Secure Your Encryption with HSMNarudom Roongsiriwong, CISSP

OWASP Thailand Chapter Meeting 4/2017June 29, 2017

WhoAmI● Lazy Blogger

– Japan, Security, FOSS, Politics, Christian– http://narudomr.blogspot.com

● Information Security since 1995● Web Application Development since 1998● Head of IT Security and Solution Architecture, Kiatnakin Bank PLC (KKP)● Consultant for OWASP Thailand Chapter● Committee Member of Cloud Security Alliance (CSA), Thailand Chapter● Consulting Team Member for National e-Payment project● Committee Member of Thailand Banking Sector CERT (TB-CERT)● Contact: narudom@owasp.org

Real World Cryptography

We spend too much time arguing about algorithm but lack of time discussing● Key controls and key management● Key change/exchange procedures● Cryptographic toolkits● Random number/seed generators● Process & documentation● Training

Brute-Forcing vs Key Thef

Left hand side: At the Passwords^12 Conference, Jeremi Gosney (a.k.a epixoip) demonstrated a rig of 25 AMD Radeon GPUs that leveraged Virtual OpenCL Open Cluster (VCL)

Cryptography uses SECRET keys

How can we keep keys being SECRET?

Key Management Fundamental

“Key management is the hardest part of cryptography and often the Achilles’ heel of an otherwise secure system.”

- Bruce Schneier, Applied Cryptography (2nd edition)

Key Management Framework

Generation Exchange Storage Rotation Archiving Destruction

Key Usage

Key Generation● Generate Key● Register Owner● Activate Key● Deactivate Key● Suspend and Re-Activate a Key● Renew a Public Key● Key Derivation or Key Update● Associate a Key with its Metadata● Modify Metadata● List Key Metadata

Key ExchangeEstablish Key● Validate Public Key Domain

Parameters● Validate Public Key● Validate Public Key Certification

Path● Validate Symmetric Key● Validate Private Key (or Key Pair)● Validate the Possession of a Private

Key● Perform a Cryptographic Function

using the Key● Manage the Trust Anchor Store

Cryptographic Key and Metadata Security: During Key Establishment● Key Transport● Key Agreement● Key Confirmation● Key Establishment Protocols

(TLS, IKE, SSH, …)

Key Storage● Store Operational Key and Metadata● Backup of a Key and its Metadata● Recover Key and/or Metadata● Enter a Key and Associated Metadata into a Cryptographic

Module● Output a Key and Associated Metadata from a Cryptographic

Module

Key Rotation (Retirement)● Replace Key (Rollover, Update and Renewal)● De-register Key● Revoke Key

– Document, Test and Maintain Compromise Management Plan– Establish and Maintain Notification Process– Assess Impact as Part of Incident Response– Do Not Delete the Keys

Key Archival● Archive Key and/or Metadata● Recover Key and/or Metadata

Key Destruction● Destruction of Encryption Key Materials● Retention of Encryption Key Meta-Data

An Overview of Hardware Security Module

What is an HSM?

● Cryptographic Computing Hardware Module● Protected Key Store● Well-Defined Interface Protocol● Hard to Compromise

Hardware Security Module

Other Names of HSM● Personal Computer Security Module (PCSM)● Secure Application Module (SAM)● Secure Cryptographic Device (SCD)● Secure Signature Creation Device (SSCD)● Hardware Cryptographic Device● Cryptographic Module

Source: SANS Institute InfoSec Reading Room, An Overview of Hardware Security Modules

Cryptographic Computing Module● Hardware Accelerate Cryptography

– Symmetric: AES, 3DES, Blowfish, Aria, Camelia– Asymmetric: RSA, DSA, Diffie-Hellman, ECC

● Secure Random Number Generator● Message Digest (Hash)● Message Authentication Code (MAC)

Protected Key Store● Keys stored in tamper-proof nonvolatile memory

– If tampering is detected, memory will be malfunction● Implemented using

– Covering components in epoxy– Thin wires covering sensitive components

How HSM Helps Key Management?● HSM has key generation functions● HSM provides key transport and key agreement functions● HSM provides protected key storage and key handling

functions● HSM provides ciphertext translation function from one key to

another for key rotation● HSM provides key backup/recover functions for key archival● HSM is able to delete keys inside protected storage.

Main Application Areas● PKI Environments

– Certification Authority (CA) and Registration Authority (RA)– Generate, store and handle key pairs

● Card Payment Systems– Authentication and integrity checking of messages– Confidentiality (e.g. PIN)– On-line PIN verification– Checking card security codes– Re-encryption of PIN blocks– Card creation: PIN mailers, generation of magnetic stripe data,

personalization of chip cards– E-commerce and M-commerce– Home banking

Other Application Areas● Key Distribution Centers● SSL connectivity● PayTV● Access control: one time passwords, user authentication● (Qualified) Digital signatures● Time-stamping● Trusted Platform Modules (TPM)● Document protection

HSM Selection Criteria

Smart Card / SIM SD Card

HSM Form Factors

USB

Network / Remote InterfaceLocal Interface (PCI/PCIe)

HSM Key Store Architectures

Keys stored in HSM● Pros:

– No additional component is needed

– Ease of maintenance● Cons:

– Limited numbers of keys● Example Product: Safenet,

USB Type, Smart Card Type

Keys stored externally and encrypted by master key in HSM● Pros:

– Unlimited or large numbers of keys

● Cons:– Additional components are

needed– Hard to maintain

● Example Product: Thales

HSM: General Purpose vs Specific PurposeGeneral Purpose● Equipped with standard

cryptographic algorithms Symmetric, Asymmetric, Hashing)

