SigUtil (Javadocs [I2P+ 2.13.0+] - API Version 0.9.70+)

java.lang.Object
- net.i2p.crypto.SigUtil

```
public final class SigUtil
extends Object
```
Comprehensive utility class for I2P signing keys and digital signatures. This class provides essential methods for converting between I2P's native key formats and standard Java cryptographic key representations, as well as utilities for signature encoding/decoding and key validation.
Key functionalities include:
- Conversion between I2P and Java key formats
- Support for DSA, ECDSA, EdDSA, and RSA algorithms
- ASN.1 signature encoding and decoding
- Key validation and rectification

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static NativeBigInteger[]`	`aSN1ToBigInteger(byte[] asn, int len)` See above.
`static void`	`clearCaches()` Clear all cached Java key conversions.
`(package private) static byte[]`	`combine(BigInteger x, BigInteger y, int len)` Combine two BigIntegers of nominal length = len / 2
`static SigningPrivateKey`	`fromJavaKey(DSAPrivateKey pk)` Convert a Java DSAPrivateKey to an I2P DSA private key.
`static SigningPublicKey`	`fromJavaKey(DSAPublicKey pk)` Convert a Java DSAPublicKey to an I2P DSA public key.
`static SigningPrivateKey`	`fromJavaKey(ECPrivateKey pk, SigType type)` Convert a Java ECPrivateKey to an I2P SigningPrivateKey of the given type.
`static SigningPublicKey`	`fromJavaKey(ECPublicKey pk, SigType type)` Convert a Java ECPublicKey to an I2P SigningPublicKey of the given type.
`static SigningPrivateKey`	`fromJavaKey(EdDSAPrivateKey pk, SigType type)` Convert a Java EdDSAPrivateKey to an I2P SigningPrivateKey.
`static SigningPublicKey`	`fromJavaKey(EdDSAPublicKey pk, SigType type)` Convert a Java EdDSAPublicKey to an I2P SigningPublicKey.
`static SigningPrivateKey`	`fromJavaKey(PrivateKey pk)` Use if SigType is unknown.
`static SigningPrivateKey`	`fromJavaKey(PrivateKey pk, SigType type)` Use if SigType is known.
`static SigningPublicKey`	`fromJavaKey(PublicKey pk)` Use if SigType is unknown.
`static SigningPublicKey`	`fromJavaKey(PublicKey pk, SigType type)` Use if SigType is known.
`static SigningPrivateKey`	`fromJavaKey(RSAPrivateKey pk, SigType type)` Convert a Java RSAPrivateKey to an I2P RSA private key of the given type.
`static SigningPublicKey`	`fromJavaKey(RSAPublicKey pk, SigType type)` Convert a Java RSAPublicKey to an I2P RSA public key of the given type.
`static Signature`	`fromJavaSig(byte[] asn, SigType type)` Convert a Java ASN.1 signature byte array to an I2P Signature.
`static PrivateKey`	`importJavaPrivateKey(File file, SigType type)` Import a Java PKCS8-encoded private key from a file.
`static PublicKey`	`importJavaPublicKey(File file, SigType type)` Import a Java X.509-encoded public key from a file.
`static int`	`intToASN1(byte[] d, int idx, int val)` Output an length or integer value in ASN.1 Does NOT output the tag e.g.
`static byte[]`	`rectify(BigInteger bi, int len)` Convert a BigInteger to a fixed-length byte array, trimming or zero-padding as needed.
`static byte[]`	`sigBytesToASN1(BigInteger r, BigInteger s)` http://download.oracle.com/javase/1.5.0/docs/guide/security/CryptoSpec.html
`static DSAPrivateKey`	`toJavaDSAKey(SigningPrivateKey pk)` Convert an I2P DSA private key to a Java DSAPrivateKey.
`static DSAPublicKey`	`toJavaDSAKey(SigningPublicKey pk)` Convert an I2P DSA public key to a Java DSAPublicKey.
`static ECPrivateKey`	`toJavaECKey(SigningPrivateKey pk)` Convert an I2P EC private key to a Java ECPrivateKey, with caching.
`static ECPublicKey`	`toJavaECKey(SigningPublicKey pk)` Convert an I2P EC public key to a Java ECPublicKey, with caching.
`static EdDSAPrivateKey`	`toJavaEdDSAKey(SigningPrivateKey pk)` Convert an I2P EdDSA private key to a Java EdDSAPrivateKey, with caching.
`static EdDSAPublicKey`	`toJavaEdDSAKey(SigningPublicKey pk)` Convert an I2P EdDSA public key to a Java EdDSAPublicKey, with caching.
`static PrivateKey`	`toJavaKey(SigningPrivateKey pk)` Convert an I2P SigningPrivateKey to a Java PrivateKey, dispatching by algorithm.
`static PublicKey`	`toJavaKey(SigningPublicKey pk)` Convert an I2P SigningPublicKey to a Java PublicKey, dispatching by algorithm.
`static RSAPrivateKey`	`toJavaRSAKey(SigningPrivateKey pk)` Convert an I2P RSA private key to a Java RSAPrivateKey.
`static RSAPublicKey`	`toJavaRSAKey(SigningPublicKey pk)` Prefer toJavaKey(SigningPublicKey) for type-generic conversion.
`static byte[]`	`toJavaSig(Signature sig)` Convert an I2P Signature to a Java ASN.1 signature byte array.

