Nits

Author: jedisct1

www/_implementations/dart.md

@@ -1,7 +1,7 @@
 ---
 layout: implementation
 title: IPCrypt Dart Implementation
-description: Dart implementation of IPCrypt supporting all three encryption modes with native Dart SDK.
+description: Dart implementation of IPCrypt supporting all four encryption modes with native Dart SDK.
 permalink: /implementations/dart/
 language: Dart
 repository: https://github.com/elliotwutingfeng/ipcrypt
@@ -122,7 +122,7 @@ examples:
 
 ## IPCrypt Dart Implementation
 
-A Dart implementation of IPCrypt that provides IP address encryption and obfuscation methods following the IPCrypt specification. This implementation supports all three encryption modes and is designed for native Dart applications.
+A Dart implementation of IPCrypt that provides IP address encryption and obfuscation methods following the IPCrypt specification. This implementation supports all four encryption modes and is designed for native Dart applications.
 
 ## Installation
 
@@ -146,11 +146,12 @@ dart pub get
 
 ## Usage
 
-The Dart implementation provides three encryption methods as global functions:
+The Dart implementation provides encryption methods as global functions:
 
 1. `ipCryptDeterministic` - Deterministic encryption using AES-128
-2. `ipCryptNonDeterministic` - Non-deterministic encryption using KIASU-BC
-3. `ipCryptExtendedNonDeterministic` - Extended non-deterministic encryption
+2. `ipCryptPrefixPreserving` - Prefix-preserving encryption using dual AES-128
+3. `ipCryptNonDeterministic` - Non-deterministic encryption using KIASU-BC
+4. `ipCryptExtendedNonDeterministic` - Extended non-deterministic encryption
 
 ### Deterministic Encryption
 

www/_implementations/python.md

@@ -1,7 +1,7 @@
 ---
 layout: implementation
 title: IPCrypt Python Implementation
-description: Reference implementation of IPCrypt in Python, supporting all three encryption modes.
+description: Reference implementation of IPCrypt in Python, supporting all four encryption modes.
 permalink: /implementations/python/
 language: Python
 repository: https://github.com/jedisct1/draft-denis-ipcrypt/tree/main/implementations/python
@@ -58,7 +58,7 @@ examples:
 
 ## IPCrypt Python Implementation
 
-The Python implementation serves as the reference implementation for IPCrypt. It provides all three encryption modes and is designed to be clear, well-documented, and easy to understand.
+The Python implementation serves as the reference implementation for IPCrypt. It provides all four encryption modes and is designed to be clear, well-documented, and easy to understand.
 
 ## Installation
 
@@ -83,11 +83,12 @@ cd draft-denis-ipcrypt/implementations/python
 
 ## Usage
 
-The Python implementation provides three separate classes for the different encryption modes:
+The Python implementation provides separate classes for the different encryption modes:
 
 1. `IPCryptDeterministic` - Deterministic encryption using AES-128
-2. `IPCryptNd` - Non-deterministic encryption using KIASU-BC
-3. `IPCryptNdx` - Non-deterministic extended encryption using AES-XTS
+2. `IPCryptPfx` - Prefix-preserving encryption using dual AES-128
+3. `IPCryptNd` - Non-deterministic encryption using KIASU-BC
+4. `IPCryptNdx` - Non-deterministic extended encryption using AES-XTS
 
 ### Deterministic Encryption
 

www/pages/about.md

@@ -29,7 +29,7 @@ IPCrypt resolves these conflicts through purpose-built cryptographic techniques
 
 - **Efficiency and Compactness**: All variants operate on exactly 128 bits, achieving single-block encryption speed
 - **High Usage Limits**: Non-deterministic variants safely handle ~4 billion (nd) to ~18 quintillion (ndx) operations per key
-- **Format Preservation**: Deterministic mode produces valid IP addresses that flow through existing infrastructure
+- **Format Preservation**: Deterministic and prefix-preserving modes produce valid IP addresses that flow through existing infrastructure
 - **Interoperability**: Identical results across implementations enable seamless data exchange
 
 ### For Privacy Advocates
@@ -99,15 +99,15 @@ Many organizations currently use flawed mechanisms to protect IP addresses:
 
 IPCrypt offers fundamental advantages:
 
