diff --git a/.travis.yml b/.travis.yml
index a934724e..26dea44d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -17,7 +17,7 @@ env:
 before_script:
   - travis/setup-secure-shell.sh
   - sh -c "if [ '$TRAVIS_PHP_VERSION' != 'hhvm' ]; then travis/install-php-extensions.sh; fi"
-  - sh -c "if [ '$TRAVIS_PHP_VERSION' = '5.5' ]; then composer install --dev --no-interaction; fi"
+  - sh -c "if [ '$TRAVIS_PHP_VERSION' != '5.2' ]; then travis/setup-composer.sh; fi"
 
 script:
   - sh -c "if [ '$TRAVIS_PHP_VERSION' = '5.5' ]; then vendor/bin/phpcs -s --extensions=php --standard=build/code-sniffer-ruleset.xml phpseclib/; fi"
diff --git a/composer.json b/composer.json
index 0b0789f9..14e01f6a 100644
--- a/composer.json
+++ b/composer.json
@@ -49,6 +49,7 @@
         "php": ">=5.3.0"
     },
     "require-dev": {
+        "phpunit/phpunit": "4.0.*",
         "squizlabs/php_codesniffer": "1.*"
     },
     "suggest": {
diff --git a/composer.lock b/composer.lock
index 1b5ff07e..94aa5131 100644
--- a/composer.lock
+++ b/composer.lock
@@ -3,11 +3,592 @@
         "This file locks the dependencies of your project to a known state",
         "Read more about it at http://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file"
     ],
-    "hash": "4975b8cde04a99d6e78e108753845af6",
+    "hash": "47815ecdbeb5586e01973e3e961c4b14",
     "packages": [
 
     ],
     "packages-dev": [
+        {
+            "name": "phpunit/php-code-coverage",
+            "version": "2.0.5",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/sebastianbergmann/php-code-coverage.git",
+                "reference": "3dcca2120451b98a98fe60221ca279a184ee64db"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/sebastianbergmann/php-code-coverage/zipball/3dcca2120451b98a98fe60221ca279a184ee64db",
+                "reference": "3dcca2120451b98a98fe60221ca279a184ee64db",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.3",
+                "phpunit/php-file-iterator": "~1.3.1",
+                "phpunit/php-text-template": "~1.2",
+                "phpunit/php-token-stream": "~1.2.2",
+                "sebastian/environment": "~1.0",
+                "sebastian/version": "~1.0.3"
+            },
+            "require-dev": {
+                "ext-xdebug": ">=2.1.4",
+                "phpunit/phpunit": ">=4.0.0,<4.1.0"
+            },
+            "suggest": {
+                "ext-dom": "*",
+                "ext-xdebug": ">=2.2.1"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "2.0.x-dev"
+                }
+            },
+            "autoload": {
+                "classmap": [
+                    "src/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "include-path": [
+                ""
+            ],
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sb@sebastian-bergmann.de",
+                    "role": "lead"
+                }
+            ],
+            "description": "Library that provides collection, processing, and rendering functionality for PHP code coverage information.",
+            "homepage": "https://github.com/sebastianbergmann/php-code-coverage",
+            "keywords": [
+                "coverage",
+                "testing",
+                "xunit"
+            ],
+            "time": "2014-03-28 10:54:55"
+        },
+        {
+            "name": "phpunit/php-file-iterator",
+            "version": "1.3.4",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/sebastianbergmann/php-file-iterator.git",
+                "reference": "acd690379117b042d1c8af1fafd61bde001bf6bb"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/sebastianbergmann/php-file-iterator/zipball/acd690379117b042d1c8af1fafd61bde001bf6bb",
+                "reference": "acd690379117b042d1c8af1fafd61bde001bf6bb",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.3"
+            },
+            "type": "library",
+            "autoload": {
+                "classmap": [
+                    "File/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "include-path": [
+                ""
+            ],
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sb@sebastian-bergmann.de",
+                    "role": "lead"
+                }
+            ],
+            "description": "FilterIterator implementation that filters files based on a list of suffixes.",
+            "homepage": "https://github.com/sebastianbergmann/php-file-iterator/",
+            "keywords": [
+                "filesystem",
+                "iterator"
+            ],
+            "time": "2013-10-10 15:34:57"
+        },
+        {
+            "name": "phpunit/php-text-template",
+            "version": "1.2.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/sebastianbergmann/php-text-template.git",
+                "reference": "206dfefc0ffe9cebf65c413e3d0e809c82fbf00a"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/sebastianbergmann/php-text-template/zipball/206dfefc0ffe9cebf65c413e3d0e809c82fbf00a",
