3. Agenda
• Data Security Considerations for the Cloud
• Basic Cryptographic Concepts and Applications
• 1-way hashes and digests
• Secure Credential Storage
• Symmetric Key Cryptography
• Data Confidentiality – in storage and in transit
• Asymmetric Key Cryptography
• Authentication and Secure Communications
• Recent Trends in Cloud Security
• HSMs for Safe Key Storage
• Encryption Gateways into the Cloud
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5. Cloud Data Security: Context
• Data Security is crucial for Enterprises
• Data Protection is vital for Reputation
• Concerns on Data Security are a deterrent to broader
adoption of Cloud Computing
• Data moves out of Enterprise boundaries
• Trust on Cloud providers
• Shared infrastructure
• Yet benefits of Cloud Computing are compelling
• Need for comprehensive and non-intrusive data security
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6. Top Cloud Data Security Issues: Gartner
• Breach notification and data residency
• Data management at rest
• Data protection in motion
• Encryption key management
• Access controls
• Long-term resiliency of the encryption system
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7. Cloud Data Security: Who is responsible ?
“Encryption of sensitive data is generally a good security practice,
and AWS encourages users to encrypt their sensitive data before it
is uploaded to Amazon S3.”
– Amazon Web Services: Overview of Security Processes
• Who is responsible for the overall security ?
• Different levels of providers
• Shared infrastructure can make extent of breach higher
• APIs allow many admin functions to be carried out
• Malicious entities can look for weaknesses in the API
• Can gain broad access to shared infrastructure
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8. Cloud Data Security: Encryption Layers
• Different Layers of Encryption
• Block Storage / Disks
• File and API
• Databases
• Applications
Applications
Databases
File, API
Disks
• Higher-level encryption can protect better but is harder
• Key question: Who has the key ? They have access
• Only Disks encrypted by provider
• Provider can see disk content
• Files and APIs encrypted by provider
• Provider can see API flows and file content
• … and so on
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9. Cloud Data Security: Broad Concerns
• Is server based encryption sufficient ?
• Encryption Gateways on the client/enterprise side
• How secure are the encryption keys ?
• Stored in the Cloud - Secured VM, HSM
• Stored by Client/enterprise (Encryption Gateways)
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11. Basic Conceptual Terms (1/2)
• Cryptography Provisions
• Authentication, Confidentiality, Non Repudiation, Integrity
• Deals with making communications and storage secure
• Encryption/Decryption
• Encryption: clear-text message to cipher-text
• Decryption: cipher-text back to clear-text
• Types of encryption algorithms
• Symmetric Key
• Asymmetric Key
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12. Basic Conceptual Terms (2/2)
• 1-way Hash functions
• Also known as a message digest or fingerprint functions
• Data Integrity
• Digital Signatures
• Uses Public-key/Asymmetric Cryptography and 1-way hashes
• Data Origin Authentication and Data Integrity Assurance
• Digital Certificates and Public Key Infrastructure
• Digitally Signed Public Keys
• Infrastructure for the Web of Trust
• Key Security
• Secure storage of secret keys
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13. 1-way Hashes: Overview
• Message digest or fingerprint
• Variable-length input string
converted into a short fixed-length
binary sequence
• Easy to compute
• Infeasible to reverse
• Infeasible to craft collisions
Note: MD5 is not considered secure today.
Only for illustration.
