#include <stdint.h>
#include <string.h>
#include <immintrin.h> // For AES-NI instructions
#include <openssl/aes.h>
#include <openssl/rand.h>

// AES-NI optimized implementation
typedef struct {
    __m128i round_keys[15]; // Maximum rounds for AES-256
    int num_rounds;
    size_t key_length;
    
    // Performance counters
    uint64_t blocks_encrypted;
    uint64_t blocks_decrypted;
    uint64_t total_bytes;
    
    // Security features
    bool constant_time_enabled;
    bool side_channel_protection;
} aes_context_t;

// AES key schedule using AES-NI instructions
static void aes_key_schedule_ni(aes_context_t *ctx, const uint8_t *key, size_t key_len)
{
    ctx->key_length = key_len;
    
    switch (key_len) {
        case 16: // AES-128
            ctx->num_rounds = 10;
            break;
        case 24: // AES-192
            ctx->num_rounds = 12;
            break;
        case 32: // AES-256
            ctx->num_rounds = 14;
            break;
        default:
            return; // Invalid key length
    }
    
    // Load initial key
    ctx->round_keys[0] = _mm_loadu_si128((__m128i*)key);
    
    if (key_len == 16) {
        // AES-128 key expansion
        __m128i temp1, temp2;
        __m128i *round_key = ctx->round_keys;
        
        temp1 = round_key[0];
        
        // Round 1
        temp2 = _mm_aeskeygenassist_si128(temp1, 0x01);
        temp1 = aes_128_key_expansion(temp1, temp2);
        round_key[1] = temp1;
        
        // Round 2
        temp2 = _mm_aeskeygenassist_si128(temp1, 0x02);
        temp1 = aes_128_key_expansion(temp1, temp2);
        round_key[2] = temp1;
        
        // Continue for all rounds...
        // (Simplified for brevity - real implementation would include all rounds)
    }
    // Similar implementations for AES-192 and AES-256
}

// AES-128 key expansion helper function
static __m128i aes_128_key_expansion(__m128i key, __m128i keygened)
{
    keygened = _mm_shuffle_epi32(keygened, _MM_SHUFFLE(3,3,3,3));
    key = _mm_xor_si128(key, _mm_slli_si128(key, 4));
    key = _mm_xor_si128(key, _mm_slli_si128(key, 4));
    key = _mm_xor_si128(key, _mm_slli_si128(key, 4));
    return _mm_xor_si128(key, keygened);
}

// High-performance AES encryption using AES-NI
static void aes_encrypt_block_ni(const aes_context_t *ctx, 
                                const uint8_t *plaintext, 
                                uint8_t *ciphertext)
{
    __m128i block = _mm_loadu_si128((__m128i*)plaintext);
    
    // Initial round
    block = _mm_xor_si128(block, ctx->round_keys[0]);
    
    // Main rounds
    for (int round = 1; round < ctx->num_rounds; round++) {
        block = _mm_aesenc_si128(block, ctx->round_keys[round]);
    }
    
    // Final round
    block = _mm_aesenclast_si128(block, ctx->round_keys[ctx->num_rounds]);
    
    _mm_storeu_si128((__m128i*)ciphertext, block);
}

// Vectorized AES encryption for multiple blocks
static void aes_encrypt_blocks_parallel(const aes_context_t *ctx,
                                       const uint8_t *plaintext,
                                       uint8_t *ciphertext,
                                       size_t num_blocks)
{
    const size_t parallel_blocks = 8; // Process 8 blocks in parallel
    
    for (size_t i = 0; i < num_blocks; i += parallel_blocks) {
        size_t blocks_to_process = (num_blocks - i < parallel_blocks) ? 
                                  num_blocks - i : parallel_blocks;
        
        __m128i blocks[8];
        
        // Load blocks
        for (size_t j = 0; j < blocks_to_process; j++) {
            blocks[j] = _mm_loadu_si128((__m128i*)(plaintext + (i + j) * 16));
        }
        
        // Initial round
        for (size_t j = 0; j < blocks_to_process; j++) {
            blocks[j] = _mm_xor_si128(blocks[j], ctx->round_keys[0]);
        }
        
        // Main rounds
        for (int round = 1; round < ctx->num_rounds; round++) {
            for (size_t j = 0; j < blocks_to_process; j++) {
                blocks[j] = _mm_aesenc_si128(blocks[j], ctx->round_keys[round]);
            }
        }
        
        // Final round
        for (size_t j = 0; j < blocks_to_process; j++) {
            blocks[j] = _mm_aesenclast_si128(blocks[j], ctx->round_keys[ctx->num_rounds]);
        }
        
        // Store results
        for (size_t j = 0; j < blocks_to_process; j++) {
            _mm_storeu_si128((__m128i*)(ciphertext + (i + j) * 16), blocks[j]);
        }
    }
}

// AES-GCM implementation with authentication
typedef struct {
    aes_context_t aes_ctx;
    __m128i auth_key;
    __m128i ghash_key;
    uint64_t total_aad_len;
    uint64_t total_plaintext_len;
} aes_gcm_context_t;

// GHASH function for AES-GCM authentication
static __m128i ghash_multiply(__m128i a, __m128i b)
{
    __m128i tmp0, tmp1, tmp2, tmp3;
    __m128i zero = _mm_setzero_si128();
    
    tmp0 = _mm_clmulepi64_si128(a, b, 0x00);
    tmp1 = _mm_clmulepi64_si128(a, b, 0x01);
    tmp2 = _mm_clmulepi64_si128(a, b, 0x10);
    tmp3 = _mm_clmulepi64_si128(a, b, 0x11);
    
    tmp1 = _mm_xor_si128(tmp1, tmp2);
    tmp2 = _mm_slli_si128(tmp1, 8);
    tmp1 = _mm_srli_si128(tmp1, 8);
    
    tmp0 = _mm_xor_si128(tmp0, tmp2);
    tmp3 = _mm_xor_si128(tmp3, tmp1);
    
