forked from nektro/zig-asn1
-
Notifications
You must be signed in to change notification settings - Fork 0
/
kerberos.zig
144 lines (126 loc) · 5.94 KB
/
kerberos.zig
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
const std = @import("std");
const asn1 = @import("asn1.zig");
const Tag = asn1.Tag;
pub fn encodeAsReq(buffer: []u8, user_name: []const u8, realm: []const u8) ![]const u8 {
std.debug.assert(user_name.len <= 100);
std.debug.assert(realm.len <= 100);
var fbs_write = std.io.fixedBufferStream(buffer);
const w = fbs_write.writer();
// Length of the entire packet
try w.writeInt(u32, 0xffff_ffff, .big); // Dummy value, computed later
// AS-REQ ::= [APPLICATION 10] KDC-REQ
try w.writeByte(Tag.extra(.constructed, .application, 10).int());
try w.writeByte(0b1000_0010); // 2-bytes length
try w.writeInt(u16, 0xffff, .big); // Dummy value, computed later, offset: 6
// KDC-REQ ::= SEQUENCE {
try w.writeByte(@intFromEnum(Tag.sequence));
try w.writeByte(0b1000_0010); // 2-bytes length
try w.writeInt(u16, 0xffff, .big); // Dummy value, computed later, offset: 10
// pvno [1] INTEGER (5) , (version)
try w.writeByte(Tag.extra(.constructed, .context, 1).int());
try w.writeByte(3);
try w.writeByte(@intFromEnum(Tag.integer));
try w.writeByte(1);
try w.writeByte(5);
// msg-type [2] INTEGER (10 -- AS -- | 12 -- TGS --),
try w.writeByte(Tag.extra(.constructed, .context, 2).int());
try w.writeByte(3);
try w.writeByte(@intFromEnum(Tag.integer));
try w.writeByte(1);
try w.writeByte(10);
// req-body [4] KDC-REQ-BODY
try w.writeByte(Tag.extra(.constructed, .context, 4).int());
try w.writeByte(0b1000_0010); // 2-bytes length
try w.writeInt(u16, 0xffff, .big); // Dummy value, computed later, offset: 24
// KDC-REQ-BODY ::= SEQUENCE {
try w.writeByte(@intFromEnum(Tag.sequence));
try w.writeByte(0b1000_0010); // 2-bytes length
try w.writeInt(u16, 0xffff, .big); // Dummy value, computed later, offset: 28
// kdc-options [0] KDCOptions,
try w.writeByte(Tag.extra(.constructed, .context, 0).int());
try w.writeByte(7);
try w.writeByte(@intFromEnum(Tag.bit_string));
try w.writeByte(5);
try w.writeByte(0); // padding
try w.writeInt(u32, 0x40000000, .big);
// cname [1] PrincipalName OPTIONAL
try w.writeByte(Tag.extra(.constructed, .context, 1).int());
try w.writeByte(@intCast(user_name.len + 13));
try w.writeByte(@intFromEnum(Tag.sequence));
try w.writeByte(@intCast(user_name.len + 11));
try w.writeByte(Tag.extra(.constructed, .context, 0).int());
try w.writeByte(3);
try w.writeByte(@intFromEnum(Tag.integer));
try w.writeByte(1);
try w.writeByte(1); // type == 1 (NT-PRINCIPAL)
try w.writeByte(Tag.extra(.constructed, .context, 1).int());
try w.writeByte(@intCast(user_name.len + 4));
try w.writeByte(@intFromEnum(Tag.sequence));
try w.writeByte(@intCast(user_name.len + 2));
try w.writeByte(@intFromEnum(Tag.general_string));
try w.writeByte(@intCast(user_name.len));
try w.writeAll(user_name);
// realm [2] Realm
try w.writeByte(Tag.extra(.constructed, .context, 2).int());
try w.writeByte(@intCast(realm.len + 2));
try w.writeByte(@intFromEnum(Tag.general_string));
try w.writeByte(@intCast(realm.len));
try w.writeAll(realm);
// sname [3] PrincipalName OPTIONAL,
try w.writeByte(Tag.extra(.constructed, .context, 3).int());
try w.writeByte(@intCast(realm.len + 21));
try w.writeByte(@intFromEnum(Tag.sequence));
try w.writeByte(@intCast(realm.len + 19));
try w.writeByte(Tag.extra(.constructed, .context, 0).int());
try w.writeByte(3);
try w.writeByte(@intFromEnum(Tag.integer));
try w.writeByte(1);
try w.writeByte(2); // type == 2 (NT-SRV-INST)
try w.writeByte(Tag.extra(.constructed, .context, 1).int());
try w.writeByte(@intCast(realm.len + 12));
try w.writeByte(@intFromEnum(Tag.sequence));
try w.writeByte(@intCast(realm.len + 10));
try w.writeByte(@intFromEnum(Tag.general_string));
try w.writeByte("krbtgt".len);
try w.writeAll("krbtgt");
try w.writeByte(@intFromEnum(Tag.general_string));
try w.writeByte(@intCast(realm.len));
try w.writeAll(realm);
// till [5] KerberosTime,
try w.writeByte(Tag.extra(.constructed, .context, 5).int());
try w.writeByte(17);
try w.writeByte(@intFromEnum(Tag.generalized_time));
try w.writeByte(15);
try w.writeAll("19700101000000Z"); // No expiration date
// nonce [7] UInt32,
try w.writeByte(Tag.extra(.constructed, .context, 7).int());
try w.writeByte(6);
try w.writeByte(@intFromEnum(Tag.integer));
try w.writeByte(4);
try w.writeInt(u32, 155874945, .big);
// etype [8] SEQUENCE OF Int32 -- EncryptionType
try w.writeByte(Tag.extra(.constructed, .context, 8).int());
try w.writeByte(14);
try w.writeByte(@intFromEnum(Tag.sequence));
try w.writeByte(12);
try w.writeByte(@intFromEnum(Tag.integer));
try w.writeByte(1);
try w.writeByte(18); // { ['aes256-cts-hmac-sha1-96'] = 18 },
try w.writeByte(@intFromEnum(Tag.integer));
try w.writeByte(1);
try w.writeByte(17); // { ['aes128-cts-hmac-sha1-96'] = 17 },
try w.writeByte(@intFromEnum(Tag.integer));
try w.writeByte(1);
try w.writeByte(16); // { ['des3-cbc-sha1'] = 16 },
try w.writeByte(@intFromEnum(Tag.integer));
try w.writeByte(1);
try w.writeByte(23); // { ['rc4-hmac'] = 23 },
// Fixups
const total_len: u32 = @intCast(fbs_write.getWritten().len);
std.mem.writeInt(u32, buffer[0..4], total_len - 4, .big);
std.mem.writeInt(u16, buffer[6..8], @intCast(total_len - 8), .big);
std.mem.writeInt(u16, buffer[10..12], @intCast(total_len - 12), .big);
std.mem.writeInt(u16, buffer[24..26], @intCast(total_len - 26), .big);
std.mem.writeInt(u16, buffer[28..30], @intCast(total_len - 30), .big);
return fbs_write.getWritten();
}