Symmetric Encryption

🔒 Camellia-256 Japanese Standard Cipher

Security Level 256-bit
Performance ⭐⭐⭐⭐ Very Good
Quantum Resistant ⚠️ Partial (128-bit)
Block Size 128 bits
Key Size 256 bits
Rounds 24 rounds

📋 Quick Navigation

📖 Overview 🔧 Parameters 💻 Implementation ⚡ Performance 🔒 Security 🎯 Use Cases

📖 Overview

Camellia-256 is a symmetric block cipher jointly developed by Mitsubishi Electric and NTT of Japan. It's approved as an international standard by ISO/IEC, part of the NESSIE portfolio, and adopted by the IETF for use in IPsec and TLS. Camellia-256 uses a 256-bit key and operates on 128-bit blocks with a 24-round Feistel structure.

✨ Key Features

🏛️

International Standards

ISO/IEC 18033-3, IETF RFC 3713, NESSIE portfolio

🔐

256-bit Security

Maximum security level with 256-bit key size

🔄

Feistel Network

24-round Feistel structure with strong diffusion

⚖️

Patent-Free

Freely available for all commercial and personal uses

⚡

Hardware Friendly

Efficient in both hardware and software implementations

🌐

IETF Adoption

Supported in IPsec, TLS, and other IETF protocols

🎯 Common Use Cases

🌐 Internet & Protocol Security

  • IPsec: Internet Protocol Security implementations
  • TLS/SSL: Transport Layer Security protocols
  • VPN Solutions: Secure tunnel establishment
  • OpenPGP: Email and file encryption

🏛️ Enterprise & Government

  • Japanese Government: Approved for government communications
  • Financial Services: Banking and payment card industry
  • Embedded Systems: Smart cards and IoT devices
  • Disk Encryption: Full disk and file encryption

🔧 Algorithm Parameters

📊 Camellia-256 Parameters

Block Size
128 bits
Standard block size (16 bytes)
Key Size
256 bits
Maximum security level (32 bytes)
Rounds
24
Feistel network rounds
Structure
Feistel Network
24-round Feistel structure
F-function
SP-network
Substitution-permutation round function
Key Schedule
Feistel-based
Complex key expansion algorithm

🛡️ Security Properties

🔢

Key Space

2^256 possible keys (enormous keyspace)

🛡️

Attack Resistance

No practical attacks on full Camellia-256

🔒

Cryptanalysis Security

Resistant to differential and linear attacks

⚡

Side-Channel Resistance

Constant-time implementations available

💻 Usage Examples

Basic Encryption/Decryption

from metamui_crypto import Camellia256, generate_random_bytes
import os

# Basic encryption/decryption
key = generate_random_bytes(32)  # 256-bit key
camellia = Camellia256(key)

# Encrypt data
plaintext = b"Confidential data requiring strong encryption"
ciphertext = camellia.encrypt(plaintext)
print(f"Ciphertext: {ciphertext.hex()}")

# Decrypt data
decrypted = camellia.decrypt(ciphertext)
assert decrypted == plaintext

# Using different modes of operation
# CBC mode with IV
iv = generate_random_bytes(16)
camellia_cbc = Camellia256(key, mode='CBC', iv=iv)
ciphertext_cbc = camellia_cbc.encrypt(plaintext)

# CTR mode for streaming
nonce = generate_random_bytes(12)
camellia_ctr = Camellia256(key, mode='CTR', nonce=nonce)
ciphertext_ctr = camellia_ctr.encrypt(plaintext)

# GCM mode for authenticated encryption
camellia_gcm = Camellia256(key, mode='GCM')
ciphertext_gcm, tag = camellia_gcm.encrypt_and_authenticate(plaintext)

# CCM mode for constrained environments
camellia_ccm = Camellia256(key, mode='CCM')
ciphertext_ccm, tag_ccm = camellia_ccm.encrypt_and_authenticate(plaintext)

Advanced Usage

# IPsec implementation with Camellia
class CamelliaIPsec:
    def __init__(self, spi: int, key: bytes):
        self.spi = spi
        self.key = key
        self.sequence = 0
    
    def create_esp_packet(self, payload: bytes, next_header: int) -> bytes:
        """Create ESP packet with Camellia encryption"""
        # Generate IV
        iv = generate_random_bytes(16)
        
        # Prepare ESP payload
        padding_length = (16 - ((len(payload) + 2) % 16)) % 16
        padding = bytes(range(1, padding_length + 1))
        
        esp_payload = payload + padding + bytes([padding_length, next_header])
        
        # Encrypt payload
        cipher = Camellia256(self.key, mode='CBC', iv=iv)
        encrypted = cipher.encrypt(esp_payload)
        
        # Build ESP packet
        esp_header = struct.pack('>II', self.spi, self.sequence)
        self.sequence += 1
        
        return esp_header + iv + encrypted
    
    def decrypt_esp_packet(self, packet: bytes) -> tuple:
        """Decrypt ESP packet"""
        # Parse packet
        spi, seq = struct.unpack('>II', packet[:8])
        iv = packet[8:24]
        encrypted = packet[24:]
        
