Download PA165: Úvod do Java EE

Java Security
Petr Adámek
Content: Java Security
• Java SE Security
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Platform security
Cryptography
Public Key Infrastructure
Secure communication
Java Platform Security Architecture
• Authentication and Access Control
– Java Authentication and Authorization Service
– Java EE Authentication and Authorization
• Spring Security
• Best Practices
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PLATFORM SECURITY
Java Security
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Platform security
• Strong data typing
– More robust code
• Automatic memory management
– More robust code
– No buffer overflow
• Bytecode verification
– Does bytecode conforms to Java JVM specification?
• Secure class loading
– Just trusted code is loaded into JVM
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JAVA CRYPTOGRAPHY
ARCHITECTURE (JCA)
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Java Cryptography Architecture
• Java APIs for
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digital signatures
message digests (hashes)
certificates and certificate validation
Encryption (symmetric/asymmetric block/stream ciphers)
key generation and management
secure random number generation
• Basic principles
– Implementation independence
– Implementation interoperability
– Algorithm extensibility
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Cryptographic Service Provider
• CSP is ensuring Implementation independence
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Implementation can be easily changed without modifying application
Provider can be optimized for particular hw/sw platform
Provider can support new algorithms
Easy support for specialized HW (Crypto accelerators, secure random
number generators, secure key and/or certificate stores, smart cards,
etc.)
• Implementation interoperability
– Various implementation can work together (eg. key generated by one
provider can be used by another one)
• One or more default providers are always installed with JDK
• Additional providers can be installed with preference order
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Sun Crypto Accelerator 6000
• http://www.oracle.com/us/products/networking/ethernet/cr
ypto6000-pcie/overview/index.html
• Hardware based Secure Key Store
• Random number generator
• SSL, TLS, IPSec or bulk encryption acceleration
• SHA2, MD5, DES, 3DES, AES, RSA, DSA, ECC
• Physical protection
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Adding new CSP
• Make jar with provider available to Java
– Place on regular Classpath
– Install as extension ($JAVA_HOME/lib/ext)
• Register a provider
– Static registration
($JAVA_HOME/lib/security/java.security)
– Dynamic registration (Security.addProvider(...); can be
done only when security manager does allow it)
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Engine classes
• Provide particular crypto services
– MessageDigest, Signature, KeyFactory, KeyPairGenerator, Cipher, etc.
• Implementations for various algorithms are available
• Instance can be obtained using factory method
Cipher c = Cipher.getInstance("AES");
Cipher c = Cipher.getInstance("AES","MyProvider");
• Some instances must be initialized (with key, seed, etc.)
• Some algorithm specific parameters can be specified with
AlgorithmParameterSpec parameter
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Key
• Key class represents some key
– SecretKey (symmetric key)
– PrivateKey (private part of public/private key pair)
– PublicKey (public part of public/private key pair)
• Public/Private key pair is represented by KeyPair class.
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Key Generator
• Symmetric key can be generated using KeyGenerator
KeyGenerator kg = KeyGenerator.getInstance("AES");
kg.init(128);
SecretKey key = kg.generateKey();
• Asymmetric key pair can be generated using KeyPairGenerator
KeyPairGenerator kpg =
KeyPairGenerator.getInstance("RSA");
kpg.init(2048);
KeyPair keyPair = kpg.genKeyPair();
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SecureRandom
• SecureRandom engine class provides cryptography strong
random numbers.
• Critical part of security architecture, good source of entropy is
needed.
– HW source (eg. white noise on p–n junction of diode)
– Computer environment (events from keyboard or mouse, incoming
network packets, interrupts from peripherals, noise from microphone)
• The generation speed is limited by available entropy and
operation may be blocked until the entropy is available
• The generator can be seeded explicitly (setSeed(…)),
otherwise it is seeded automatically at first nextBytes call.
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SecureRandom
• Instance can be obtained
– using factory method
– with constructor (the default provider is used)
• Generator is uninitialized and internal state must be
randomized
– explicitly using setSeed(…)method
– automatically at first random number request
SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
byte[] randomBytes = new byte[256];
sr.nextBytes(randomBytes);
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MessageDigest
• MessageDigest Calculates Message Digest (hash) of some
byte sequence
• Instance is obtained using factory method
MessageDigest md =
MessageDigest.getInstance(“SHA-256");
• Data are supplied to digest with update(…) method
• When all data have been supplied, the digest is computed
with digest(…) method.
