KeysAndCert (Javadocs [I2P+ 2.11.0+]

java.lang.Object
- net.i2p.data.DataStructureImpl
- - net.i2p.data.KeysAndCert

All Implemented Interfaces:

Serializable, DataStructure

Direct Known Subclasses:

Destination, RouterIdentity
```
public class KeysAndCert
extends DataStructureImpl
```
Container for cryptographic keys and certificate as used by I2P identities.
KeysAndCert provides the fundamental cryptographic identity components:
- Public Key: Encryption key for encrypted communication
- Signing Public Key: Key for verifying signatures and identity
- Certificate: Optional metadata about the keys and identity
- Cached Hash: Pre-computed SHA-256 hash for efficient identification
Structure:
- Public key (variable length, typically 256 bytes for ElGamal)
- Signing public key (variable length, typically 128 bytes for DSA, 32 bytes for Ed25519)
- Certificate (type + length + payload)
- Optional padding for consistent serialization
Usage:
- Base Class: Extended by Destination and RouterIdentity
- Identity: Forms the core of I2P cryptographic identities
- Verification: Provides keys for signature verification
- Encryption: Contains encryption key for secure communication
Key Types:
- Encryption: ElGamal 2048-bit (legacy) or ECIES X25519 (modern)
- Signing: DSA-SHA1 (legacy), ECDSA-P256, or EdDSA-Ed25519 (modern)
- Certificates: NULL, HIDDEN, SIGNED, MULTIPLE, or KEY types
Immutability:
- As of 0.9.9, instances are immutable after keys and certificate are set
- Attempts to modify will throw IllegalStateException
- Ensures thread safety and prevents accidental corruption
History:
- Implemented in 0.8.2 and retrofitted over existing Destination and RouterIdentity classes
- No functional difference between Destination and RouterIdentity at this level
- Provides unified interface for identity management across I2P
See Also:

Serialized Form

Field Summary

Fields
Modifier and Type	Field and Description
`protected Certificate`	`_certificate`
`protected int`	`_paddingBlocks` If compressed, the padding size / 32, else 0
`protected PublicKey`	`_publicKey`
`protected SigningPublicKey`	`_signingKey`

Constructor Summary

Constructors
Constructor and Description

KeysAndCert()

Constructors
Constructor and Description
`KeysAndCert()`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`Hash`	`calculateHash()` Throws IllegalStateException if keys and cert are not initialized, as of 0.9.12.
`protected static byte[]`	`combinePadding(byte[] pad1, byte[] pad2)` Combines two padding arrays.
`boolean`	`equals(Object object)`
`Certificate`	`getCertificate()`
`EncType`	`getEncType()` Gets the encryption type from the certificate.
`Hash`	`getHash()` Throws IllegalStateException if keys and cert are not initialized, as of 0.9.12.
`byte[]`	`getPadding()` Gets the padding bytes.
`PublicKey`	`getPublicKey()` Valid for RouterIdentities.
`SigningPublicKey`	`getSigningPublicKey()`
`SigType`	`getSigType()` Gets the signature type from the certificate.
`int`	`hashCode()` the signing key has enough randomness in it to use it by itself for speed
`boolean`	`isCompressible()` Is there compressible padding?
`void`	`readBytes(InputStream in)` Load up the current object with data from the given stream.
`void`	`setCertificate(Certificate cert)` Sets the certificate.
`void`	`setPadding(byte[] padding)` Sets the padding bytes.
`void`	`setPublicKey(PublicKey key)` Sets the public key.
`void`	`setSigningPublicKey(SigningPublicKey key)` Sets the signing public key.
`String`	`toString()`
`void`	`writeBytes(OutputStream out)` Write out the data structure to the stream, using the format defined in the I2P data structure specification.
`protected int`	`writePaddingBytes(byte[] target, int off)` For Destination.writeBytes()

Methods inherited from class net.i2p.data.DataStructureImpl
fromBase64, fromByteArray, read, toBase64, toByteArray

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Field Detail
  - _certificate
```
protected Certificate _certificate
```
  - _paddingBlocks
```
protected int _paddingBlocks
```
    If compressed, the padding size / 32, else 0
  - _publicKey
```
protected PublicKey _publicKey
```
  - _signingKey
```
protected SigningPublicKey _signingKey
```
- Constructor Detail
  - KeysAndCert
```
public KeysAndCert()
```
- Method Detail
  - calculateHash
```
public Hash calculateHash()
```
    Throws IllegalStateException if keys and cert are not initialized, as of 0.9.12. Prior to that, returned null.
    
