
public IReadOnlyDictionary<string, string> Parameters => _parameters;
/// <summary>
/// Gets the salt used for hashing the password.
/// </summary>
/// <value>Returns the salt used for hashing the password.</value>
public ReadOnlySpan<byte> Salt => _salt;
/// <summary>
/// Gets the hashed password.
/// </summary>
/// <value>Return the hashed password.</value>
public ReadOnlySpan<byte> Hash => _hash;
public static PasswordHash Parse(ReadOnlySpan<char> hashString)
{
if (hashString.IsEmpty)
{
throw new ArgumentException("String can't be empty", nameof(hashString));
}
if (hashString[0] != '$')
{
throw new FormatException("Hash string must start with a $");
}
// Ignore first $
hashString = hashString[1..];
int nextSegment = hashString.IndexOf('$');
if (hashString.IsEmpty || nextSegment == 0)
{
throw new FormatException("Hash string must contain a valid id");
}
else if (nextSegment == -1)
{
return new PasswordHash(hashString.ToString(), Array.Empty<byte>());
}
ReadOnlySpan<char> id = hashString[..nextSegment];
hashString = hashString[(nextSegment + 1)..];
Dictionary<string, string>? parameters = null;
nextSegment = hashString.IndexOf('$');
// Optional parameters
ReadOnlySpan<char> parametersSpan = nextSegment == -1 ? hashString : hashString[..nextSegment];
if (parametersSpan.Contains('='))
{
while (!parametersSpan.IsEmpty)
{
ReadOnlySpan<char> parameter;
int index = parametersSpan.IndexOf(',');
if (index == -1)
{
parameter = parametersSpan;
parametersSpan = ReadOnlySpan<char>.Empty;
}
else
{
parameter = parametersSpan[..index];
parametersSpan = parametersSpan[(index + 1)..];
}
int splitIndex = parameter.IndexOf('=');
if (splitIndex == -1 || splitIndex == 0 || splitIndex == parameter.Length - 1)
{
throw new FormatException("Malformed parameter in password hash string");
}
(parameters ??= new Dictionary<string, string>()).Add(
parameter[..splitIndex].ToString(),
parameter[(splitIndex + 1)..].ToString());
}
if (nextSegment == -1)
{
// parameters can't be null here
return new PasswordHash(id.ToString(), Array.Empty<byte>(), Array.Empty<byte>(), parameters!);
}
hashString = hashString[(nextSegment + 1)..];
nextSegment = hashString.IndexOf('$');
}
if (nextSegment == 0)
{
throw new FormatException("Hash string contains an empty segment");
}
byte[] hash;
byte[] salt;
if (nextSegment == -1)
{
salt = Array.Empty<byte>();
hash = Convert.FromHexString(hashString);
}
else
{
salt = Convert.FromHexString(hashString[..nextSegment]);
hashString = hashString[(nextSegment + 1)..];
nextSegment = hashString.IndexOf('$');
if (nextSegment != -1)
{
throw new FormatException("Hash string contains too many segments");
}
if (hashString.IsEmpty)
{
throw new FormatException("Hash segment is empty");
}
hash = Convert.FromHexString(hashString);
}
return new PasswordHash(id.ToString(), hash, salt, parameters ?? new Dictionary<string, string>());
}
private void SerializeParameters(StringBuilder stringBuilder)
{
if (_parameters.Count == 0)
{
return;
}
stringBuilder.Append('$');
foreach (var pair in _parameters)
{
stringBuilder.Append(pair.Key)
.Append('=')
.Append(pair.Value)
.Append(',');
}
// Remove last ','
stringBuilder.Length -= 1;
}
/// <inheritdoc />
public override string ToString()
{
var str = new StringBuilder()
.Append('$')
.Append(Id);
SerializeParameters(str);
if (_salt.Length != 0)
{
str.Append('$')
.Append(Convert.ToHexString(_salt));
}
if (_hash.Length != 0)
{
str.Append('$')
.Append(Convert.ToHexString(_hash));
}
return str.ToString();
}
}
}
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