JCA/JCE
Java Crypto Architecture / Java Crypto Extensions
Dušan Klinec
deadcode.me
Provider architecture
Provider architecture
MessageDigest.
getInstance(“MD5”);
Provider architecture
MessageDigest.
getInstance(“MD5”,
“ProviderC”);
JCA
•  java.security.*
•  SecureRandom - PRNG
•  MessageDigest – SHA256, MD5, ...
•  Signature – RSA, DSA
•  KeyStore – PKCS12
•  KeyPairGenerator, KeyFactory,
CertificateFactory,
JCE
•  javax.crypto.*
•  Cipher – AES, RSA, ElGamal, RC4, Salsa20
•  Mac – HMACWithSHA256
•  KeyGenerator
•  Implementation independence
•  Implementation interoperability
•  Algorithm extensibility
Provider architecture
Bouncy Castle
Bouncy Castle
BouncyCastle
Bouncy Castle
•  Implements a LOT OF ciphers, cipher suites,
algorithms, modes, ASN.1, PEM, Certs, …
•  Origin: Australian, former advantage (crypto
regulations)
•  Android
•  getInstance()
•  update()
•  digest()
•  reset()
Provider architecture – Engine classes
•  getInstance()
•  init()
•  update()
•  doFinal()
Provider architecture – Engine classes
Provider architecture – Spi skeleton
Provider architecture – Spi skeleton
Provider architecture – Spi skeleton
Strong cryptography
•  Limits the strength of your crypto
•  the size of the Key
•  AES-256, RSA-2048 not available by default
•  Java Cryptography Extension (JCE) Unlimited
Strength Jurisdiction Policy Files
Strong cryptography
Strong cryptography
Algorithm Key size
DES 64
DESede *
RC2 128
RC4 128
RC5 128
RSA * (KeyPairGenerator 1024)
other 128
Download NetBeans project
Case sensitive
goo.gl/ntSDHP
Pls open
NetBeans
Pls open
Getting started
Cipher – import missing
Cipher – import missing
Lighbulb helps
Getting started
CTRL+SHIFT+I
Problem again
Problem again
The web
Pls open – the guide
Case sensitive
goo.gl/4Ztqen
Task01 - SecureRandom
•  SecureRandom rnd = new SecureRandom()
•  rnd.nextDouble()
•  rnd.nextByte()
•  rnd. ....
SecureRandom - solution
•  SecureRandom rnd = new SecureRandom();
•  rnd.nextBytes(buffer);
•  System.out.println(Globals.bytesToHex(buffer));
Task02 - MessageDigest
•  MessageDigest md5 =
MessageDigest.getInstance(“MD5”);
MessageDigest
•  MessageDigest md5 =
MessageDigest.getInstance(“MD5”);
•  md5.update(inputBuffer, 0, bytesRead);
•  md5.update(inputBuffer, 0, bytesRead);
•  md5.update(inputBuffer, 0, bytesRead);
•  byte[] md5hash = md5.digest()
MessageDigest – incremental API
MD5
md5.update(data)
md5.update(data)
md5.update(data)
md5.update(data)
md5.update(data)
md5.update(data)
md5.digest()
byte[] hash
MessageDigest – incremental API
MessageDigest – solution
Task03 - Cipher
•  getInstance(“algorithm/mode/padding”);
•  Default mode: ECB
•  Default padding: PKCS5
Cipher
Cipher
•  init(mode, key, algorithmParameterSpec)
•  Cipher.DECRYPT_MODE
•  new SecretKeySpec(aesKey, "AES")
•  new IvParameterSpec(iv)
Cipher – Key vs KeySpec
•  Key – opaque key, used in engine
•  getAlgoritm(), getEncoded()
•  KeySpec – key specification, transport & storage
•  getP(), getQ(), getN()
Cipher – Key vs KeySpec
•  SecretKeySpec = Spec & Key in the same time
Cipher – Key vs KeySpec
Cipher – Key vs KeySpec
•  Why separated?
Cipher – Key vs KeySpec
•  Why separated?
Cipher.init(Cipher.DECRYPT_MODE, key)
Cipher – Key vs KeySpec
•  Why separated?
Cipher.init(Cipher.DECRYPT_MODE, key)
Handle=0x123330
Cipher – Key vs KeySpec
•  Why separated?
Cipher.init(Cipher.DECRYPT_MODE, key)
Handle=0x123330,
endpoint=https://…
Cloud
encryption HSM
Cipher – Key materials
•  String vs. char[]
•  String is immutable, cannot zero out
•  Zero-out mutable byte[] after use to prevent key
leakage to swap files (or Heartblead)
Cipher – Key materials
•  GC deallocates but does not zero-out – key still there
•  Modern GC can copy, reorder mem (heap defrag),
unable to properly delete keys from memory
nowadays (Java does not specify behaviour, can
differ).
Cipher – Solution
Key Factories
•  KeySpec à Key
•  Key à KeySpec
•  KeyFactory – asymetric keys
•  SecretKeyFactory – symmetric keys
Key generators
•  KeyGenerator – symmetric
•  generateSecret() à SecretKey
•  KeyPairGenerator – asymmetric
•  generateKeyPair() à KeyPair
Certificate Builder
•  X509V3CertificateGenerator
•  goo.gl/I9WLUD
Diffie Hellman
•  KeyPairGenerator
•  KeyAgreement
•  goo.gl/Lus40Y
Thank you for your attention!
Questions
References / resources
•  TBD