Add an aes_key_size config option that defaults to 256 for backward
compatability and support setting custom key sizes either in config
or when creating the instance of the SSL class

Signed-off-by: R.I.Pienaar <[email protected]>
---
Local-branch: feature/master/7191
 lib/mcollective/config.rb                |    8 ++++-
 lib/mcollective/ssl.rb                   |   16 +++++++--
 spec/unit/ssl_spec.rb                    |   47 +++++++++++++++++++++++++++++-
 website/changelog.md                     |    1 +
 website/reference/basic/configuration.md |    1 +
 5 files changed, 66 insertions(+), 7 deletions(-)

diff --git a/lib/mcollective/config.rb b/lib/mcollective/config.rb
index ea84166..fc8bfaf 100644
--- a/lib/mcollective/config.rb
+++ b/lib/mcollective/config.rb
@@ -8,7 +8,7 @@ module MCollective
                     :securityprovider, :factsource, :registration, 
:registerinterval, :topicsep,
                     :classesfile, :rpcauditprovider, :rpcaudit, :configdir, 
:rpcauthprovider,
                     :rpcauthorization, :color, :configfile, :rpchelptemplate, 
:rpclimitmethod,
-                    :logger_type, :fact_cache_time, :collectives, 
:main_collective
+                    :logger_type, :fact_cache_time, :collectives, 
:main_collective, :aes_key_size
 
         def initialize
             @configured = false
@@ -89,7 +89,10 @@ module MCollective
                                     @logger_type = val
                                 when "fact_cache_time"
                                     @fact_cache_time = val.to_i
-
+                                when "aes_key_size"
+                                    if [256, 192, 128].include?(val.to_i)
+                                        @aes_key_size = val.to_i
+                                    end
                                 else
                                     raise("Unknown config parameter #{key}")
                             end
@@ -143,6 +146,7 @@ module MCollective
             @loglevel = "info"
             @collectives = ["mcollective"]
             @main_collective = @collectives.first
+            @aes_key_size = 256
         end
 
         def read_plugin_config_dir(dir)
diff --git a/lib/mcollective/ssl.rb b/lib/mcollective/ssl.rb
index 3f31392..587a2f8 100644
--- a/lib/mcollective/ssl.rb
+++ b/lib/mcollective/ssl.rb
@@ -31,14 +31,22 @@ module MCollective
     # There are matching methods for using a public key to encrypt
     # data to be decrypted using a private key
     class SSL
-        attr_reader :public_key_file, :private_key_file
+        attr_reader :public_key_file, :private_key_file, :aes_key_size, 
:ssl_cipher
 
-        def initialize(pubkey=nil, privkey=nil, passphrase=nil)
+        def initialize(pubkey=nil, privkey=nil, passphrase=nil, 
aes_key_size=nil)
             @public_key_file = pubkey
             @private_key_file = privkey
 
             @public_key  = read_key(:public, pubkey)
             @private_key = read_key(:private, privkey, passphrase)
+
+            @aes_key_size = 256
+            @aes_key_size = Config.instance.aes_key_size if 
Config.instance.aes_key_size
+            @aes_key_size = aes_key_size if aes_key_size
+
+            raise "AES Key size can only be 128, 192 or 256 not 
'#{@aes_key_size}'" unless [128, 192, 256].include?(@aes_key_size)
+
+            @ssl_cipher = "aes-#{@aes_key_size}-cbc"
         end
 
         # Encrypts supplied data using AES and then encrypts using RSA
@@ -135,7 +143,7 @@ module MCollective
 
         # encrypts a string, returns a hash of key, iv and data
         def aes_encrypt(plain_string)
-            cipher = OpenSSL::Cipher::Cipher.new('aes-256-cbc')
+            cipher = OpenSSL::Cipher::Cipher.new(ssl_cipher)
             cipher.encrypt
 
             key = cipher.random_key
@@ -149,7 +157,7 @@ module MCollective
 
         # decrypts a string given key, iv and data
         def aes_decrypt(key, crypt_string)
-            cipher = OpenSSL::Cipher::Cipher.new('aes-256-cbc')
+            cipher = OpenSSL::Cipher::Cipher.new(ssl_cipher)
 
             cipher.decrypt
             cipher.key = key
diff --git a/spec/unit/ssl_spec.rb b/spec/unit/ssl_spec.rb
index 8b7b38e..1a81243 100644
--- a/spec/unit/ssl_spec.rb
+++ b/spec/unit/ssl_spec.rb
@@ -44,6 +44,39 @@ module MCollective
             @ssl.decrypt_with_public(@ssl.encrypt_with_private("foo", false), 
false).should == "foo"
         end
 