+                "reference": "206dfefc0ffe9cebf65c413e3d0e809c82fbf00a",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.3"
+            },
+            "type": "library",
+            "autoload": {
+                "classmap": [
+                    "Text/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "include-path": [
+                ""
+            ],
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sb@sebastian-bergmann.de",
+                    "role": "lead"
+                }
+            ],
+            "description": "Simple template engine.",
+            "homepage": "https://github.com/sebastianbergmann/php-text-template/",
+            "keywords": [
+                "template"
+            ],
+            "time": "2014-01-30 17:20:04"
+        },
+        {
+            "name": "phpunit/php-timer",
+            "version": "1.0.5",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/sebastianbergmann/php-timer.git",
+                "reference": "19689d4354b295ee3d8c54b4f42c3efb69cbc17c"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/sebastianbergmann/php-timer/zipball/19689d4354b295ee3d8c54b4f42c3efb69cbc17c",
+                "reference": "19689d4354b295ee3d8c54b4f42c3efb69cbc17c",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.3"
+            },
+            "type": "library",
+            "autoload": {
+                "classmap": [
+                    "PHP/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "include-path": [
+                ""
+            ],
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sb@sebastian-bergmann.de",
+                    "role": "lead"
+                }
+            ],
+            "description": "Utility class for timing",
+            "homepage": "https://github.com/sebastianbergmann/php-timer/",
+            "keywords": [
+                "timer"
+            ],
+            "time": "2013-08-02 07:42:54"
+        },
+        {
+            "name": "phpunit/php-token-stream",
+            "version": "1.2.2",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/sebastianbergmann/php-token-stream.git",
+                "reference": "ad4e1e23ae01b483c16f600ff1bebec184588e32"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/sebastianbergmann/php-token-stream/zipball/ad4e1e23ae01b483c16f600ff1bebec184588e32",
+                "reference": "ad4e1e23ae01b483c16f600ff1bebec184588e32",
+                "shasum": ""
+            },
+            "require": {
+                "ext-tokenizer": "*",
+                "php": ">=5.3.3"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.2-dev"
+                }
+            },
+            "autoload": {
+                "classmap": [
+                    "PHP/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "include-path": [
+                ""
+            ],
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sb@sebastian-bergmann.de",
+                    "role": "lead"
+                }
+            ],
+            "description": "Wrapper around PHP's tokenizer extension.",
+            "homepage": "https://github.com/sebastianbergmann/php-token-stream/",
+            "keywords": [
+                "tokenizer"
+            ],
+            "time": "2014-03-03 05:10:30"
+        },
+        {
+            "name": "phpunit/phpunit",
+            "version": "4.0.14",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/sebastianbergmann/phpunit.git",
+                "reference": "a80b77d92a6c7723d77c6728b4ae37e92a65ac1d"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/sebastianbergmann/phpunit/zipball/a80b77d92a6c7723d77c6728b4ae37e92a65ac1d",
+                "reference": "a80b77d92a6c7723d77c6728b4ae37e92a65ac1d",
+                "shasum": ""
+            },
+            "require": {
+                "ext-dom": "*",
+                "ext-pcre": "*",
+                "ext-reflection": "*",
+                "ext-spl": "*",
+                "php": ">=5.3.3",
+                "phpunit/php-code-coverage": ">=2.0.0,<2.1.0",
+                "phpunit/php-file-iterator": "~1.3.1",
+                "phpunit/php-text-template": "~1.2",
+                "phpunit/php-timer": "~1.0.2",
+                "phpunit/phpunit-mock-objects": ">=2.0.0,<2.1.0",
+                "sebastian/diff": "~1.1",
+                "sebastian/environment": "~1.0",
+                "sebastian/exporter": "~1.0.1",
+                "sebastian/version": "~1.0.3",
+                "symfony/yaml": "~2.0"
+            },
+            "suggest": {
+                "ext-json": "*",
+                "ext-simplexml": "*",
+                "ext-tokenizer": "*",
+                "phpunit/php-invoker": "~1.1"
+            },
+            "bin": [
+                "phpunit"
+            ],
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "4.0.x-dev"
+                }
+            },
+            "autoload": {
+                "classmap": [
