KeyDerivationExtensions

Namespace: WvdS.System.Security.Cryptography.KeyDerivation

Statični razred za izpeljavo ključev (Key Derivation Functions) s podporo za post-kvantno kriptografijo. Podpira HKDF, PBKDF2 in Argon2id.

Podprti KDF-algoritmi:

Izpelje ključe iz skupne skrivnosti (HKDF-Extract-then-Expand).

// ML-KEM skupna skrivnost iz izmenjave ključev
byte[] sharedSecret = session.SharedSecret;
 
// Standardna izpeljava (SHA-256)
byte[] aesKey = KeyDerivationExtensions.DeriveKey(
    sharedSecret,
    outputLength: 32);  // 256 bitov
 
// S soljo in kontekstnimi informacijami
byte[] salt = RandomNumberGenerator.GetBytes(32);
byte[] info = Encoding.UTF8.GetBytes("MyApp-Session-Key");
 
byte[] sessionKey = KeyDerivationExtensions.DeriveKey(
    sharedSecret,
    outputLength: 32,
    salt: salt,
    info: info,
    hashAlgorithm: HashAlgorithmName.SHA384);  // Opcijsko

Ekstrahira PRK (Pseudorandom Key) iz vhodnega materiala ključa.

byte[] inputKeyMaterial = GetSharedSecret();
byte[] salt = RandomNumberGenerator.GetBytes(32);
 
byte[] prk = KeyDerivationExtensions.HkdfExtract(
    inputKeyMaterial,
    salt: salt,
    hashAlgorithm: HashAlgorithmName.SHA256);
 
// PRK ima enako dolžino kot izhod zgoščevalne funkcije (32 bajtov pri SHA-256)

Razširi PRK v izhodni material ključa.

byte[] prk = GetPrk();
 
// Šifrirni ključ
byte[] encKey = KeyDerivationExtensions.HkdfExpand(
    prk,
    outputLength: 32,
    info: Encoding.UTF8.GetBytes("encryption"));
 
// MAC ključ
byte[] macKey = KeyDerivationExtensions.HkdfExpand(
    prk,
    outputLength: 32,
    info: Encoding.UTF8.GetBytes("mac"));

Kombinira klasične (ECDH/DH) in PQ (ML-KEM) skupne skrivnosti.

byte[] ecdhSecret = GetEcdhSharedSecret();
byte[] mlKemSecret = GetMlKemSharedSecret();
 
// Hibridni način: Obe skrivnosti sta kombinirani
byte[] hybridKey = KeyDerivationExtensions.DeriveHybridKey(
    classicSecret: ecdhSecret,
    pqSecret: mlKemSecret,
    outputLength: 32,
    mode: CryptoMode.Hybrid);
 
// Samo klasično
byte[] classicKey = KeyDerivationExtensions.DeriveHybridKey(
    classicSecret: ecdhSecret,
    pqSecret: null,
    outputLength: 32,
    mode: CryptoMode.Classic);
 
// Samo post-kvantno
byte[] pqKey = KeyDerivationExtensions.DeriveHybridKey(
    classicSecret: null,
    pqSecret: mlKemSecret,
    outputLength: 32,
    mode: CryptoMode.PostQuantum);
 
// Lastne informacije
byte[] customKey = KeyDerivationExtensions.DeriveHybridKey(
    classicSecret: ecdhSecret,
    pqSecret: mlKemSecret,
    outputLength: 64,
    mode: CryptoMode.Hybrid,
    info: Encoding.UTF8.GetBytes("MyProtocol-v1"));

Kombinacija ključev:

Hybrid Mode:
  IKM = classicSecret || pqSecret
  Key = HKDF-SHA256(IKM, info="WvdS-Hybrid-Key")

Izpelje več ključev za različne namene.

using HybridKeyMaterial keyMaterial = KeyDerivationExtensions.DeriveHybridKeyMaterial(
    classicSecret: ecdhSecret,
    pqSecret: mlKemSecret,
    mode: CryptoMode.Hybrid);
 
// Uporaba
byte[] encKey = keyMaterial.EncryptionKey;  // 32 bajtov
byte[] macKey = keyMaterial.MacKey;         // 32 bajtov
byte[] iv = keyMaterial.Iv;                 // 16 bajtov
byte[] authKey = keyMaterial.AuthKey;       // 32 bajtov
 
// IDisposable: Ključi so varno izbrisani

string password = "SecurePassword123!";
byte[] salt = RandomNumberGenerator.GetBytes(32);
 
// Standardni PBKDF2
byte[] key = KeyDerivationExtensions.Pbkdf2(
    password,
    salt,
    iterations: 100000,
    outputLength: 32);
 
// S PQ-entropijo (dodatna zaščita)
byte[] pqEntropy = GetPqEntropy();
 
byte[] enhancedKey = KeyDerivationExtensions.Pbkdf2(
    password,
    salt,
    iterations: 100000,
    outputLength: 32,
    pqEntropy: pqEntropy,  // Kombinirana s soljo
    hashAlgorithm: HashAlgorithmName.SHA512);

