加密和加密；解密:

在C#中使用哈希验证进行文件加密/解密 [ ^ ]
http://support.microsoft.com/kb/307010 [从SQL Server数据库上载文件和从中下载文件 [ ^ ]

Encryption & Decryption:

File Encryption/Decryption with Hash Verification in C#[^]
http://support.microsoft.com/kb/307010[^]

Upload & Download file:

Uploading and downloading files to/from a SQL Server database[^]