    // Reduction
    __m128i poly = _mm_setr_epi32(0x1, 0, 0, 0xc2000000);
    tmp1 = _mm_clmulepi64_si128(tmp3, poly, 0x01);
    tmp2 = _mm_shuffle_epi32(tmp3, 0x4e);
    tmp3 = _mm_xor_si128(tmp1, tmp2);
    
    tmp1 = _mm_clmulepi64_si128(tmp3, poly, 0x00);
    tmp3 = _mm_shuffle_epi32(tmp3, 0x4e);
    tmp3 = _mm_xor_si128(tmp1, tmp3);
    
    return _mm_xor_si128(tmp0, tmp3);
}

// AES-GCM encryption with authentication
static int aes_gcm_encrypt(aes_gcm_context_t *ctx,
                          const uint8_t *plaintext, size_t plaintext_len,
                          const uint8_t *aad, size_t aad_len,
                          const uint8_t *iv, size_t iv_len,
                          uint8_t *ciphertext, uint8_t *tag, size_t tag_len)
{
    if (tag_len > 16) return -1;
    
    __m128i counter, auth_block;
    __m128i ghash_state = _mm_setzero_si128();
    
    // Process IV
    if (iv_len == 12) {
        counter = _mm_loadu_si128((__m128i*)iv);
        counter = _mm_insert_epi32(counter, 0x01000000, 3); // Big-endian 1
    } else {
        // GHASH the IV if it's not 96 bits
        // (Implementation details omitted for brevity)
    }
    
    // Generate authentication key
    __m128i zero_block = _mm_setzero_si128();
    aes_encrypt_block_ni(&ctx->aes_ctx, (uint8_t*)&zero_block, (uint8_t*)&ctx->auth_key);
    
    // Process AAD
    if (aad_len > 0) {
        size_t aad_blocks = (aad_len + 15) / 16;
        for (size_t i = 0; i < aad_blocks; i++) {
            __m128i aad_block = _mm_setzero_si128();
            size_t block_len = (i == aad_blocks - 1 && aad_len % 16) ? 
                              aad_len % 16 : 16;
            memcpy(&aad_block, aad + i * 16, block_len);
            
            ghash_state = _mm_xor_si128(ghash_state, aad_block);
            ghash_state = ghash_multiply(ghash_state, ctx->auth_key);
        }
    }
    
    // Encrypt plaintext and update GHASH
    size_t plaintext_blocks = (plaintext_len + 15) / 16;
    for (size_t i = 0; i < plaintext_blocks; i++) {
        // Increment counter
        counter = _mm_add_epi32(counter, _mm_setr_epi32(0, 0, 0, 0x01000000));
        
        // Encrypt counter
        __m128i keystream_block;
        aes_encrypt_block_ni(&ctx->aes_ctx, (uint8_t*)&counter, (uint8_t*)&keystream_block);
        
        // XOR with plaintext
        __m128i plaintext_block = _mm_setzero_si128();
        size_t block_len = (i == plaintext_blocks - 1 && plaintext_len % 16) ?
                          plaintext_len % 16 : 16;
        memcpy(&plaintext_block, plaintext + i * 16, block_len);
        
        __m128i ciphertext_block = _mm_xor_si128(plaintext_block, keystream_block);
        memcpy(ciphertext + i * 16, &ciphertext_block, block_len);
        
        // Update GHASH
        ghash_state = _mm_xor_si128(ghash_state, ciphertext_block);
        ghash_state = ghash_multiply(ghash_state, ctx->auth_key);
    }
    
    // Final GHASH with lengths
    __m128i length_block = _mm_setr_epi64x(aad_len * 8, plaintext_len * 8);
    ghash_state = _mm_xor_si128(ghash_state, length_block);
    ghash_state = ghash_multiply(ghash_state, ctx->auth_key);
    
    // Generate authentication tag
    __m128i tag_mask;
    counter = _mm_loadu_si128((__m128i*)iv);
    counter = _mm_insert_epi32(counter, 0x01000000, 3);
    aes_encrypt_block_ni(&ctx->aes_ctx, (uint8_t*)&counter, (uint8_t*)&tag_mask);
    
    __m128i auth_tag = _mm_xor_si128(ghash_state, tag_mask);
    memcpy(tag, &auth_tag, tag_len);
    
    return 0;
}

#include <gmp.h> // GNU Multiple Precision Arithmetic Library

typedef struct {
    mpz_t n; // Modulus
    mpz_t e; // Public exponent
    mpz_t d; // Private exponent
    mpz_t p; // Prime factor 1
    mpz_t q; // Prime factor 2
    
    // CRT components for fast decryption
    mpz_t dp; // d mod (p-1)
    mpz_t dq; // d mod (q-1)
    mpz_t qinv; // q^-1 mod p
    
    size_t key_size; // In bits
    bool crt_enabled;
    
    // Performance counters
    uint64_t encryptions;
    uint64_t decryptions;
    uint64_t signatures;
    uint64_t verifications;
} rsa_key_t;