+                    "src/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "include-path": [
+                "",
+                "../../symfony/yaml/"
+            ],
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sebastian@phpunit.de",
+                    "role": "lead"
+                }
+            ],
+            "description": "The PHP Unit Testing framework.",
+            "homepage": "http://www.phpunit.de/",
+            "keywords": [
+                "phpunit",
+                "testing",
+                "xunit"
+            ],
+            "time": "2014-03-28 11:10:03"
+        },
+        {
+            "name": "phpunit/phpunit-mock-objects",
+            "version": "2.0.4",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/sebastianbergmann/phpunit-mock-objects.git",
+                "reference": "c5e6274b8f2bf983cf883bb375cf44f99aff200e"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/sebastianbergmann/phpunit-mock-objects/zipball/c5e6274b8f2bf983cf883bb375cf44f99aff200e",
+                "reference": "c5e6274b8f2bf983cf883bb375cf44f99aff200e",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.3",
+                "phpunit/php-text-template": "~1.2"
+            },
+            "require-dev": {
+                "phpunit/phpunit": ">=4.0.0,<4.1.0"
+            },
+            "suggest": {
+                "ext-soap": "*"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "2.0.x-dev"
+                }
+            },
+            "autoload": {
+                "classmap": [
+                    "src/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "include-path": [
+                ""
+            ],
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sb@sebastian-bergmann.de",
+                    "role": "lead"
+                }
+            ],
+            "description": "Mock Object library for PHPUnit",
+            "homepage": "https://github.com/sebastianbergmann/phpunit-mock-objects/",
+            "keywords": [
+                "mock",
+                "xunit"
+            ],
+            "time": "2014-03-18 08:56:48"
+        },
+        {
+            "name": "sebastian/diff",
+            "version": "1.1.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/sebastianbergmann/diff.git",
+                "reference": "1e091702a5a38e6b4c1ba9ca816e3dd343df2e2d"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/sebastianbergmann/diff/zipball/1e091702a5a38e6b4c1ba9ca816e3dd343df2e2d",
+                "reference": "1e091702a5a38e6b4c1ba9ca816e3dd343df2e2d",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.3"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.1-dev"
+                }
+            },
+            "autoload": {
+                "classmap": [
+                    "src/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sebastian@phpunit.de",
+                    "role": "lead"
+                },
+                {
+                    "name": "Kore Nordmann",
+                    "email": "mail@kore-nordmann.de"
+                }
+            ],
+            "description": "Diff implementation",
+            "homepage": "http://www.github.com/sebastianbergmann/diff",
+            "keywords": [
+                "diff"
+            ],
+            "time": "2013-08-03 16:46:33"
+        },
+        {
+            "name": "sebastian/environment",
+            "version": "1.0.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/sebastianbergmann/environment.git",
+                "reference": "79517609ec01139cd7e9fded0dd7ce08c952ef6a"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/sebastianbergmann/environment/zipball/79517609ec01139cd7e9fded0dd7ce08c952ef6a",
+                "reference": "79517609ec01139cd7e9fded0dd7ce08c952ef6a",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.3"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "4.0.*@dev"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.0.x-dev"
+                }
+            },
+            "autoload": {
+                "classmap": [
+                    "src/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sebastian@phpunit.de",
+                    "role": "lead"
+                }
+            ],
+            "description": "Provides functionality to handle HHVM/PHP environments",
+            "homepage": "http://www.github.com/sebastianbergmann/environment",
+            "keywords": [
+                "Xdebug",
+                "environment",
+                "hhvm"
+            ],
+            "time": "2014-02-18 16:17:19"
+        },
+        {
+            "name": "sebastian/exporter",
+            "version": "1.0.1",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/sebastianbergmann/exporter.git",
+                "reference": "1f9a98e6f5dfe0524cb8c6166f7c82f3e9ae1529"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/sebastianbergmann/exporter/zipball/1f9a98e6f5dfe0524cb8c6166f7c82f3e9ae1529",
