exif_oxide/implementations/nikon/

encryption.rs

//! Nikon encryption key management and ProcessNikonEncrypted foundation
//!
//! **Trust ExifTool**: This code translates ExifTool's Nikon encryption system verbatim.
//!
//! ExifTool Reference: lib/Image/ExifTool/Nikon.pm ProcessNikonEncrypted function
//!
//! Nikon's encryption system uses multiple keys derived from camera metadata:
//! - Serial number (tag 0x001d) as primary encryption key
//! - Shutter count (tag 0x00a7) as secondary encryption key
//! - Model-specific decryption algorithms
//!
//! Phase 1 Implementation: Key management and detection only
//! Phase 2 Implementation: Encrypted section detection and cataloging
//! Phase 3+ Implementation: Actual decryption algorithms (future milestone)

use crate::exif::ExifReader;
use crate::tiff_types::{ByteOrder, IfdEntry};
use crate::types::{Result, TagValue};
use tracing::{debug, trace, warn};

/// Nikon encryption key management system
/// ExifTool: Nikon.pm encryption key storage and validation
#[derive(Debug, Clone)]
pub struct NikonEncryptionKeys {
    /// Camera serial number for encryption (tag 0x001d)
    /// ExifTool: $$et{NikonSerialKey} = $val
    pub serial_number: Option<String>,

    /// Shutter count for encryption (tag 0x00a7)  
    /// ExifTool: $$et{NikonCountKey} = $val
    pub shutter_count: Option<u32>,

    /// Camera model for algorithm selection
    /// ExifTool: Model-specific decryption handling
    pub camera_model: String,

    /// Additional encryption parameters (future use)
    /// ExifTool: Various model-specific encryption parameters
    pub additional_params: std::collections::HashMap<String, String>,
}

impl NikonEncryptionKeys {
    /// Create new encryption key manager for a Nikon camera
    /// ExifTool: Initialize encryption context for camera model
    pub fn new(model: String) -> Self {
        debug!("Initializing Nikon encryption keys for model: {}", model);
        Self {
            serial_number: None,
            shutter_count: None,
            camera_model: model,
            additional_params: std::collections::HashMap::new(),
        }
    }

    /// Store serial number encryption key
    /// ExifTool: Nikon.pm:1234 - if ($tagID == 0x001d) { $$et{NikonSerialKey} = $val; }
    pub fn store_serial_key(&mut self, serial: String) {
        debug!("Storing Nikon serial encryption key: {}", serial);
        self.serial_number = Some(serial);
    }

    /// Store shutter count encryption key
    /// ExifTool: Nikon.pm:1267 - if ($tagID == 0x00a7) { $$et{NikonCountKey} = $val; }
    pub fn store_count_key(&mut self, count: u32) {
        debug!("Storing Nikon shutter count encryption key: {}", count);
        self.shutter_count = Some(count);
    }

    /// Check if required encryption keys are available
    /// ExifTool: Validation before ProcessNikonEncrypted
    pub fn has_required_keys(&self) -> bool {
        let has_keys = self.serial_number.is_some() && self.shutter_count.is_some();

        if has_keys {
            debug!("Nikon encryption keys available (serial + count)");
        } else {
            trace!(
                "Nikon encryption keys incomplete - serial: {}, count: {}",
                self.serial_number.is_some(),
                self.shutter_count.is_some()
            );
        }

        has_keys
    }

    /// Get serial number key if available
    /// ExifTool: Access to $$et{NikonSerialKey}
    pub fn get_serial_key(&self) -> Option<&str> {
        self.serial_number.as_deref()
    }

    /// Get shutter count key if available
    /// ExifTool: Access to $$et{NikonCountKey}
    pub fn get_count_key(&self) -> Option<u32> {
        self.shutter_count
    }

    /// Store additional encryption parameter
    /// ExifTool: Model-specific parameter storage
    pub fn set_parameter(&mut self, key: String, value: String) {
        trace!("Setting Nikon encryption parameter: {} = {}", key, value);
        self.additional_params.insert(key, value);
    }

    /// Get encryption parameter
    /// ExifTool: Model-specific parameter retrieval
    pub fn get_parameter(&self, key: &str) -> Option<&str> {
        self.additional_params.get(key).map(|s| s.as_str())
    }
}

/// ProcessNikonEncrypted skeleton - detection and key validation only
/// ExifTool: Nikon.pm ProcessNikonEncrypted function (Phase 1: detection only)
pub fn process_nikon_encrypted(
    reader: &mut crate::exif::ExifReader,
    data: &[u8],
    keys: &NikonEncryptionKeys,
) -> crate::types::Result<()> {
    debug!("Processing Nikon encrypted data (Phase 1: detection only)");

    if data.is_empty() {
        warn!("No encrypted data to process");
        return Ok(());
    }

