Cryptographic session keys stored exclusively in DRAM volatile memory can be rendered forensically unrecoverable within 100 milliseconds of explicit erasure using secure memory overwrite protocols (multiple-pass zero and random fill with compiler barrier), provided no cold-boot attack occurs during the erasure window — establishing that hardware-level ephemeral key destruction is achievable without trusted hardware modules.

Cryptographic session keys (128-bit to 512-bit AES/RSA session keys) stored exclusively in DRAM volatile memory on commodity x86-64 hardware can be rendered forensically unrecoverable — defined as achieving bit-error rates ≥50% on any recovered key material, indistinguishable from random noise — within 100 milliseconds of initiating a secure memory overwrite protocol consisting of ≥3 passes (zero-fill, random-fill, zero-fill) with compiler memory barriers (volatile writes + memory fences), under ambient temperature conditions (20–25°C), in the absence of cold-boot attacks during the erasure window, and without requiring TPM, HSM, or other trusted hardware modules.

Phase 1 — Baseline Key Residency Measurement (2 weeks) Establish ground truth for key material persistence in DRAM without erasure. Inject known 256-bit AES keys into controlled memory regions, perform immediate forensic imaging, and measure recovery rates.

Phase 2 — Erasure Protocol Implementation and Timing (2 weeks) Implement 4 variants of secure erasure: (A) naive memset, (B) volatile-qualified multi-pass, (C) explicit_bzero/SecureZeroMemory, (D) assembly-level MOVNTI non-temporal stores with SFENCE. Measure erasure completion time across N=1000 trials per variant on 5 hardware platforms.

Phase 3 — Post-Erasure Forensic Recovery Attempts (3 weeks) Immediately following erasure (T+1ms, T+10ms, T+50ms, T+100ms, T+500ms), perform: (a) direct memory imaging via /dev/mem or DMA, (b) cold-boot simulation (controlled DRAM cooling to -20°C then reimaging), (c) cache-state analysis via FLUSH+RELOAD, (d) ECC log analysis for bit-flip patterns.

Phase 4 — Statistical Analysis and Cross-Platform Validation (1 week) Apply Shannon entropy analysis, Hamming distance from known key, and chi-squared randomness tests to all recovered samples. Validate across DDR3/DDR4/DDR5 and ARM64 (Raspberry Pi 5) as negative control.

/* Secure Key Erasure Validation Framework — Core Implementation */
/* Target: x86-64, GCC/Clang, Linux 6.x */

#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <sys/mman.h>
#include <immintrin.h>  /* For MOVNTI/SFENCE */

#define KEY_SIZE_BYTES 32        /* 256-bit AES key */
#define PAGE_SIZE      4096
#define NUM_TRIALS     1000
#define ERASURE_PASSES 3

/* === Key Injection === */
typedef struct {
    uint8_t  key_material[KEY_SIZE_BYTES];
    uint8_t  padding[PAGE_SIZE - KEY_SIZE_BYTES];  /* Isolate to single page */
    uint64_t physical_addr;   /* Resolved via /proc/self/pagemap */
    uint64_t inject_time_ns;
    uint64_t erase_time_ns;
} KeyPage __attribute__((aligned(PAGE_SIZE)));

KeyPage* allocate_key_page(void) {
    KeyPage* kp = mmap(NULL, PAGE_SIZE, PROT_READ|PROT_WRITE,
                       MAP_ANONYMOUS|MAP_PRIVATE|MAP_LOCKED, -1, 0);
    mlock(kp, PAGE_SIZE);  /* Prevent paging to swap */
    return kp;
}

/* === Erasure Variant B: Volatile Multi-Pass with Compiler Barrier === */
void erase_variant_b(volatile uint8_t* ptr, size_t len) {
    /* Pass 1: Zero fill */
    for (size_t i = 0; i < len; i++) ptr[i] = 0x00;
    __asm__ __volatile__("" ::: "memory");  /* Compiler barrier */
    
    /* Pass 2: Random fill */
    for (size_t i = 0; i < len; i++) ptr[i] = (uint8_t)(rand() & 0xFF);
    __asm__ __volatile__("" ::: "memory");
    
    /* Pass 3: Zero fill */
    for (size_t i = 0; i < len; i++) ptr[i] = 0x00;
    __asm__ __volatile__("" ::: "memory");
    __asm__ __volatile__("mfence" ::: "memory");  /* Full memory fence */
}

/* === Erasure Variant D: Non-Temporal MOVNTI (bypasses cache) === */
void erase_variant_d_nontemporal(void* ptr, size_t len) {
    uint64_t* p64 = (uint64_t*)ptr;
    size_t n64 = len / 8;
    
    /* Pass 1: NT zero */
    for (size_t i = 0; i < n64; i++) _mm_stream_si64((long long*)(p64+i), 0LL);
    _mm_sfence();
    
    /* Pass 2: NT random */
    for (size_t i = 0; i < n64; i++) {
        uint64_t r = ((uint64_t)rand() << 32) | rand();
        _mm_stream_si64((long long*)(p64+i), (long long)r);
    }
    _mm_sfence();
    
    /* Pass 3: NT zero */
    for (size_t i = 0; i < n64; i++) _mm_stream_si64((long long*)(p64+i), 0LL);
    _mm_sfence();
    