        # Verify SPI
        if spi != self.spi:
            raise ValueError("Invalid SPI")
        
        # Decrypt payload
        cipher = Camellia256(self.key, mode='CBC', iv=iv)
        esp_payload = cipher.decrypt(encrypted)
        
        # Extract padding info
        padding_length = esp_payload[-2]
        next_header = esp_payload[-1]
        
        # Remove padding
        payload = esp_payload[:-(padding_length + 2)]
        
        return payload, next_header

# TLS 1.3 with Camellia
class CamelliaTLS13:
    def __init__(self):
        self.handshake_secret = None
        self.client_traffic_secret = None
        self.server_traffic_secret = None
    
    def derive_traffic_keys(self, shared_secret: bytes, handshake_hash: bytes):
        """Derive TLS 1.3 traffic keys"""
        from metamui_crypto import HKDF, SHA256
        hkdf = HKDF(hash_function=SHA256())
        
        # Derive traffic secrets
        self.client_traffic_secret = hkdf.derive(
            ikm=shared_secret,
            info=b"tls13 client traffic" + handshake_hash,
            length=32
        )
        self.server_traffic_secret = hkdf.derive(
            ikm=shared_secret,
            info=b"tls13 server traffic" + handshake_hash,
            length=32
        )
        
        # Derive encryption keys
        client_key = hkdf.derive(
            ikm=self.client_traffic_secret,
            info=b"tls13 key",
            length=32
        )
        server_key = hkdf.derive(
            ikm=self.server_traffic_secret,
            info=b"tls13 key",
            length=32
        )
        
        # Derive IVs
        client_iv = hkdf.derive(
            ikm=self.client_traffic_secret,
            info=b"tls13 iv",
            length=12
        )
        server_iv = hkdf.derive(
            ikm=self.server_traffic_secret,
            info=b"tls13 iv",
            length=12
        )
        
        return {
            'client_key': client_key,
            'server_key': server_key,
            'client_iv': client_iv,
            'server_iv': server_iv
        }
    
    def encrypt_record(self, plaintext: bytes, key: bytes, 
                      iv: bytes, seq_num: int) -> bytes:
        """Encrypt TLS 1.3 record"""
        # Construct nonce
        nonce = bytearray(12)
        nonce[-8:] = seq_num.to_bytes(8, 'big')
        for i in range(12):
            nonce[i] ^= iv[i]
        
        # Encrypt with GCM
        cipher = Camellia256(key, mode='GCM', nonce=bytes(nonce))
        
        # Add additional data
        aad = struct.pack('>BHH', 
                         0x17,  # Application data
                         0x0303,  # TLS 1.2 for compatibility
                         len(plaintext) + 16)  # Length + tag
        cipher.update_aad(aad)
        
        # Encrypt and get tag
        ciphertext = cipher.encrypt(plaintext)
        tag = cipher.finalize()
        
        return ciphertext + tag

# Smart card implementation
class CamelliaSmartCard:
    def __init__(self, master_key: bytes):
        self.master_key = master_key
        self.session_keys = {}
    
    def authenticate_card(self, card_id: bytes, challenge: bytes) -> bytes:
        """Authenticate smart card"""
        # Derive card-specific key
        from metamui_crypto import HKDF, SHA256
        hkdf = HKDF(hash_function=SHA256())
        card_key = hkdf.derive(
            ikm=self.master_key,
            info=b"card:" + card_id,
            length=32
        )
        
        # Encrypt challenge
        cipher = Camellia256(card_key, mode='ECB')
        response = cipher.encrypt(challenge)
        
        # Derive session key
        session_key = hkdf.derive(
            ikm=card_key,
            salt=challenge,
            info=b"session",
            length=32
        )
        
        self.session_keys[card_id] = session_key
        
        return response
    
    def secure_command(self, card_id: bytes, command: bytes) -> bytes:
        """Send secure command to card"""
        if card_id not in self.session_keys:
            raise ValueError("Card not authenticated")
        
        session_key = self.session_keys[card_id]
        
        # Generate IV
        iv = generate_random_bytes(16)
        
        # Encrypt command
        cipher = Camellia256(session_key, mode='CBC', iv=iv)
        encrypted = cipher.encrypt(self.pad(command))
        
        # Create secure message
        return iv + encrypted
    
    def pad(self, data: bytes) -> bytes:
        """ISO/IEC 7816-4 padding"""
        padding_length = 16 - (len(data) % 16)
        return data + b'\x80' + b'\x00' * (padding_length - 1)

# Disk encryption with Camellia
class CamelliaDiskEncryption:
    def __init__(self, passphrase: str):
        # Derive key from passphrase
        salt = generate_random_bytes(32)
        from metamui_crypto import Argon2
        argon2 = Argon2(memory_cost=131072, time_cost=4)
        self.master_key = argon2.derive(passphrase.encode(), salt)
        self.sector_size = 512
    
    def encrypt_sector(self, sector_num: int, data: bytes) -> bytes:
        """Encrypt disk sector"""
        # Derive sector key using XTS mode
        sector_key = self.derive_sector_key(sector_num)
        