● Support major OS drivers including VMWare and Hyper-V

● Support standard APIs– PKCS#11– Open SSL– Java (JCE)– Microsoft CAPI and CNG

Specific Purpose● Optimized for specific function

– Security Application Module (SAM) / SIM

– Electronics Fund Transfer / Payment System

● Limited Cryptographic algorithm● Support specific applications

– EFT Key Management– MAC (Message Authentication

Code)● May not support standard APIs

HSM Speed● RSA Signing Speed → Signing operations per second (at 1024-

bit, public exponent 3 or 65537)● RSA Key Generation Speed → Keys per second (at 1024-bit

and 2048-bit)● Visa PIN Verification → Operation per second● AES Encryption → MB per second (at 256-bit key length)

HSM Licensing● HSM specification may support many cryptography algorithms

but not all are activated– Algorithm activation based on the license

● Maximum encryption/decryption speed may not be the same as declare in the specification– Speed limit by the license

● Network or remote interface type HSM may limit the number of hosts or IP addresses connected to the HSM upon the license

HSM: Standard and Certification● FIPS 140-2● Common Criteria Evaluation Assurance Level (CC-EAL)● PCI HSM● APCA● MEPS

FIPS 140-2

Level Requirement

1 Basic security requirements

2 Tamper evidence, user authentication

3 Tamper detection/resistance, data zeroisation, splitting user roles

4 Very high tamper detection/resistance, Environmental protection

CC-EAL● What Protection Profile (PP)

has been used for the Target of Evaluation (ToE)?– CMCKG-PP – Key

Generation– CMCSO-PP – Signing

Operations

EAL1 Functionally tested

EAL2 Structurally tested

EAL3 Methodically tested and checked

EAL4 Methodically designed, tested, and reviewed

EAL5 Semi-formally designed and tested

EAL6 Semi-formally verified design and tested

EAL7 Formally verified design and tested

HSM Key Backup/Restore● How do you backup your keystore?

– Smart Card– Secure USB Storage

● Key synchronization among two HSMs or more?● Can you restore a backup elsewhere?

– e.g. on a hot-standby site● Split key backup possible?● Well-known backup format?

Cloud HSM● Amazon AWS CloundHSM● IBM Bluemix HSM

https://aws.amazon.com/cloudhsm/https://www.ibm.com/cloud-computing/bluemix/hardware-security-module

HSM API● PKCS#11● OpenSSL Engine● Microsoft CAPI● Java Cryptography Extension● Vendor specific API● Low level programming (need for speed)

– USB Type or Smart Card Type + Reader: PC/SC + vendor specific smart card application protocol data unit (APDU)

– Network Type: Socket programming with vendor specific protocol

PKCS#11● PKCS #11 is one of the Public-Key Cryptography Standards but

also support other cryptographic functions● Defines a platform-independent API to cryptographic tokens,

such as hardware security modules (HSM) and smart cards● API name is “Cryptoki”, but often called PKCS#11 API as its

standard. Complex C API.● Wrappers

– Java Cryptography Architecture/Extension (JCA/JCE)– Pkcs11Interop → .NET (Open source, Nuget package available)– PyKCS11 → Python– Ruby-pkcs11 → Ruby

PKCS#11 Functions● Key Management

– Key & Key Pair Generation– Key Factory– Key Agreement (Diffie-Hellman)– Key Store (Keys & Certificates)

● Cipher (Encrypt/Decrypt)● Secure Random Number Generator● Message Digest● Message Authentication● Digital Signature

Key Management with HSM Web Service

Pain Points● How can we encourage developers adopt HSM and key

management process?● How can we ensure that developers properly implement only

approved cryptography algorithm?● How can we help applications rotate keys properly and

correctly?● If we need stronger encryption algorithm or longer key

length in the future, how can we migrate the encrypted data without application modification?

HSM Wrapper API Connection Diagram

Wrapping Functions● decryptdata(AppKeyID, Ciphertext)

– Return Plaintext● encryptdata(AppKeyID, Plaintext)

– Return Ciphertext● translatedata(AppKeyID, Ciphertext)

– Return new CipherText

● AppKeyID is not the same as HSM key ID but a pointer to a configuration record of– Encryption algorithm– History list of HSM key IDs usage– decryptdata & encryptdata will always use

current key that associates with AppKeyID● Ciphertext is encrypted data● Plaintext is original data

HSMKeyID AppKeyID ValidFrom

39 3 Last Jan 1

40 4 Last Feb 1

41 3 Next Jan 1

42 4 Next Feb 1

translatedata function will decrypt an input ciphertext with the current key and re-encrypt with the nearest future keyFor example from key history table, if AppKeyID=3, translatedata function will use HSMKeyID=39 to decrypt input ciphertext to a plaintext, then will encrypt that plaintext with HSMKeyID=41 to a new ciphertext.

Application Example: PGP Decryption

Data

Encrypt key using receiver‘s

public key

RSA

Encrypted Message

Encrypt Decrypt

Encrypt data using random

key

q4fzNeBCRSYqv

Encrypted Key

Generate Random

Key

Data

TIakvAQkCu2u

Random Key

Encrypted Message

Data

q4fzNeBCRSYqv

Encrypted Key

Decrypt data using key

Decrypt using receiver‘s private key

RSA

TIakvAQkCu2u

Data

● Call Wrapper API’s “decryptdata” function with parameters– AppID (Which App Profile)– q4fzNeBCRSYqv as

Encrypted Data● Receive TIakvAQkCu2u as

Decrypted Data

Application Example:Secure Password for Deployment Automation