What is Security?

Common Goals in Computer Security

Confidentiality

Ensuring that there is no deliberate or accidental improper disclosure of sensitive automated information.
• Information should only be accessed by authorised users
• If confidentiality is broken then it should be made known

Integrity

Protecting against deliberate or accidental corruption of automated information.
• Information should be able to be trusted as being correct
• Programs should only do what they are intended
• Sources of information should be able to be trusted

Availability

Protecting against deliberate or accidental actions that cause automated information resources to be unavailable to users when needed.
• Computer Systems should always be availaible to authenticated users
• Information should always be available to authenticated and authorised users
• If a system becomes unavailable there should be predefined time-frames for availability

Why do we need Security?

How do you make things Secure?

• Encryption/Decryption - translating data into a "secret language", using an algorithm
  • The Data Encryption Standard (DES) (NIST FIPS 46-1 and 46-2)
  • Rivest, Shamir and Adleman AsymmetricCipher algorithm (RSA) (RSA Laboratory Technical Note PKCS#1)
  • International Data Encryption Algorithm (IDEA) from ASCOM Systec, Switzerland.

  • Simple encryption algorithm in Java
  • Cryptography joke
• Digital Signatures
  • A relatively short (often fixed-size) string of bytes
  • Computed from the data and the private key
  • Its authenticity can be verified, via a computation that uses the public key corresponding to the private key used to generate the signature.
  • It cannot be forged, assuming the private key is kept secret.
  • If the data the signature is attached to is different from the data the signature was computed from, the signature will no longer verify as being valid.
  • Digital Signature Algorithm (DSA)(NIST FIPS 186)[in JDK 1.1]
  • MD2 with RSA (defined by RSA DSI in RFC 1423)
  • MD5 with RSA (defined by RSA DSI in RFC 1321)
  • SHA-1 with DSA
  • SHA-1 with RSA
  • RSA Cryptosystem (RSA)(??)
• Message Digests Message digests are secure one-way hash functions that take arbitrary-sized data and output a fixed-length hash value.
  • MD5 (RFC 1321) [in JDK 1.1]
  • Secure Hash Algorithm (SHA-1) (NIST FIPS 180-1) [in JDK 1.1]
  • MD2
• Certificates

How do you do this with Java?

Java Security API in JDK 1.1

• Provider Class
  Various companies provide Java packages that contain one or more classes that implement the various security algorithms. Provider class is the interface to such a package or set of packages. It has methods for accessing the provider name, version number, and other information.

  The JDK comes with a package written by Sun, however you can get other packages from independant vendors. To install a new package, create a classes directory in the JDK installation directory, and install the provider classes (the .class files) in that directory. For example, if the JDK is installed in a directory called jdk1.1.1, and the classes implementing the provider are in the COM.acme.provider package, install the classes in the directory jdk1.1.1/classes/COM/acme/provider.
  Alternatively, a zip or JAR (Java ARchive) file containing the classes can be located anywhere on your CLASSPATH.

• Engine Class (KeyPairGenerator, MessageDigest, Signature)
  For each engine class in the API, a particular implementation is requested and instantiated by calling a getInstance() method on the engine class, specifying the name of the desired algorithm and, optionally, the name of the provider whose implementation is desired. If no provider is specified, getInstance() searches the registered providers for an implementation of the named algorithm. Providers are installed with a preference order, so prefered providers are searched first.

  Signature dsa = Signature.getInstance("SHA/DSA", "PROVIDER_2");

• The Security Class
  The Security class manages installed providers and security-wide properties. It only contains static methods and is never instantiated. It can add, remove, and query providers and maintains a list of system-wide security properties that are accessible and settable by a trusted program.

  What it can't do

  • Import or export public or private keys used to generate and verify digital signatures
  • Support some certificate formats