// Initialize RSA key structure
static void rsa_key_init(rsa_key_t *key)
{
    mpz_init(key->n);
    mpz_init(key->e);
    mpz_init(key->d);
    mpz_init(key->p);
    mpz_init(key->q);
    mpz_init(key->dp);
    mpz_init(key->dq);
    mpz_init(key->qinv);
    
    key->crt_enabled = true;
    key->encryptions = 0;
    key->decryptions = 0;
    key->signatures = 0;
    key->verifications = 0;
}

// Generate RSA key pair with secure random primes
static int rsa_generate_key(rsa_key_t *key, size_t key_size)
{
    if (key_size < 2048 || key_size % 8 != 0) {
        return -1; // Minimum 2048 bits, multiple of 8
    }
    
    key->key_size = key_size;
    size_t prime_bits = key_size / 2;
    
    gmp_randstate_t rstate;
    gmp_randinit_default(rstate);
    
    // Seed with secure random data
    unsigned char seed[32];
    if (RAND_bytes(seed, sizeof(seed)) != 1) {
        return -1;
    }
    gmp_randseed(rstate, *(mpz_t*)seed);
    
    mpz_t phi_n, gcd_temp, p_minus_1, q_minus_1;
    mpz_init(phi_n);
    mpz_init(gcd_temp);
    mpz_init(p_minus_1);
    mpz_init(q_minus_1);
    
    // Generate prime p
    do {
        mpz_urandomb(key->p, rstate, prime_bits);
        mpz_setbit(key->p, prime_bits - 1); // Ensure high bit is set
        mpz_setbit(key->p, 0); // Ensure odd
        
        // Miller-Rabin primality test
    } while (mpz_probab_prime_p(key->p, 50) == 0);
    
    // Generate prime q (different from p)
    do {
        mpz_urandomb(key->q, rstate, prime_bits);
        mpz_setbit(key->q, prime_bits - 1);
        mpz_setbit(key->q, 0);
        
        // Ensure q != p and |p - q| is large enough
        mpz_sub(gcd_temp, key->p, key->q);
        mpz_abs(gcd_temp, gcd_temp);
        
    } while (mpz_probab_prime_p(key->q, 50) == 0 || 
             mpz_cmp(key->p, key->q) == 0 ||
             mpz_sizeinbase(gcd_temp, 2) < prime_bits - 100);
    
    // Calculate n = p * q
    mpz_mul(key->n, key->p, key->q);
    
    // Calculate phi(n) = (p-1)(q-1)
    mpz_sub_ui(p_minus_1, key->p, 1);
    mpz_sub_ui(q_minus_1, key->q, 1);
    mpz_mul(phi_n, p_minus_1, q_minus_1);
    
    // Choose public exponent e = 65537
    mpz_set_ui(key->e, 65537);
    
    // Verify gcd(e, phi(n)) = 1
    mpz_gcd(gcd_temp, key->e, phi_n);
    if (mpz_cmp_ui(gcd_temp, 1) != 0) {
        // This should be extremely rare with e = 65537
        return -1;
    }
    
    // Calculate private exponent d = e^-1 mod phi(n)
    if (mpz_invert(key->d, key->e, phi_n) == 0) {
        return -1;
    }
    
    // Calculate CRT components for fast decryption
    mpz_mod(key->dp, key->d, p_minus_1);
    mpz_mod(key->dq, key->d, q_minus_1);
    mpz_invert(key->qinv, key->q, key->p);
    
    // Cleanup
    mpz_clear(phi_n);
    mpz_clear(gcd_temp);
    mpz_clear(p_minus_1);
    mpz_clear(q_minus_1);
    gmp_randclear(rstate);
    
    return 0;
}

// RSA encryption (public key operation)
static int rsa_encrypt(const rsa_key_t *key, const mpz_t plaintext, mpz_t ciphertext)
{
    // Verify plaintext < n
    if (mpz_cmp(plaintext, key->n) >= 0) {
        return -1;
    }
    
    // c = m^e mod n
    mpz_powm(ciphertext, plaintext, key->e, key->n);
    
    ((rsa_key_t*)key)->encryptions++;
    
    return 0;
}

// RSA decryption using Chinese Remainder Theorem
static int rsa_decrypt_crt(const rsa_key_t *key, const mpz_t ciphertext, mpz_t plaintext)
{
    if (!key->crt_enabled) {
        // Fallback to standard decryption
        mpz_powm(plaintext, ciphertext, key->d, key->n);
        ((rsa_key_t*)key)->decryptions++;
        return 0;
    }
    
    mpz_t m1, m2, h, temp;
    mpz_init(m1);
    mpz_init(m2);
    mpz_init(h);
    mpz_init(temp);
    
    // m1 = c^dp mod p
    mpz_powm(m1, ciphertext, key->dp, key->p);
    
    // m2 = c^dq mod q
    mpz_powm(m2, ciphertext, key->dq, key->q);
    
    // h = qinv * (m1 - m2) mod p
    mpz_sub(temp, m1, m2);
    mpz_mul(temp, temp, key->qinv);
    mpz_mod(h, temp, key->p);
    
    // m = m2 + h * q
    mpz_mul(temp, h, key->q);
    mpz_add(plaintext, m2, temp);
    
    // Cleanup
    mpz_clear(m1);
    mpz_clear(m2);
    mpz_clear(h);
    mpz_clear(temp);
    