• The result is in binary form and sometimes we need to
convert it into hex string representation
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Signature
• Signature allows to sign and/or verify some byte sequence
• Based on asymmetric cryptography and Public/Private key
pair
• Usually just message digest is signed
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Signature
• Instance is obtained using factory method
Signature s =
Signature.getInstance("SHA512withRSA");
• Instance must be initialized for signing or verifying
s.initSign(privateKey);
s.initVerify(publicKey) or s.initVerify(certificate);
• Data are supplied with update(…) method.
• Signing is finished with sign() method
byte[] signature = s.sign();
• Verifying is finished with verify method
boolean verified = s.verify(signature);
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Cipher
• Cipher is encrypting or decrypting byte sequence.
• Regarding used keys, cipher can be
– Symmetric (the same secret key is used for encryption and decryption)
– Asymetric (the private/public key pair is used; data encrypted with
private key is decrypted with public key and vice versa)
• Asymmetric cipher is generally much slower than the
symmetric one, therefore it is usually used just to exchange
secret key for the data encryption
• Cipher can be also
– Block (the whole block is processed at a time, data must be padded)
– Stream (data are processed as stream, byte after byte)
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Cipher
• To create and instance of Cipher, we need to specify
transformation that consists of algorithm, mode and padding
Cipher c = Cipher.getInstance("AES/ECB/PKCS5Padding");
• Cipher must be initialized with the mode and key
c.init(Cipher.ENCRYPT_MODE, key);
c.init(Cipher.DECRYPT_MODE, key);
• Now we can encrypt/decrypt data with
– update(…)/doFinal(…) methods
– CipherInputStream of CipherOutputStream
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Cipher: wrapping keys
• If we need to encrypt or decrypt the key (eg. for exchange
secret key with asymetric cipher), we can use wrap/unwrap
mode of Cipher
c.init(Cipher.WRAP_MODE, publicKey);
byte[] encryptedKey = c.wrap(secretKey);
c.init(Cipher.UNWRAP_MODE, privateKey);
Key secretKey = c.unwrap(encryptedKey,
secretKeyAlgorithm, Cipher.SECRET_KEY);
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How to store keys?
• Key Factory
• KeyStore
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Key Factory
• SecretKeyFactory or KeyFactory can be used for
converting keys from or to some key specification
(representation of the key in some specific format)
Path keyFile = Paths.get("public.der");
byte[] encodedPubKey = Files.readAllBytes(keyFile);
KeySpec pubKeySpec = new
X509EncodedKeySpec(encodedPubKey);
KeyFactory keyFactory = KeyFactory.getInstance("DSA");
PublicKey pubKey = keyFactory.generatePublic(pubKeySpec);
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KeyStore
• KeyStore represents storage of keys and certificates
– PrivateKeyEntry (private key + certificate with public key)
– SecretKeyEntry (just secret key)
– TrustedCertificateEntry (certificate with public key)
• Each entry has some alias
• The whole KeyStore and/or each entry can be password
protected
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KeyStore: providers
• Common providers
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JKS (default)
JCEKS
PKCS12
PKCS11
BKS (BouncyCastle)
Windows-MY/Windows-ROOT (Windows certificates store,
certmgr.msc)
– KeychainStore (OSX)
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KeyStore: JKS
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File based
Default location is $HOME/.keystore
Can be managed with keytool command
keytool-maven-plugin
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KeyAgreement
• Protocol allowing to establish the same cryptographic keys for
two or more participants without need to exchange any secret
information
• Each participant has its own private/public key pair
• Allows to exchange information without on-line connection
(but you still need to distribute public keys trustworthy)
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Password Based Encryption
• PBEKeySpec
• PBEParameterSpec
• Passwords are stored as char[]
– String is immutable therefore it is not possible to clean the content
when it is no more needed
– This is important to decrease the chance of password disclosure
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PUBLIC KEY INFRASTRUCTURE (PKI)
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Public Key Infrastructure
• http://docs.oracle.com/javase/7/docs/technotes/guides/secu
rity/certpath/CertPathProgGuide.html
• How to distribute public keys trustworthy
• X509
• CRL, OCSP
• Certificate management
– keytool
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SECURE COMMUNICATION
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Java Secure Socket Extension (JSSE)
• http://docs.oracle.com/javase/7/docs/technotes/guides/secu
rity/jsse/JSSERefGuide.html
• Protocols
– SSL 3.0
– TLS 1.0
– https
• packages
– javax.net
– javax.net.ssl
– java.security.cert
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Truststore
• Default truststore is loaded from the JKS file
– Defined with system property javax.net.ssl.trustStore
– $JAVA_HOME/lib/security/jssecacerts
– $JAVA_HOME/lib/security/cacerts
• How to establish connection to site with self-signed certificate
or certificate signed by CA that is not in our truststore
– Add certificate to default trustore
– Use our own trustore and set javax.net.ssl.trustStore
– Use our own SSLContext with our own TrustManager using our own
trustore/certificate
– Use our own SSLContext with our own TrustManager accepting all
certificates (strongly unrecommended!)
