Chapter 9: Database Security: An Introduction CuuDuongThanCong.com https://fb.com/tailieudientucntt Contents Introduction to Database Security Issues Discretionary Access Control (DAC) Mandatory Access Control (MAC) Role-Based Access Control (RBAC) Encryption & PKI (Public Key Infrastructure) Jan - 2015 CuuDuongThanCong.com https://fb.com/tailieudientucntt Contents Introduction to Database Security Issues Discretionary Access Control (DAC) Mandatory Access Control (MAC) Role-Based Access Control (RBAC) Encryption & PKI (Public Key Infrastructure) Jan - 2015 CuuDuongThanCong.com https://fb.com/tailieudientucntt Introduction to Database Security Issues (1)  Types of Security:     Jan - 2015 Legal and ethical issues Policy issues System-related issues The need to identify multiple security levels CuuDuongThanCong.com https://fb.com/tailieudientucntt Introduction to Database Security Issues (2)  Three Basic Concepts:    Jan - 2015 Authentication: a mechanism that determines whether a user is who he or she claims to be Authorization: the granting of a right or privilege, which enables a subject to legitimately have access to a system or a system’s objects Access Control: a security mechanism (of a DBMS) for restricting access to a system’s objects (the database) as a whole CuuDuongThanCong.com https://fb.com/tailieudientucntt Introduction to Database Security Issue (3)  Threats:   Any situation or event, whether intentional or unintentional, that will adversely affect a system and consequently an organization Threats to:   Jan - 2015 Computer systems Databases CuuDuongThanCong.com https://fb.com/tailieudientucntt Threats to Computer Systems Jan - 2015 CuuDuongThanCong.com https://fb.com/tailieudientucntt Scope of Data Security Needs     Must protect databases & the servers on which they reside Must administer & protect the rights of internal database users Must guarantee the confidentiality of ecommerce customers as they access the database With the Internet continually growing, the threat to data traveling over the network increases exponentially Jan - 2015 CuuDuongThanCong.com https://fb.com/tailieudientucntt Introduction to Database Security Issues (4)  Threats to databases:     Loss of integrity Loss of availability Loss of confidentiality To protect databases against these types of threats four kinds of countermeasures can be implemented:     Jan - 2015 Access control Inference control Flow control Encryption CuuDuongThanCong.com https://fb.com/tailieudientucntt Introduction to Database Security Issues (5)  A DBMS typically includes a database security and authorization subsystem that is responsible for ensuring the security portions of a database against unauthorized access  Two types of database security mechanisms:   Jan - 2015 Discretionary security mechanisms Mandatory security mechanisms CuuDuongThanCong.com https://fb.com/tailieudientucntt Encryption (2) ban ro     Plaintext is the original content which is readable as textual material Plaintext needs protecting ban ma Ciphertext is the result of encryption performed on plaintext using an algorithm Ciphertext is not readable Cryptosystems = encryption + decryption algorithms Encryption, decryption process needs keys Jan - 2015 CuuDuongThanCong.com https://fb.com/tailieudientucntt Encryption (3)   Symmetric (shared-/secret-key) cryptosystem: the same key for (en/de)cryption algorithms (KE = KD) Asymmetric (public-key) cryptosystem: public & private keys (KE KD) KE Plaintext Ciphertext Hello, ắôĐả This content is confidential … 01000100…… … Encryption Cryptosystem   ………………… ………………… … Decryption Jan - 2015 KD CuuDuongThanCong.com https://fb.com/tailieudientucntt Encryption (4)  (Most popular) Symmetric techniques: DES, AES     The same key is used for both encryption and decryption Faster than encryption and decryption in publickey (PK) cryptosystems Less security comparing to encryption and decryption in PK cryptosystems Asymmetric techniques: RSA, DSA Jan - 2015 CuuDuongThanCong.com https://fb.com/tailieudientucntt Symmetric techniques (1)  DES: Data Encryption Standard     A message is divided into 64-bit blocks Key: 56 bits Brute-force or exhaustive key search attacks: Some hours Triple DES: run the DES algorithm a multiple number of times using different keys 𝑚: plaintext; 𝑐: ciphertext  