    ((rsa_key_t*)key)->decryptions++;
    
    return 0;
}

// Constant-time RSA operations for side-channel resistance
static int rsa_decrypt_constant_time(const rsa_key_t *key, 
                                    const mpz_t ciphertext, 
                                    mpz_t plaintext)
{
    // Montgomery ladder for constant-time exponentiation
    mpz_t r0, r1, temp;
    mpz_init_set_ui(r0, 1);
    mpz_init_set(r1, ciphertext);
    mpz_init(temp);
    
    size_t d_bits = mpz_sizeinbase(key->d, 2);
    
    for (long i = d_bits - 2; i >= 0; i--) {
        int bit = mpz_tstbit(key->d, i);
        
        if (bit == 0) {
            // r1 = r0 * r1 mod n, r0 = r0^2 mod n
            mpz_mul(temp, r0, r1);
            mpz_mod(r1, temp, key->n);
            mpz_mul(temp, r0, r0);
            mpz_mod(r0, temp, key->n);
        } else {
            // r0 = r0 * r1 mod n, r1 = r1^2 mod n
            mpz_mul(temp, r0, r1);
            mpz_mod(r0, temp, key->n);
            mpz_mul(temp, r1, r1);
            mpz_mod(r1, temp, key->n);
        }
    }
    
    mpz_set(plaintext, r0);
    
    mpz_clear(r0);
    mpz_clear(r1);
    mpz_clear(temp);
    
    return 0;
}

// Elliptic curve point structure (Jacobian coordinates)
typedef struct {
    mpz_t x, y, z;
    bool is_infinity;
} ec_point_t;

// Elliptic curve parameters
typedef struct {
    mpz_t p; // Prime modulus
    mpz_t a, b; // Curve parameters y^2 = x^3 + ax + b
    ec_point_t G; // Generator point
    mpz_t n; // Order of generator
    size_t bit_length;
    
    // Precomputed values for optimization
    ec_point_t *precomputed_G; // Precomputed multiples of G
    size_t precomputed_count;
    
    // Montgomery curve parameters (if applicable)
    mpz_t A24; // (A + 2) / 4 for Montgomery ladder
} ec_curve_t;

// Initialize elliptic curve point
static void ec_point_init(ec_point_t *point)
{
    mpz_init(point->x);
    mpz_init(point->y);
    mpz_init(point->z);
    point->is_infinity = true;
}

// Set point to infinity
static void ec_point_set_infinity(ec_point_t *point)
{
    mpz_set_ui(point->x, 1);
    mpz_set_ui(point->y, 1);
    mpz_set_ui(point->z, 0);
    point->is_infinity = true;
}

// Convert from affine to Jacobian coordinates
static void ec_point_affine_to_jacobian(ec_point_t *jac, 
                                       const mpz_t x, const mpz_t y)
{
    mpz_set(jac->x, x);
    mpz_set(jac->y, y);
    mpz_set_ui(jac->z, 1);
    jac->is_infinity = false;
}

// Point doubling in Jacobian coordinates
static void ec_point_double(const ec_curve_t *curve, 
                           const ec_point_t *P, 
                           ec_point_t *result)
{
    if (P->is_infinity) {
        ec_point_set_infinity(result);
        return;
    }
    
    mpz_t A, B, C, D, E, F, temp;
    mpz_init(A); mpz_init(B); mpz_init(C); mpz_init(D);
    mpz_init(E); mpz_init(F); mpz_init(temp);
    
    // A = X1^2
    mpz_mul(A, P->x, P->x);
    mpz_mod(A, A, curve->p);
    
    // B = Y1^2
    mpz_mul(B, P->y, P->y);
    mpz_mod(B, B, curve->p);
    
    // C = B^2
    mpz_mul(C, B, B);
    mpz_mod(C, C, curve->p);
    
    // D = 2*((X1+B)^2-A-C)
    mpz_add(temp, P->x, B);
    mpz_mul(temp, temp, temp);
    mpz_sub(temp, temp, A);
    mpz_sub(temp, temp, C);
    mpz_mul_ui(D, temp, 2);
    mpz_mod(D, D, curve->p);
    
    // E = 3*A
    mpz_mul_ui(E, A, 3);
    mpz_mod(E, E, curve->p);
    
    // F = E^2
    mpz_mul(F, E, E);
    mpz_mod(F, F, curve->p);
    
    // X3 = F - 2*D
    mpz_mul_ui(temp, D, 2);
    mpz_sub(result->x, F, temp);
    mpz_mod(result->x, result->x, curve->p);
    
    // Y3 = E*(D-X3) - 8*C
    mpz_sub(temp, D, result->x);
    mpz_mul(temp, E, temp);
    mpz_mul_ui(C, C, 8);
    mpz_sub(result->y, temp, C);
    mpz_mod(result->y, result->y, curve->p);
    
    // Z3 = 2*Y1*Z1
    mpz_mul(result->z, P->y, P->z);
    mpz_mul_ui(result->z, result->z, 2);
    mpz_mod(result->z, result->z, curve->p);
    
    result->is_infinity = false;
    
    // Cleanup
    mpz_clear(A); mpz_clear(B); mpz_clear(C); mpz_clear(D);
    mpz_clear(E); mpz_clear(F); mpz_clear(temp);
}

// Point addition in Jacobian coordinates
static void ec_point_add(const ec_curve_t *curve,
                        const ec_point_t *P, const ec_point_t *Q,
                        ec_point_t *result)
{
    if (P->is_infinity) {
        mpz_set(result->x, Q->x);
        mpz_set(result->y, Q->y);
        mpz_set(result->z, Q->z);
        result->is_infinity = Q->is_infinity;
        return;
    }
    
    if (Q->is_infinity) {
        mpz_set(result->x, P->x);
        mpz_set(result->y, P->y);
        mpz_set(result->z, P->z);
        result->is_infinity = P->is_infinity;
        return;
    }
    
    mpz_t U1, U2, S1, S2, H, r, temp1, temp2;
    mpz_init(U1); mpz_init(U2); mpz_init(S1); mpz_init(S2);
    mpz_init(H); mpz_init(r); mpz_init(temp1); mpz_init(temp2);
    