    // Phase 1: Detect and report encryption status
    let tag_source = reader.create_tag_source_info("MakerNotes");

    let status = if keys.has_required_keys() {
        debug!("Nikon encrypted section detected with valid keys");
        format!(
            "Encrypted data detected (keys available: serial={}, count={}, decryption not implemented)",
            keys.get_serial_key().unwrap_or("none"),
            keys.get_count_key().map(|c| c.to_string()).unwrap_or("none".to_string())
        )
    } else {
        debug!("Nikon encrypted section detected without keys");
        "Encrypted data detected (keys required for decryption)".to_string()
    };

    reader.store_tag_with_precedence(
        0x00FE, // Use a custom tag ID for encryption detection
        crate::types::TagValue::String(status),
        tag_source,
    );

    // TODO: Phase 2+ implementation will add actual decryption here
    // This will include:
    // - Model-specific decryption algorithms
    // - Serial number and shutter count key derivation
    // - Encrypted data block processing
    // - Re-encryption for write support

    Ok(())
}

/// Validate encryption keys for specific camera model
/// ExifTool: Model-specific key validation logic
pub fn validate_encryption_keys(keys: &NikonEncryptionKeys, model: &str) -> Result<()> {
    use crate::types::ExifError;

    // Basic key availability check
    if !keys.has_required_keys() {
        return Err(ExifError::ParseError(
            "Required encryption keys not available".to_string(),
        ));
    }

    // Model-specific validation (skeleton)
    // TODO: Add model-specific key format validation in Phase 2+
    match model {
        model if model.contains("Z 9") => {
            debug!("Validated encryption keys for Nikon Z 9");
        }
        model if model.contains("D850") => {
            debug!("Validated encryption keys for Nikon D850");
        }
        _ => {
            debug!("Generic encryption key validation for model: {}", model);
        }
    }

    Ok(())
}

/// Process encrypted Nikon data sections
/// ExifTool: Nikon.pm ProcessNikonEncrypted function
pub fn process_encrypted_sections(
    reader: &mut ExifReader,
    base_offset: usize,
    keys: &NikonEncryptionKeys,
) -> Result<()> {
    trace!(
        "Processing encrypted Nikon sections at offset {:#x}",
        base_offset
    );

    let data = reader.get_data().to_vec();

    // Validate we have enough data for an IFD
    if base_offset + 2 > data.len() {
        debug!(
            "Insufficient data for encrypted section processing at offset {:#x}",
            base_offset
        );
        return Ok(());
    }

    // Get byte order from the reader's header
    let byte_order = match &reader.header {
        Some(header) => header.byte_order,
        None => {
            debug!("No TIFF header available for byte order, using little endian");
            ByteOrder::LittleEndian
        }
    };

    // Read number of IFD entries
    let num_entries = match byte_order.read_u16(&data, base_offset) {
        Ok(count) => count as usize,
        Err(_) => {
            debug!(
                "Failed to read IFD entry count for encrypted section at offset {:#x}",
                base_offset
            );
            return Ok(());
        }
    };

    debug!("Scanning {} entries for encrypted Nikon data", num_entries);

    let mut encrypted_sections_found = 0;
    let mut encrypted_tags = Vec::new();

    // Scan IFD entries for encrypted data indicators
    // ExifTool: Nikon.pm identifies encrypted sections by specific patterns
    for index in 0..num_entries {
        let entry_offset = base_offset + 2 + 12 * index;

        if entry_offset + 12 > data.len() {
            debug!(
                "Entry {} at offset {:#x} beyond data bounds during encryption scan",
                index, entry_offset
            );
            break;
        }

        // Parse IFD entry
        let entry = match IfdEntry::parse(&data, entry_offset, byte_order) {
            Ok(entry) => entry,
            Err(e) => {
                trace!(
                    "Failed to parse IFD entry {} during encryption scan: {:?}",
                    index,
                    e
                );
                continue;
            }
        };

        // Check for known encrypted data tags
        // ExifTool: Nikon.pm ProcessNikonEncrypted identifies these patterns
        if is_encrypted_nikon_tag(entry.tag_id) {
            encrypted_sections_found += 1;
            encrypted_tags.push(entry.tag_id);

            trace!("Found encrypted tag {:#x} at entry {}", entry.tag_id, index);

            // Store information about the encrypted tag
            let tag_source = reader.create_tag_source_info("Nikon");
            let tag_info = if keys.has_required_keys() {
                format!(
                    "Encrypted tag {:#x} (keys available, decryption not implemented)",
                    entry.tag_id
                )
            } else {
                format!(
                    "Encrypted tag {:#x} (keys required for decryption)",
                    entry.tag_id
                )
            };

            reader.store_tag_with_precedence(
                0x1000 + entry.tag_id, // Use offset to avoid conflicts
                TagValue::String(tag_info),
                tag_source,
            );
        }
    }

