Information security programming in ruby

Information Security
Programming in Ruby
@nahi

@nahi - Twitter, Github
Software Engineer at https://www.treasuredata.com
OSS developer and enthusiast;
committer of CRuby and JRuby
Information Security Specialist

Information Security
Programming in Ruby
scripts:
https://github.com/nahi/ruby-crypt/tree/master/odrk05

References
JUS 2003 “PKI入門 - Ruby/OpenSSLを触りながら学ぶPKI”
https://github.com/nahi/ruby-crypt/raw/master/jus-pki.ppt
RubyKaigi 2006 “セキュアアプリケーションプログラミング”
https://github.com/nahi/ruby-
crypt/blob/master/rubykaigi2006/RubyKaigi2006_SAP_20060610.pdf
RubyConf 2012 “Ruby HTTP clients comparison”
http://www.slideshare.net/HiroshiNakamura/rubyhttp-clients-comparison

Information Security Programming
Confidentially
Authentication
Integrity
(Availability)
(Privacy)

(D) S for external C
[F] Encryption in S
[G] Encryption in C
[E] authentication
(C) S for internal C
(B) C for external S
7 Implementation Patterns
(A) C for internal S
(A)
(A)
(B)
(B)
(C)
(D)
[F]
[G]
[E]
[E]
Orange: Implementation target
Gray: External system

… in Ruby
[E] authentication
[F] Encryption in S
[G] Encryption in C
(A)
(A)
(B)
(B)
(C)
[E]
[F]
[G]
(D)
[E]
Blue: Acceptable
Orange: Pitfalls
Red: No way

Protected communication
Fixed server authentication
➔ SSL configuration:
CBC, SSLv3.0, compression,
TLSv1.0, RC4, DHE1024, …
➔ Fails for wrong endpoint
(A)
(A)

SSL configuration
require 'httpclient'
client = HTTPClient.new
client.get('https://www.ruby-lang.org/en/').status
% ruby a1.rb
ok: "/C=BE/O=GlobalSign nv-sa/OU=Root CA/CN=GlobalSign Root CA"
ok: "/C=BE/O=GlobalSign nv-sa/CN=GlobalSign Domain Validation CA -
SHA256 - G2"
ok: "/OU=Domain Control Validated/CN=*.ruby-lang.org"
Protocol version: TLSv1.2
Cipher: ["ECDHE-RSA-AES128-GCM-SHA256", "TLSv1/SSLv3", 128, 128]
State: SSLOK : SSL negotiation finished successfully

Fails for wrong endpoint
client.get('https://hyogo-9327.herokussl.com/en/').status
% ruby -d a2.rb
ok: "/C=BE/O=GlobalSign nv-sa/OU=Root CA/CN=GlobalSign Root CA"
ok: "/C=BE/O=GlobalSign nv-sa/CN=GlobalSign Domain Validation CA -
SHA256 - G2"
ok: "/OU=Domain Control Validated/CN=*.ruby-lang.org"
Protocol version: TLSv1.2
Cipher: ["ECDHE-RSA-AES128-GCM-SHA256", "TLSv1/SSLv3", 128, 128]
State: SSLOK : SSL negotiation finished successfully
Exception `OpenSSL::SSL::SSLError' - hostname "hyogo-9327.
herokussl.com" does not match the server certificate

require 'aws-sdk'
class KMSEncryptor
CTX = { 'purpose' => 'odrk05 demonstration' }
GCM_IV_SIZE = 12; GCM_TAG_SIZE = 16
def initialize(region, key_id)
@region, @key_id = region, key_id
@kms = Aws::KMS::Client.new(region: @region)
end
def generate_data_key
resp = @kms.generate_data_key_without_plaintext(
key_id: @key_id, encryption_context: CTX, key_spec: 'AES_128'
)
resp.ciphertext_blob
end
def with_key(wrapped_key)
key = nil
begin
key = @kms.decrypt(
ciphertext_blob: wrapped_key, encryption_context: CTX
).plaintext
yield key
ensure
# TODO: confirm that key is deleted from memory
key.tr!("0-xff".force_encoding('BINARY'), "0")
end
end

Fails for weak connection
client.ssl_config.ssl_version = :TLSv1_2
client.get('https://localhost:17443/').status
=begin
% ruby a3.rb
SSL_connect returned=1 errno=0 state=SSLv3 read server hello A:
wrong version number (OpenSSL::SSL::SSLError)
=end

Net::HTTP sample
require 'net/https'
class NetHTTPClient < Net::HTTP
def do_start
if $DEBUG && @use_ssl
self.verify_callback = HTTPClient::SSLConfig.new(nil).
method(:default_verify_callback)
end
super
end
def on_connect
if $DEBUG && @use_ssl
ssl_socket = @socket.io
if ssl_socket.respond_to?(:ssl_version)
warn("Protocol version: #{ssl_socket.ssl_version}")
end
warn("Cipher: #{ssl_socket.cipher.inspect}")
warn("State: #{ssl_socket.state}")
end
super
end
end
# =>
# =>
client = NetHTTPClient.new(
"www.ruby-lang.org", 443)
client.use_ssl = true
client.cert_store =
store = OpenSSL::X509::Store.new
store.set_default_paths
client.get("/")

Restricted server authentication
➔ SSL configuration
➔ Fails for revoked server
(A)
(A)
(B)
(B)

Revocation check
require 'httpclient' # >= 2.7.0
client.get('https://test-sspev.verisign.com:2443/test-SSPEV-
revoked-verisign.html').status
% ruby b.rb # => 200
% jruby b.rb # => 200
% jruby -J-Dcom.sun.security.enableCRLDP=true
-J-Dcom.sun.net.ssl.checkRevocation=true b.rb
OpenSSL::SSL::SSLError:
sun.security.validator.ValidatorException: PKIX path validation
failed: java.security.cert.CertPathValidatorException: Certificate
has been revoked, reason: UNSPECIFIED, revocation date: Thu Oct 30
06:29:37 JST 2014, authority: CN=Symantec Class 3 EV SSL CA - G3,
OU=Symantec Trust Network, O=Symantec Corporation, C=US
OpenSSL...?