PBKDF2 s PQ-okrepljeno soljo (javni ključ je vključen v izračun soli).

string password = "UserPassword";
byte[] baseSalt = RandomNumberGenerator.GetBytes(16);
byte[] mlKemPublicKey = GetRecipientPublicKey();
 
// Salt = SHA256(baseSalt || pqPublicKey)
byte[] key = KeyDerivationExtensions.Pbkdf2WithPqSalt(
    password,
    baseSalt,
    mlKemPublicKey,
    iterations: 100000,
    outputLength: 32);

Argon2id preko OpenSSL 3.6 - odporen proti GPU/ASIC napadom.

byte[] password = Encoding.UTF8.GetBytes("SecurePassword");
byte[] salt = RandomNumberGenerator.GetBytes(16);  // Najmanj 16 bajtov
 
byte[] key = KeyDerivationExtensions.Argon2id(
    password,
    salt,
    outputLength: 32,     // Dolžina ključa
    iterations: 3,        // Časovni stroški (t)
    memoryKiB: 65536,     // Pomnilnik: 64 MB
    parallelism: 4);      // Niti (p)

string password = "UserPassword123";
byte[] salt = RandomNumberGenerator.GetBytes(16);
 
byte[] key = KeyDerivationExtensions.Argon2id(
    password,
    salt,
    outputLength: 32,
    iterations: 3,
    memoryKiB: 65536,
    parallelism: 4);

Priporočeni parametri:

byte[] preMasterSecret = GetPreMasterSecret();
byte[] clientRandom = GetClientRandom();
byte[] serverRandom = GetServerRandom();
 
using TlsKeyMaterial keys = KeyDerivationExtensions.DeriveTlsKeys(
    preMasterSecret,
    clientRandom,
    serverRandom,
    mode: CryptoMode.Hybrid);
 
// Uporaba
var clientKey = keys.ClientWriteKey;   // 32 bajtov
var serverKey = keys.ServerWriteKey;   // 32 bajtov
var clientIv = keys.ClientWriteIv;     // 12 bajtov
var serverIv = keys.ServerWriteIv;     // 12 bajtov

TLS 1.3 kompatibilen razpored ključev.

byte[]? pskSecret = null;  // Pre-Shared Key (opcijsko)
byte[] ecdhSecret = GetEcdhSecret();
byte[] pqSecret = GetMlKemSecret();
byte[] clientHello = GetClientHelloBytes();
byte[] serverHello = GetServerHelloBytes();
 
using Tls13KeySchedule schedule = KeyDerivationExtensions.DeriveTls13Keys(
    pskSecret,
    ecdhSecret,
    pqSecret,
    clientHello,
    serverHello,
    mode: CryptoMode.Hybrid);
 
// Handshake Traffic Secrets
var clientHsSecret = schedule.ClientHandshakeTrafficSecret;
var serverHsSecret = schedule.ServerHandshakeTrafficSecret;
 
// Application Traffic Secrets
var clientAppSecret = schedule.ClientApplicationTrafficSecret;
var serverAppSecret = schedule.ServerApplicationTrafficSecret;
 
// Resumption Secret
var resumptionSecret = schedule.ResumptionMasterSecret;

Vsebnik za izpeljane ključe z varnim čiščenjem pomnilnika.

using HybridKeyMaterial keys = DeriveKeys();
 
// Ključi so pri Dispose() varno izbrisani
// (CryptographicOperations.ZeroMemory)

TLS 1.2 stil materiala ključev.

TLS 1.3 razpored ključev.

using WvdS.System.Security.Cryptography;
using WvdS.System.Security.Cryptography.KeyDerivation;
using WvdS.System.Security.Cryptography.KeyExchange;
 
// 1. Izvedba izmenjave ključev
using var session = new KeyExchangeService();
await session.InitiateKeyExchangeAsync(recipientPublicKey, CryptoMode.Hybrid);
 
// 2. Izpeljava hibridnega materiala ključev
using HybridKeyMaterial keys = KeyDerivationExtensions.DeriveHybridKeyMaterial(
    classicSecret: session.ClassicSharedSecret,
    pqSecret: session.PqSharedSecret,
    mode: CryptoMode.Hybrid);
 
// 3. Uporaba ključev
using var aes = Aes.Create();
aes.Key = keys.EncryptionKey;
 
using var hmac = new HMACSHA256(keys.MacKey);
 
// 4. Izvedba šifriranja
// ...
 
// 5. Ključi so samodejno varno izbrisani

• KeyDerivation Namespace
• HybridKeyMaterial
• TlsKeyMaterial
• Tls13KeySchedule
• KeyExchange Namespace
• Encryption Namespace
• Algoritem ML-KEM

Wolfgang van der Stille @ EMSR DATA d.o.o. - Post-Quantum Cryptography Professional