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
Visit study
materials
Pls open / download
NetBeans 12
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. ....
Task01 - SecureRandom
Task 01
• You can work now
SecureRandom - solution
• SecureRandom rnd = new SecureRandom();
• rnd.nextBytes(buffer);
• System.out.println(Globals.bytesToHex(buffer));
Task02 - MessageDigest
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
Task 02
• You can work now
MessageDigest – solution
Task03 - Cipher
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).
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
Task 03
• You can work now
Cipher – Solution
Task04 - Signature
Certificate Builder
• X509V3CertificateGenerator
• goo.gl/I9WLUD
Diffie Hellman
• KeyPairGenerator
• KeyAgreement
• goo.gl/Lus40Y
Homework
Check study materials for the assignment.
Thank you for your attention!
Questions