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JAVA SE PLATFORM SECURITY
ARCHITECTURE
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Java SE Platform Security Architecture
• http://docs.oracle.com/javase/7/docs/technotes/guides/secu
rity/spec/security-specTOC.fm.html
• Jar Signer
• webstart-maven-plugin
• Java Web Start / applets
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AUTHENTICATION AND ACCESS
CONTROL
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Java Authentication and Authorization
Service (JAAS)
• http://docs.oracle.com/javase/7/docs/technotes/guides/secu
rity/jaas/JAASRefGuide.html
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Authentication in Java EE
• Authentication can be done by Application Server or Servlet
Container
– HTTP Auth
– User form
• User/Caller identity is propagated with the request
– Bound to thread servicing the request
• If you want to do your own authentication, you could need to
configure application server to not consume authentication
headers.
– Weblogic and <enforce-valid-basic-auth-credentials>
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Authorization in Java EE
• Imperative way
• Declarative way (javax.annotation.security) – JSR 250
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@DeclareRoles
@DenyAll
@PermitAll
@RolesAllowed
@RunAs
• http://www.packtpub.com/article/hands-on-tutorial-ejbsecurity
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SPRING SECURITY
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Spring Security
• Started as Acegi Security in 2003
– Focused on authorization, Container Managed Security used for
authentication
• Became official part of Spring portfolio in 2007
• Features
– Comprehensive and extensible support for both Authentication and
Authorization
– Protection against attacks like session fixation, clickjacking, cross site
request forgery, etc
– Servlet API integration
– Optional integration with Spring Web MVC
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Supported technologies
• HTTP BASIC authentication
• HTTP Digest authentication
• HTTP X.509 client certificate
exchange
• LDAP
• Form-based authentication
• OpenID authentication
• Authentication based on preestablished request headers
(such as Computer Associates
Siteminder)
• JA-SIG Central Authentication
Service (CAS)
Java Security
• Transparent authentication
context propagation for RMI
and HttpInvoker
• Automatic "remember-me"
authentication
• Anonymous authentication
• Run-as authentication
• JAAS
• JEE container authentication
• Kerberos
• Your own authentication
systems (see below)
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Supported technologies (3rd party)
• Java Open Source Single Sign
On (JOSSO)
• OpenNMS Network
Management Platform
• AppFuse
• AndroMDA
• Mule ESB
• Direct Web Request (DWR)
• Grails
• Tapestry
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JTrac
Jasypt
Roller
Elastic Path
Atlassian Crowd
Java Configuration
• Java Confing
– http://docs.spring.io/springsecurity/site/docs/3.2.0.RELEASE/reference/htmlsingle/#jc
• XML
– http://docs.spring.io/springsecurity/site/docs/3.2.0.RELEASE/reference/htmlsingle/#ns-config
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Method Authorization
• Spring native @Secure annotation
– security configuration attributes
• JSR 250 annotations
– @DeclareRoles, @DenyAll, @PermitAll, @RolesAllowed, @RunAs
• Spring native Expression-Based Access Control
– @PreAuthorize, @PreFilter, @PostAuthorize, @PostFilter
– http://docs.spring.io/springsecurity/site/docs/3.2.0.RELEASE/reference/htmlsingle/#el-access
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BEST PRACTICES
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Attacks to Web Applications
• Protect from SQL Injection
– Allways use preprared statements or similar technique, don’t try to
compose SQL query with parameters with your own code
• Protection from Cross Site Scripting
– Allways escape all output to web page (eg. with <c:out/> from JSTL)
– Use X-XSS-Protection header
• Protection from Phising
– Desing application to make phising hard
– Educate your users (to not click links in the mails, to check certificates
and the validity, to keep system and antivirus updated, to report all
suspicious behavior of system or application)
– Don’t spoil users (eg. with untrusted certificates)
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Secure communication
• Understand well what you are doing and why you are doing
that
– I don’t understand cryptography but I will use some cipher and it will
be secure
– It is important to understand all aspects (properties and weaknesses)
of particular algorithm/cipher/technique/implementation
• Never use Trust Everybody TrustManager
– Common question is How to make connection to server signed with
self-signed certificate?
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Questions
?
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