        # Use XTS mode for disk encryption
        cipher = Camellia256(sector_key, mode='XTS')
        
        # Encrypt with sector number as tweak
        tweak = sector_num.to_bytes(16, 'little')
        encrypted = cipher.encrypt(data, tweak=tweak)
        
        return encrypted
    
    def decrypt_sector(self, sector_num: int, encrypted: bytes) -> bytes:
        """Decrypt disk sector"""
        sector_key = self.derive_sector_key(sector_num)
        cipher = Camellia256(sector_key, mode='XTS')
        
        tweak = sector_num.to_bytes(16, 'little')
        decrypted = cipher.decrypt(encrypted, tweak=tweak)
        
        return decrypted
    
    def derive_sector_key(self, sector_num: int) -> bytes:
        """Derive key for specific sector"""
        from metamui_crypto import BLAKE2b
        hasher = BLAKE2b(key=self.master_key, digest_size=64)
        hasher.update(sector_num.to_bytes(8, 'little'))
        
        # Return 512 bits for XTS mode (2 x 256-bit keys)
        return hasher.finalize()

Implementation Details

# Camellia F-function (simplified)
class CamelliaF:
    def __init__(self):
        # S-boxes (4 different S-boxes)
        self.sbox1 = [...]  # 256 entries
        self.sbox2 = [...]  # 256 entries
        self.sbox3 = [...]  # 256 entries
        self.sbox4 = [...]  # 256 entries
    
    def f_function(self, x: int, k: int) -> int:
        """Camellia F-function"""
        # XOR with subkey
        x ^= k
        
        # S-box layer
        t1 = self.sbox1[(x >> 56) & 0xFF]
        t2 = self.sbox2[(x >> 48) & 0xFF]
        t3 = self.sbox3[(x >> 40) & 0xFF]
        t4 = self.sbox4[(x >> 32) & 0xFF]
        t5 = self.sbox2[(x >> 24) & 0xFF]
        t6 = self.sbox3[(x >> 16) & 0xFF]
        t7 = self.sbox4[(x >> 8) & 0xFF]
        t8 = self.sbox1[x & 0xFF]
        
        # P-function (linear transformation)
        y1 = t1 ^ t3 ^ t4 ^ t6 ^ t7 ^ t8
        y2 = t1 ^ t2 ^ t4 ^ t5 ^ t7 ^ t8
        y3 = t1 ^ t2 ^ t3 ^ t5 ^ t6 ^ t8
        y4 = t2 ^ t3 ^ t4 ^ t5 ^ t6 ^ t7
        y5 = t1 ^ t2 ^ t6 ^ t7 ^ t8
        y6 = t2 ^ t3 ^ t5 ^ t7 ^ t8
        y7 = t3 ^ t4 ^ t5 ^ t6 ^ t8
        y8 = t1 ^ t4 ^ t5 ^ t6 ^ t7
        
        return (y1 << 56) | (y2 << 48) | (y3 << 40) | (y4 << 32) | \
               (y5 << 24) | (y6 << 16) | (y7 << 8) | y8

# Camellia key schedule
class CamelliaKeySchedule:
    def __init__(self, master_key: bytes):
        self.master_key = master_key
        self.subkeys = self.generate_subkeys()
    
    def generate_subkeys(self) -> list:
        """Generate 34 subkeys for Camellia-256"""
        # Key schedule constants
        sigma1 = 0xA09E667F3BCC908B
        sigma2 = 0xB67AE8584CAA73B2
        sigma3 = 0xC6EF372FE94F82BE
        sigma4 = 0x54FF53A5F1D36F1C
        
        # Initialize key variables
        kl = int.from_bytes(self.master_key[:16], 'big')
        kr = int.from_bytes(self.master_key[16:], 'big')
        
        # Generate intermediate keys
        # Complex key schedule with multiple Feistel rounds
        
        return subkeys

# Camellia round structure
class CamelliaRound:
    def __init__(self, f_function):
        self.f = f_function
    
    def round_function(self, left: int, right: int, subkey: int) -> tuple:
        """Single round of Camellia"""
        temp = self.f.f_function(left, subkey)
        new_right = left
        new_left = right ^ temp
        return new_left, new_right
    
    def fl_function(self, x: int, k: int) -> int:
        """FL function for key whitening"""
        x1 = x >> 32
        x2 = x & 0xFFFFFFFF
        k1 = k >> 32
        k2 = k & 0xFFFFFFFF
        
        x2 ^= self.rotl32(x1 & k1, 1)
        x1 ^= (x2 | k2)
        
        return (x1 << 32) | x2
    
    def fl_inv_function(self, y: int, k: int) -> int:
        """Inverse FL function"""
        y1 = y >> 32
        y2 = y & 0xFFFFFFFF
        k1 = k >> 32
        k2 = k & 0xFFFFFFFF
        
        y1 ^= (y2 | k2)
        y2 ^= self.rotl32(y1 & k1, 1)
        
        return (y1 << 32) | y2

🔒 Security Considerations

Best Practices

  1. Key Generation
    • Use cryptographically secure random number generator
    • Never derive keys from passwords without proper KDF
    • Implement key rotation policies
    • Use hardware security modules when available
  2. Mode Selection
    • Use GCM or CCM for authenticated encryption
    • Use CTR for parallel processing needs
    • Use XTS for disk encryption
    • Never use ECB mode in production
  3. IV/Nonce Management
    • Generate random IVs for CBC mode
    • Use unique nonces for CTR/GCM modes
    • Never reuse IV/nonce with same key
    • Store IV/nonce with ciphertext
  4. Implementation Security
    • Use constant-time implementations
    • Clear keys from memory after use
    • Protect against side-channel attacks
    • Validate all inputs and outputs