+        describe "#initialize" do
+            it "should default to 256 bit AES" do
+                @ssl.aes_key_size.should == 256
+                @ssl.ssl_cipher.should == "aes-256-cbc"
+            end
+
+            it "should take the configured value when present" do
+                Config.any_instance.stubs("aes_key_size").returns(128)
+                @ssl = SSL.new("#{@rootdir}/../fixtures/test-public.pem", 
"#{@rootdir}/../fixtures/test-private.pem")
+
+                @ssl.aes_key_size.should == 128
+                @ssl.ssl_cipher.should == "aes-128-cbc"
+            end
+
+            it "should set the supplied AES key size" do
+                @ssl = SSL.new("#{@rootdir}/../fixtures/test-public.pem", 
"#{@rootdir}/../fixtures/test-private.pem", nil, 128)
+                @ssl.aes_key_size.should == 128
+            end
+
+            it "should prefer the supplied key size over configured key size" 
do
+                Config.any_instance.stubs("aes_key_size").returns(193)
+                @ssl = SSL.new("#{@rootdir}/../fixtures/test-public.pem", 
"#{@rootdir}/../fixtures/test-private.pem", nil, 128)
+
+                @ssl.aes_key_size.should == 128
+            end
+
+            it "should fail on invalid key sizes" do
+                expect {
+                    @ssl = SSL.new("#{@rootdir}/../fixtures/test-public.pem", 
"#{@rootdir}/../fixtures/test-private.pem", nil, 1)
+                }.to raise_error("AES Key size can only be 128, 192 or 256 not 
'1'")
+            end
+        end
+
         describe "#read_key" do
             it "should fail on non exiting files" do
                 expect {
@@ -94,12 +127,24 @@ module MCollective
         end
 
         describe "#aes_decrypt" do
-            it "should decrypted correctly given key and data" do
+            it "should decrypt correctly given key and data" do
                 key = 
@ssl.base64_decode("rAaCyW6qB0XqZNa9hji0qHwrI3P47t8diLNXoemW9ss=")
                 data = @ssl.base64_decode("mSthvO/wSl0ArNOcgysTVw==")
 
                 @ssl.aes_decrypt(key, data).should == "foo"
             end
+
+            it "should decrypt correctly given key, data and key size" do
+                key = @ssl.base64_decode("VEma3a/R7fjw2M4d0NIctA==")
+                data = @ssl.base64_decode("FkH6qLvKTn7a+uNPe8ciHA==")
+
+                # the default 256 should fail here, the key above is 128 bit
+                expect { @ssl.aes_decrypt(key, data) }.to raise_error(/key 
length too short: no start line/)
+
+                # new ssl instance configured for 128, should work
+                @ssl = SSL.new("#{@rootdir}/../fixtures/test-public.pem", 
"#{@rootdir}/../fixtures/test-private.pem", nil, 128)
+                @ssl.aes_decrypt(key, data).should == "foo"
+            end
         end
 
         describe "#decrypt_with_public" do
diff --git a/website/changelog.md b/website/changelog.md
index 365cde7..d9f7db5 100644
--- a/website/changelog.md
+++ b/website/changelog.md
@@ -11,6 +11,7 @@ title: Changelog
 
 |Date|Description|Ticket|
 |----|-----------|------|
+|2011/04/20|Make the AES key size configurable using the aes_key_size config 
option|7191|
 |2011/04/20|Add a clear method to the PluginManager that deletes all plugins, 
improve test isolation|7176|
 |2011/04/19|Abstract the creation of request and reply hashes to simplify 
connector plugin development|5701|
 |2011/04/15|Improve the shellsafe validator and add a Util method to do shell 
escaping|7066|
diff --git a/website/reference/basic/configuration.md 
b/website/reference/basic/configuration.md
index 1598a27..26e3b3b 100644
--- a/website/reference/basic/configuration.md
+++ b/website/reference/basic/configuration.md
@@ -42,6 +42,7 @@ Configuration is a simple *key = val* style configuration 
file.
 |securityprovider|Psk|Which security model to use, see [SSL Security 
Plugin][SSLSecurity] and [AES Security Plugin][AESSecurity] for details on 
others|
 |rpchelptemplate|/etc/mcollective/rpc-help.erb|The path to the erb template 
used for generating help|
 |loggertype|file|Valid logger types, currently file, syslog or console|
+|aes_key_size|256|Sets the key size in use for AES encryption, should be set 
the same everywhere|
 
 ## Server Configuration
 The server configuration file should be root only readable
-- 
1.7.1

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