    // U1 = X1*Z2^2
    mpz_mul(temp1, Q->z, Q->z);
    mpz_mod(temp1, temp1, curve->p);
    mpz_mul(U1, P->x, temp1);
    mpz_mod(U1, U1, curve->p);
    
    // U2 = X2*Z1^2
    mpz_mul(temp1, P->z, P->z);
    mpz_mod(temp1, temp1, curve->p);
    mpz_mul(U2, Q->x, temp1);
    mpz_mod(U2, U2, curve->p);
    
    // S1 = Y1*Z2^3
    mpz_mul(temp1, Q->z, Q->z);
    mpz_mul(temp1, temp1, Q->z);
    mpz_mod(temp1, temp1, curve->p);
    mpz_mul(S1, P->y, temp1);
    mpz_mod(S1, S1, curve->p);
    
    // S2 = Y2*Z1^3
    mpz_mul(temp1, P->z, P->z);
    mpz_mul(temp1, temp1, P->z);
    mpz_mod(temp1, temp1, curve->p);
    mpz_mul(S2, Q->y, temp1);
    mpz_mod(S2, S2, curve->p);
    
    // Check if points are equal
    if (mpz_cmp(U1, U2) == 0) {
        if (mpz_cmp(S1, S2) == 0) {
            // Points are equal, perform doubling
            ec_point_double(curve, P, result);
        } else {
            // Points are additive inverses
            ec_point_set_infinity(result);
        }
        goto cleanup;
    }
    
    // H = U2 - U1
    mpz_sub(H, U2, U1);
    mpz_mod(H, H, curve->p);
    
    // r = S2 - S1
    mpz_sub(r, S2, S1);
    mpz_mod(r, r, curve->p);
    
    // X3 = r^2 - H^3 - 2*U1*H^2
    mpz_mul(temp1, r, r);
    mpz_mul(temp2, H, H);
    mpz_mul(temp2, temp2, H); // H^3
    mpz_sub(result->x, temp1, temp2);
    
    mpz_mul(temp1, H, H); // H^2
    mpz_mul(temp1, temp1, U1);
    mpz_mul_ui(temp1, temp1, 2);
    mpz_sub(result->x, result->x, temp1);
    mpz_mod(result->x, result->x, curve->p);
    
    // Y3 = r*(U1*H^2 - X3) - S1*H^3
    mpz_mul(temp1, H, H);
    mpz_mul(temp1, temp1, U1);
    mpz_sub(temp1, temp1, result->x);
    mpz_mul(temp1, r, temp1);
    
    mpz_mul(temp2, H, H);
    mpz_mul(temp2, temp2, H);
    mpz_mul(temp2, temp2, S1);
    
    mpz_sub(result->y, temp1, temp2);
    mpz_mod(result->y, result->y, curve->p);
    
    // Z3 = Z1*Z2*H
    mpz_mul(result->z, P->z, Q->z);
    mpz_mul(result->z, result->z, H);
    mpz_mod(result->z, result->z, curve->p);
    
    result->is_infinity = false;

cleanup:
    mpz_clear(U1); mpz_clear(U2); mpz_clear(S1); mpz_clear(S2);
    mpz_clear(H); mpz_clear(r); mpz_clear(temp1); mpz_clear(temp2);
}

// Scalar multiplication using windowed NAF method
static void ec_point_mul(const ec_curve_t *curve, 
                        const mpz_t scalar, 
                        const ec_point_t *point,
                        ec_point_t *result)
{
    if (mpz_cmp_ui(scalar, 0) == 0) {
        ec_point_set_infinity(result);
        return;
    }
    
    // Precompute odd multiples: P, 3P, 5P, ..., (2^w-1)P
    const int window_size = 4;
    const int precomp_size = 1 << (window_size - 1);
    
    ec_point_t precomp[precomp_size];
    for (int i = 0; i < precomp_size; i++) {
        ec_point_init(&precomp[i]);
    }
    
    // precomp[0] = P
    mpz_set(precomp[0].x, point->x);
    mpz_set(precomp[0].y, point->y);
    mpz_set(precomp[0].z, point->z);
    precomp[0].is_infinity = point->is_infinity;
    
    // precomp[1] = 2P
    ec_point_t double_P;
    ec_point_init(&double_P);
    ec_point_double(curve, point, &double_P);
    
    // Compute remaining odd multiples
    for (int i = 1; i < precomp_size; i++) {
        ec_point_add(curve, &precomp[i-1], &double_P, &precomp[i]);
    }
    
    // Convert scalar to NAF representation
    // (Implementation simplified for brevity)
    
    // Perform scalar multiplication using precomputed values
    ec_point_set_infinity(result);
    
    size_t scalar_bits = mpz_sizeinbase(scalar, 2);
    for (long i = scalar_bits - 1; i >= 0; i--) {
        ec_point_double(curve, result, result);
        
        if (mpz_tstbit(scalar, i)) {
            ec_point_add(curve, result, point, result);
        }
    }
    
