Public WAP Key Infrastructure
CSCI 5939.02 Independent Study Fall 2002 Jaleel Syed Presentation No 5
Cryptography
Encryption: Transforming a message
containing critical data into a cipher text. Decryption: Decoding encoded data and reproducing the original message.
Types
Symmetric cryptosystems: encoding and decoding
done using the same secret key.
Asymmetric cryptosystems. Encoding done using
Highly insecure. Faster when compared to asymmetric crypto. Algorithms such as Data Encryption Standard(DES) are used both for encryption and decryption.
public key and decoding done using private key.
Secure. Slower computing speed. Algorithms such as RSA, ECDSA etc. Are used.
Example
Hashing
It is method to obtain a digital fingerprint(hash) of
an original message. This is used to test the integrity but not to reproduce the message.
Hashing example(Sender)..
Digital Signature Associated with message encryption
Hashing example(Receiver)..
Receiving side
What is Public Key Infrastructure ?
It is a system which enables users to securely and
privately exchange data and money through the use of public and private key pair. It provides a digital certificate that can identify an individual. It provides directory services(repository) that can store or cancel certificates when necessary.
Components of wired PKI
Certificate Authority Issues/updates/cancels the digital certificates to the requestor. Registration Authority
Authenticates the requestor
Repository A directory service that stores digital certificates. Subscriber Relying party
Components of wired PKI contd..
WAP PKI Model
Types of Authentication
WTLS Class 1 WTLS Class 2
WAP Device and WAP Gateway are not authenticated. It provides the capability for the WAP Device to authenticate the identity of the WAP Gateway.
SignText It provides a mechanism for the client device to create a digital signature of text sent to it.
It provides the capability for the WAP device to authenticate the identity of the WAP gateway as well as for the WAP gateway to authenticate the identity of the WAP device. Similar to signText, except that, in this the clients private key is used to sign a challenge from the server.
WTLS Class 3
WTLS Class 1
Security limitations of WAP
WTLS Class 2
Two Phase security model
WAP Client communicates to the origin server(content server) via the gateway.
End to End Security model
WAP client communicates with a WAP Server(WAP gateway + Origin server).
WTLS Class 2 contd..
Two Phase Security Model
WTLS Class 2 contd..
1. The WAP Gateway generates a key pair- public key & 2. 3. 4. 5. 6. 7.
private key. WAP Gateway sends certificate request to WPKI Portal. WPKI Portal confirms ID and forwards request to CA. CA sends Gateway Public Certificate to WAP Gateway. CA populates online repository with WAP Gateway certificate. WTLS session established between the device and the gateway. SSL/TSL Session established between the gateway and the server.
WTLS Class 2 contd..
End to End Security Model
WTLS Class 2 contd..
1. The WAP Server generates a key pair- public key 2. 3. 4. 5.
& private key. WAP Server sends certificate request to WPKI portal. WPKI portal confirms ID and forwards request to CA. CA sends Server Public certificate to WAP Server WTLS session established between the WAP server and the WAP device.
SignText
Message Signing
SignText contd..
1. WAP device requests certificate and sends 2. 3.
4. 5.
certificate URL to WAP device. WPKI Portal ID confirms and passes request to CA. CA generates User Certificate and sends Certificate URL(or entire certificate) to the WAP device. CA populates the database with User Public key certificate. User signs transaction at the WAP device and sends transaction, signature and certificate URL(or certificate) to Origin Server.
SignText contd..
1. Origin Server uses certificate URL to
retrieve user certificate from database(if not already in possession of certificate). 2. CA database sends user certificate to the Origin Server(if necessary). 3. Origin server verifies the signed transaction sent from the WAP device.
WTLS Class 3
Similar to signText, except that, in this the
clients private key is used to sign a challenge from the server. Used for Non-repudiation.
Digital Certificate.
Name of the certificate holder. The certificate holders public key. Certification Authority A Serial Number Validity period
Types of Digital certificates
Client Certificate.
Authenticates the client.
WAP Server WTLS Certificate.
It authenticates the identity of the WAP server Encrypt information for server.
CA Certificate.
Authenticates the Certification Authority
Overview
WAP PKI Operations
Trusted CA information Handling. WTLS Server Certificate Handling. Client Registration. Client Certificate URLs.
Trusted CA Information Handling
This operation verifies whether the CA that
issued the certificate, can be trusted or not. The CA information should be distributed to each client. The CA.
WSP(wireless session protocol): URL is distributed. Provisioning: CA information is downloaded on the client.
Trusted CA information Handling contd..
The CA information is sent to the client by. Out of band hash verification method: the CA certificate is hashed and sent through an in-band channel whereas the display form of hash is sent in an out of band channel(phone or mail). Signature verification method: if a new CA has issued the certificate, then it can only be trusted if it is accompanied by the cert of a CA already trusted by the client. The CA updates the CA certificate th...