Security Products in E-Commerce. Anjali Shende

Transcription

1 Security Products in E-Commerce Anjali Shende

2 Introduction What is E-commerce? Process of buying, selling or interacting with customers via Internet, smart cards, or other computer networks E-commerce is simply business conducted over the Internet Why do we need security? Protection of sensitive data Privacy Theft & Fraud Violation of Data Integrity

3 Secure Electronic Commerce It is not just about electronic payments Secure Communication But there are problems. Multi-party problems: payments, notarized contract signing, auctioning, copy protection Multi-party security: limited trust in others Data Integrity But we also need Privacy and anonymity of our transactions Accountability Lots of legal questions

4 Main Issues in Electronic Commerce Web-Client Security Security of the machine used by the customer to navigate on the web Web-Server Security Security of the machine used by the merchants to display and sell their products Operating System Security Preventing unauthorized people from accessing and tampering with your data Data Transport Security Relates to secure exchange of data over the Internet Topic of this talk.

5 Data Transport Security Confidentiality: Cryptography & Encryption To prevent fraud in electronic commerce To assure validity of financial transactions To assure privacy Authentication: Digital Certificates Reliable verification of identity Required by both the customer and the merchant Data Integrity: Digital Signatures To make sure that the data has not been altered on its way to the destination Non-repudiation: Digital Signatures The author of a message cannot deny sending that message

6 Example of Electronic Transaction Electronic Check Create a text asking your bank to pay someone a specific amoun And send it. But sending this file has security problems: Any one could intercept and read it - need privacy Someone else could create a similar counterfeit file - authentication Originator could deny creating the file - non-repudiation Someone could alter the file - data integrity Steps needed to execute the electronic version of check Encryption Mathematical transformation using a key to encrypt the document - makes it unreadable Symmetric Algorithms: same key used to decrypt Fast

7 Electronic Check. Problem: Need to send the encrypted document AND the secret key to decrypt Public Key Cryptography To Deliver Secret Key Uses asymmetric algorithms: two keys One key to encrypt (public - known to everyone) Another key to decrypt (private or secret) Slow algorithm - good for short messages, like symmetric keys Digital Signature To Authenticate the Sender Hash (mathematical summary) of the check Switch the role of private and secret keys: encrypt with your private key This hash can be decrypted by anyone with public key Verification of this hash provides authentication

8 Electronic Check.. Writing & sending a check using Public-Key Cryptography

9 Weakness of Symmetric Keys Key Proliferation Each file transfer with every user needs a new key Number of keys required grows exponentially with the number of users: n 2 -n And a problem of safe key delivery File Proliferation (sharing resources) If a file is to be shared Need multiple encrypted copies of the same file Storage (waste of disk space) Version control becomes difficult Public Key Technology Solves These Problems (shown in electronic check transaction)

10 Symmetric Key Algorithms Fast, hence important Plaintext Ciphertext Plaintext Encryption DES: Data Encryption Standard Decryption Block algorithm with 64-bit block 56-bit key for encryption Federal Information Processing Standard Will be replaced by AES - Advanced Encryption Std. Finalists for AES standard MARS (IBM), RC6 (RSA), Rijndael, Serpent, and TWOFISH Different derivatives of DES, like Triple-DES IDEA: International Data Encryption Algorithm Uses 64-bit block size algorithm 128-bit key size for encryption Considered secure. Used by PGP and others

11 Public-key Cryptography: Methods Diffie-Hellman (1976) A way to share private key over public network Discrete logarithm problem Equivalent to factoring large integers Secure with sufficiently long keys (>64-bits) RSA - Rivest, Shamir, and Adleman Problem: Factoring Large Integers Provides both Confidentiality and Authentication Confidentiality Encryption: use public key Decryption: use private key Authenticity Create Digital Signature: Encrypt Hash using private k Verify Digital Signature: Decrypt Hash using public ke and verify Hash

12 Public-key Cryptography: Methods. ElGamal: Discrete Logarithm Problem Encryption and Digital Signatures Used in DSA (Digital Signature Algorithm, a federal standard) RSA & ElGamal: Similar security for equivalent keys Elliptic Curve Algorithms Operations defined over Elliptic Curves Very Hard Problems Two Classes: Analogs to RSA Analogs to Discrete Logarithm Systems (e.g. ElGamal) Smaller key size, better performance 160-bit key equivalent to 1024-bit key for RSA

13 Comparison of Encryption Systems System Algorithms/Methods Provides PGP IDEA, RSA, MD5 Confidentiality, authenticat integrity & non-repudiation S/MIME User- specified Confidentiality, authenticat integrity & non-repudiation SSL RSA,RCZ,RC4,MD5 & Confidentiality, authenticat others integrity & non-repudiation S-HTTP RSA,MD5 & others Confidentiality, authenticat integrity & non-repudiation however, it's obsolete SET & CyberCash RSA,MD5,RC2 Confidentiality, integrity, authentication, nonrepudiat IPsec Diffie-Hellman & others Confidentiality(optional), authentication, integrity Kerberos DES Confidentiality, authenticat

14 Products: Analysis and Comparison ID2 Baltimore Technologies Unicert Xcert Sentry Entrust RSA KEON Netscape CMS VeriSign Entegri Notary Smart Card supprt? yes yes yes no yes yes Hardware key support yes yes yes no yes VPN support no no no yes yes Certificate Revocation? CRL CRL CRL, OCSP CRL CRL CRL Encryption and Certificates X.509 yes yes yes yes yes yes PKCS#11 yes yes yes no yes yes SSL yes yes yes yes yes DSA yes yes yes ECDSA yes yes RSA yes yes yes Diffie-Hellman no no no no no no no yes S/MIME yes yes yes no yes yes SET yes yes no IPSEC, Netscape, Microsoft IE IPSec IPSec IPSec Others PKCS#7, IPSEC, SET Cross -certification yes no key backup and recovery yes no yes yes LDAP support yes yes yes yes Elliptic curve cryptography no no Signing key 4096 Encryption key length Dual key/split key (nonrepudiation) yes yes yes yes yes Platforms WindowsNT, Solaris WindowNT, Solaris PKIX, PKCS#10 PKCS#7

15 Security Products Entrust/PKI Encryption, Digital Signatures, Authentication Key Features Certificatoin Authority: X.509 certificate standard Registration Authority: Administrative functions Key and Certificate Management: Automatic key update & tracking Certificate update & revocation Key Backup and Recovery: Decryption key history Certificate Revocation: CRL standard Dual Key Support: Non-repudiation Supports Cross Certification

16 Security Products RSA KEON PKI-based application security product Two components: Security Server: Central management CRL Verification Certificate Authority Trust Relationship Interoperable with LDAP-enabled Directories & CA Certificate Server Supports Dual Keys Has Self-contained LDAP Server Personal Certificates Allowed for Authentication, S/MIME Full Certificate Revocation Support

17 Security Products Netscape CMS Supports Virtual Private Network ( VPN ) Supports Dual-Key Certificates Encryption: RSA, DSA Standard Supported: X.509v3 Certificates CRLs PKCS#11 SSL Key Lengths 4096 bits for digital signature 128 bits for encryption Does not Support: Elliptic Curve Cryptography

18 Security Products Baltimore Technologies: UNICERT Supports CA, RA, VPN Supported Standards Certificates: X.509v3, SSL, S/MIME Cryptography: RSA, DSA, ECDSA Digital Signatures for Authentication Non-repudiation Data Integrity By Message Digest Digital Signature Handles Wide Variety Of PKI Requirements Different certificate types, multiple delivery systems, multiple key support