SigningPrivateKey (Javadocs [I2P+ 2.13.0+]

java.lang.Object
- net.i2p.data.SimpleDataStructure
- - net.i2p.data.SigningPrivateKey

All Implemented Interfaces:
Destroyable, DataStructure
Direct Known Subclasses:
RSASigningPrivateCrtKey
```
public class SigningPrivateKey
extends SimpleDataStructure
implements Destroyable
```
Cryptographic private key for digital signature generation in I2P.
SigningPrivateKey provides signature generation capabilities:
- Default Algorithm: DSA-SHA1 (20 bytes)
- Modern Support: Variable length and type support since 0.9.8
- Key Structure: Contains only private exponent/coordinates
- Security: Implements Destroyable for secure cleanup
Supported Algorithms:
- DSA-SHA1: Legacy algorithm, 20-byte keys
- ECDSA-P256: Modern algorithm, variable length keys
- EdDSA-Ed25519: Modern algorithm, 32-byte keys
- Future Types: Extensible design for new algorithms
Key Format:
- DSA: 20-byte private exponent (x)
- ECDSA: Variable length private scalar
- EdDSA: 32-byte private seed
- Type Encoding: Algorithm type embedded in data
Usage:
- Signature Generation: Sign data with corresponding SigningPublicKey
- Identity Creation: Part of Destination identity
- LeaseSet Signing: Sign LeaseSet for network publication
- Router Identity: Sign router information for NetDb
Security Considerations:
- Confidentiality: Private signing keys must never be exposed
- Secure Destruction: Call destroy() when no longer needed
- Memory Protection: Zeroize memory after use
- Algorithm Choice: Prefer modern algorithms (Ed25519, ECDSA-P256)
Blinding Support:
- Key Blinding: Support for generating blinded key variants
- Privacy: Enable anonymous service endpoints
- BlindData: Integration with BlindData for blinding operations
Performance Features:
- Efficient Storage: Optimized byte representation
- Factory Methods: Static creation methods for consistency
- Fast Operations: Optimized for high-frequency signing
Migration Path:
- Legacy: DSA-SHA1 for backward compatibility
- Modern: Ed25519 for better performance and security
- Transition: Mixed algorithm support during migration
Thread Safety:
- Immutable Data: Key data cannot be modified after creation
- Safe Destruction: Thread-safe key zeroization
- Exclusive Use: Each instance should be used by only one thread

Field Summary
Fields
Modifier and Type Field and Description
static int KEYSIZE_BYTES
Default key size in bytes (20 for DSA-SHA1).
- Fields inherited from class net.i2p.data.SimpleDataStructure
  _data

Fields
Modifier and Type	Field and Description
`static int`	`KEYSIZE_BYTES` Default key size in bytes (20 for DSA-SHA1).

Constructor Summary

Constructors
Constructor and Description
`SigningPrivateKey()` Creates a new SigningPrivateKey with the default DSA-SHA1 type.
`SigningPrivateKey(byte[] data)` Creates a new SigningPrivateKey from byte data with default type.
`SigningPrivateKey(SigType type)`
`SigningPrivateKey(SigType type, byte[] data)`
`SigningPrivateKey(String base64Data)` constructs from base64

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`SigningPrivateKey`	`blind(SigningPrivateKey alpha)` Only for SigType EdDSA_SHA512_Ed25519
`void`	`destroy()` javax.security.auth.Destroyable interface
`boolean`	`equals(Object obj)` Warning - this returns true for two different classes with the same size and same data, e.g.
`SigType`	`getType()` Gets the signature type of this private key.
`int`	`hashCode()` Hash code combining the type and data.
`boolean`	`isDestroyed()` javax.security.auth.Destroyable interface
`boolean`	`isOffline()` Constant time
`int`	`length()` Key length in bytes, determined by the signature type.
`SigningPublicKey`	`toPublic()` Converts this signing private key to its public equivalent.
`String`	`toString()` Returns a string representation of this data structure.

Methods inherited from class net.i2p.data.SimpleDataStructure
calculateHash, fromBase64, fromByteArray, getData, read, readBytes, setData, toBase64, toByteArray, writeBytes

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

- Field Detail
  - KEYSIZE_BYTES
```
public static final int KEYSIZE_BYTES
```
    Default key size in bytes (20 for DSA-SHA1).
- Constructor Detail
  - SigningPrivateKey
```
public SigningPrivateKey()
```
    Creates a new SigningPrivateKey with the default DSA-SHA1 type.
  - SigningPrivateKey
```
public SigningPrivateKey(byte[] data)
```
    Creates a new SigningPrivateKey from byte data with default type.
  - SigningPrivateKey
```
public SigningPrivateKey(SigType type)
```
  - SigningPrivateKey
```
public SigningPrivateKey(SigType type,
                         byte[] data)
```
  - SigningPrivateKey
```
public SigningPrivateKey(String base64Data)
                  throws DataFormatException
```
    constructs from base64
    Parameters:
    base64Data - a string of base64 data (the output of .toBase64() called on a prior instance of SigningPrivateKey
    Throws:
    DataFormatException
- Method Detail
  - blind
```
public SigningPrivateKey blind(SigningPrivateKey alpha)
```
    Only for SigType EdDSA_SHA512_Ed25519
    Parameters:
    alpha - the secret data
    Returns:
    the blinded private key
    Throws:
    UnsupportedOperationException - unless supported
  - destroy
```
public void destroy()
```
    javax.security.auth.Destroyable interface
    Specified by:
    destroy in interface Destroyable
  - equals
```
public boolean equals(Object obj)
```
    Description copied from class: SimpleDataStructure
    Warning - this returns true for two different classes with the same size and same data, e.g. SessionKey and SessionTag, but you wouldn't put them in the same Set, would you?
    Overrides:
    equals in class SimpleDataStructure
    Parameters:
    obj - the object to compare
    Returns:
    true if equal
  - getType
```
public SigType getType()
```
    Gets the signature type of this private key.
    Returns:
    the type
  - hashCode
```
public int hashCode()
```
    Hash code combining the type and data.
    Overrides:
    hashCode in class SimpleDataStructure
    Returns:
    the hash code
  - isDestroyed
```
public boolean isDestroyed()
```
    javax.security.auth.Destroyable interface
    Specified by:
    isDestroyed in interface Destroyable
    Returns:
    whether destroyed
  - isOffline
```
public boolean isOffline()
```
    Constant time
    Returns:
    true if all zeros
  - length
```
public int length()
```
    Key length in bytes, determined by the signature type.
    Specified by:
    length in class SimpleDataStructure
    Returns:
    the legal length of the byte array
  - toPublic
```
public SigningPublicKey toPublic()
```
    Converts this signing private key to its public equivalent. As of 0.9.16, supports all key types.
    Returns:
    a SigningPublicKey object derived from this private key
    Throws:
    IllegalArgumentException - on bad key or unknown or unsupported type
  - toString
```
public String toString()
```
    Description copied from class: SimpleDataStructure
    Returns a string representation of this data structure.
    Overrides:
    toString in class SimpleDataStructure

Class SigningPrivateKey

Field Summary

Fields inherited from class net.i2p.data.SimpleDataStructure

Constructor Summary

Method Summary

Methods inherited from class net.i2p.data.SimpleDataStructure

Methods inherited from class java.lang.Object

Field Detail

KEYSIZE_BYTES

Constructor Detail

SigningPrivateKey

SigningPrivateKey

SigningPrivateKey

SigningPrivateKey

SigningPrivateKey

Method Detail

blind

destroy

equals

getType

hashCode

isDestroyed

isOffline

length

toPublic

toString