Restricted client authentication
➔ Server key management
➔ Certificate rotation
➔ Fails for unexpected clients
(C)

WEBrick SSL server
require 'webrick/https'
require 'logger'
logger = Logger.new(STDERR)
server = WEBrick::HTTPServer.new(
BindAddress: "localhost",
Logger: logger,
Port: 17443,
DocumentRoot: '/dev/null',
SSLEnable: true,
SSLCACertificateFile: 'ca-chain.cert',
SSLCertificate:
OpenSSL::X509::Certificate.new(
File.read('server.cert')),
SSLPrivateKey: OpenSSL::PKey::RSA.new(
File.read('server.key')),
)
basic_auth=WEBrick::HTTPAuth::BasicAuth.new(
Logger: logger,
Realm: 'auth',
UserDB: WEBrick::HTTPAuth::Htpasswd.new(
'htpasswd')
)
# =>
# =>
server.mount('/hello',
WEBrick::HTTPServlet::ProcHandler.new(
->(req, res) {
basic_auth.authenticate(req, res)
res['content-type'] = 'text/plain'
res.body = 'hello'
})
)
trap(:INT) do
server.shutdown
end
t = Thread.new {
Thread.current.abort_on_exception =
true
server.start
}
while server.status != :Running
sleep 0.1
raise unless t.alive?
end
puts $$
t.join

Client authentication
➔ Server key management
➔ Certificate rotation
➔ Fails for unexpected clients
➔ Recovery from key compromise
You have better solutions (Apache, Nginx, ELB, …)
(C)
(D)

Client authentication
On unprotected network
➔ Cipher algorithm
➔ Tamper detection
➔ Constant time operation
Use well-known library
[E] authentication
[E]
[E]

Data protection at rest
➔ Cipher algorithm
➔ Encryption key management
◆ Storage
◆ Usage authn / authz
◆ Usage auditing
◆ Rotation
➔ Tamper detection
➔ Processing throughput / latency
[F] Encryption in S / [G] in C
[F]
[G]

def encrypt(wrapped_key, plaintext)
with_key(wrapped_key) do |key|
cipher = OpenSSL::Cipher::Cipher.new('aes-128-gcm')
iv = OpenSSL::Random.random_bytes(GCM_IV_SIZE)
cipher.encrypt; cipher.key = key;cipher.iv = iv
iv + cipher.update(plaintext) + cipher.final
end
end
def decrypt(wrapped_key, ciphertext)
iv, data = ciphertext.unpack("a#{GCM_IV_SIZE}a*")
auth_tag = data.slice!(data.bytesize - GCM_TAG_SIZE, GCM_TAG_SIZE)
cipher = OpenSSL::Cipher::Cipher.new('aes-128-gcm')
cipher.decrypt; cipher.key = key; cipher.iv = iv
cipher.auth_tag = auth_tag
cipher.update(data) + cipher.final
end
end
end
encryptor = KMSEncryptor.new('ap-northeast-1', 'alias/nahi-test-tokyo')
# generate key for each data, customer, or something
wrapped_key = encryptor.generate_data_key
plaintext = File.read(__FILE__)
ciphertext = encryptor.encrypt(wrapped_key, plaintext)
# save wrapped_key and ciphertext in DB, File or somewhere
# restore wrapped_key and ciphertext from DB, File or somewhere
puts encryptor.decrypt(wrapped_key, ciphertext)
jruby-openssl does not
support aes-gcm…
-> next page

if defined?(JRuby)
require 'java'
java_import 'javax.crypto.Cipher'
java_import 'javax.crypto.SecretKey'
java_import 'javax.crypto.spec.SecretKeySpec'
java_import 'javax.crypto.spec.GCMParameterSpec'
class KMSEncryptor
# Overrides
def encrypt(wrapped_key, plaintext)
cipher = Cipher.getInstance('AES/GCM/PKCS5Padding')
iv = OpenSSL::Random.random_bytes(GCM_IV_SIZE)
spec = GCMParameterSpec.new(GCM_TAG_SIZE * 8, iv.to_java_bytes)
cipher.init(1, SecretKeySpec.new(key.to_java_bytes, 0, key.bytesize, 'AES'), spec)
ciphertext = String.from_java_bytes(
cipher.doFinal(plaintext.to_java_bytes), Encoding::BINARY)
iv + ciphertext
end
end
# Overrides
def decrypt(wrapped_key, ciphertext)
cipher = Cipher.getInstance('AES/GCM/PKCS5Padding')
iv, data = ciphertext.unpack("a#{GCM_IV_SIZE}a*")
spec = GCMParameterSpec.new(GCM_TAG_SIZE * 8, iv.to_java_bytes)
cipher.init(2, SecretKeySpec.new(key.to_java_bytes, 0, key.bytesize, 'AES'), spec)
String.from_java_bytes(cipher.doFinal(data.to_java_bytes), Encoding::BINARY)
end
end
end
end
aes-128-gcm in JRuby!

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