+                "reference": "1f9a98e6f5dfe0524cb8c6166f7c82f3e9ae1529",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.3"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "4.0.*@dev"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.0.x-dev"
+                }
+            },
+            "autoload": {
+                "classmap": [
+                    "src/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sebastian@phpunit.de",
+                    "role": "lead"
+                },
+                {
+                    "name": "Jeff Welch",
+                    "email": "whatthejeff@gmail.com"
+                },
+                {
+                    "name": "Volker Dusch",
+                    "email": "github@wallbash.com"
+                },
+                {
+                    "name": "Adam Harvey",
+                    "email": "aharvey@php.net"
+                },
+                {
+                    "name": "Bernhard Schussek",
+                    "email": "bschussek@2bepublished.at"
+                }
+            ],
+            "description": "Provides the functionality to export PHP variables for visualization",
+            "homepage": "http://www.github.com/sebastianbergmann/exporter",
+            "keywords": [
+                "export",
+                "exporter"
+            ],
+            "time": "2014-02-16 08:26:31"
+        },
+        {
+            "name": "sebastian/version",
+            "version": "1.0.3",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/sebastianbergmann/version.git",
+                "reference": "b6e1f0cf6b9e1ec409a0d3e2f2a5fb0998e36b43"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/sebastianbergmann/version/zipball/b6e1f0cf6b9e1ec409a0d3e2f2a5fb0998e36b43",
+                "reference": "b6e1f0cf6b9e1ec409a0d3e2f2a5fb0998e36b43",
+                "shasum": ""
+            },
+            "type": "library",
+            "autoload": {
+                "classmap": [
+                    "src/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sebastian@phpunit.de",
+                    "role": "lead"
+                }
+            ],
+            "description": "Library that helps with managing the version number of Git-hosted PHP projects",
+            "homepage": "https://github.com/sebastianbergmann/version",
+            "time": "2014-03-07 15:35:33"
+        },
         {
             "name": "squizlabs/php_codesniffer",
             "version": "1.5.2",
@@ -77,6 +658,55 @@
                 "standards"
             ],
             "time": "2014-02-04 23:49:58"
+        },
+        {
+            "name": "symfony/yaml",
+            "version": "v2.4.3",
+            "target-dir": "Symfony/Component/Yaml",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/Yaml.git",
+                "reference": "77a41c2835ab7cfe8bf6d15e25d3af8f3eb3bacd"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/Yaml/zipball/77a41c2835ab7cfe8bf6d15e25d3af8f3eb3bacd",
+                "reference": "77a41c2835ab7cfe8bf6d15e25d3af8f3eb3bacd",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.3"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "2.4-dev"
+                }
+            },
+            "autoload": {
+                "psr-0": {
+                    "Symfony\\Component\\Yaml\\": ""
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Fabien Potencier",
+                    "email": "fabien@symfony.com",
+                    "homepage": "http://fabien.potencier.org",
+                    "role": "Lead Developer"
+                },
+                {
+                    "name": "Symfony Community",
+                    "homepage": "http://symfony.com/contributors"
+                }
+            ],
+            "description": "Symfony Yaml Component",
+            "homepage": "http://symfony.com",
+            "time": "2014-03-12 18:29:58"
         }
     ],
     "aliases": [
@@ -87,7 +717,7 @@
 
     ],
     "platform": {
-        "php": ">=5.0.0"
+        "php": ">=5.3.0"
     },
     "platform-dev": [
 
diff --git a/travis/run-phpunit.sh b/travis/run-phpunit.sh
index e685858c..a3da43f0 100755
--- a/travis/run-phpunit.sh
+++ b/travis/run-phpunit.sh
@@ -7,13 +7,20 @@ export PHPSECLIB_SSH_USERNAME='phpseclib'
 export PHPSECLIB_SSH_PASSWORD='EePoov8po1aethu2kied1ne0'
 export PHPSECLIB_SSH_HOME='/home/phpseclib'
 
+if [ "$TRAVIS_PHP_VERSION" = '5.2' ]
+then
+  PHPUNIT="phpunit"
+else
+  PHPUNIT="$(dirname "$0")/../vendor/bin/phpunit"
+fi
+
 PHPUNIT_EXTRA_ARGS=''
 if [ "$TRAVIS_PHP_VERSION" = '5.3.3' ]
 then
   PHPUNIT_EXTRA_ARGS="$PHPUNIT_EXTRA_ARGS -d zend.enable_gc=0"
 fi
 
-phpunit \
+"$PHPUNIT" \
   $PHPUNIT_EXTRA_ARGS \
   --verbose \
   --coverage-text \
diff --git a/travis/setup-composer.sh b/travis/setup-composer.sh
new file mode 100755
index 00000000..3416074c
--- /dev/null
+++ b/travis/setup-composer.sh
@@ -0,0 +1,3 @@
+#!/bin/sh
+composer self-update --no-interaction
+composer install --no-interaction