    // Cleanup
    for (int i = 0; i < precomp_size; i++) {
        mpz_clear(precomp[i].x);
        mpz_clear(precomp[i].y);
        mpz_clear(precomp[i].z);
    }
    ec_point_init(&double_P);
}

#include <cpuid.h>

// CPU feature detection
typedef struct {
    bool aes_ni;
    bool pclmulqdq;
    bool rdrand;
    bool rdseed;
    bool sha_extensions;
    bool avx;
    bool avx2;
    bool avx512f;
} cpu_features_t;

// Detect available CPU cryptographic features
static cpu_features_t detect_crypto_features(void)
{
    cpu_features_t features = {0};
    unsigned int eax, ebx, ecx, edx;
    
    // Check if CPUID is available
    if (__get_cpuid_max(0, NULL) < 1) {
        return features;
    }
    
    // Get feature flags from CPUID
    __cpuid_count(1, 0, eax, ebx, ecx, edx);
    
    features.aes_ni = (ecx & bit_AES) != 0;
    features.pclmulqdq = (ecx & bit_PCLMUL) != 0;
    features.rdrand = (ecx & bit_RDRND) != 0;
    features.avx = (ecx & bit_AVX) != 0;
    
    // Check extended features
    if (__get_cpuid_max(0, NULL) >= 7) {
        __cpuid_count(7, 0, eax, ebx, ecx, edx);
        
        features.rdseed = (ebx & bit_RDSEED) != 0;
        features.sha_extensions = (ebx & bit_SHA) != 0;
        features.avx2 = (ebx & bit_AVX2) != 0;
        features.avx512f = (ebx & bit_AVX512F) != 0;
    }
    
    return features;
}

// Hardware random number generation
static int hardware_random_bytes(uint8_t *buffer, size_t length)
{
    cpu_features_t features = detect_crypto_features();
    
    if (features.rdseed) {
        // Use RDSEED instruction for cryptographic randomness
        size_t generated = 0;
        while (generated < length) {
            uint64_t random_val;
            int success = 0;
            
            // Try RDSEED with retry loop
            for (int retry = 0; retry < 10; retry++) {
                if (_rdseed64_step(&random_val)) {
                    success = 1;
                    break;
                }
                _mm_pause(); // Pause instruction for better performance
            }
            
            if (!success) {
                return -1; // RDSEED failed
            }
            
            size_t copy_bytes = (length - generated < sizeof(random_val)) ?
                               length - generated : sizeof(random_val);
            memcpy(buffer + generated, &random_val, copy_bytes);
            generated += copy_bytes;
        }
        return 0;
    } else if (features.rdrand) {
        // Fallback to RDRAND
        size_t generated = 0;
        while (generated < length) {
            uint64_t random_val;
            int success = 0;
            
            for (int retry = 0; retry < 10; retry++) {
                if (_rdrand64_step(&random_val)) {
                    success = 1;
                    break;
                }
                _mm_pause();
            }
            
            if (!success) {
                return -1;
            }
            
            size_t copy_bytes = (length - generated < sizeof(random_val)) ?
                               length - generated : sizeof(random_val);
            memcpy(buffer + generated, &random_val, copy_bytes);
            generated += copy_bytes;
        }
        return 0;
    }
    
    return -1; // No hardware random available
}

// SHA-256 using Intel SHA extensions
static void sha256_ni_transform(uint32_t *state, const uint8_t *data)
{
    __m128i STATE0, STATE1;
    __m128i MSG, TMP;
    __m128i MSG0, MSG1, MSG2, MSG3;
    __m128i ABEF_SAVE, CDGH_SAVE;
    
    // Load initial hash values
    TMP = _mm_loadu_si128((__m128i*)(state + 0));
    STATE1 = _mm_loadu_si128((__m128i*)(state + 4));
    
    TMP = _mm_shuffle_epi32(TMP, 0xB1);
    STATE1 = _mm_shuffle_epi32(STATE1, 0x1B);
    STATE0 = _mm_alignr_epi8(TMP, STATE1, 8);
    STATE1 = _mm_blend_epi16(STATE1, TMP, 0xF0);
    
    // Save current state
    ABEF_SAVE = STATE0;
    CDGH_SAVE = STATE1;
    
    // Load message data
    MSG0 = _mm_loadu_si128((__m128i*)(data + 0));
    MSG1 = _mm_loadu_si128((__m128i*)(data + 16));
    MSG2 = _mm_loadu_si128((__m128i*)(data + 32));
    MSG3 = _mm_loadu_si128((__m128i*)(data + 48));
    
    // Byte swap for little-endian
    MSG0 = _mm_shuffle_epi8(MSG0, _mm_set_epi64x(0x0c0d0e0f08090a0b, 0x0405060700010203));
    MSG1 = _mm_shuffle_epi8(MSG1, _mm_set_epi64x(0x0c0d0e0f08090a0b, 0x0405060700010203));
    MSG2 = _mm_shuffle_epi8(MSG2, _mm_set_epi64x(0x0c0d0e0f08090a0b, 0x0405060700010203));
    MSG3 = _mm_shuffle_epi8(MSG3, _mm_set_epi64x(0x0c0d0e0f08090a0b, 0x0405060700010203));
    
    // Rounds 0-3
    MSG = _mm_add_epi32(MSG0, _mm_set_epi64x(0xE9B5DBA5B5C0FBCF, 0x71374491428A2F98));
    STATE1 = _mm_sha256rnds2_epu32(STATE1, STATE0, MSG);
    MSG = _mm_shuffle_epi32(MSG, 0x0E);
    STATE0 = _mm_sha256rnds2_epu32(STATE0, STATE1, MSG);
    
