// nofuture.go - Post-Quantum Cryptography Core System
// Build: CGO_ENABLED=1 go build -tags="oqs,purego,harden" -trimpath -ldflags="-s -w"
package main

import (
    "crypto/rand"
    "encoding/binary"
    "fmt"
    "io"
    "os"
    "runtime"
    "syscall"
    "unsafe"
    
    "github.com/awnumar/memguard"
    "github.com/open-quantum-safe/liboqs-go/oqs"
    "golang.org/x/crypto/argon2"
    "golang.org/x/crypto/blake2b"
    "golang.org/x/sys/unix"
)

const (
    KEM_ALG         = "Kyber1024-90s"
    SIG_ALG         = "Dilithium5-AES"
    HASH_ALG        = "BLAKE2b-512"
    SALT_SIZE       = 64
    ARGON2_TIME     = 4
    ARGON2_MEMORY   = 256 * 1024
    ARGON2_THREADS  = 4
    ENCLAVE_KEY_LEN = 48
)

var (
    secureEntropy = memguard.NewEnclaveRandom
    guard         = memguard.NewEnclave
)

type QuantumSession struct {
    sessionKey   *memguard.Enclave
    remotePubKey *memguard.Enclave
    nonce        [24]byte
    handshake    bool
}

func init() {
    // Hardening runtime
    unix.Mlockall(unix.MCL_CURRENT | unix.MCL_FUTURE)
    runtime.GOMAXPROCS(1)
    memguard.CatchInterrupt()
    memguard.Purge()
}

func deriveEnclaveKey(passphrase *memguard.Enclave, salt []byte) (*memguard.LockedBuffer, error) {
    passBuf, err := passphrase.Open()
    if err != nil {
        return nil, err
    }
    defer passBuf.Destroy()

    key := argon2.IDKey(passBuf.Bytes(), salt, ARGON2_TIME, ARGON2_MEMORY, ARGON2_THREADS, ENCLAVE_KEY_LEN)
    lockedKey, err := memguard.NewImmutableFromBytes(key)
    if err != nil {
        return nil, err
    }
    return lockedKey, nil
}

func quantumKEMKeyPair() (*memguard.LockedBuffer, *memguard.LockedBuffer, error) {
    kem := oqs.KeyEncapsulation{}
    if err := kem.Init(KEM_ALG, nil); err != nil {
        return nil, nil, err
    }
    defer kem.Free()

    pubKey, err := kem.GenerateKeyPair()
    if err != nil {
        return nil, nil, err
    }

    secKey := kem.ExportSecretKey()

    lockedPub, err := memguard.NewImmutableFromBytes(pubKey)
    if err != nil {
        return nil, nil, err
    }

    lockedSec, err := memguard.NewImmutableFromBytes(secKey)
    if err != nil {
        lockedPub.Destroy()
        return nil, nil, err
    }

    return lockedPub, lockedSec, nil
}

func quantumEncapsulate(pubKey *memguard.LockedBuffer) (*memguard.LockedBuffer, *memguard.LockedBuffer, error) {
    kem := oqs.KeyEncapsulation{}
    defer kem.Free()

    pubBytes := pubKey.Bytes()
    if err := kem.Init(KEM_ALG, pubBytes); err != nil {
        return nil, nil, err
    }

    ct, ss, err := kem.EncapSecretKey(rand.Reader)
    if err != nil {
        return nil, nil, err
    }

    lockedCt, err := memguard.NewImmutableFromBytes(ct)
    if err != nil {
        return nil, nil, err
    }

    lockedSs, err := memguard.NewImmutableFromBytes(ss)
    if err != nil {
        lockedCt.Destroy()
        return nil, nil, err
    }

    return lockedCt, lockedSs, nil
}

func quantumDecapsulate(ct *memguard.LockedBuffer, secKey *memguard.LockedBuffer) (*memguard.LockedBuffer, error) {
    kem := oqs.KeyEncapsulation{}
    defer kem.Free()

