cipherrun 0.3.0

// Kani Proof Harnesses for Vulnerability Tester Functions
//
// These proofs verify that vulnerability detection parsing functions
// handle untrusted network input safely without panics, buffer overflows,
// or integer overflows.

/// Proof: Heartbleed malicious heartbeat record construction
///
/// Verifies that building malicious heartbeat records for testing
/// does not cause panics or overflows.
#[cfg(kani)]
#[kani::proof]
fn proof_heartbleed_record_construction() {
    use crate::constants::{CONTENT_TYPE_HEARTBEAT, HEARTBEAT_REQUEST, VERSION_TLS_1_2};

    // Build heartbeat record (simulating HeartbleedTester logic)
    let mut heartbeat: [u8; 8] = [0u8; 8];

    // Content type
    heartbeat[0] = CONTENT_TYPE_HEARTBEAT;

    // Version bytes
    heartbeat[1] = (VERSION_TLS_1_2 >> 8) as u8;
    heartbeat[2] = (VERSION_TLS_1_2 & 0xff) as u8;

    // Record length
    heartbeat[3] = 0x00;
    heartbeat[4] = 0x03;

    // Heartbeat request
    heartbeat[5] = HEARTBEAT_REQUEST;

    // Payload length (malicious)
    let payload_len: u16 = kani::any();
    heartbeat[6] = (payload_len >> 8) as u8;
    heartbeat[7] = (payload_len & 0xff) as u8;

    // Verify record is correctly formed
    kani::assert(heartbeat.len() == 8, "Heartbeat record should be 8 bytes");
    kani::assert(heartbeat[0] == CONTENT_TYPE_HEARTBEAT, "First byte should be heartbeat type");
}

/// Proof: POODLE malformed record construction (invalid padding)
///
/// Verifies that building malformed TLS records for POODLE testing
/// is safe for all symbolic inputs.
#[cfg(kani)]
#[kani::proof]
#[kani::unwind(64)]
fn proof_poodle_malformed_record_construction() {
    use crate::constants::{CONTENT_TYPE_APPLICATION_DATA, VERSION_TLS_1_2};

    let mut record: [u8; 60] = [0u8; 60];
    let mut idx: usize = 0;

    // TLS record header
    record[idx] = CONTENT_TYPE_APPLICATION_DATA;
    idx += 1;
    record[idx] = (VERSION_TLS_1_2 >> 8) as u8;
    idx += 1;
    record[idx] = (VERSION_TLS_1_2 & 0xff) as u8;
    idx += 1;

    // Length (48 bytes payload)
    record[idx] = 0x00;
    idx += 1;
    record[idx] = 0x30;
    idx += 1;

    // Encrypted data (32 bytes)
    for _ in 0..32 {
        record[idx] = 0x41;
        idx += 1;
    }

    // MAC (16 bytes)
    for _ in 0..16 {
        record[idx] = 0x00;
        idx += 1;
    }

    // Invalid padding
    for i in 0..7u8 {
        // Safe: i is bounded by loop
        record[idx] = i.wrapping_mul(3);
        idx += 1;
    }

    // Verify structure
    kani::assert(idx == 60, "Record should be 60 bytes");
    kani::assert(record[0] == CONTENT_TYPE_APPLICATION_DATA, "Should be application data");
}

/// Proof: Zero-length TLS record construction
///
/// Verifies that building zero-length records (for CVE-2011-4576 testing)
/// is safe.
#[cfg(kani)]
#[kani::proof]
fn proof_zero_length_record_construction() {
    use crate::constants::{CONTENT_TYPE_APPLICATION_DATA, VERSION_TLS_1_2};

    let record: [u8; 5] = [
        CONTENT_TYPE_APPLICATION_DATA,
        (VERSION_TLS_1_2 >> 8) as u8,
        (VERSION_TLS_1_2 & 0xff) as u8,
        0x00,
        0x00, // Zero length
    ];

    kani::assert(record.len() == 5, "Zero-length record header should be 5 bytes");
    kani::assert(record[3] == 0x00 && record[4] == 0x00, "Length should be zero");
}

/// Proof: Valid PKCS#7 padding construction
///
/// Verifies that constructing valid padding for oracle testing is correct.
#[cfg(kani)]
#[kani::proof]
fn proof_valid_pkcs7_padding_construction() {
    let padding_len: u8 = kani::any();
    kani::assume(padding_len > 0 && padding_len <= 16);

    let mut padding: [u8; 16] = [0u8; 16];
    for i in 0..(padding_len as usize) {
        padding[i] = padding_len - 1;
    }

    // Verify all bytes are equal to padding_len - 1
    for i in 0..(padding_len as usize) {
        kani::assert(padding[i] == padding_len - 1, "All padding bytes should be equal");
    }
}