-| Feature                     | Common Approaches           | IPCrypt                                     |
-| --------------------------- | --------------------------- | ------------------------------------------- |
-| Speed                       | Varies, often slow          | Single-block speed for network rates        |
-| Data Size                   | Often expands significantly | Compact: 16-32 bytes total                 |
+| Feature                     | Common Approaches           | IPCrypt                                    |
+| --------------------------- | --------------------------- | ------------------------------------------ |
+| Speed                       | Varies, often slow          | Single-block speed for network rates       |
+| Data Size                   | Often expands significantly | Compact: 4-32 bytes total                  |
 | Reversibility               | Usually one-way             | Fully reversible with key                  |
 | Security Analysis           | Often unclear               | Mathematically provable properties         |
 | Interoperability            | Usually proprietary         | Standardized across implementations        |
 | Privacy Guarantees          | Inconsistent                | Configurable: deterministic or randomized  |
-| Format Preservation         | Rarely supported            | Available in deterministic mode            |
+| Format Preservation         | Rarely supported            | Available in deterministic and pfx modes   |
 
 ## Real-World Applications
 
@@ -139,6 +139,7 @@ def log_network_event(client_ip, event_type, timestamp):
 ```
 
 **Benefits:**
+
 - Logs can still be analyzed for patterns and anomalies
 - IP addresses are protected from casual observation
 - Compliance with privacy regulations is improved
@@ -179,6 +180,7 @@ def prepare_data_for_sharing(attack_data):
 ```
 
 **Benefits:**
+
 - Attack patterns can be shared without exposing actual IP addresses
 - Each sharing instance uses different tweaks, preventing correlation
 - The original organization can still decrypt if needed
@@ -218,6 +220,7 @@ LIMIT 10;
 ```
 
 **Benefits:**
+
 - IP addresses are not stored in plaintext
 - Queries can still be performed efficiently using indexes
 - Analytics and grouping operations work as expected
@@ -264,6 +267,7 @@ class PrivacyCompliantAnalytics:
 ```
 
 **Benefits:**
+
 - Analytics can be collected without storing personal data
 - Unique visitor counting still works accurately
 - No need to obtain explicit consent for IP storage
@@ -283,4 +287,4 @@ When implementing IPCrypt in real-world applications, consider the following:
 
 Ready to implement IPCrypt in your project? Check out our [developer resources]({{ site.baseurl }}/resources/) and choose from [multiple language implementations]({{ site.baseurl }}/implementations/).
 
-For a detailed understanding of the cryptographic constructions, read the full [specification](https://datatracker.ietf.org/doc/draft-denis-ipcrypt/){:target="_blank" rel="noopener"}.
+For a detailed understanding of the cryptographic constructions, read the full [specification](https://datatracker.ietf.org/doc/draft-denis-ipcrypt/){:target="_blank" rel="noopener"}.

www/pages/encryption-modes.md

@@ -1,7 +1,7 @@
 ---
 layout: page
 title: IPCrypt Encryption Modes
-description: Detailed explanations of IPCrypt's encryption modes - deterministic, non-deterministic (nd), and extended non-deterministic (ndx).
+description: Detailed explanations of IPCrypt's four encryption modes - deterministic, prefix-preserving (pfx), non-deterministic (nd), and extended non-deterministic (ndx).
 permalink: /encryption-modes/
 ---
 
@@ -405,7 +405,11 @@ IPCrypt offers the following encryption modes:
     <div class="feature-list">
         <div class="feature-item">
             <div class="feature-icon">🔑</div>
-            <div class="feature-text"><strong>Key Requirement</strong>: Uses a 32-byte key for enhanced security</div>
+            <div class="feature-text"><strong>Key Requirement</strong>: Uses a 32-byte key split into two independent 16-byte AES-128 keys (K1 and K2) for the sum-of-permutations PRF construction</div>
+        </div>
+        <div class="feature-item">
+            <div class="feature-icon">⚠️</div>
+            <div class="feature-text"><strong>Critical Constraint</strong>: The two 16-byte halves of the key MUST NOT be identical. Using identical values for K1 and K2 causes the XOR operation to cancel out, returning the original IP address unchanged.</div>
         </div>
         <div class="feature-item">
             <div class="feature-icon">🔍</div>

www/pages/examples.md

@@ -191,7 +191,7 @@ The following examples demonstrate the four encryption modes of IPCrypt:
             <li>Maintains native IP address sizes (4 bytes for IPv4, 16 bytes for IPv6)</li>
             <li>Enables network-level analytics while protecting actual network identities</li>
             <li>Deterministic - same input always produces same output with same key</li>
-            <li>Uses 32-byte key for enhanced security</li>
+            <li>Uses 32-byte key (two independent 16-byte AES-128 keys)</li>
         </ul>
     </div>
 </div>
@@ -337,7 +337,7 @@ def get_data():
   "events": [
     {
       "timestamp": "2025-04-24T10:15:32Z",
-      "encrypted_ip": "08e0c289bff23b7cb349aadfe3bcef56221c384c7c217b16",
+      "encrypted_ip": "a73f4e19c0d285b6f1e8d3a7924bc50e61d7f83a4b92c1e5",
       "user_agent": "Mozilla/5.0...",
       "page": "/products",
       "action": "view"