    // Store overall encryption status
    let tag_source = reader.create_tag_source_info("Nikon");

    if encrypted_sections_found > 0 {
        let encryption_summary = if keys.has_required_keys() {
            format!(
                "Found {} encrypted sections (keys available: serial={}, count={})",
                encrypted_sections_found,
                keys.get_serial_key().unwrap_or("none"),
                keys.get_count_key()
                    .map(|c| c.to_string())
                    .unwrap_or("none".to_string())
            )
        } else {
            format!(
                "Found {encrypted_sections_found} encrypted sections (keys incomplete for decryption)"
            )
        };

        reader.store_tag_with_precedence(
            0x00FF, // Custom tag for encryption summary
            TagValue::String(encryption_summary),
            tag_source,
        );

        debug!(
            "Detected {} encrypted Nikon sections: {:?}",
            encrypted_sections_found, encrypted_tags
        );
    } else {
        reader.store_tag_with_precedence(
            0x00FF, // Custom tag for encryption summary
            "No encrypted sections detected".into(),
            tag_source,
        );

        debug!("No encrypted Nikon sections detected");
    }

    debug!(
        "Encrypted section processing completed - {} sections found",
        encrypted_sections_found
    );
    Ok(())
}

/// Check if a tag ID represents encrypted Nikon data
/// ExifTool: Nikon.pm encrypted tag identification
pub fn is_encrypted_nikon_tag(tag_id: u16) -> bool {
    // ExifTool: Nikon.pm identifies these tags as commonly encrypted
    // This is a simplified version - real ExifTool has model-specific lists
    match tag_id {
        // Common encrypted tags from ExifTool Nikon.pm
        0x0088 => true, // AFInfo (often encrypted)
        0x0091 => true, // ShotInfo (often encrypted)
        0x0097 => true, // ColorBalance (often encrypted)
        0x0098 => true, // LensData (often encrypted)
        0x00A8 => true, // FlashInfo (often encrypted)
        0x00B0 => true, // MultiExposure (often encrypted)
        0x00B7 => true, // AFInfo2 (often encrypted)
        0x00B9 => true, // AFTune (often encrypted)
        _ => false,     // Other tags are typically not encrypted
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_encryption_keys_initialization() {
        let keys = NikonEncryptionKeys::new("NIKON Z 9".to_string());
        assert_eq!(keys.camera_model, "NIKON Z 9");
        assert!(!keys.has_required_keys());
    }

    #[test]
    fn test_serial_key_storage() {
        let mut keys = NikonEncryptionKeys::new("NIKON D850".to_string());
        keys.store_serial_key("12345678".to_string());

        assert_eq!(keys.get_serial_key(), Some("12345678"));
        assert!(!keys.has_required_keys()); // Still need count key
    }

    #[test]
    fn test_count_key_storage() {
        let mut keys = NikonEncryptionKeys::new("NIKON Z 9".to_string());
        keys.store_count_key(1000);

        assert_eq!(keys.get_count_key(), Some(1000));
        assert!(!keys.has_required_keys()); // Still need serial key
    }

    #[test]
    fn test_complete_key_set() {
        let mut keys = NikonEncryptionKeys::new("NIKON D850".to_string());
        keys.store_serial_key("12345678".to_string());
        keys.store_count_key(1500);

        assert!(keys.has_required_keys());
        assert_eq!(keys.get_serial_key(), Some("12345678"));
        assert_eq!(keys.get_count_key(), Some(1500));
    }

    #[test]
    fn test_additional_parameters() {
        let mut keys = NikonEncryptionKeys::new("NIKON Z 9".to_string());
        keys.set_parameter("DecryptStart".to_string(), "0x100".to_string());

        assert_eq!(keys.get_parameter("DecryptStart"), Some("0x100"));
        assert_eq!(keys.get_parameter("Unknown"), None);
    }

    #[test]
    fn test_encryption_validation_without_keys() {
        let keys = NikonEncryptionKeys::new("NIKON D850".to_string());
        let result = validate_encryption_keys(&keys, "NIKON D850");

        assert!(result.is_err());
        assert!(result
            .unwrap_err()
            .to_string()
            .contains("Required encryption keys not available"));
    }

    #[test]
    fn test_encryption_validation_with_keys() {
        let mut keys = NikonEncryptionKeys::new("NIKON Z 9".to_string());
        keys.store_serial_key("12345678".to_string());
        keys.store_count_key(2000);

        let result = validate_encryption_keys(&keys, "NIKON Z 9");
        assert!(result.is_ok());
    }
}