/// Proof: Timing measurement does not overflow
///
/// Verifies that timing calculations used in oracle detection
/// do not overflow.
#[cfg(kani)]
#[kani::proof]
fn proof_timing_calculation_no_overflow() {
    let sample_count: usize = kani::any();
    kani::assume(sample_count > 0 && sample_count <= 1000);

    // Simulate timing values (in milliseconds, realistic range)
    let mut total: f64 = 0.0;

    for _ in 0..sample_count {
        let timing_ms: f64 = kani::any();
        kani::assume(timing_ms >= 0.0 && timing_ms <= 10000.0); // Max 10 seconds

        total += timing_ms;
    }

    // Calculate average
    let avg = total / (sample_count as f64);

    // Verify result is valid (not NaN or infinite)
    kani::assert(!avg.is_nan(), "Average should not be NaN");
    kani::assert(avg.is_finite(), "Average should be finite");
}

/// Proof: Alert type parsing is safe
///
/// Verifies that parsing TLS alert types from network data is safe.
#[cfg(kani)]
#[kani::proof]
#[kani::unwind(16)]
fn proof_alert_type_parsing() {
    use crate::constants::CONTENT_TYPE_ALERT;

    let len: usize = kani::any();
    kani::assume(len <= 10);

    let mut response: [u8; 10] = [0u8; 10];
    for i in 0..len {
        response[i] = kani::any();
    }

    // Simulate alert parsing logic
    let alert_type: Option<u8> = if len > 0 && response[0] == CONTENT_TYPE_ALERT && len >= 7 {
        Some(response[6])
    } else {
        None
    };

    // Verify we get a valid result
    match alert_type {
        Some(t) => {
            let _ = t;
            // If we produced an alert, the input satisfied the alert framing conditions.
            kani::assert(len >= 7, "Alert parsing requires at least 7 bytes");
            kani::assert(response[0] == CONTENT_TYPE_ALERT, "Alert parsing requires alert content type");
        }
        None => {
            // Expected for invalid/short input
        }
    }
}

/// Proof: Response oracle detection calculation
///
/// Verifies that the oracle detection algorithm handles edge cases safely.
#[cfg(kani)]
#[kani::proof]
fn proof_oracle_detection_calculation() {
    // Simulate average alert type values
    let avg_a: f64 = kani::any();
    let avg_b: f64 = kani::any();

    kani::assume(avg_a.is_finite() && avg_a >= 0.0 && avg_a <= 255.0);
    kani::assume(avg_b.is_finite() && avg_b >= 0.0 && avg_b <= 255.0);

    let diff = (avg_a - avg_b).abs();
    let oracle_detected = diff > 0.5;

    // Verify result is deterministic
    kani::assert(!diff.is_nan(), "Difference should not be NaN");
    let _ = oracle_detected;
}

/// Proof: Timing threshold comparison
///
/// Verifies that timing-based oracle detection handles all valid timing values.
#[cfg(kani)]
#[kani::proof]
fn proof_timing_threshold_comparison() {
    const TIMING_THRESHOLD_MS: f64 = 5.0;

    let valid_avg: f64 = kani::any();
    let invalid_avg: f64 = kani::any();

    kani::assume(valid_avg.is_finite() && valid_avg >= 0.0);
    kani::assume(invalid_avg.is_finite() && invalid_avg >= 0.0);

    let timing_diff = (valid_avg - invalid_avg).abs();
    let oracle_detected = timing_diff > TIMING_THRESHOLD_MS;

    kani::assert(!timing_diff.is_nan(), "Timing diff should not be NaN");
    let _ = oracle_detected;
}

/// Proof: Application data record length calculation
///
/// Verifies that record length calculations don't overflow.
#[cfg(kani)]
#[kani::proof]
fn proof_record_length_calculation() {
    let header_size: usize = 5;
    let payload_size: usize = kani::any();
    let mac_size: usize = 20;
    let padding_size: usize = kani::any();

    kani::assume(payload_size <= 16384); // Max TLS record size
    kani::assume(padding_size <= 256);

    // Calculate total record length
    let total_opt = header_size
        .checked_add(payload_size)
        .and_then(|s| s.checked_add(mac_size))
        .and_then(|s| s.checked_add(padding_size));

    match total_opt {
        Some(total) => {
            // Verify it fits in u16 for TLS length field
            if total <= 65535 + header_size {
                let record_len = total - header_size;
                let len_bytes = (record_len as u16).to_be_bytes();
                kani::assert(len_bytes.len() == 2, "Length is 2 bytes");
            }
        }
        None => {
            // Overflow case - should be handled gracefully
        }
    }
}