    if err := kem.Init(KEM_ALG, nil); err != nil {
        return nil, err
    }

    if err := kem.ImportSecretKey(secKey.Bytes()); err != nil {
        return nil, err
    }

    ss, err := kem.DecapSecretKey(ct.Bytes())
    if err != nil {
        return nil, err
    }

    lockedSs, err := memguard.NewImmutableFromBytes(ss)
    if err != nil {
        return nil, err
    }

    return lockedSs, nil
}

func quantumSign(msg []byte, secKey *memguard.LockedBuffer) (*memguard.LockedBuffer, error) {
    sig := oqs.Signature{}
    defer sig.Free()

    if err := sig.Init(SIG_ALG, nil); err != nil {
        return nil, err
    }

    signature, err := sig.Sign(msg, secKey.Bytes())
    if err != nil {
        return nil, err
    }

    lockedSig, err := memguard.NewImmutableFromBytes(signature)
    if err != nil {
        return nil, err
    }

    return lockedSig, nil
}

func quantumVerify(msg []byte, sig *memguard.LockedBuffer, pubKey *memguard.LockedBuffer) (bool, error) {
    verifier := oqs.Signature{}
    defer verifier.Free()

    if err := verifier.Init(SIG_ALG, pubKey.Bytes()); err != nil {
        return false, err
    }

    isValid, err := verifier.Verify(msg, sig.Bytes(), pubKey.Bytes())
    return isValid, err
}

func secureTransmission(session *QuantumSession, data []byte) ([]byte, error) {
    nonce := make([]byte, 24)
    if _, err := rand.Read(nonce); err != nil {
        return nil, err
    }

    ss, err := session.sessionKey.Open()
    if err != nil {
        return nil, err
    }
    defer ss.Destroy()

    hash, err := blake2b.New512(nil)
    if err != nil {
        return nil, err
    }

    hash.Write(ss.Bytes())
    hash.Write(nonce)
    hmacKey := hash.Sum(nil)

    sealedData, err := memguard.NewImmutableFromBytes(data)
    if err != nil {
        return nil, err
    }
    defer sealedData.Destroy()

    ciphertext := make([]byte, len(data)+blake2b.Size256)
    binary.LittleEndian.PutUint64(ciphertext[:8], uint64(len(data)))

    // XChaCha20-Poly1305 implementation here (omitted for brevity)
    // ... 

    return ciphertext, nil
}

func main() {
    // Esempio di utilizzo completo
    passphrase, err := memguard.NewImmutableRandom(32)
    if err != nil {
        fmt.Fprintln(os.Stderr, "Critical entropy failure:", err)
        os.Exit(1)
    }
    defer passphrase.Destroy()

    salt := make([]byte, SALT_SIZE)
    if _, err := rand.Read(salt); err != nil {
        fmt.Fprintln(os.Stderr, "Entropy failure:", err)
        os.Exit(1)
    }

    // Deriva la chiave dell'enclave
    enclaveKey, err := deriveEnclaveKey(guard(passphrase.Bytes()), salt)
    if err != nil {
        fmt.Fprintln(os.Stderr, "Key derivation failed:", err)
        os.Exit(1)
    }
    defer enclaveKey.Destroy()

    // Genera chiavi PQ
    pubKey, secKey, err := quantumKEMKeyPair()
    if err != nil {
        fmt.Fprintln(os.Stderr, "PQ Keygen failed:", err)
        os.Exit(1)
    }
    defer pubKey.Destroy()
    defer secKey.Destroy()

    // Simula trasmissione sicura
    ct, ss, err := quantumEncapsulate(pubKey)
    if err != nil {
        fmt.Fprintln(os.Stderr, "Encapsulation failed:", err)
        os.Exit(1)
    }
    defer ct.Destroy()
    defer ss.Destroy()

    // Decapsula il segreto
    decryptedSs, err := quantumDecapsulate(ct, secKey)
    if err != nil {
        fmt.Fprintln(os.Stderr, "Decapsulation failed:", err)
        os.Exit(1)
    }
    defer decryptedSs.Destroy()

    fmt.Println("Post-Quantum Secure Channel Established")
}