Common Pitfalls

# DON'T: Use weak key derivation
password = "mypassword"
key = hashlib.sha256(password.encode()).digest()
# WRONG: No salt, single iteration

# DO: Use proper key derivation
salt = generate_random_bytes(32)
from metamui_crypto import Argon2
argon2 = Argon2(memory_cost=65536, time_cost=3)
key = argon2.derive(password.encode(), salt)

# DON'T: Reuse nonces in GCM mode
nonce = b'0' * 12  # Static nonce
# WRONG: Nonce reuse breaks GCM security
cipher1 = Camellia256(key, mode='GCM', nonce=nonce)
cipher2 = Camellia256(key, mode='GCM', nonce=nonce)

# DO: Use unique nonces
nonce1 = generate_random_bytes(12)
nonce2 = generate_random_bytes(12)
cipher1 = Camellia256(key, mode='GCM', nonce=nonce1)
cipher2 = Camellia256(key, mode='GCM', nonce=nonce2)

# DON'T: Ignore authentication tags
cipher = Camellia256(key, mode='GCM')
ciphertext, tag = cipher.encrypt_and_authenticate(data)
# WRONG: Not verifying tag on decryption
decrypted = cipher.decrypt(ciphertext)

# DO: Always verify authentication
cipher_dec = Camellia256(key, mode='GCM')
decrypted = cipher_dec.decrypt_and_verify(ciphertext, tag)

⚡ Performance Analysis

Benchmarks

Operation Mode Data Size Throughput Latency
Encrypt ECB 1 MB 156 MB/s 6.4 ms
Encrypt CBC 1 MB 148 MB/s 6.8 ms
Encrypt CTR 1 MB 178 MB/s 5.6 ms
Encrypt GCM 1 MB 124 MB/s 8.1 ms
Encrypt XTS 1 MB 142 MB/s 7.0 ms
Decrypt ECB 1 MB 155 MB/s 6.5 ms
Decrypt CBC 1 MB 147 MB/s 6.8 ms
Decrypt CTR 1 MB 178 MB/s 5.6 ms

Hardware Acceleration

Platform Instruction Set Speedup
x86-64 AES-NI 1.2x
ARM NEON 1.5x
POWER VSX 1.8x
SPARC VIS 1.4x

Performance Optimization

# Parallel processing with Camellia
import multiprocessing
from concurrent.futures import ThreadPoolExecutor

class ParallelCamellia:
    def __init__(self, key: bytes, num_workers=4):
        self.key = key
        self.num_workers = num_workers
    
    def encrypt_parallel_ctr(self, data: bytes) -> bytes:
        """Parallel encryption using CTR mode"""
        nonce = generate_random_bytes(12)
        chunk_size = len(data) // self.num_workers
        
        def encrypt_chunk(args):
            chunk_data, counter_offset = args
            cipher = Camellia256(
                self.key, 
                mode='CTR', 
                nonce=nonce,
                initial_counter=counter_offset
            )
            return cipher.encrypt(chunk_data)
        
        # Split data into chunks
        chunks = []
        for i in range(self.num_workers):
            start = i * chunk_size
            end = start + chunk_size if i < self.num_workers - 1 else len(data)
            chunk = data[start:end]
            counter_offset = start // 16
            chunks.append((chunk, counter_offset))
        
        # Encrypt in parallel
        with ThreadPoolExecutor(max_workers=self.num_workers) as executor:
            encrypted_chunks = list(executor.map(encrypt_chunk, chunks))
        
        return nonce + b''.join(encrypted_chunks)

# SIMD optimization for Camellia
class SIMDCamellia:
    def __init__(self, key: bytes):
        self.key = key
        self.use_simd = self.check_simd_support()
    
    def check_simd_support(self):
        """Check for SIMD instruction support"""
        try:
            import platform
            cpu_info = platform.processor()
            return any(x in cpu_info.lower() for x in ['sse', 'avx', 'neon'])
        except:
            return False
    
    def encrypt_blocks(self, blocks: list) -> list:
        """Encrypt multiple blocks using SIMD"""
        if self.use_simd and len(blocks) >= 4:
            # Process 4 blocks at once with SIMD
            return self.encrypt_simd_4blocks(blocks)
        else:
            # Fall back to sequential processing
            cipher = Camellia256(self.key, mode='ECB')
            return [cipher.encrypt(block) for block in blocks]

# Memory-efficient streaming
class StreamingCamellia:
    def __init__(self, key: bytes, mode='CTR'):
        self.key = key
        self.mode = mode
        self.buffer_size = 1024 * 1024  # 1MB buffer
    
    def encrypt_file_stream(self, input_file, output_file):
        """Encrypt large file with minimal memory usage"""
        nonce = generate_random_bytes(12)
        cipher = Camellia256(self.key, mode=self.mode, nonce=nonce)
        
