Introduction to PKI Based Application Development cyber Security Div' , NIC HQ

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Introduction to PKI Based Application
Development cyber Security Div. , NIC HQ
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An Introduction to Public key cryptography (PKC)

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PKC is based on the following security techniques

• Authentication
• Confidentiality
• Integrity
• Non-repudiation

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Symmetric-key Cryptography

• Data encrypted and decrypted with same key
• Classical examples Caesar cipher, one-time pad,
  Enigma Machine

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Asymmetric Key Encryption

• Important to know who should know which key(s)
• In general
• Sender encrypts with recipients public key
• Recipient decrypts with its private key

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Matrix of Keys
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Asymmetric Key Cryptography
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Asymmetric Key Example

• Consider a bank and its customers
• Customers encrypt their messages with banks
  public key
• Bank decrypts messages with its private key

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Asymmetric Key Cryptography Example
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Public Key Cryptography

• Each user has a key pair, consisting of a public
  and private key
• Anything encrypted with one key may only be
  decrypted by the other.
• To make message readable only by B, encrypt
  message using B's public key

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Digital Signature Concept

• Sender encrypts message or its fingerprint with
  its private key
• Guarantees that only the sender could have
  created this message
• Basis for Non-repudiation

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Basis for Digital Signatures
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Digital Signatures
Signature Generation
Signature Verification
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Message Digest Concept

• Also called as Hash
• Unique representation of a message
• Similar to finger print of a human

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Message Digest Concept
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Message Digest Demands - 1
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Message Digest Demands - 2
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Message Digest Demands - 3
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Message Digest Differences

• Even if the original messages differ minutely,
  message digests differ dramatically
• Basis for the guarantee of uniqueness

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Message Digest Example
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Message Digest Algorithms

• Basic principle Take the original message, and
  reduce it to a smaller fingerprint
• Examples MD5, SHA-1
• SHA-1 is considered stronger

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Cryptographic Hash Algorithms

• Reduces a message to a fixed size message digest
• used for authentication and integrity
• digital signatures, with public key algorithms
• Hashed Message Authentication Codes (HMAC) with
  secret key

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Hash Standards

• FIPS 180-1
• SHA-1 160-bit hash preferred hash algorithm
  today
• FIPS 180-2 planned to include larger hash fields
• SHA-1 (160-bit)
• SHA-256
• SHA-384
• SHA-512

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Digital ID ?

• Binds a Subject with a key pair
• Contents of a Digital ID
• Certificate Serial Number
• Subject
• Issuer
• Valid From
• Valid To

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Digital ID ?

• Contents of a Digital ID
• Public key
• Key Usage
• Basic Purpose of Key Digital Signature, Non
  Repudiation, CRL signing
• Extended Key Usage
• Secure Email, Server Authentication, Client
  Authentication, Code Signing, Time Stamping

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Digital ID ?

• Contents of a Digital ID
• Thumbprint
• The CAs signature validating the certificate
• Thumbprint Algorithm

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Developing PKI Applications

• What is CAPICOM
• Digital Signing with CAPICOM
• Data Encryption with CAPICOM
• Accessing Certificate Stores
• Requesting and Installing Digital Certificate
• Demo Digital Signing and Verification
• Java Cryptography

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What is CAPICOM?

• CAPICOM is a new security technology from
  Microsoft
• Allows an application developer to easily
  incorporate digital signing and encryption into
  an application
• Built on top of MS CAPI
• COM based for every one!
• Visual Basic, Visual Basic script,ASP,C
• Free!

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Supported Platforms

• Windows 95/98 with Internet Explorer 5 or later
• Windows NT 4.0 with SP4
• Windows 2000
• Windows XP

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How to install CAPICOM

• Packaged as an ActiveX control
• Have your app install and register it
• Regsvr32 capicom.dll
• Use in web application, installation and
  registration done automatically
• One file, size 249 KB
• Redistributable

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What can CAPICOM do?

