Student: Ying Hong

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How To Protect Keys

• Student Ying Hong
• Course Database Security
• Instructor Dr. Yang

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Introduction

• As public key cryptography has become the basis
  of computer security, the weak point in security
  has shifted from the data itself to the keys
  which protect them.
• Tow approaches
• one is from RSA Security
• one is from nCipher Security World

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RSA Approach

• Traditional approach is to save the keys and
  encrypted data within the database together.
• RSA approach is to build an Encryption Server to
  provide centralized encryption services, which
  separates encryption keys from the encrypted data
  stored in the database.

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Internal Database Encryption
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External Database Encryption
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Sample Implementation
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Weak Point

• Traditional approach vs. RSA approach
• You may notice
• RSA approach did NOT yet solve the problem of the
  exposure of the keys and sensitive data
  thoroughly. It moves the weak point from the
  server application (ProcessLogin) to the
  CryptoServer.

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nCipher Approach

• nCipher approach is to provide Hardware security
  modules (HSMs) with software to control key
  management.
• nCipher also developed a new system called Secure
  Execution Engine (SEE), which can protect
  application software as its executed by allowing
  the sensitive code being executed inside the HSMs.

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Secure Key Storage

• The keys can only be used inside the HSMs, so
  that strong security perimeter is provided.
• However, its not good idea to store keys inside
  HSM
• HSM is attacked, keys are destroyed
• the number of keys which can be created, used and
  stored is restricted by the capacity of storage
  built into HSM unit
• HSMs module key is often pre-installed and known
  to the HSM manufacturer, so the chain of trust is
  not entirely under the control of the HSM
  administrator.

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Key Backup Recovery

• Key backup and recovery should be implemented in
  a consistently secure manner.
• Basic concepts of protecting stored keys
• Strong encryption triple-DES
• Fragmentation of keys k of n key fragments
• ACL a list of operation associated with each key

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Key Backup Recovery cont.
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Key Backup Recovery cont.

• Steps of creating key blob
• The target key is encrypted using Triple-DES
  encryption. Its ACL is also, separately,
  encrypted.
• The key and ACL are encrypted together and the
  result is signed with a wrapper key (module key),
  to form blob. A Message Authentication Code (MAC)
  is stored with the key blob, ensuring that
  tampering is detectable.
• The wrapper key in turn is associated with
  another ACL, which determines who can access it.

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Key Backup Recovery cont.

• If required, key fragments can each be wrapped
  with their own access control mechanisms.
• Now, encrypted key blob can be exported and
  stored server storage also key fragments can be
  stored separately so that k smart cards out of a
  total set n are required to access the key.

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Access To Key Blob
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Access To Key Blob cont.

• Access to key blobs is physically controlled
• Smart cards must be presented in order to load
  the key blob into the HSM and unwrap it for
  decryption
• Knowing the key blob is not sufficient to recover
  the original key object by itself, since any key
  stored on physical tokens is encrypted with the
  module key and module keys are held securely
  within the HSM.
• Instead of just encrypting keys with the module
  key, the HSM can combine the module key with a
  phrase supplied by the user, so that it
  significantly improves the weak point on the
  chain of the trust we mentioned earlier.

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Sample Implementation
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Extension

• nCiphers SEE technology enable the code to
  perform security functions inside the HSMs.

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Sample Implementation
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Benefits

• Non-hierarchical key management
• the administrator card set
• the operator card set(s)
• Initialization key uniqueness
• the module key is not known outside the HSM and
  remains valid until the module is reinitialized
• Scalability
• Its possible to share module keys across a
  series of HSMs

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Conclusion

• RSA approach is a software-only solution, so its
  easier to use.
• nCipher approach may be more secure than the RSA
  approach, and it takes one more step further to
  protect the sensitive code, but its obviously
  more complicated.

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References

• http//www.placewareforum.com/rsasecurity/page.cfm
  ?peventeventid12458subcatid11728, Securing
  Data At Rest Developing a Database Encryption
  Strategy
• http//active.ncipher.com/whitepapers/nCipher_secu
  rity_world_wp.pdf, nCipher Security World white
  paper
• http//active.ncipher.com/whitepapers/SEE_white_pa
  per.pdf, Secure Execution Engine white paper