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14. 1-way Hashes: Uses
• Used for storage of
credentials like passwords
• 1-way encryption
• Not feasible to compute
password from the hash
• Not feasible to compute other
passwords producing same hash
• Also used in
• Digital Signatures
• File integrity checks
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15. 1-way Hashes: Details
• Algorithms
• MD5 (128 bits), SHA-1(160 bits), SHA-256 (256 bits), SHA-512
(512 bits)
• Attacks
• Pre-computed dictionary attacks/ Rainbow attacks
• Hash Collision
• Mitigation
• Use random salts
• Use stronger versions e.g. SHA-256 upwards
• 2-Factor authentication
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16. 1-way Hashes: Upshot for Cloud
• If your cloud provider is able to send you your password
for Forgot Password, …
• Apps hosted by you on provider’s infra should use 1-
way hashes with salt for storing passwords in the
database
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17. Symmetric Crypto: Overview
Secret Key
Plaintext Ciphertext Plaintext
Encryption
Decryption
• Same key is used for encryption and decryption
• Parties need a mechanism to exchange the shared
key securely
• Key must be secret and safely stored
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18. Symmetric Crypto: Uses
• Basis for Data Confidentiality
• Vital for secure storage and secure transmission
• Prevents attackers from being able to make sense of disk data or
network packets they illegitimately accessed
• Symmetric key ciphers are efficient
• Relatively inexpensive to produce a strong key
• Smaller keys for the same level of protection
• Comparatively inexpensive encryption/decryption
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19. Symmetric Crypto: Details
• Algorithms
• 3DES, AES-x (x=128,192,256), RC4
• Attacks
• Cryptanalysis
• Key compromise
• Mitigation
• Rotate/Rollover keys every N years
• Secure Key Storage
• Restricted filesystem/VM, HSM
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20. Symmetric Crypto: Upshot for Cloud
• Secure way to store uploaded data, sensitive personal
information in databases, VM images, emails etc.
• To infrastructure provider and SaaS provider
• What is encrypted and using what mechanism?
• How and where are secret keys stored ? Are they rotated ?
• Is there a way that only I can use the secret key without the
provider having access to it ?
• For apps hosted by you
• Are you encrypting sensitive data stored in databases, Text
Search indexes etc.
• How secure is your secret key ?
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21. Comparable Crypto Strengths
• Smaller Keys are more
efficient
• Faster generation
• Faster encrypt/decrypt
• Smaller encrypted output
• Longer keys have higher
crypto strength
• For same algorithm
• Symmetric Keys are
stronger for same size
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22. Asymmetric Crypto: Overview
Public Key Private Key
Plaintext Ciphertext Plaintext
Encryption Decryption
• Public Key is well-known and published to all
• Private Key is secret and must be stored safely by owner
• Encrypt with one Key, Decrypt with another Key
• Infeasible to compute Private Key from Public Key
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23. Asymmetric Crypto: Overview
• Key generation, encryption/decryption are expensive
compared to symmetric keys
• Used to encrypt small amounts of data, mostly for authentication
• Rarely used for encryption of regular data which is voluminous
• Private key must be securely stored similar to symmetric
keys
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24. Asymmetric Crypto: Uses
• Secure Communications
• Data origin authentication
• No interception/diversion aka Man-in-the-middle
• Symmetric Key exchange during session establishment
• SSL, PGP, SSH
• Mechanisms
• Digital Signatures
• Digital Certificates
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25. Digital Signatures: Overview
• Builds on Hashing and Asymmetric Crypto
• Actual data remains in plaintext but signature is attached
• Data origin authentication, Data integrity assurance
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27. Digital Certificates: Signatures + Chain of Trust
• Builds on Digital Signatures and PKI
• Certificate is a "Digitally Signed Public Key"
• Chain of Trust with Certificate Authorities
• DNSSEC also has Chain of Trust but no certs
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28. Digital Certificates: Details
• Certificate is public and valid for a
time interval (typically years)
• Certifies that Public Key identifies
Subject
• DNS hostname, Email address etc.
• Affixed with CA signature
• Verifier configures Trust Anchor
• a node in the Chain of Trust
• root always trusted
• Root CA is ultimate authority
• Self-signed certificate trusted by clients
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29. Digital Certificates: Details
• Attacks
• Private key compromise (anywhere in Trust Chain)
• Fraudulent yet cryptographically valid certs
• Digital Signature forgery typically via Hash collisions
• Mitigation
• Use reputed CAs
• Strong encryption and hash functions
• Secure Key Storage
• Certificate Revocation
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30. Asymmetric Crypto: Upshot for Cloud
• To Cloud Providers
• Are they using valid non-expired SSL certificates and strong
encryption ?