    // Continue for all 64 rounds (simplified here)
    // ... (remaining rounds follow similar pattern)
    
    // Add back to state
    STATE0 = _mm_add_epi32(STATE0, ABEF_SAVE);
    STATE1 = _mm_add_epi32(STATE1, CDGH_SAVE);
    
    // Store results back
    TMP = _mm_shuffle_epi32(STATE0, 0x1B);
    STATE1 = _mm_shuffle_epi32(STATE1, 0xB1);
    STATE0 = _mm_blend_epi16(TMP, STATE1, 0xF0);
    STATE1 = _mm_alignr_epi8(STATE1, TMP, 8);
    
    _mm_storeu_si128((__m128i*)(state + 0), STATE0);
    _mm_storeu_si128((__m128i*)(state + 4), STATE1);
}

// Optimized ChaCha20 implementation using AVX2
static void chacha20_block_avx2(uint32_t *output, 
                               const uint32_t *input, 
                               size_t blocks)
{
    if (blocks >= 8) {
        // Process 8 blocks in parallel using AVX2
        __m256i s0, s1, s2, s3, s4, s5, s6, s7;
        __m256i s8, s9, s10, s11, s12, s13, s14, s15;
        
        // Load state
        s0 = _mm256_broadcastd_epi32(_mm_loadu_si128((__m128i*)(input + 0)));
        s1 = _mm256_broadcastd_epi32(_mm_loadu_si128((__m128i*)(input + 1)));
        // ... (load remaining state elements)
        
        // Set up counters for 8 parallel blocks
        s12 = _mm256_add_epi32(s12, _mm256_set_epi32(7, 6, 5, 4, 3, 2, 1, 0));
        
        // Perform 20 rounds (10 double rounds)
        for (int round = 0; round < 10; round++) {
            // Quarter round on columns
            s0 = _mm256_add_epi32(s0, s4);
            s12 = _mm256_xor_si256(s12, s0);
            s12 = _mm256_or_si256(_mm256_slli_epi32(s12, 16), _mm256_srli_epi32(s12, 16));
            
            s8 = _mm256_add_epi32(s8, s12);
            s4 = _mm256_xor_si256(s4, s8);
            s4 = _mm256_or_si256(_mm256_slli_epi32(s4, 12), _mm256_srli_epi32(s4, 20));
            
            // Continue quarter round...
            // (Full implementation would include all operations)
        }
        
        // Add original state back
        s0 = _mm256_add_epi32(s0, _mm256_broadcastd_epi32(_mm_loadu_si128((__m128i*)(input + 0))));
        // ... (add remaining state elements)
        
        // Store results
        _mm256_storeu_si256((__m256i*)(output + 0), s0);
        // ... (store remaining output)
    } else {
        // Fallback to scalar implementation for small block counts
        // (Implementation omitted for brevity)
    }
}

// Constant-time conditional selection
static void ct_select_u32(uint32_t *result, uint32_t a, uint32_t b, uint32_t condition)
{
    // condition must be 0 or 1
    uint32_t mask = -condition; // 0 becomes 0x00000000, 1 becomes 0xFFFFFFFF
    *result = (a & mask) | (b & ~mask);
}

// Constant-time memory comparison
static int ct_memcmp(const void *a, const void *b, size_t len)
{
    const uint8_t *pa = (const uint8_t*)a;
    const uint8_t *pb = (const uint8_t*)b;
    uint8_t result = 0;
    
    for (size_t i = 0; i < len; i++) {
        result |= pa[i] ^ pb[i];
    }
    
    return (int)result;
}

// Constant-time conditional copy
static void ct_copy(void *dst, const void *src, size_t len, uint32_t condition)
{
    uint8_t *pdst = (uint8_t*)dst;
    const uint8_t *psrc = (const uint8_t*)src;
    uint8_t mask = -condition; // 0x00 or 0xFF
    
    for (size_t i = 0; i < len; i++) {
        pdst[i] = (pdst[i] & ~mask) | (psrc[i] & mask);
    }
}

// Secure memory clearing to prevent compiler optimization
static void secure_memzero(void *ptr, size_t len)
{
    volatile uint8_t *vptr = (volatile uint8_t*)ptr;
    for (size_t i = 0; i < len; i++) {
        vptr[i] = 0;
    }
}

// Constant-time modular exponentiation
static void ct_mod_exp(mpz_t result, const mpz_t base, const mpz_t exponent, const mpz_t modulus)
{
    mpz_t temp, acc;
    mpz_init_set_ui(acc, 1);
    mpz_init_set(temp, base);
    
    size_t exp_bits = mpz_sizeinbase(exponent, 2);
    
    for (size_t i = 0; i < exp_bits; i++) {
        int bit = mpz_tstbit(exponent, i);
        
        // Always perform both operations to maintain constant time
        mpz_t mult_result, square_result;
        mpz_init(mult_result);
        mpz_init(square_result);
        
        mpz_mul(mult_result, acc, temp);
        mpz_mod(mult_result, mult_result, modulus);
        
        mpz_mul(square_result, temp, temp);
        mpz_mod(square_result, square_result, modulus);
        
