1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
|
using Microsoft.AspNetCore.Cryptography.KeyDerivation;
using Microsoft.Extensions.Logging;
using System;
using System.Runtime.CompilerServices;
using System.Security.Cryptography;
namespace Timeline.Services
{
public interface IPasswordService
{
/// <summary>
/// Returns a hashed representation of the supplied <paramref name="password"/>.
/// </summary>
/// <param name="password">The password to hash.</param>
/// <returns>A hashed representation of the supplied <paramref name="password"/>.</returns>
string HashPassword(string password);
/// <summary>
/// Returns a boolean indicating the result of a password hash comparison.
/// </summary>
/// <param name="hashedPassword">The hash value for a user's stored password.</param>
/// <param name="providedPassword">The password supplied for comparison.</param>
/// <returns>True indicating success. Otherwise false.</returns>
bool VerifyPassword(string hashedPassword, string providedPassword);
}
//TODO! Use exceptions!!!
/// <summary>
/// Copied from https://github.com/aspnet/AspNetCore/blob/master/src/Identity/Extensions.Core/src/PasswordHasher.cs
/// Remove V2 format and unnecessary format version check.
/// Remove configuration options.
/// Remove user related parts.
/// Add log for wrong format.
/// </summary>
public class PasswordService : IPasswordService
{
/* =======================
* HASHED PASSWORD FORMATS
* =======================
*
* Version 3:
* PBKDF2 with HMAC-SHA256, 128-bit salt, 256-bit subkey, 10000 iterations.
* Format: { 0x01, prf (UInt32), iter count (UInt32), salt length (UInt32), salt, subkey }
* (All UInt32s are stored big-endian.)
*/
private static EventId BadFormatEventId { get; } = new EventId(4000, "BadFormatPassword");
private readonly RandomNumberGenerator _rng = RandomNumberGenerator.Create();
private readonly ILogger<PasswordService> _logger;
public PasswordService(ILogger<PasswordService> logger)
{
_logger = logger;
}
// Compares two byte arrays for equality. The method is specifically written so that the loop is not optimized.
[MethodImpl(MethodImplOptions.NoInlining | MethodImplOptions.NoOptimization)]
private static bool ByteArraysEqual(byte[] a, byte[] b)
{
if (a == null && b == null)
{
return true;
}
if (a == null || b == null || a.Length != b.Length)
{
return false;
}
var areSame = true;
for (var i = 0; i < a.Length; i++)
{
areSame &= (a[i] == b[i]);
}
return areSame;
}
public string HashPassword(string password)
{
if (password == null)
throw new ArgumentNullException(nameof(password));
return Convert.ToBase64String(HashPasswordV3(password, _rng));
}
private byte[] HashPasswordV3(string password, RandomNumberGenerator rng)
{
return HashPasswordV3(password, rng,
prf: KeyDerivationPrf.HMACSHA256,
iterCount: 10000,
saltSize: 128 / 8,
numBytesRequested: 256 / 8);
}
private static byte[] HashPasswordV3(string password, RandomNumberGenerator rng, KeyDerivationPrf prf, int iterCount, int saltSize, int numBytesRequested)
{
// Produce a version 3 (see comment above) text hash.
byte[] salt = new byte[saltSize];
rng.GetBytes(salt);
byte[] subkey = KeyDerivation.Pbkdf2(password, salt, prf, iterCount, numBytesRequested);
var outputBytes = new byte[13 + salt.Length + subkey.Length];
outputBytes[0] = 0x01; // format marker
WriteNetworkByteOrder(outputBytes, 1, (uint)prf);
WriteNetworkByteOrder(outputBytes, 5, (uint)iterCount);
WriteNetworkByteOrder(outputBytes, 9, (uint)saltSize);
Buffer.BlockCopy(salt, 0, outputBytes, 13, salt.Length);
Buffer.BlockCopy(subkey, 0, outputBytes, 13 + saltSize, subkey.Length);
return outputBytes;
}
private void LogBadFormatError(string hashedPassword, string message, Exception exception = null)
{
if (_logger == null)
return;
if (exception != null)
_logger.LogError(BadFormatEventId, exception, $"{message} Hashed password is {hashedPassword} .");
else
_logger.LogError(BadFormatEventId, $"{message} Hashed password is {hashedPassword} .");
}
public virtual bool VerifyPassword(string hashedPassword, string providedPassword)
{
if (hashedPassword == null)
throw new ArgumentNullException(nameof(hashedPassword));
if (providedPassword == null)
throw new ArgumentNullException(nameof(providedPassword));
byte[] decodedHashedPassword = Convert.FromBase64String(hashedPassword);
// read the format marker from the hashed password
if (decodedHashedPassword.Length == 0)
{
LogBadFormatError(hashedPassword, "Decoded hashed password is of length 0.");
return false;
}
switch (decodedHashedPassword[0])
{
case 0x01:
return VerifyHashedPasswordV3(decodedHashedPassword, providedPassword, hashedPassword);
default:
LogBadFormatError(hashedPassword, "Unknown format marker.");
return false; // unknown format marker
}
}
private bool VerifyHashedPasswordV3(byte[] hashedPassword, string password, string hashedPasswordString)
{
try
{
// Read header information
KeyDerivationPrf prf = (KeyDerivationPrf)ReadNetworkByteOrder(hashedPassword, 1);
int iterCount = (int)ReadNetworkByteOrder(hashedPassword, 5);
int saltLength = (int)ReadNetworkByteOrder(hashedPassword, 9);
// Read the salt: must be >= 128 bits
if (saltLength < 128 / 8)
{
LogBadFormatError(hashedPasswordString, "Salt length < 128 bits.");
return false;
}
byte[] salt = new byte[saltLength];
Buffer.BlockCopy(hashedPassword, 13, salt, 0, salt.Length);
// Read the subkey (the rest of the payload): must be >= 128 bits
int subkeyLength = hashedPassword.Length - 13 - salt.Length;
if (subkeyLength < 128 / 8)
{
LogBadFormatError(hashedPasswordString, "Subkey length < 128 bits.");
return false;
}
byte[] expectedSubkey = new byte[subkeyLength];
Buffer.BlockCopy(hashedPassword, 13 + salt.Length, expectedSubkey, 0, expectedSubkey.Length);
// Hash the incoming password and verify it
byte[] actualSubkey = KeyDerivation.Pbkdf2(password, salt, prf, iterCount, subkeyLength);
return ByteArraysEqual(actualSubkey, expectedSubkey);
}
catch (Exception e)
{
// This should never occur except in the case of a malformed payload, where
// we might go off the end of the array. Regardless, a malformed payload
// implies verification failed.
LogBadFormatError(hashedPasswordString, "See exception.", e);
return false;
}
}
private static uint ReadNetworkByteOrder(byte[] buffer, int offset)
{
return ((uint)(buffer[offset + 0]) << 24)
| ((uint)(buffer[offset + 1]) << 16)
| ((uint)(buffer[offset + 2]) << 8)
| ((uint)(buffer[offset + 3]));
}
private static void WriteNetworkByteOrder(byte[] buffer, int offset, uint value)
{
buffer[offset + 0] = (byte)(value >> 24);
buffer[offset + 1] = (byte)(value >> 16);
buffer[offset + 2] = (byte)(value >> 8);
buffer[offset + 3] = (byte)(value >> 0);
}
}
}
|
