/
salmon.rb
233 lines (190 loc) · 6.6 KB
/
salmon.rb
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
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
# Copyright (c) 2010, Disapora Inc. This file is
# licensed under the Affero General Public License version 3. See
# the COPYRIGHT file.
# Add URL safe Base64 support
module Base64
module_function
# Returns the Base64-encoded version of +bin+.
# This method complies with RFC 4648.
# No line feeds are added.
def strict_encode64(bin)
[bin].pack("m0")
end
# Returns the Base64-decoded version of +str+.
# This method complies with RFC 4648.
# ArgumentError is raised if +str+ is incorrectly padded or contains
# non-alphabet characters. Note that CR or LF are also rejected.
def strict_decode64(str)
str.unpack("m0").first
end
# Returns the Base64-encoded version of +bin+.
# This method complies with ``Base 64 Encoding with URL and Filename Safe
# Alphabet'' in RFC 4648.
# The alphabet uses '-' instead of '+' and '_' instead of '/'.
def urlsafe_encode64(bin)
strict_encode64(bin).tr("+/", "-_")
end
# Returns the Base64-decoded version of +str+.
# This method complies with ``Base 64 Encoding with URL and Filename Safe
# Alphabet'' in RFC 4648.
# The alphabet uses '-' instead of '+' and '_' instead of '/'.
def urlsafe_decode64(str)
strict_decode64(str.tr("-_", "+/"))
end
end
# Verify documents secured with Magic Signatures
module Salmon
class SalmonSlap
attr_accessor :magic_sig, :author, :author_email, :data, :data_type, :sig
def self.parse(xml)
slap = self.new
doc = Nokogiri::XML(xml)
sig_doc = doc.search('entry')
slap.magic_sig = MagicSigEnvelope.parse sig_doc
if 'base64url' == slap.magic_sig.encoding
slap.data = decode64url(slap.magic_sig.data)
slap.sig = slap.magic_sig.sig
else
raise ArgumentError, "Magic Signature data must be encoded with base64url, was #{slap.magic_sig.encoding}"
end
slap.data_type = slap.magic_sig.data_type
raise ArgumentError, "Magic Signature data must be signed with RSA-SHA256, was #{slap.magic_sig.alg}" unless 'RSA-SHA256' == slap.magic_sig.alg
uri = doc.search('uri').text
slap.author_email = uri.split("acct:").last
slap
end
def self.create(user, activity)
salmon = self.new
salmon.author = user.person
salmon.magic_sig = MagicSigEnvelope.create(user , activity)
salmon
end
def to_xml
xml =<<ENTRY
<?xml version='1.0' encoding='UTF-8'?>
<entry xmlns='http://www.w3.org/2005/Atom'>
<author>
<name>#{@author.real_name}</name>
<uri>acct:#{@author.diaspora_handle}</uri>
</author>
#{@magic_sig.to_xml}
</entry>
ENTRY
end
def author
if @author
@author
else
Person.by_webfinger @author_email
end
end
# Decode URL-safe-Base64. This implements
def self.decode64url(str)
# remove whitespace
sans_whitespace = str.gsub(/\s/, '')
# pad to a multiple of 4
string = sans_whitespace + '=' * ((4 - sans_whitespace.size) % 4)
# convert to standard Base64
# string = padded.tr('-','+').tr('_','/')
# Base64.decode64(string)
Base64.urlsafe_decode64 string
end
# def verified?
#
# end
# Check whether this envelope's signature can be verified with the
# provided OpenSSL::PKey::RSA public_key.
# Example:
#
# env.verified_for_key? OpenSSL::PKey::RSA.new(File.open('public_key.pem'))
# # -> true
def verified_for_key?(public_key)
signature = Base64.urlsafe_decode64(self.magic_sig.sig)
signed_data = self.magic_sig.signable_string# Base64.urlsafe_decode64(self.magic_sig.signable_string)
public_key.verify(OpenSSL::Digest::SHA256.new, signature, signed_data )
end
# Decode a string containing URL safe Base64 into an integer
# Example:
#
# MagicSig.b64_to_n('AQAB')
# # -> 645537
def self.b64_to_n(str)
packed = decode64url(str)
packed.unpack('B*')[0].to_i(2)
end
# Parse a string containing a magic-public-key into an OpenSSL::PKey::RSA key.
# Example:
#
# key = MagicSig.parse_key('RSA.mVgY8RN6URBTstndvmUUPb4UZTdwvwmddSKE5z_jvKUEK6yk1u3rrC9yN8k6FilGj9K0eeUPe2hf4Pj-5CmHww.AQAB')
# key.n
# # -> 8031283789075196565022891546563591368344944062154100509645398892293433370859891943306439907454883747534493461257620351548796452092307094036643522661681091
# key.e
# # -> 65537
def self.parse_key(str)
n,e = str.match(/^RSA.([^.]*).([^.]*)$/)[1..2]
build_key(b64_to_n(n),b64_to_n(e))
end
# Take two integers e, n and create a new OpenSSL::PKey::RSA key with them
# Example:
#
# n = 9487834027867356975347184933768917275269369900665861930617802608089634337052392076689226301419587057117740995382286148368168197915234368486155306558161867
# e = 65537
# key = MagicSig.build_key(n,e)
# key.public_encrypt(...) # for sending to strangers
# key.public_decrypt(...) # very rarely used
# key.verify(...) # for verifying signatures
def self.build_key(n,e)
key = OpenSSL::PKey::RSA.new
key.n = n
key.e = e
key
end
end
class MagicSigEnvelope
attr_accessor :data, :data_type, :encoding, :alg, :sig, :author
def self.parse(doc)
env = self.new
ns = {'me'=>'http://salmon-protocol.org/ns/magic-env'}
env.encoding = doc.search('//me:env/me:encoding', ns).text.strip
env.data = doc.search('//me:env/me:data', ns).text
env.alg = doc.search('//me:env/me:alg', ns).text.strip
env.sig = doc.search('//me:env/me:sig', ns).text
env.data_type = doc.search('//me:env/me:data', ns).first['type'].strip
env
end
def self.create(user, activity)
env = MagicSigEnvelope.new
env.author = user.person
env.data = Base64.urlsafe_encode64(activity)
env.data_type = env.get_data_type
env.encoding = env.get_encoding
env.alg = env.get_alg
env.sig = Base64.urlsafe_encode64(
user.encryption_key.sign OpenSSL::Digest::SHA256.new, env.signable_string )
env
end
def signable_string
[@data, Base64.urlsafe_encode64(@data_type),Base64.urlsafe_encode64(@encoding), Base64.urlsafe_encode64(@alg)].join(".")
end
def to_xml
xml= <<ENTRY
<me:env xmlns:me="http://salmon-protocol.org/ns/magic-env">
<me:data type='#{@data_type}'>#{@data}</me:data>
<me:encoding>#{@encoding}</me:encoding>
<me:alg>#{@alg}</me:alg>
<me:sig>#{@sig}</me:sig>
</me:env>
ENTRY
xml
end
def get_encoding
'base64url'
end
def get_data_type
'application/atom+xml'
end
def get_alg
'RSA-SHA256'
end
end
end