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
|
require 'securerandom'
module Net
module SSH
module Authentication
# Class for representing an SSH certificate.
#
# http://cvsweb.openbsd.org/cgi-bin/cvsweb/~checkout~/src/usr.bin/ssh/PROTOCOL.certkeys?rev=1.10&content-type=text/plain
class Certificate
attr_accessor :nonce
attr_accessor :key
attr_accessor :serial
attr_accessor :type
attr_accessor :key_id
attr_accessor :valid_principals
attr_accessor :valid_after
attr_accessor :valid_before
attr_accessor :critical_options
attr_accessor :extensions
attr_accessor :reserved
attr_accessor :signature_key
attr_accessor :signature
# Read a certificate blob associated with a key of the given type.
def self.read_certblob(buffer, type)
cert = Certificate.new
cert.nonce = buffer.read_string
cert.key = buffer.read_keyblob(type)
cert.serial = buffer.read_int64
cert.type = type_symbol(buffer.read_long)
cert.key_id = buffer.read_string
cert.valid_principals = buffer.read_buffer.read_all(&:read_string)
cert.valid_after = Time.at(buffer.read_int64)
cert.valid_before = if RUBY_PLATFORM == "java"
# 0x20c49ba5e353f7 = 0x7fffffffffffffff/1000, the largest value possible for JRuby
# JRuby Time.at multiplies the arg by 1000, and then stores it in a signed long.
# 0x20c49ba2d52500 = 292278993-01-01 00:00:00 +0000
# JRuby 9.1 does not accept the year 292278994 because of edge cases (https://github.com/JodaOrg/joda-time/issues/190)
Time.at([0x20c49ba2d52500, buffer.read_int64].min)
else
Time.at(buffer.read_int64)
end
cert.critical_options = read_options(buffer)
cert.extensions = read_options(buffer)
cert.reserved = buffer.read_string
cert.signature_key = buffer.read_buffer.read_key
cert.signature = buffer.read_string
cert
end
def ssh_type
key.ssh_type + "-cert-v01@openssh.com"
end
def ssh_signature_type
key.ssh_type
end
# Serializes the certificate (and key).
def to_blob
Buffer.from(
:raw, to_blob_without_signature,
:string, signature
).to_s
end
def ssh_do_sign(data)
key.ssh_do_sign(data)
end
def ssh_do_verify(sig, data, options = {})
key.ssh_do_verify(sig, data, options)
end
def to_pem
key.to_pem
end
def fingerprint
key.fingerprint
end
# Signs the certificate with key.
def sign!(key, sign_nonce = nil)
# ssh-keygen uses 32 bytes of nonce.
self.nonce = sign_nonce || SecureRandom.random_bytes(32)
self.signature_key = key
self.signature = Net::SSH::Buffer.from(
:string, key.ssh_signature_type,
:mstring, key.ssh_do_sign(to_blob_without_signature)
).to_s
self
end
def sign(key, sign_nonce = nil)
cert = clone
cert.sign!(key, sign_nonce)
end
# Checks whether the certificate's signature was signed by signature key.
def signature_valid?
buffer = Buffer.new(signature)
buffer.read_string # skip signature format
signature_key.ssh_do_verify(buffer.read_string, to_blob_without_signature)
end
def self.read_options(buffer)
names = []
options = buffer.read_buffer.read_all do |b|
name = b.read_string
names << name
data = b.read_string
data = Buffer.new(data).read_string unless data.empty?
[name, data]
end
raise ArgumentError, "option/extension names must be in sorted order" if names.sort != names
Hash[options]
end
private_class_method :read_options
def self.type_symbol(type)
types = { 1 => :user, 2 => :host }
raise ArgumentError("unsupported type: #{type}") unless types.include?(type)
types.fetch(type)
end
private_class_method :type_symbol
private
def type_value(type)
types = { user: 1, host: 2 }
raise ArgumentError("unsupported type: #{type}") unless types.include?(type)
types.fetch(type)
end
def ssh_time(t)
# Times in certificates are represented as a uint64.
[[t.to_i, 0].max, 2 << 64 - 1].min
end
def to_blob_without_signature
Buffer.from(
:string, ssh_type,
:string, nonce,
:raw, key_without_type,
:int64, serial,
:long, type_value(type),
:string, key_id,
:string, valid_principals.inject(Buffer.new) { |acc, elem| acc.write_string(elem) }.to_s,
:int64, ssh_time(valid_after),
:int64, ssh_time(valid_before),
:string, options_to_blob(critical_options),
:string, options_to_blob(extensions),
:string, reserved,
:string, signature_key.to_blob
).to_s
end
def key_without_type
# key.to_blob gives us e.g. "ssh-rsa,<key>" but we just want "<key>".
tmp = Buffer.new(key.to_blob)
tmp.read_string # skip the underlying key type
tmp.read
end
def options_to_blob(options)
options.keys.sort.inject(Buffer.new) do |b, name|
b.write_string(name)
data = options.fetch(name)
data = Buffer.from(:string, data).to_s unless data.empty?
b.write_string(data)
end.to_s
end
end
end
end
end
|