www/pages/index.md

@@ -51,7 +51,7 @@ permalink: /
             <div class="feature-card">
                 <h3 class="text-xl font-bold mb-3">Format Preservation</h3>
                 <p>
-                    Deterministic mode produces valid IP addresses, enabling encrypted addresses to flow through existing infrastructure without modification.
+                    Deterministic and prefix-preserving modes produce valid IP addresses, enabling encrypted addresses to flow through existing infrastructure without modification.
                 </p>
             </div>
             
@@ -181,7 +181,7 @@ permalink: /
                     <h3>ipcrypt-ndx</h3>
                     <span class="badge badge-orange">Extended non-deterministic</span>
                 </div>
-                <p class="example-description">32-byte output, unlimited operations per key</p>
+                <p class="example-description">32-byte output, ~2<sup>64</sup> operations per key</p>
                 <div class="example-samples">
                     <div class="sample">
                         <span class="input">192.168.1.1</span>

www/pages/playground.md

@@ -23,7 +23,7 @@ permalink: /playground/
         <div class="mb-4">
             <label for="encryption-key" class="block mb-2 font-medium">Encryption Key (hex):</label>
             <input type="text" id="encryption-key" class="w-full p-2 border rounded" placeholder="Enter a 16-byte hex key (32 characters)" value="000102030405060708090a0b0c0d0e0f">
-            <p class="text-sm text-gray-600 mt-1" id="key-help">For deterministic and nd modes: 16 bytes (32 hex chars). For ndx mode: 32 bytes (64 hex chars). Default key provided for demonstration.</p>
+            <p class="text-sm text-gray-600 mt-1" id="key-help">For deterministic and nd modes: 16 bytes (32 hex chars). For pfx and ndx modes: 32 bytes (64 hex chars). Default key provided for demonstration.</p>
         </div>
         
         <div class="mb-4">

www/pages/resources.md

@@ -25,32 +25,33 @@ To implement IPCrypt:
 
 1. **Choose an encryption mode** based on your requirements:
    - `ipcrypt-deterministic`: When you need format preservation or duplicate detection
+   - `ipcrypt-pfx`: When you need to preserve network structure for analytics
    - `ipcrypt-nd`: For general privacy protection with reasonable storage overhead
    - `ipcrypt-ndx`: For maximum privacy protection when storage permits
 2. **Generate appropriate keys**:
    - 16 bytes (128 bits) for deterministic and nd modes
-   - 32 bytes (256 bits) for ndx mode
+   - 32 bytes (256 bits) for pfx and ndx modes
 3. **For non-deterministic modes**, use uniformly random tweaks
 4. **Test against the specification's test vectors** to ensure correctness
 
 ## Implementation Information
 
 ### Key Management Suggestions
 
-Good key management practices are important when using IPCrypt:
+Good key management practices are essential when using IPCrypt:
 
-- **Creating Keys**: Consider using a cryptographically secure random number generator
-- **Storing Keys**: Try to store keys securely, such as in a key management system
-- **Changing Keys**: Consider rotating keys periodically as a security practice
-- **Key Separation**: Use different keys for different applications or data sets
+- **Creating Keys**: Keys MUST be generated using a cryptographically secure random number generator (see RFC 4086)
+- **Storing Keys**: Store keys securely, such as in a key management system
+- **Changing Keys**: Rotate keys periodically as a security practice
+- **Key Separation**: Use different keys for different applications or data sets. The specification defines HKDF-based key derivation for deriving mode-specific keys from a single master key
 
 ### Helpful Tips
 
 When working with IPCrypt, here are some suggestions that might be helpful:
 
 1. **Check IP Formats**: It's a good idea to make sure IP addresses are properly formatted before encryption
 2. **Handle Errors Kindly**: Consider how your code will respond if something unexpected happens
-3. **Think About Timing**: For security-sensitive applications, constant-time operations can help prevent timing analysis
+3. **Constant-time Operations**: Implementations MUST use constant-time operations to mitigate side-channel attacks
 4. **Test Your Code**: You might want to check your implementation against the examples in the specification
 5. **Performance Optimization**: All variants are designed for single-block speed critical for network-rate processing