CKEDITOR.plugins.add('blockimagepaste',
{
    init: function (editor) {
        function replaceImgText(html) {
            var ret = html.replace(/<img[^>]*src="data:image\/(bmp|dds|gif|jpg|jpeg|png|psd|pspimage|tga|thm|tif|tiff|yuv|ai|eps|ps|svg);base64,.*?"[^>]*>/gi, function (img) {
                alert("Direct image paste is not allowed.");
                return '';

            });
            return ret;
        }

        function chkImg() {
            // don't execute code if the editor is readOnly
            if (editor.readOnly)
                return;

            setTimeout(function () {
                editor.document.$.body.innerHTML = replaceImgText(editor.document.$.body.innerHTML);
            }, 100);
        }

        editor.on('contentDom', function () {
            // For Firefox
            editor.document.on('drop', chkImg);
            // For IE
            editor.document.getBody().on('drop', chkImg);
        });

        editor.on('paste', function (e) {
            var html = e.data.dataValue;
            if (!html)
                return;
            e.data.dataValue = replaceImgText(html);
        });

    } //Init
});