• Digitally sign data
• With software key, smart card, token
• Uses PKCS7 for interop
• Verify Digitally sign data
• Check certificate revocation
• Encrypt data
• Uses a password
• Uses a public key(for enveloping)
• Access Certificate Stores
• You dont have to use CAPICOM everywhere
• Mix and match CAPICOM, CAPI and other toolkit

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Digital signing in CAPICOM
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Main Objects in Signing

• Certificate
• Represents an X.509 certificate
• Signer
• Represents a Signer
• Authenticated attributes
• Additional meta-data included with signature
• Examples document name,description,signing time
• Protected with the content by the signature
• SignedData
• Object used to sign data

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Steps for Digitally Signing

• Which certificate to use
• Where to store the signature
• More than one signer
• How to validate a digital signature

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Supported Certificates

• Use any X.509 certificate
• Issued from anywhere
• From a certificate authority(NICCA,Verisign)
• From Windows 2000 PKI
• Use a self signed certificate
• Use any device to store the private key
• Can utilize whatever CAPI supports
• Software keys
• Smart cards
• USB tokens

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Which Certificate to use

• Application can preselect
• Enumerate Certificate in store and select
• Let CAPICOM do it
• If only one certificate, CAPICOM will use it
• If more than one certificate, CAPICOM will pop
  certificate selection dialog

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Certificate Selection Dialog
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Certificate view Dialog
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What Is A Signature?
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Where to store SignatureAttached Signature

• Signature stored as PKCS 7 format
• Data stored with signature
• Only one file to manage
• Must extract the original data to use it
• This is done through verify operation

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Where to store SignatureDetached Signature

• Data and signature stored seperately
• Signature stored in PKCS 7 format
• Both files are required to verify signature
• Easier to store in separate fields in the
  database

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More than one signer?

• Can store one or more signature
• SignedData.Sign() creates primary signature
• Add other signature by calling SignedData.Cosign()
  
• Cosigning is useful when multiple parties are
  signing a contract

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Multiple signers, continued

• Can also layer signature where one attached
  signature is input to another signing operation.
• Inner signature cannot be removed.

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Digital Signature Verification

• Signature verification consists of
• Integrity check on the signed message
• Whether data changed?
• Certificate chain must be valid
• All certificates in chain can be found
• No chaining errors
• Revocation Check
• Repeat for each signer

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Certificate validity checking

• SignedData.verify() does not do a revocation
  check.
• Use CertificateStatus Object

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Encryption in CAPICOM
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Encryption

• Two ways to encrypt data
• Encrypt with a password
• Symmetric encryption
• Shared secret
• Encrypt with a public key
• Asymmetric encryption
• Only recipients can decode message

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Symmetric encryption

• Encrypts with a password
• Use a long password for better symmetric keys
• Use a random salt
• Supported algorithms
• RC2(40 bit, 60 bit, or 128 bit)
• RC4(40 bit, 60 bit, or 128 bit)
• DES
• Triple DES
• Underlying platform must support the algorithms.

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Symmetric Encryption
Decrypt with Symmetric Key
Encrypt with Symmetric Key
Encryption
Decryption
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Data Enveloping

• Combines symmetric and asymmetric encryption
• Message encrypted with symmetric key because
  asymmetric encryption is slow
• Symmetric key is encrypted using public key
  stored in recipients certificate
• Recipients decode the symmetric key with their
  private key

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Data EnvelopingStep one Encrypt message
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Data Enveloping Step two encrypt the symmetric
key to the recipients
Step Two Encrypt the Symmetric Key to the
Recipients
Symmetric Key
Encryption
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Data EnvelopingStep three Put it All together
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Managing Certificate Stores

• Named, permanent storage for a collection of
  certificates
• Several predefined Stores
• My store houses certificates with private keys
• Root store houses trusted, self-signed
  certificates
• Application can define their own
• Logical stores and Physical stores
• Each logical store has one or more physical store
• HKLM\Software\Microsoft\SystemCertificates
• Logical stores support inheritance

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Logical, Physical stores and inheritance

• User Root Store

Current User store inherits from Local Computer
store
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Certificate Stores

