System security and confidentiality designs

Information security technology
Encryption and decryption technologies
There are two forms of attack to electronic data: One is passive attack, meaning illegally intercepting information from the transmission channels, or stealing and copying information from the storage carriers. The other is active attacks, meaning conducting malicious deletion or manipulation on transmitted or stored data. Practices prove that the password technology is an effective and economical way to prevent attacks to the data.
Encryption algorithms
• Symmetric encryption, the advantage being efficient and fast algorithm implementation. Common algorithms include DES (Data Encryption Standard), IDEA (International Data Encryption Algorithm) and HMAC-SHA1.
• Asymmetric encryption, including the RSA algorithm, can be used for digital signature.
• MD5 hashing algorithm: one-way encryption algorithm which can only encrypt data, but cannot decrypt data.
Digital certificates
Digital signatures and public key encryption are all based on the asymmetric encryption technology. The existing problems include: how to ensure the authenticity of the public key holder, and how to generate, distribute and manage public keys in a large-scale information system environment.
Digital certificate is an authoritative electronic document signed and issued by an authorized and just third-party organization, that is, the CA (Certificate Authentication) center, such as VeriSign.
Its digital certificate-cored encryption technology can encrypt and decrypt the information transmitted on the network, and issue digital signatures and verify signatures to ensure the confidentiality and integrity of the information transmitted on the internet. With the digital certificate, even if the information you sent is intercepted by others on the internet or your personal account or password is lost, the safety of your account and money can be ensured. E-businesses based on internet and the banking systems all require the security verification of digital certificates.
Identity authentication technology
• User name and password authentication (what you know). Three authentication means are available: verifying the plaintext transmission of data, verifying data using the one-way hashing functions, and verifying data using one-way hashing and random numbers.
• Token verification (what you own). The key for verification is stored in the token (Soft Token or Hard Token) and access to the key is managed by the password (PIN code).  
The token implementation is divided to the challenge-response token and the timestamp token.
• Biometric identification (what you are) and three-factor authentication. Biometric identification relies on the photo, fingerprint or odour of the authenticator for the identification. The three-factor authentication based on what the user knows, owns and is the mostly widely used among the strong authentication means.

Security protocols
• IPSec protocol
• SSL (Secure Socket Layer) protocol
SSL’s security service is located between the transport layer communication protocol (TCP/IP) and the application layer and can secure the application layer such as HTTP, FTP and SMTP.
HTTPS = HTTP + SSL
Working principles:
In SSL, the sending end compresses the data transmitted from the top layer (HTTP) and encrypts the data using MAC (Message Authentication Code). It adds the SSL head and transmits the SSL message through TCP. The receiving end decrypts the data received using the SSL protocol, verifies, decompresses and reassembles the data to get the plaintext (HTTP) message.
To ensure data integrity, the MAC (Message Authentication Code) is placed at the end of the data packet and encrypted with the data together. In this way, if the data is modified, its hashed value will not match the original verification code, and thus whether the data has been modified can be tested. MAC is also used to protect the SSL connection from interference.
• Establish an SSL session (handshake negotiation):
1. Built the security capability
2. Server identity authentication and key exchange
3. Client authentication and key exchange
4. Completion
SSL protocol security analysis:
1. Prevent being tapped or attacked by intermediaries (Data eavesdropping between channels produces no risks because of the encryption) - against passive attacks.
2. Prevent clipboard hijack attacks (to prevent malicious manipulation and deletion of information) - against active attacks.
3. Prevent replay attacks and short packet attacks (SSL adopts the serial number to protect communicators from message replay attacks. Throughout the SSL handshake process, there is always a unique random number to mark this SSL handshake, leaving no chance for the replay attacks no leverage. )
• PGP (Pretty Good Privacy) protocol
It is a hybrid encryption system designed to secure e-mail communication over the internet. PCG includes four password units, namely one-key cryptosystem (encrypt e-mails), two-key cryptosystem (encrypt the key), one-way hashing (digital signature) and random number generation algorithm.

Data backup
Many reasons can cause data damages and loss, such as a broken hard disk or invasion of viruses. In general, we adopt firewalls or anti-virus software against such risks. However, things are not always following what we expect. Data security and accuracy have been challenged seriously. Therefore, data backup becomes quite necessary, and it is also the most important defense against “active attacks”.
Data backup types
• Full backup
• Differential backup, that is, only back up all the changed files after last full backup. In other words, files that are not changed will not be backed up.
• Incremental backup, that is, only back up the changed files after last backup (full or differential).
• On-demand backup, highly selective.
Remote backup is the core technology of a disaster recovery system.

Information security support system
• Set up a uniform identity authentication system
Identity authentication is the most fundamental element for information exchange. If the identities of the two sides for the exchange cannot be authenticated, the information security is impossible. Identity authentication instance, CA digital certificate and VPN token.
• Establish a uniform information security management system
• Establish a standard information security confidentiality system
Information confidentiality is inevitable for a large information application network.
• Establish a sound network perimeter defense system
Crucial information networks are usually isolated to some extent from the public internet. There is a network perimeter between the internal information network and the internet. A sound network perimeter defense system must be in place.
The feature of information security is to guarantee the information confidentiality, integrity, availability, controllability and non-repudiation.