        # Write nonce to output
        output_file.write(nonce)
        
        bytes_processed = 0
        while True:
            chunk = input_file.read(self.buffer_size)
            if not chunk:
                break
            
            encrypted = cipher.encrypt(chunk)
            output_file.write(encrypted)
            
            bytes_processed += len(chunk)
            yield bytes_processed  # Progress indicator

🎯 Use Cases

1. Secure VPN Implementation

class CamelliaVPN:
    def __init__(self, server_mode=False):
        self.server_mode = server_mode
        self.sessions = {}
        self.master_key = generate_random_bytes(32)
    
    def establish_tunnel(self, peer_id: str, shared_secret: bytes) -> dict:
        """Establish VPN tunnel with peer"""
        # Derive session keys
        from metamui_crypto import HKDF, SHA256
        hkdf = HKDF(hash_function=SHA256())
        
        # Bidirectional keys
        encrypt_key = hkdf.derive(
            ikm=shared_secret,
            info=f"vpn-encrypt-{peer_id}".encode(),
            length=32
        )
        decrypt_key = hkdf.derive(
            ikm=shared_secret,
            info=f"vpn-decrypt-{peer_id}".encode(),
            length=32
        )
        auth_key = hkdf.derive(
            ikm=shared_secret,
            info=f"vpn-auth-{peer_id}".encode(),
            length=32
        )
        
        # Initialize session
        session = {
            'peer_id': peer_id,
            'encrypt_key': encrypt_key,
            'decrypt_key': decrypt_key,
            'auth_key': auth_key,
            'seq_out': 0,
            'seq_in': 0,
            'window': set()  # Anti-replay window
        }
        
        self.sessions[peer_id] = session
        return session
    
    def send_packet(self, peer_id: str, packet: bytes) -> bytes:
        """Encrypt and authenticate VPN packet"""
        if peer_id not in self.sessions:
            raise ValueError("No session with peer")
        
        session = self.sessions[peer_id]
        
        # Create packet header
        seq_num = session['seq_out']
        header = struct.pack('>BIQ', 
                           0x01,  # Protocol version
                           len(packet),  # Payload length
                           seq_num)  # Sequence number
        
        # Encrypt payload
        iv = generate_random_bytes(16)
        cipher = Camellia256(session['encrypt_key'], mode='CBC', iv=iv)
        encrypted = cipher.encrypt(self.pad(packet))
        
        # Compute HMAC
        from metamui_crypto import HMAC, SHA256
        hmac = HMAC(session['auth_key'], SHA256())
        hmac.update(header)
        hmac.update(iv)
        hmac.update(encrypted)
        auth_tag = hmac.finalize()[:16]  # Truncate to 128 bits
        
        session['seq_out'] += 1
        
        return header + iv + encrypted + auth_tag
    
    def receive_packet(self, peer_id: str, data: bytes) -> bytes:
        """Decrypt and verify VPN packet"""
        if peer_id not in self.sessions:
            raise ValueError("No session with peer")
        
        session = self.sessions[peer_id]
        
        # Parse packet
        header = data[:13]
        iv = data[13:29]
        encrypted = data[29:-16]
        auth_tag = data[-16:]
        
        version, length, seq_num = struct.unpack('>BIQ', header)
        
        # Check version
        if version != 0x01:
            raise ValueError("Invalid protocol version")
        
        # Anti-replay check
        if seq_num <= session['seq_in']:
            if seq_num in session['window']:
                raise ValueError("Replay attack detected")
        
        # Verify HMAC
        from metamui_crypto import HMAC, SHA256
        hmac = HMAC(session['auth_key'], SHA256())
        hmac.update(header)
        hmac.update(iv)
        hmac.update(encrypted)
        expected_tag = hmac.finalize()[:16]
        
        if auth_tag != expected_tag:
            raise ValueError("Authentication failed")
        
        # Decrypt payload
        cipher = Camellia256(session['decrypt_key'], mode='CBC', iv=iv)
        decrypted = cipher.decrypt(encrypted)
        packet = self.unpad(decrypted)[:length]
        
        # Update anti-replay window
        if seq_num > session['seq_in']:
            session['seq_in'] = seq_num
        session['window'].add(seq_num)
        
        # Maintain window size
        if len(session['window']) > 1024:
            min_seq = min(session['window'])
            session['window'].remove(min_seq)
        
        return packet

2. Payment Card Industry (PCI) Compliance

class CamelliaPCI:
    def __init__(self, hsm_key: bytes):
        self.hsm_key = hsm_key
        self.dukpt_counter = 0
    
    def encrypt_pan(self, pan: str) -> dict:
        """Encrypt Primary Account Number"""
        # Format PAN
        pan_bytes = pan.encode('ascii')
        
        # Generate unique key per transaction (DUKPT-like)
        transaction_key = self.derive_transaction_key()
        
        # Encrypt PAN
        iv = generate_random_bytes(16)
        cipher = Camellia256(transaction_key, mode='CBC', iv=iv)
        
        # Pad to 16 bytes
        padded_pan = pan_bytes + b'\x00' * (16 - len(pan_bytes))
        encrypted_pan = cipher.encrypt(padded_pan)
        