ℰ𝑘1 : encryption by key 𝑘1; 𝒟𝑘1 : decryption by key 𝑘1;  Encryption: 𝒄 ← 𝓔𝒌𝟏 (𝓓𝒌𝟐 𝓔𝒌𝟏 𝒎 )  Decryption: 𝒎 ← 𝓓𝒌𝟏 (𝓔𝒌𝟐 𝓓𝒌𝟏 𝒄 )  Be compatible with DES when 𝑘1=𝑘2;  The triple DES can also use three different keys  Jan - 2015 CuuDuongThanCong.com https://fb.com/tailieudientucntt Symmetric techniques (2)    AES: Advanced Encryption Standard (Rijndael)  Jan 2, 1997, NIST announced the initiation of a new symmetric-key block cipher algorithm, AES, as the new encryption standard to replace the DES  Oct 2, 2000: Rijndael was selected Rijndael is designed by two Belgium cryptographers: Daemen and Rijmen thuat toan ma hoa Rijndael is a block cipher with a variable block size and variable key size The key size and the block size can be independently specified to 128, 192 or 256 bits Jan - 2015 CuuDuongThanCong.com https://fb.com/tailieudientucntt Asymmetric techniques (1)  RSA: named after inventors Rivest, Shamir, Adleman  Two keys: public key and private key  Public key is used for encrytion  Private key is used for decrytion Jan - 2015 CuuDuongThanCong.com https://fb.com/tailieudientucntt Asymmetric techniques (2)  Encryption key: public key  Decryption key: private key  Asymmetric techniques: more secure but expensive in terms of computational costs Sender Use public key of receiver to encrypt the message encryption key Receiver Encrypted message using a symmetric key Jan - 2015 CuuDuongThanCong.com https://fb.com/tailieudientucntt Public Key Infrastructure (PKI) (1) CA (certificate authority) Alice Jan - 2015 CuuDuongThanCong.com Bob https://fb.com/tailieudientucntt Public Key Infrastructure (PKI) (2)  How does PKI work? Jan - 2015 CuuDuongThanCong.com https://fb.com/tailieudientucntt Digital Signatures    A digital signature is an example of using encryption techniques to provide authentication services in ecommerce applications A digital signature is a means of associating a mark unique to an individual with a body of text  The mark should be unforgettable, meaning that others should be able to check that the signature does come from the originator A digital signature consists of a string of symbols  Signature must be different for each use  This can be achieved by making each digital signature a function of the message that it is signing, together with a time stamp Public key techniques are the means creating digital signatures Jan - 2015  CuuDuongThanCong.com https://fb.com/tailieudientucntt How digital signature works? Jan - 2015 CuuDuongThanCong.com https://fb.com/tailieudientucntt Digital certificates  One concern with the public key approach: must ensure that you are encrypting to the correct person’s public key     Otherwise, you can only encrypt/decrypt to those key handed to you A solution: digital certificates (or certs) A form of credentials (like a physical passport) Included with a person’s public key to verify that a key is valid Jan - 2015 CuuDuongThanCong.com https://fb.com/tailieudientucntt Components of a digital certificate  A digital certificate      A public key Certificate info (identifying information such as name, ID) One (or more) digital signatures A stamp of approval from a trusted entity Certificates are used when it is necessary to exchange public keys with someone (when you cannot manually exchange via a diskette or USB drive) Jan - 2015 CuuDuongThanCong.com https://fb.com/tailieudientucntt Summary Introduction to Database Security Issues Discretionary Access Control (DAC) Mandatory Access Control (MAC) Role-Based Access Control (RBAC) Encryption & PKI (Public Key Infrastructure) Jan - 2015 CuuDuongThanCong.com https://fb.com/tailieudientucntt Jan - 2015 CuuDuongThanCong.com https://fb.com/tailieudientucntt ... 2015 Computer systems Databases CuuDuongThanCong .com https://fb .com/ tailieudientucntt Threats to Computer Systems Jan - 2015 CuuDuongThanCong .com https://fb .com/ tailieudientucntt Scope of Data Security. .. CuuDuongThanCong .com https://fb .com/ tailieudientucntt Introduction to Database Security Issues (7)  The security problem associated with databases is that of controlling the access to a statistical database, ... criteria  Jan - 2015 The countermeasures to statistical database security problem is called inference control measures CuuDuongThanCong .com https://fb .com/ tailieudientucntt Introduction to Database