安装Composer Asset插件老是失败是什么问题

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在win7下运行composer,安装asset插件时，出现SSL报错：
D:\data\www\mmoyu\symapp>composer global require "fxp/composer-asset-plugin:1.0.0"
Loading composer repositories with package information

[Composer\Downloader\TransportException]
The "https://packagist.org/packages.json" file could not be downloaded: SSL
operation failed with code 1. OpenSSL Error messages:
error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify
failed
Failed to enable crypto
failed to open stream: operation failed

install [--prefer-source] [--prefer-dist] [--dry-run] [--dev] [--no-dev] [--no-p
lugins] [--no-custom-installers] [--no-scripts] [--no-progress] [-v|vv|vvv|--ver
bose] [-o|--optimize-autoloader]

没有安装CA证书导致的！！！
CA证书下载地址：http://curl.haxx.se/docs/caextract.html
然后修改php.ini文件 增加
openssl.cafile= D:/wamp/php/verify/cacert.pem

就OK了~