• Two viewing Tools
• MMC certificate snap in(certmgr.msc)
• Internet explorer certificate manager
• Tools-gtoptions-gtContent-gtCertificates
• CAPICOM
• Store.open
• Store Location(User, Machine, AD, Memory)
• Store Name(user string or predefined constants)
• Open mode read only, read-write

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Demo Digital Signing and Verification
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Cryptography with Java

• Two main technologies are JCA AND JCE.
• JCA is part of JRE
• JCE is an extension to JCA
• JCE adds simple encryption and decryption to JCA

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JCA(Java cryptographic Architecture)

• JCA is composed of number of classes in
  java.security package and its sub-packages.
• Provides APIs for functions like digital
  signatures and message digests.
• Important classes are MessageDigest, Signature,
  KeyPairGenerator etc

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Message Digest Example

• Import java.security.
• //Use the MD5 algorithm
• MessageDigest md MessageDigest.getInstance(MD5
  )
• byte buf Message.getBytes()
• //Update the data
• Md.update(byte)
• //after input is ready, digest the data
• Byte digestBuf md.digest()

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JCE(Java Cryptographic Ex tension)

• JCE is an extension to JCA
• JCE contains the classes in the javax.crypto
  package and its sub-packages
• It includes classes like Cipher, KeyGenarator,
  Mac etc

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Encryption example

• import java.security.
• import javax.crypto.
• // Get the key Generator
• KeyGenerator keyGenerator KeyGenerator.getInstan
  ce(Blowfish)
• //Generate a key
• Key key KeyGenerator.generateKey()
• //Get the Cipher and initialise it with key

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Encryption Example ctd.

• Cipher cipher Cipher.getInstance(Blowfish/ECB/P
  KCS5Padding)
• cipher.init(Cipher.ENCRYPT_MODE, key)
• // assume data to encrypt is myData
• Byte cipherText cipher.doFinal(myData)

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Tour Management System

• eTour
• PKI Integration

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Existing Procedure

• Manual
• Time Consuming
• Management of Information
• Reports , Locating information

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eTour Features

• Web enabled system
• Workflow based system
• Digital Signature enabled
• Ensures integrity, authenticity and non
  repudiation
• Connects to existing Directory Server for
  authentication
• Supports Air as well as Train Travel
• Mail alert at every stage

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Roles supported

• Initiating officer
• HOD
• HOG
• DG
• DDO

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State Diagram Air Travel
HOD Forwards
HOG Forwards
Request Forwarded
Request Forwarded

• Request
• Initiated

DG Approves
DDO Processes
Request Processed
Request Approved
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State Diagram Train Travel
HOD Forwards
DDO Processes
Request Processed
Request Approved

• Request
• Initiated

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eTour Features

• Initiating officer may initiate a request.
• HOD may forward the request
• HOG may forward the request
• DG may approve the request
• DDO may update the request
• DDO may print the Tour Sheet
• Multiple DDOs supported

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Security features

• Shows last logon date and time
• Digital Signature
• Certificate Based Logon Support
• Automatic CRL download
• User Certificate Mapping
• Client side and server side validation
• Configurable CAs

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Tour Procedure Air Approval

• Initiating officer fills up the form and submit
  it to HOD
• HOD may forward it either to HOG or DG
• HOD may forward
• DG may finally approve

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Tour Procedure Train Approval

• Initiating officer fills up the form and submit
  it to HOD
• HOD may approve

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Login process
Auth with Directory
Application Server
Fetch registered Certificates.
Directory Authentication, Certificates
Submit auth info
Launch Application
Database Roles , Data , work flow
Client
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Digital Signature Verification
Application Server
Fetch CRL
CA Repository
Submit Signed Form
Database
Client
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Certificate Based Logon
Application Server
2. Fetch cert list
5. Verify Signature,check CRL log results.
6. Launch app / logout
Database
Directory
3. Send logon String to be signed , certificate
list and scripts
1. Submit login name
4. Sign and send login String
Client
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Platform Information
Application Server Tomcat , JAVA , JSP on
windows 2000
LDAP,HTTP
CA Repository
Database SQL Server
Client IE , CAPICOM , JScript
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Thank you!Cyber Security DivisionNIC HQ