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

- Method Detail
  - aSN1ToBigInteger
```
public static NativeBigInteger[] aSN1ToBigInteger(byte[] asn,
                                                  int len)
                                           throws SignatureException
```
    See above. Only supports sigs up to about 65530 bytes. See code to fix BER encoding for bigger than that.
    Parameters:
    len - nominal length of each BigInteger
    Returns:
    two BigIntegers
    Throws:
    SignatureException
  - clearCaches
```
public static void clearCaches()
```
    Clear all cached Java key conversions. Should be called when key types or configurations change.
  - combine
```
static byte[] combine(BigInteger x,
                      BigInteger y,
                      int len)
               throws InvalidKeyException
```
    Combine two BigIntegers of nominal length = len / 2
    Parameters:
    x - non-negative first value
    y - non-negative second value
    len - total output length (must be even)
    Returns:
    array of exactly len bytes
    Throws:
    InvalidKeyException - if length is odd or either value is too large
  - fromJavaKey
```
public static SigningPrivateKey fromJavaKey(DSAPrivateKey pk)
                                     throws GeneralSecurityException
```
    Convert a Java DSAPrivateKey to an I2P DSA private key.
    Parameters:
    pk - non-null
    Returns:
    I2P DSA private key
    Throws:
    GeneralSecurityException - if conversion fails
  - fromJavaKey
```
public static SigningPublicKey fromJavaKey(DSAPublicKey pk)
                                    throws GeneralSecurityException
```
    Convert a Java DSAPublicKey to an I2P DSA public key.
    Parameters:
    pk - non-null
    Returns:
    I2P DSA public key
    Throws:
    GeneralSecurityException - if conversion fails
  - fromJavaKey
```
public static SigningPrivateKey fromJavaKey(ECPrivateKey pk,
                                            SigType type)
                                     throws GeneralSecurityException
```
    Convert a Java ECPrivateKey to an I2P SigningPrivateKey of the given type.
    Parameters:
    pk - non-null
    type - the I2P signature type
    Returns:
    I2P private key
    Throws:
    GeneralSecurityException - if conversion fails
  - fromJavaKey
```
public static SigningPublicKey fromJavaKey(ECPublicKey pk,
                                           SigType type)
                                    throws GeneralSecurityException
```
    Convert a Java ECPublicKey to an I2P SigningPublicKey of the given type.
    Parameters:
    pk - non-null
    type - the I2P signature type
    Returns:
    I2P public key
    Throws:
    GeneralSecurityException - if conversion fails
  - fromJavaKey
```
public static SigningPrivateKey fromJavaKey(EdDSAPrivateKey pk,
                                            SigType type)
                                     throws GeneralSecurityException
```
    Convert a Java EdDSAPrivateKey to an I2P SigningPrivateKey. Handles EdDSA (seed-based) and RedDSA (private scalar) key types.
    Parameters:
    pk - non-null
    type - the I2P signature type
    Returns:
    I2P private key
    Throws:
    GeneralSecurityException
  - fromJavaKey
```
public static SigningPublicKey fromJavaKey(EdDSAPublicKey pk,
                                           SigType type)
```
    Convert a Java EdDSAPublicKey to an I2P SigningPublicKey.
    Parameters:
    pk - non-null
    type - the I2P signature type
    Returns:
    I2P public key
  - fromJavaKey
```
public static SigningPrivateKey fromJavaKey(PrivateKey pk)
                                     throws GeneralSecurityException
```
    Use if SigType is unknown. For efficiency, use fromJavakey(pk, type) if type is known.
    Parameters:
    pk - JAVA key!
    Returns:
    the I2P signing private key
    Throws:
    InvalidKeyException - on unknown type
    GeneralSecurityException
  - fromJavaKey
```
public static SigningPrivateKey fromJavaKey(PrivateKey pk,
                                            SigType type)
                                     throws GeneralSecurityException
```
    Use if SigType is known.
    Parameters:
    pk - JAVA key!
    Returns:
    I2P private key
    Throws:
    GeneralSecurityException
  - fromJavaKey
```
public static SigningPublicKey fromJavaKey(PublicKey pk)
                                    throws GeneralSecurityException
```
    Use if SigType is unknown. For efficiency, use fromJavakey(pk, type) if type is known.
    Parameters:
    pk - JAVA key!
    Returns:
    the I2P signing public key
