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Certificate Revocation Mỗi một certificate được tạo ra đều có một khoảng thời gian hiệu lực ( validity period  ) nhất định và thường từ 1 hoặc 2 năm. Khi vượt ra khỏi khoảng thời gian này thì nó bị hết hạn và không còn giá trị nữa. Thông tin này được chứa trong bản thân certificate (giá trị  valid from  và  valid to   ) và cần được kiểm tra trước khi quyết định có nên tin dùng nó hay không. Tuy nhiên, có những trường hợp mà một certificate cũng cần bị thu hồi ( revoke ) dù rằng thời gian hiệu lực vẫn còn như: Người sở hữu certificate không còn làm trong tổ chức nữa. CA phát hiện ra là đã cấp phát sai certificate. Sự cố liên quan tới các CA  Comodo , DigiNotar  xảy ra gần đây là một ví dụ. Private key bị lộ hoặc thiết bị chứa private key bị mất hoặc bị đánh cắp. Công việc thu hồi certificate này được gọi là certificate revocation và do CA thực hiện. Có 2 trạng thái revocation được quy định trong  RFC 3280  là: Revoked : một...

Introduction: Bacula is an on-linebased back up tool. Which is used to backup files from different servers into back up server where the bacula is running. For setup this backup tool across network first you have to install bacula server package on backup server machine where you are storing your backup contents ,and install bacula client daemon on all other servers from where we are going to backup data. Bacula has five main components. 1.Director daemon This daemon co-ordinate all working of backup,and through its configuration file we can specify all these things. 2.File daemon This daemon works in all clients from that client we are backup data. Director daemon connect to this daemon after authentication and backup the files from this client. 3.Storage daemon This daemon is for store the backup data from client in to hard disk of backup server,usually this daemon and director daemon works in the same backup server. director works as intermediate between the file ...

Software Requirements To deploy Forward Secrecy, you need to have both your web server and the underlying SSL/TLS library support Elliptic Curve cryptography. For Apache, Nginx, and OpenSSL, the following minimum versions will suffice: OpenSSL 1.0.1c+ Apache 2.4.x nginx 1.0.6+ and 1.1.0+ You will probably want to upgrade to the most recent versions wherever possible, because you don’t want to be running old and obsolete and potentially vulnerable software. You are probably aware that Linux distributions often ship modified packages. The modifications are usually improvements, but could mean feature removal in some cases. For example, Red Hat appears to have no support for Elliptic Curve crypto on their operating systems, because of  patent issues . If you’re running CentOS, for example, and wish to support Forward Secrecy, you will need to recompile the key packages to put EC support back in . (There appear to be plenty tutorials on the Web for this.) Once the correct...

To encrypt communications between you and your end users, you purchase a SSL Certificate, install it on your server, and then configure your website to use the certificate to protect these communications. The SSL connection begins when the end user’s browser reaches out to shake hands with your website. During this handshake, information regarding the ability of the browser and server are exchanged, validation occurs, and a session key that meets both the browser’s and server’s criteria is created. Once the session key is created, the rest of the conversation between the end user and your site is encrypted and thus secured. Historically, the most common method for negotiating the session key involved the RSA public-key cryptosystem. The RSA approach uses the server’s public key to protect the session key parameters created by the browser once they are sent the server. The server is able to decrypt this handshake with its corresponding private key. When you use the RSA key exchange...