• Server certs and client certs (if applicable)
• Are their domains DNSSEC enabled ?
• Protection against DNS Cache Poisoning Attacks
• Do they renew certificates and roll over DNSSEC keys ?
• For your hosted apps
• Is HTTPS used for all confidential exchanges ?
• Are signed emails used especially for input emails that trigger
workflow actions ?
• Is certificate-based client authentication implemented properly ?
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32. Hardware Security Modules
• Secure and tamper-resistant storage for high-value keys
• Traditionally used for CAs, DNSSEC signers
• Now being considered for more uses in the Cloud
• Very difficult to access/steal keys from the device
• Various FIPS levels
• May Respond to tamper attempts
• Highly secure ones can self-destruct keys
• Often JCE KeyStore provider is supplied by vendor
• Can use JCE KeyStore abstraction directly from Java apps
• If not, need to use a JCE PKCS#11 Provider
• Uses JNI to invoke the native PKCS#11 API libraries
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33. Hardware Security Modules
• Key stays within the HSM
• Cryptographic operations
occur within the hardware
• signing
• encryption/decryption
• Cryptographic black box
• input data goes in
• cryptographically
transformed data comes out
Storage
Creation
Destruction
Usage Distribution
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34. Cloud Encryption Gateways
SaaS
PaaS
IaaS
Encryption
Gateway
SaaS forms
PaaS API
Cloud DB
JDBC
• Intercept and transform sensitive data before it goes out
• Replace it with a random token or strongly encrypted value
• Must be of same size and type, else things will break
• Do reverse operation for data coming back into premises
• Real-time crypto operation on every request/response
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35. Cloud Encryption Gateways
• Enterprise owns encryption key or token vault
• Data stored in Cloud provider’s datastores is mangled
• Data stores include databases, Text Search indexes
• Sensitive data not compromised
• Field-based operation
• Can specify the sensitive fields
• Only those will be transformed
• Cloud platform aware
• Gateway needs to do transformations specific to the SaaS, PaaS
involved in the interaction
• Not platform-agnostic
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36. Cloud Encryption Gateways – Format Preservation
• Format preserving encryption
• Usually encryption produces longer ciphertext than plain-text
• logical data type may change too
• e.g. 1234567812345670 (16 digit number) ->
lqRcvPnCqUJc3p4nSUjLZw==, (24 char base64 encoded string)
• Size and datatype mismatch in transformation will break things
• Database column type and length
• Application data types and length
• Ciphertext is in same format (type and length) as input plaintext
• Input: 10 digit numeric id, Output: a different 10 digit numeric id
• Input: 30 character address, Output: 30 character mangled string
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37. Cloud Encryption Gateways – Function Preservation
• Function preserving encryption
• Just format preservation may not be sufficient
• What about
• Wildcard matches
• Sort orders
• Need encryption/tokenization that is order-preserving
• More generally function-preserving
• Claims of such encryption have been made
• Possibility of reduced encryption strength
• Not yet clear if strength is within acceptable limits
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38. Conclusion
• Many pieces to the Cloud Data Security puzzle
• Innovative solutions are emerging based on well-proven
building blocks
• Comprehensive approaches involving all parties are
the need
• News of breaches causes discomfort
• It may take a while before comfort levels are reached
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39. References
• NIST Special Publication 800-57 Recommendation for
KeyManagement – Part 1: General (Revision 3)
• MD5 considered harmful today: Creating a Rogue CA
Certificate
• Six security issues to tackle before encrypting cloud data
• http://www.computerweekly.com/news/2240180087/Six-security-issues-
to-tackle-before-encrypting-cloud-data
• An Illustrated Guide to Cryptographic Hashes
• http://www.unixwiz.net/techtips/iguide-crypto-hashes.html
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