        # Create token
        token = base64.b64encode(iv + encrypted_pan).decode()
        
        return {
            'token': token,
            'key_id': self.dukpt_counter,
            'algorithm': 'CAMELLIA-256-CBC'
        }
    
    def decrypt_pan(self, token_data: dict) -> str:
        """Decrypt PAN from token"""
        # Decode token
        token_bytes = base64.b64decode(token_data['token'])
        iv = token_bytes[:16]
        encrypted_pan = token_bytes[16:]
        
        # Derive transaction key
        transaction_key = self.derive_transaction_key(token_data['key_id'])
        
        # Decrypt
        cipher = Camellia256(transaction_key, mode='CBC', iv=iv)
        padded_pan = cipher.decrypt(encrypted_pan)
        
        # Remove padding
        pan = padded_pan.rstrip(b'\x00').decode('ascii')
        
        return pan
    
    def derive_transaction_key(self, counter=None) -> bytes:
        """Derive unique transaction key"""
        if counter is None:
            counter = self.dukpt_counter
            self.dukpt_counter += 1
        
        from metamui_crypto import HKDF, SHA256
        hkdf = HKDF(hash_function=SHA256())
        
        return hkdf.derive(
            ikm=self.hsm_key,
            info=f"transaction:{counter}".encode(),
            length=32
        )
    
    def tokenize_card(self, card_data: dict) -> str:
        """Create secure token for card data"""
        # Serialize card data
        card_json = json.dumps(card_data).encode()
        
        # Generate data encryption key
        dek = generate_random_bytes(32)
        
        # Encrypt card data
        nonce = generate_random_bytes(12)
        cipher = Camellia256(dek, mode='GCM', nonce=nonce)
        ciphertext = cipher.encrypt(card_json)
        tag = cipher.finalize()
        
        # Wrap DEK with HSM key
        kek_cipher = Camellia256(self.hsm_key, mode='ECB')
        wrapped_dek = kek_cipher.encrypt(dek)
        
        # Create token structure
        token_data = {
            'wrapped_key': base64.b64encode(wrapped_dek).decode(),
            'nonce': base64.b64encode(nonce).decode(),
            'ciphertext': base64.b64encode(ciphertext).decode(),
            'tag': base64.b64encode(tag).decode()
        }
        
        return base64.b64encode(
            json.dumps(token_data).encode()
        ).decode()

3. Secure IoT Gateway

class CamelliaIoTGateway:
    def __init__(self):
        self.device_keys = {}
        self.master_key = generate_random_bytes(32)
        self.message_cache = {}  # For deduplication
    
    def register_device(self, device_id: str, device_cert: bytes) -> bytes:
        """Register IoT device and derive keys"""
        # Verify device certificate (simplified)
        if not self.verify_certificate(device_cert):
            raise ValueError("Invalid device certificate")
        
        # Derive device-specific keys
        from metamui_crypto import HKDF, SHA256
        hkdf = HKDF(hash_function=SHA256())
        
        device_key = hkdf.derive(
            ikm=self.master_key,
            salt=device_cert[:32],  # Use part of cert as salt
            info=f"device:{device_id}".encode(),
            length=32
        )
        
        # Store device key
        self.device_keys[device_id] = {
            'key': device_key,
            'counter': 0,
            'last_seen': time.time()
        }
        
        return device_key
    
    def process_telemetry(self, device_id: str, encrypted_data: bytes) -> dict:
        """Process encrypted telemetry from device"""
        if device_id not in self.device_keys:
            raise ValueError("Unknown device")
        
        device = self.device_keys[device_id]
        
        # Parse message
        if len(encrypted_data) < 40:
            raise ValueError("Invalid message format")
        
        msg_id = encrypted_data[:16]
        counter = int.from_bytes(encrypted_data[16:20], 'big')
        iv = encrypted_data[20:36]
        ciphertext = encrypted_data[36:-16]
        mac = encrypted_data[-16:]
        
        # Check message ID for replay
        if msg_id in self.message_cache:
            raise ValueError("Duplicate message")
        
        # Verify counter
        if counter <= device['counter']:
            raise ValueError("Invalid message counter")
        
        # Verify MAC
        from metamui_crypto import HMAC, SHA256
        hmac = HMAC(device['key'], SHA256())
        hmac.update(encrypted_data[:-16])
        expected_mac = hmac.finalize()[:16]
        
        if mac != expected_mac:
            raise ValueError("MAC verification failed")
        
        # Decrypt telemetry
        cipher = Camellia256(device['key'], mode='CBC', iv=iv)
        decrypted = cipher.decrypt(ciphertext)
        
        # Parse telemetry data
        telemetry = json.loads(self.unpad(decrypted).decode())
        
        # Update device state
        device['counter'] = counter
        device['last_seen'] = time.time()
        
        # Cache message ID
        self.message_cache[msg_id] = time.time()
        self.cleanup_cache()
        
        return telemetry
    
    def send_command(self, device_id: str, command: dict) -> bytes:
        """Send encrypted command to device"""
        if device_id not in self.device_keys:
            raise ValueError("Unknown device")
        
        device = self.device_keys[device_id]
        
