The Public Key Muddle How to manage transparent end-to-end - - PowerPoint PPT Presentation

The Public Key Muddle

How to manage transparent end-to-end encryption in organizations

• Dr. Gunnar Jacobson

CEO

Secardeo GmbH

Business Communication

• E-Mail

– Desktop (e.g. Outlook)  Cloud (e.g. Office 365) – More than 50% opened on Mobile Device

• Instant Messaging (IM)

– WhatsApp/WeChat (private) -- Skype for Business – Business use growing faster than private use

• File Exchange

– Increasing adoption of Cloud Storage (Box, DropBox, OneDrive…)

• Voice over IP (VoIP)

– Analog/ISDN is replaced by VoIP

Why do we have to encrypt?

• Allianz Top Business Risks 2015:

#5: Cyber crime: #1: Data theft and manipulation

• Risks are caused by

– Internal attackers (data stealing) – Industrial espionage (APT) – Intelligence agencies (data interception)

• Countermeasure: End-to-End Encryption

Bob

Bob‘s Private Key

Text Directory Alice

Bob‘s Public Key

Text

Public Key Encryption

End-to-End Encryption - E2EE

E2EE Requirements

• En-/Decryption is done by the (E-mail, IM,

File-Exchange, VoIP) App on the device

• Interoperability is a key issue for B2B
• Encryption is legal – without backdoors
• Completely transparent to the user
• Low efforts for public key management

Key Management Challenges

Internet Alice Bob

„Is my private key available on all

• f my devices?“

„Do my apps work with my key?“

Key Management Challenges

Internet

„Can I trust this public key?“ „How can I retrieve Bob‘s public key?“

Alice Bob

„Is my private key available on all

• f my devices?“

„Do my apps work with my key?“

Trust Models

Alice Bob

KB KA

CA

Provider

Bilateral Trust Web-of-Trust Intermediary Trust Hierarchical Trust

Trust Models

Alice Bob

KB KA

CA

Provider

Bilateral Trust Web-of-Trust Intermediary Trust Hierarchical Trust A hierarchical trust model based on X.509 certificates is the preferred model for medium & large organizations

Public Key Retrieval

• Public Keys are retrieved from

– Keyserver – Certificate Directory Server – Intermediary (Service Provider)

• Global retrieval of any user‘s key is required
• Security mechanisms for address harvesting
• Manual or (better) automatic retrieval (LDAP)

Private Key Distribution

• Smartcards are secure and portable but

– Expensive – Poorly supported on mobile devices

• Software keys

– PKCS#12 is the standard format – Manual distribution is difficult and costly – Automated key distribution required – Limitations caused by MDMs and Apple

E2EE Applications

• Electronic Mail

PGP – used by individuals – Add-on products required S/MIME & X.509 – Widespread use by organizations – Supported by all major e-mail clients

• Instant Messaging (IM)

– Poor support of XMPP E2EE with PGP & S/MIME – Popular products use OTR (man. fingerprint check)

Contrary requirements

Business E-Mail Private IM/Chat

Non-Repudiability Repudiability Key Recovery Forward Secrecy Organisational Trust Bilateral Trust Interoperability Proprietary Solution Compliance

E2EE Applications (2)

• File Exchange

– PGP (used by individuals) – MS EFS (used within corporate domain) – Cloud storage (proprietary): BoxCryptor, ViiVo,… – Cloud storage: SecureZIP (PGP), certDrive (X.509)

• VoIP

– Poor support of SRTP E2EE with MIKEY X.509 certs – Cisco SCCP supports E2EE with X.509 certs – Popular products use ZRTP (manual check of Short Auth. String)

Key Management for E2EE

 High interoperability  S/MIME  X.509 based Key Management  Poor interoperabilty  Standards exist but  Proprietary solutions dominate

Key Management alternatives

a) Proprietary, vendor driven

– Buy best-of-breed products – Use vendor specific key management – Vendor/service provider will control your keys

b) Standardized, universal

– Rely on open and well established standards – Use products that support digital certificates – Build a universal key management infrastructure – Keep corporate control of your keys

Proprietary Key Management

Proprietary Key Management

Different product vendors: Diversity of Key Management Inconsistent Trust Models High efforts for Key Distribution Loss of corporate control of keys

Universal Key Management

Universal Key Management

Universal Key Management

Universal Key Management

Mobile Device Manage- ment

Universal Key Management

Mobile Device Manage- mentx MDM Proxy Key Reco- very Server

Certificate Enrollment Proxy

• Acts like a Windows CA
• Autoenrollment from Non-Microsoft CAs
• Auto-Revocation & -Modification
• Smart Key-Backup & Recovery
• Automated distribution of private keys to

mobile devices

• Using accepted certificates from Public CA

Certificate Directory Server

• Automated, secure publishing of internal

certificates

• Automated search for standard E-Mailclients

via LDAP and ActiveSync in 140 Directories for

• User-transparent E2EE
• Centralized trust managment & validation
• Ad-hoc issuance for partners who don‘t have a

certificate

MDM Proxy

• Solves conflicts with managed iOS
• Forwards MDM protocol messages
• Adds PKCS#12 & password to Exchange profile
• Profile is transferred securely by

– TLS – Optional E2EE of profile

Summary

• Proprietary E2EE apps cause key management

issues

• An X.509 PKI is the basis for universal corporate

key management

– Using globally accepted certificates – Automation of key management tasks – Key distribution to mobile devices

• Use E2EE apps that support X.509

– Improve security – Save operational costs – Gain user satisfaction

Thank you for your Attention!