    Throws:
    InvalidKeyException - on unknown type
    GeneralSecurityException
  - fromJavaKey
```
public static SigningPublicKey fromJavaKey(PublicKey pk,
                                           SigType type)
                                    throws GeneralSecurityException
```
    Use if SigType is known.
    Parameters:
    pk - JAVA key!
    Returns:
    I2P public key
    Throws:
    GeneralSecurityException
  - fromJavaKey
```
public static SigningPrivateKey fromJavaKey(RSAPrivateKey pk,
                                            SigType type)
                                     throws GeneralSecurityException
```
    Convert a Java RSAPrivateKey to an I2P RSA private key of the given type. As of 0.9.31, if pk is a RSAPrivateCrtKey, returns a RSASigningPrivateCrtKey.
    Parameters:
    pk - non-null
    type - the I2P signature type
    Returns:
    I2P RSA private key
    Throws:
    GeneralSecurityException - if conversion fails
  - fromJavaKey
```
public static SigningPublicKey fromJavaKey(RSAPublicKey pk,
                                           SigType type)
                                    throws GeneralSecurityException
```
    Convert a Java RSAPublicKey to an I2P RSA public key of the given type.
    Parameters:
    pk - non-null
    type - the I2P signature type
    Returns:
    I2P RSA public key
    Throws:
    GeneralSecurityException - if conversion fails
  - fromJavaSig
```
public static Signature fromJavaSig(byte[] asn,
                                    SigType type)
                             throws SignatureException
```
    Convert a Java ASN.1 signature byte array to an I2P Signature. RSA and EdDSA signatures are passed through unchanged.
    Parameters:
    asn - ASN.1 DER-encoded signature bytes (or raw for RSA/EdDSA)
    type - the I2P signature type
    Returns:
    an I2P Signature with the given type
    Throws:
    SignatureException - if ASN.1 decoding fails
  - importJavaPrivateKey
```
public static PrivateKey importJavaPrivateKey(File file,
                                              SigType type)
                                       throws GeneralSecurityException,
                                              IOException
```
    Import a Java PKCS8-encoded private key from a file.
    Parameters:
    file - non-null, containing PKCS8 encoded key data
    type - the I2P signature type
    Returns:
    Java PrivateKey
    Throws:
    GeneralSecurityException - if key conversion fails
    IOException - if file reading fails
  - importJavaPublicKey
```
public static PublicKey importJavaPublicKey(File file,
                                            SigType type)
                                     throws GeneralSecurityException,
                                            IOException
```
    Import a Java X.509-encoded public key from a file.
    Parameters:
    file - non-null, containing X.509 encoded key data
    type - the I2P signature type
    Returns:
    Java PublicKey
    Throws:
    GeneralSecurityException - if key conversion fails
    IOException - if file reading fails
  - intToASN1
```
public static int intToASN1(byte[] d,
                            int idx,
                            int val)
```
    Output an length or integer value in ASN.1 Does NOT output the tag e.g. 0x02 / 0x30
    Parameters:
    val - 0-65535
    Returns:
    the new index
  - rectify
```
public static byte[] rectify(BigInteger bi,
                             int len)
                      throws InvalidKeyException
```
    Convert a BigInteger to a fixed-length byte array, trimming or zero-padding as needed.
    Parameters:
    bi - non-negative
    len - desired output length
    Returns:
    array of exactly len bytes
    Throws:
    InvalidKeyException - if the value is negative or too large to fit
  - sigBytesToASN1
```
public static byte[] sigBytesToASN1(BigInteger r,
                                    BigInteger s)
```
    http://download.oracle.com/javase/1.5.0/docs/guide/security/CryptoSpec.html
```
  Signature Format: ASN.1 sequence of two INTEGER values: r and s, in that order:
                                SEQUENCE ::= { r INTEGER, s INTEGER }

  http://en.wikipedia.org/wiki/Abstract_Syntax_Notation_One
  30 -- tag indicating SEQUENCE
  xx - length in octets

  02 -- tag indicating INTEGER
  xx - length in octets
  xxxxxx - value
```
    Encode two BigInteger values (r, s) into ASN.1 DER SEQUENCE format. r and s are always non-negative. Only supports sigs up to about 65530 bytes. See code to fix BER encoding for this before you add a SigType with bigger signatures.