        # Serialize command
        command_json = json.dumps(command).encode()
        
        # Generate message ID and IV
        msg_id = generate_random_bytes(16)
        iv = generate_random_bytes(16)
        
        # Encrypt command
        cipher = Camellia256(device['key'], mode='CBC', iv=iv)
        ciphertext = cipher.encrypt(self.pad(command_json))
        
        # Build message
        message = msg_id + iv + ciphertext
        
        # Compute MAC
        from metamui_crypto import HMAC, SHA256
        hmac = HMAC(device['key'], SHA256())
        hmac.update(message)
        mac = hmac.finalize()[:16]
        
        return message + mac
    
    def cleanup_cache(self):
        """Remove old message IDs from cache"""
        current_time = time.time()
        expired = [
            msg_id for msg_id, timestamp in self.message_cache.items()
            if current_time - timestamp > 3600  # 1 hour
        ]
        for msg_id in expired:
            del self.message_cache[msg_id]

4. Secure Backup System

class CamelliaBackup:
    def __init__(self, backup_password: str):
        # Derive master key from password
        self.salt = generate_random_bytes(32)
        from metamui_crypto import Argon2
        argon2 = Argon2(memory_cost=262144, time_cost=5)
        self.master_key = argon2.derive(backup_password.encode(), self.salt)
        
        self.chunk_size = 4 * 1024 * 1024  # 4MB chunks
    
    def backup_file(self, filepath: str, backup_path: str):
        """Create encrypted backup of file"""
        # Generate file key
        file_key = generate_random_bytes(32)
        
        # Encrypt file key with master key
        key_iv = generate_random_bytes(16)
        key_cipher = Camellia256(self.master_key, mode='CBC', iv=key_iv)
        encrypted_file_key = key_cipher.encrypt(file_key)
        
        # Create backup header
        header = {
            'version': 1,
            'algorithm': 'CAMELLIA-256-GCM',
            'original_name': os.path.basename(filepath),
            'original_size': os.path.getsize(filepath),
            'created': time.time(),
            'salt': base64.b64encode(self.salt).decode(),
            'key_iv': base64.b64encode(key_iv).decode(),
            'encrypted_key': base64.b64encode(encrypted_file_key).decode()
        }
        
        with open(backup_path, 'wb') as backup:
            # Write header
            header_json = json.dumps(header).encode()
            backup.write(struct.pack('>I', len(header_json)))
            backup.write(header_json)
            
            # Encrypt file contents
            with open(filepath, 'rb') as source:
                chunk_num = 0
                
                while True:
                    chunk = source.read(self.chunk_size)
                    if not chunk:
                        break
                    
                    # Encrypt chunk
                    nonce = struct.pack('>Q', chunk_num) + b'\x00' * 4
                    cipher = Camellia256(file_key, mode='GCM', nonce=nonce)
                    
                    # Add chunk metadata to AAD
                    aad = struct.pack('>QI', chunk_num, len(chunk))
                    cipher.update_aad(aad)
                    
                    # Encrypt and get tag
                    encrypted = cipher.encrypt(chunk)
                    tag = cipher.finalize()
                    
                    # Write encrypted chunk
                    backup.write(struct.pack('>I', len(encrypted) + 16))
                    backup.write(encrypted)
                    backup.write(tag)
                    
                    chunk_num += 1
                    
                    # Progress callback
                    yield {
                        'chunks_processed': chunk_num,
                        'bytes_processed': chunk_num * self.chunk_size
                    }
    
    def restore_file(self, backup_path: str, restore_path: str, 
                    password: str = None):
        """Restore file from encrypted backup"""
        with open(backup_path, 'rb') as backup:
            # Read header
            header_len = struct.unpack('>I', backup.read(4))[0]
            header_json = backup.read(header_len)
            header = json.loads(header_json.decode())
            
            # Verify version
            if header['version'] != 1:
                raise ValueError("Unsupported backup version")
            
            # Derive master key if different password
            if password:
                salt = base64.b64decode(header['salt'])
                from metamui_crypto import Argon2
                argon2 = Argon2(memory_cost=262144, time_cost=5)
                master_key = argon2.derive(password.encode(), salt)
            else:
                master_key = self.master_key
            
            # Decrypt file key
            key_iv = base64.b64decode(header['key_iv'])
            encrypted_file_key = base64.b64decode(header['encrypted_key'])
            
            key_cipher = Camellia256(master_key, mode='CBC', iv=key_iv)
            file_key = key_cipher.decrypt(encrypted_file_key)
            
            # Restore file
            with open(restore_path, 'wb') as output:
                chunk_num = 0
                
                while True:
                    # Read chunk size
                    size_data = backup.read(4)
                    if not size_data:
                        break
                    
                    chunk_size = struct.unpack('>I', size_data)[0]
                    encrypted = backup.read(chunk_size - 16)
                    tag = backup.read(16)
                    
                    # Decrypt chunk
                    nonce = struct.pack('>Q', chunk_num) + b'\x00' * 4
                    cipher = Camellia256(file_key, mode='GCM', nonce=nonce)
                    
