net.i2p.data

Class SessionKey

java.lang.Object

net.i2p.data.SimpleDataStructure

net.i2p.data.SessionKey

All Implemented Interfaces:

DataStructure

Direct Known Subclasses:

SessionKeyAndNonce

public class SessionKey
extends SimpleDataStructure

Cryptographic session key for symmetric encryption in I2P.

SessionKey provides symmetric encryption capabilities for I2P communications:

• Fixed Size: 32-byte key suitable for modern symmetric algorithms
• Session-Based: Temporary keys for message encryption/decryption
• Algorithm Agnostic: Can be used with various symmetric ciphers
• Efficient Storage: Optimized for high-frequency operations

Key Generation:

• Random Creation: Use I2PAppContext.keyGenerator().generateSessionKey()
• Cryptographically Secure: Generated using cryptographically strong randomness
• Factory Methods: Static creation methods for convenience
• Invalid Key: Pre-defined all-zero key for special cases

Usage Patterns:

• Message Encryption: Encrypt I2NP messages and I2CP data
• Tunnel Encryption: Protect tunnel payload contents
• Session Establishment: Derive from key exchange protocols
• Temporary Storage: Short-lived keys for enhanced security

Security Considerations:

• Key Protection: Never expose session keys to unauthorized parties
• Secure Generation: Use cryptographically secure random sources
• Key Rotation: Change keys regularly to limit exposure
• Memory Security: Zeroize memory when keys are no longer needed

Performance Features:

• Prepared Keys: Cache for algorithm-specific prepared keys
• Efficient Storage: Optimized byte array representation
• Fast Operations: Quick access and comparison methods
• Memory Management: Careful allocation and cleanup

Integration:

• I2P Client: Used for end-to-end encryption in I2CP
• Router Operations: Tunnel and message encryption
• Garlic Encryption: Multi-layer message protection
• ElGamal Integration: Combined with asymmetric encryption for key exchange

Constants:

• KEYSIZE_BYTES - Standard 32-byte key length
• INVALID_KEY - All-zero key for invalid/placeholder use

Best Practices:

• Unique Sessions: Use different keys for different communication sessions
• Limited Lifetime: Replace keys after reasonable time period
• Secure Disposal: Clear key data when session ends
• Algorithm Selection: Use appropriate symmetric cipher for key size

Field Summary

Fields

Modifier and Type	Field and Description
static SessionKey	INVALID_KEY A key with all zeroes in the data
static int	KEYSIZE_BYTES

Fields inherited from class net.i2p.data.SimpleDataStructure

_data

Constructor Summary

Constructors

Constructor and Description
SessionKey()
SessionKey(byte[] data)

Method Summary

Modifier and Type	Method and Description
Object	getPreparedKey() retrieve an internal representation of the session key, as known by the AES engine used.
int	length() The legal length of the byte array in this data structure
void	setData(byte[] data) Sets the data.
void	setPreparedKey(Object obj)

Methods inherited from class net.i2p.data.SimpleDataStructure

calculateHash, equals, fromBase64, fromByteArray, getData, hashCode, read, readBytes, toBase64, toByteArray, toString, writeBytes

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

INVALID_KEY

public static final SessionKey INVALID_KEY

A key with all zeroes in the data

KEYSIZE_BYTES

public static final int KEYSIZE_BYTES

See Also:

Constant Field Values

Constructor Detail

SessionKey

public SessionKey()

SessionKey

public SessionKey(byte[] data)

Method Detail

getPreparedKey

public Object getPreparedKey()

retrieve an internal representation of the session key, as known by the AES engine used. this can be reused safely

length

public int length()

Description copied from class: SimpleDataStructure

The legal length of the byte array in this data structure

Specified by:

length in class SimpleDataStructure

setData

public void setData(byte[] data)

Sets the data.

Overrides:

setData in class SimpleDataStructure

Parameters:

data - 32 bytes, or null

Throws:

IllegalArgumentException - if data is not the legal number of bytes (but null is ok)

RuntimeException - if data already set.

setPreparedKey

public void setPreparedKey(Object obj)