    Specified by:
    
    calculateHash in interface DataStructure
    
    Overrides:
    
    calculateHash in class DataStructureImpl
    
    Returns:
    
    SHA256 hash, or null if there were problems (data format or io errors)
    
    Throws:
    
    IllegalStateException - if keys and cert are not initialized
  - combinePadding
```
protected static byte[] combinePadding(byte[] pad1,
                                       byte[] pad2)
```
    Combines two padding arrays.
    
    Returns:
    
    null if both are null
  - equals
```
public boolean equals(Object object)
```
    Overrides:
    
    equals in class Object
  - getCertificate
```
public Certificate getCertificate()
```
  - getEncType
```
public EncType getEncType()
```
    Gets the encryption type from the certificate.
    
    Returns:
    
    null if not set or unknown
  - getHash
```
public Hash getHash()
```
    Throws IllegalStateException if keys and cert are not initialized, as of 0.9.12. Prior to that, returned null.
    
    Throws:
    
    IllegalStateException - if keys and cert are not initialized
  - getPadding
```
public byte[] getPadding()
```
    Gets the padding bytes.
  - getPublicKey
```
public PublicKey getPublicKey()
```
    Valid for RouterIdentities. May contain random padding for Destinations.
  - getSigningPublicKey
```
public SigningPublicKey getSigningPublicKey()
```
  - getSigType
```
public SigType getSigType()
```
    Gets the signature type from the certificate.
    
    Returns:
    
    null if not set or unknown
  - hashCode
```
public int hashCode()
```
    the signing key has enough randomness in it to use it by itself for speed
    
    Overrides:
    
    hashCode in class Object
  - isCompressible
```
public boolean isCompressible()
```
    Is there compressible padding?
  - readBytes
```
public void readBytes(InputStream in)
               throws DataFormatException,
                      IOException
```
    Description copied from interface: DataStructure
    
    Load up the current object with data from the given stream. Data loaded this way must match the I2P data structure specification. Warning - many classes will throw IllegalStateException if data is already set.
    
    Parameters:
    
    in - stream to read from
    
    Throws:
    
    IllegalStateException - if data already set
    
    DataFormatException - if the data is improperly formatted
    
    IOException - if there was a problem reading the stream
  - setCertificate
```
public void setCertificate(Certificate cert)
```
    Sets the certificate.
    
    Throws:
    
    IllegalStateException - if was already set
  - setPadding
```
public void setPadding(byte[] padding)
```
    Sets the padding bytes.
    
    Throws:
    
    IllegalStateException - if was already set
  - setPublicKey
```
public void setPublicKey(PublicKey key)
```
    Sets the public key.
    
    Throws:
    
    IllegalStateException - if was already set
  - setSigningPublicKey
```
public void setSigningPublicKey(SigningPublicKey key)
```
    Sets the signing public key.
    
    Throws:
    
    IllegalStateException - if was already set
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
  - writeBytes
```
public void writeBytes(OutputStream out)
                throws DataFormatException,
                       IOException
```
    Description copied from interface: DataStructure
    
    Write out the data structure to the stream, using the format defined in the I2P data structure specification.
    
    Parameters:
    
    out - stream to write to
    
    Throws:
    
    DataFormatException - if the data was incomplete or not yet ready to be written
    
    IOException - if there was a problem writing to the stream
  - writePaddingBytes
```
protected int writePaddingBytes(byte[] target,
                                int off)
```
    For Destination.writeBytes()
    
    Returns:
    
    the new offset

Class KeysAndCert

Field Summary

Constructor Summary

Method Summary

Methods inherited from class net.i2p.data.DataStructureImpl

Methods inherited from class java.lang.Object

Field Detail

_certificate

_paddingBlocks

_publicKey

_signingKey

Constructor Detail

KeysAndCert

Method Detail

calculateHash

combinePadding

equals

getCertificate

getEncType

getHash

getPadding

getPublicKey

getSigningPublicKey

getSigType

hashCode

isCompressible

readBytes

setCertificate

setPadding

setPublicKey

setSigningPublicKey

toString

writeBytes

writePaddingBytes