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Security Advanced

Key Derivation Functions

Derive cryptographic keys using the standard KDF API.

Code Comparison

✕ Java 8

SecretKeyFactory factory =
    SecretKeyFactory.getInstance(
        "PBKDF2WithHmacSHA256");
KeySpec spec = new PBEKeySpec(
    password, salt, 10000, 256);
SecretKey key =
    factory.generateSecret(spec);

✓ Java 25

var kdf = KDF.getInstance("HKDF-SHA256");
SecretKey key = kdf.deriveKey(
    "AES",
    KDF.HKDFParameterSpec
        .ofExtract()
        .addIKM(inputKey)
        .addSalt(salt)
        .thenExpand(info, 32)
        .build()
);

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Why the modern way wins

📐

Clean API

Builder pattern instead of awkward KeySpec constructors.

🔧

HKDF support

Modern HKDF algorithm alongside PBKDF2.

🛡️

Standard

Unified API for all key derivation algorithms.

Old Approach

Manual PBKDF2

Modern Approach

KDF API

Since JDK

Difficulty

Advanced

JDK Support

Key Derivation Functions

Available

Finalized in JDK 25 LTS (JEP 510, Sept 2025).

How it works

The KDF API provides a standard interface for key derivation functions including HKDF. It replaces the awkward SecretKeyFactory + PBEKeySpec pattern with a clean builder API.

PEM encoding/decoding

Java 8

String pem = "-----BEGIN CERTIFICATE-----\n"
    + Base64.getMimeEncoder()
        .encodeToString(
            cert.getEncoded())
    + "\n-----END CERTIFICATE-----";

Java 25 (Preview)

// Encode to PEM
String pem = PEMEncoder.of()
    .encodeToString(cert);
// Decode from PEM
var cert = PEMDecoder.of()
    .decode(pemString);

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JDK 25+ →

Security Beginner

Strong random generation

Java 8

// Default algorithm — may not be
// the strongest available
SecureRandom random =
    new SecureRandom();
byte[] bytes = new byte[32];
random.nextBytes(bytes);

Java 9+

// Platform's strongest algorithm
SecureRandom random =
    SecureRandom.getInstanceStrong();
byte[] bytes = new byte[32];
random.nextBytes(bytes);

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JDK 9+ →

Security Intermediate

TLS 1.3 by default

Java 8

SSLContext ctx =
    SSLContext.getInstance("TLSv1.2");
ctx.init(null, trustManagers, null);
SSLSocketFactory factory =
    ctx.getSocketFactory();
// Must specify protocol version

Java 11+

// TLS 1.3 is the default!
var client = HttpClient.newBuilder()
    .sslContext(SSLContext.getDefault())
    .build();
// Already using TLS 1.3

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JDK 11+ →