    /* Flush any remaining cache lines */
    for (size_t i = 0; i < len; i += 64)
        _mm_clflush((char*)ptr + i);
    __asm__ __volatile__("cpuid" ::: "eax","ebx","ecx","edx","memory");
}

/* === Timing Harness === */
typedef struct {
    uint64_t rdtsc_start;
    uint64_t rdtsc_end;
    uint64_t wall_ns_start;
    uint64_t wall_ns_end;
    double   elapsed_ms;
} ErasureTiming;

ErasureTiming time_erasure(void (*erase_fn)(volatile uint8_t*, size_t),
                            volatile uint8_t* ptr, size_t len) {
    ErasureTiming t;
    struct timespec ts_start, ts_end;
    
    clock_gettime(CLOCK_MONOTONIC_RAW, &ts_start);
    __asm__ __volatile__("rdtsc" : "=A"(t.rdtsc_start));
    
    erase_fn(ptr, len);
    
    __asm__ __volatile__("rdtsc" : "=A"(t.rdtsc_end));
    clock_gettime(CLOCK_MONOTONIC_RAW, &ts_end);
    
    t.wall_ns_start = ts_start.tv_sec * 1e9 + ts_start.tv_nsec;
    t.wall_ns_end   = ts_end.tv_sec   * 1e9 + ts_end.tv_nsec;
    t.elapsed_ms    = (t.wall_ns_end - t.wall_ns_start) / 1e6;
    return t;
}

/* === Post-Erasure Forensic Imaging (via LiME kernel module) === */
/* 
 * Forensic imaging is performed by separate privileged process:
 * 1. Load LiME module: insmod lime.ko path=/tmp/mem_snapshot.lime format=raw
 * 2. Extract target page: dd if=/tmp/mem_snapshot.lime bs=4096 
 *    skip=$(physical_addr/4096) count=1 of=recovered_page.bin
 * 3. Compute metrics on recovered_page.bin
 */

/* === Statistical Analysis === */
double compute_shannon_entropy(const uint8_t* data, size_t len) {
    uint64_t freq[256] = {0};
    for (size_t i = 0; i < len; i++) freq[data[i]]++;
    double entropy = 0.0;
    for (int i = 0; i < 256; i++) {
        if (freq[i] > 0) {
            double p = (double)freq[i] / len;
            entropy -= p * log2(p);
        }
    }
    return entropy;  /* Max = 8.0 bits/byte */
}

int compute_hamming_distance(const uint8_t* a, const uint8_t* b, size_t len) {
    int dist = 0;
    for (size_t i = 0; i < len; i++)
        dist += __builtin_popcount(a[i] ^ b[i]);
    return dist;  /* Expected ~50% of (len*8) bits for random */
}

/* === Main Validation Loop === */
/*
Architecture:
  [Master Process]
       |
       +---> [Key Injection Thread] (CPU core 0)
       |          inject_key() -> mlock() -> record physical addr
       |
       +---> [Erasure Thread] (CPU core 1, pinned)
       |          wait_for_signal() -> time_erasure() -> signal_imager()
       |
       +---> [Imaging Process] (CPU core 2, separate process, root)
       |          wait_for_signal() -> LiME snapshot at T+Xms
       |
       +---> [Analysis Thread] (CPU core 3)
                  compute_entropy() -> compute_hamming() -> log_result()

Output CSV format:
  trial_id, platform, variant, erasure_ms, entropy, hamming_pct, 
  chi_sq_p, recovery_success, temperature_c, timestamp
*/

int main(void) {
    /* Initialize result log */
    FILE* log = fopen("erasure_results.csv", "w");
    fprintf(log, "trial,variant,erasure_ms,entropy,hamming_pct,success\n");
    
    for (int trial = 0; trial < NUM_TRIALS; trial++) {
        KeyPage* kp = allocate_key_page();
        
        /* Inject known key */
        generate_random_key(kp->key_material, KEY_SIZE_BYTES);
        uint8_t known_key[KEY_SIZE_BYTES];
        memcpy(known_key, kp->key_material, KEY_SIZE_BYTES);
        
        /* Erase and time */
        ErasureTiming t = time_erasure(erase_variant_b, 
                                        kp->key_material, KEY_SIZE_BYTES);
        
        /* Signal forensic imager (separate process) */
        signal_imager(kp->physical_addr);
        
        /* Receive imaged bytes */
        uint8_t recovered[KEY_SIZE_BYTES];
        receive_imaged_bytes(recovered, KEY_SIZE_BYTES);
        
        /* Analyze */
        double entropy = compute_shannon_entropy(recovered, KEY_SIZE_BYTES);
        int hamming    = compute_hamming_distance(recovered, known_key, KEY_SIZE_BYTES);
        double ham_pct = (double)hamming / (KEY_SIZE_BYTES * 8) * 100.0;
        int success    = (hamming < KEY_SIZE_BYTES * 8 * 0.10) ? 1 : 0; /* <10% error = recovery */
        
        fprintf(log, "%d,B,%.3f,%.4f,%.2f,%d\n",
                trial, t.elapsed_ms, entropy, ham_pct, success);
        
        munmap(kp, PAGE_SIZE);
    }
    
    fclose(log);
    return 0;
}