        // Conditional selection based on bit value
        if (bit) {
            mpz_set(acc, mult_result);
        }
        mpz_set(temp, square_result);
        
        mpz_clear(mult_result);
        mpz_clear(square_result);
    }
    
    mpz_set(result, acc);
    mpz_clear(acc);
    mpz_clear(temp);
}

// Blinding techniques for RSA operations
typedef struct {
    mpz_t blinding_factor;
    mpz_t unblinding_factor;
    bool valid;
} rsa_blinding_t;

static int generate_rsa_blinding(rsa_blinding_t *blinding, const rsa_key_t *key)
{
    mpz_init(blinding->blinding_factor);
    mpz_init(blinding->unblinding_factor);
    
    gmp_randstate_t rstate;
    gmp_randinit_default(rstate);
    
    // Generate random blinding factor r
    do {
        mpz_urandomm(blinding->blinding_factor, rstate, key->n);
    } while (mpz_cmp_ui(blinding->blinding_factor, 1) <= 0);
    
    // Compute r^e mod n
    mpz_powm(blinding->unblinding_factor, blinding->blinding_factor, key->e, key->n);
    
    // Compute r^(-1) mod n for unblinding
    if (mpz_invert(blinding->blinding_factor, blinding->blinding_factor, key->n) == 0) {
        mpz_clear(blinding->blinding_factor);
        mpz_clear(blinding->unblinding_factor);
        gmp_randclear(rstate);
        return -1;
    }
    
    blinding->valid = true;
    gmp_randclear(rstate);
    return 0;
}

static int rsa_decrypt_blinded(const rsa_key_t *key, 
                              const mpz_t ciphertext, 
                              mpz_t plaintext)
{
    rsa_blinding_t blinding;
    if (generate_rsa_blinding(&blinding, key) != 0) {
        return -1;
    }
    
    mpz_t blinded_ciphertext, blinded_plaintext;
    mpz_init(blinded_ciphertext);
    mpz_init(blinded_plaintext);
    
    // Blind the ciphertext: c' = c * r^e mod n
    mpz_mul(blinded_ciphertext, ciphertext, blinding.unblinding_factor);
    mpz_mod(blinded_ciphertext, blinded_ciphertext, key->n);
    
    // Perform blinded decryption
    rsa_decrypt_crt(key, blinded_ciphertext, blinded_plaintext);
    
    // Unblind the result: m = m' * r^(-1) mod n
    mpz_mul(plaintext, blinded_plaintext, blinding.blinding_factor);
    mpz_mod(plaintext, plaintext, key->n);
    
    // Cleanup
    mpz_clear(blinded_ciphertext);
    mpz_clear(blinded_plaintext);
    mpz_clear(blinding.blinding_factor);
    mpz_clear(blinding.unblinding_factor);
    
    return 0;
}

// AEAD context structure
typedef struct {
    aes_gcm_context_t gcm_ctx;
    uint8_t session_key[32];
    uint8_t iv_base[12];
    uint64_t message_counter;
    
    // Protocol state
    bool initialized;
    bool key_established;
    
    // Security parameters
    size_t key_size;
    size_t iv_size;
    size_t tag_size;
} aead_context_t;

// Initialize AEAD context
static int aead_init(aead_context_t *ctx, const uint8_t *key, size_t key_len)
{
    if (key_len != 32) return -1; // Only AES-256 supported
    
    memcpy(ctx->session_key, key, key_len);
    ctx->key_size = key_len;
    ctx->iv_size = 12;
    ctx->tag_size = 16;
    ctx->message_counter = 0;
    
    // Initialize AES-GCM context
    aes_key_schedule_ni(&ctx->gcm_ctx.aes_ctx, key, key_len);
    
    // Generate random IV base
    if (hardware_random_bytes(ctx->iv_base, sizeof(ctx->iv_base)) != 0) {
        return -1;
    }
    
    ctx->initialized = true;
    ctx->key_established = true;
    
    return 0;
}

// AEAD encryption
static int aead_encrypt(aead_context_t *ctx,
                       const uint8_t *plaintext, size_t plaintext_len,
                       const uint8_t *aad, size_t aad_len,
                       uint8_t *ciphertext, uint8_t *tag)
{
    if (!ctx->initialized || !ctx->key_established) {
        return -1;
    }
    
    // Construct IV: base || counter
    uint8_t iv[12];
    memcpy(iv, ctx->iv_base, sizeof(ctx->iv_base));
    
    // Encode counter in big-endian format
    uint64_t counter = ++ctx->message_counter;
    for (int i = 7; i >= 0; i--) {
        iv[4 + i] = counter & 0xFF;
        counter >>= 8;
    }
    
    // Perform AES-GCM encryption
    return aes_gcm_encrypt(&ctx->gcm_ctx, plaintext, plaintext_len,
                          aad, aad_len, iv, sizeof(iv),
                          ciphertext, tag, ctx->tag_size);
}

// AEAD decryption with authentication
static int aead_decrypt(aead_context_t *ctx,
                       const uint8_t *ciphertext, size_t ciphertext_len,
                       const uint8_t *aad, size_t aad_len,
                       const uint8_t *iv, const uint8_t *tag,
                       uint8_t *plaintext)
{
    if (!ctx->initialized || !ctx->key_established) {
        return -1;
    }
    
    // Verify IV format and extract counter
    if (memcmp(iv, ctx->iv_base, 4) != 0) {
        return -1; // Invalid IV base
    }
    
    uint64_t message_counter = 0;
    for (int i = 0; i < 8; i++) {
        message_counter = (message_counter << 8) | iv[4 + i];
    }
    
    // Check for replay attacks
    if (message_counter <= ctx->message_counter) {
        return -1; // Replay attack detected
    }
    
    // Perform AES-GCM decryption (implementation would include verification)
    // ... (simplified for brevity)
    
    ctx->message_counter = message_counter;
    return 0;
}