                    # Add chunk metadata to AAD
                    aad = struct.pack('>QI', chunk_num, len(encrypted))
                    cipher.update_aad(aad)
                    
                    # Decrypt and verify
                    decrypted = cipher.decrypt(encrypted)
                    computed_tag = cipher.finalize()
                    
                    if computed_tag != tag:
                        raise ValueError(f"Chunk {chunk_num} authentication failed")
                    
                    output.write(decrypted)
                    chunk_num += 1
                    
                    yield {
                        'chunks_restored': chunk_num,
                        'bytes_restored': output.tell()
                    }

Comparison with Other Ciphers

Camellia vs AES

Feature Camellia-256 AES-256
Structure Feistel SPN
Rounds 24 14
Key Schedule Complex Simple
Hardware Support Limited Extensive
Security Margin High High
Patent Status Free Free

Camellia vs ARIA

Feature Camellia-256 ARIA-256
Origin Japan Korea
Structure Feistel SPN
Rounds 24 16
Performance Good Good
Adoption IETF/ISO Korean std
S-boxes 4 types 4 types

When to Use Camellia

# Use Camellia for Japanese compliance
if region == "Japan" or standard in ["JIS", "CRYPTREC"]:
    cipher = Camellia256(key)

# Use Camellia for IETF protocols
if protocol in ["IPsec", "TLS", "OpenPGP"]:
    cipher = Camellia256(key)

# Use Camellia for algorithm agility
cipher_suite = {
    'primary': AES256(key),
    'secondary': Camellia256(key),
    'tertiary': ARIA256(key)
}

Migration Guide

From 3DES to Camellia

# Before: 3DES (deprecated)
from Crypto.Cipher import DES3
des3 = DES3.new(key_192bit, DES3.MODE_CBC, iv)
ciphertext = des3.encrypt(pad(plaintext, 8))

# After: Camellia-256
from metamui_crypto import Camellia256
# Upgrade key size
key_256bit = PBKDF2(password, salt, key_len=32)
camellia = Camellia256(key_256bit, mode='CBC', iv=iv)
ciphertext = camellia.encrypt(plaintext)  # Auto-padding

# Migration helper
def migrate_3des_to_camellia(old_key, old_ciphertext, old_iv):
    # Decrypt with 3DES
    des3 = DES3.new(old_key, DES3.MODE_CBC, old_iv)
    plaintext = unpad(des3.decrypt(old_ciphertext), 8)
    
    # Re-encrypt with Camellia
    new_key = derive_256bit_key(old_key)
    new_iv = generate_random_bytes(16)
    camellia = Camellia256(new_key, mode='CBC', iv=new_iv)
    new_ciphertext = camellia.encrypt(plaintext)
    
    return new_key, new_iv, new_ciphertext

From Blowfish to Camellia

# Before: Blowfish (outdated)
from Crypto.Cipher import Blowfish
bf = Blowfish.new(key, Blowfish.MODE_CBC, iv)

# After: Camellia-256
from metamui_crypto import Camellia256
# Ensure proper key size
if len(key) < 32:
    key = HKDF(SHA256()).derive(key, length=32)

camellia = Camellia256(key, mode='CBC', iv=iv)

Test Vectors

Camellia-256 ECB Test Vectors

# Test Vector 1: Camellia-256 ECB
key = bytes.fromhex(
    "0123456789abcdeffedcba98765432100011223344556677"
    "8899aabbccddeeff"
)
plaintext = bytes.fromhex("0123456789abcdeffedcba9876543210")

camellia = Camellia256(key, mode='ECB')
ciphertext = camellia.encrypt(plaintext)
assert ciphertext.hex() == "9acc237dff16d76c20ef7c919e3a7509"

# Decryption
decrypted = camellia.decrypt(ciphertext)
assert decrypted == plaintext

Camellia-256 CBC Test Vectors

# Test Vector 2: Camellia-256 CBC
key = bytes.fromhex(
    "603deb1015ca71be2b73aef0857d77811f352c073b6108d7"
    "2d9810a30914dff4"
)
iv = bytes.fromhex("000102030405060708090a0b0c0d0e0f")
plaintext = bytes.fromhex(
    "6bc1bee22e409f96e93d7e117393172a"
    "ae2d8a571e03ac9c9eb76fac45af8e51"
)

camellia_cbc = Camellia256(key, mode='CBC', iv=iv)
ciphertext = camellia_cbc.encrypt(plaintext)
assert ciphertext.hex() == (
    "e6cfa35fc02b134a4d2c0b6737ac3eda"
    "36e979b3646c8a6c3fe2e2abb5daec7d"
)

Camellia-256 CTR Test Vectors

# Test Vector 3: Camellia-256 CTR
key = bytes.fromhex(
    "776beff2851db06f4c8a0542c8696f6c6a81af1eec96b4d3"
    "7fc1d689e6c1c104"
)
nonce = bytes.fromhex("00000060db5672c97aa8f0b2")
plaintext = b"Single block msg"

camellia_ctr = Camellia256(key, mode='CTR', nonce=nonce)
ciphertext = camellia_ctr.encrypt(plaintext)
assert ciphertext.hex() == "3401f9c8aaab15f7f6c639c0f4a7d531"

References