    Parameters:
    r - non-negative
    s - non-negative
    Returns:
    ASN.1 DER-encoded SEQUENCE { r INTEGER, s INTEGER }
    Throws:
    IllegalArgumentException - if too big
  - toJavaDSAKey
```
public static DSAPrivateKey toJavaDSAKey(SigningPrivateKey pk)
                                  throws GeneralSecurityException
```
    Convert an I2P DSA private key to a Java DSAPrivateKey.
    Parameters:
    pk - non-null
    Returns:
    Java DSAPrivateKey
    Throws:
    GeneralSecurityException - if conversion fails
  - toJavaDSAKey
```
public static DSAPublicKey toJavaDSAKey(SigningPublicKey pk)
                                 throws GeneralSecurityException
```
    Convert an I2P DSA public key to a Java DSAPublicKey.
    Parameters:
    pk - non-null
    Returns:
    Java DSAPublicKey
    Throws:
    GeneralSecurityException - if conversion fails
  - toJavaECKey
```
public static ECPrivateKey toJavaECKey(SigningPrivateKey pk)
                                throws GeneralSecurityException
```
    Convert an I2P EC private key to a Java ECPrivateKey, with caching.
    Parameters:
    pk - non-null
    Returns:
    Java ECPrivateKey
    Throws:
    GeneralSecurityException - if conversion fails
  - toJavaECKey
```
public static ECPublicKey toJavaECKey(SigningPublicKey pk)
                               throws GeneralSecurityException
```
    Convert an I2P EC public key to a Java ECPublicKey, with caching.
    Parameters:
    pk - non-null
    Returns:
    Java ECPublicKey
    Throws:
    GeneralSecurityException - if conversion fails
  - toJavaEdDSAKey
```
public static EdDSAPrivateKey toJavaEdDSAKey(SigningPrivateKey pk)
                                      throws GeneralSecurityException
```
    Convert an I2P EdDSA private key to a Java EdDSAPrivateKey, with caching.
    Parameters:
    pk - non-null
    Returns:
    Java EdDSAPrivateKey
    Throws:
    GeneralSecurityException
  - toJavaEdDSAKey
```
public static EdDSAPublicKey toJavaEdDSAKey(SigningPublicKey pk)
                                     throws GeneralSecurityException
```
    Convert an I2P EdDSA public key to a Java EdDSAPublicKey, with caching.
    Parameters:
    pk - non-null
    Returns:
    Java EdDSAPublicKey
    Throws:
    GeneralSecurityException
  - toJavaKey
```
public static PrivateKey toJavaKey(SigningPrivateKey pk)
                            throws GeneralSecurityException
```
    Convert an I2P SigningPrivateKey to a Java PrivateKey, dispatching by algorithm.
    Parameters:
    pk - non-null
    Returns:
    Java PrivateKey (DSA, EC, EdDSA, or RSA)
    Throws:
    GeneralSecurityException - if conversion fails
  - toJavaKey
```
public static PublicKey toJavaKey(SigningPublicKey pk)
                           throws GeneralSecurityException
```
    Convert an I2P SigningPublicKey to a Java PublicKey, dispatching by algorithm.
    Parameters:
    pk - non-null
    Returns:
    Java PublicKey (DSA, EC, EdDSA, or RSA)
    Throws:
    GeneralSecurityException - if conversion fails
  - toJavaRSAKey
```
public static RSAPrivateKey toJavaRSAKey(SigningPrivateKey pk)
                                  throws GeneralSecurityException
```
    Convert an I2P RSA private key to a Java RSAPrivateKey. As of 0.9.31, if pk is a RSASigningPrivateCrtKey, returns a RSAPrivateCrtKey.
    Parameters:
    pk - non-null
    Returns:
    Java RSAPrivateKey
    Throws:
    GeneralSecurityException - if conversion fails
  - toJavaRSAKey
```
public static RSAPublicKey toJavaRSAKey(SigningPublicKey pk)
                                 throws GeneralSecurityException
```
    Prefer toJavaKey(SigningPublicKey) for type-generic conversion.
    Parameters:
    pk - non-null
    Returns:
    Java RSA public key
    Throws:
    GeneralSecurityException - if conversion fails
  - toJavaSig
```
public static byte[] toJavaSig(Signature sig)
```
    Convert an I2P Signature to a Java ASN.1 signature byte array. RSA and EdDSA signatures are passed through unchanged.
    Parameters:
    sig - non-null
    Returns:
    ASN.1 DER-encoded signature bytes (or raw for RSA/EdDSA)

Class SigUtil

Method Summary

Methods inherited from class java.lang.Object

Method Detail

aSN1ToBigInteger

clearCaches

combine

fromJavaKey

fromJavaKey

fromJavaKey

fromJavaKey

fromJavaKey

fromJavaKey

fromJavaKey

fromJavaKey

fromJavaKey

fromJavaKey

fromJavaKey

fromJavaKey

fromJavaSig

importJavaPrivateKey

importJavaPublicKey

intToASN1

rectify

sigBytesToASN1

toJavaDSAKey

toJavaDSAKey

toJavaECKey

toJavaECKey

toJavaEdDSAKey

toJavaEdDSAKey

toJavaKey

toJavaKey

toJavaRSAKey

toJavaRSAKey

toJavaSig