Method Details

• resolveCPUType

  private static String resolveCPUType()

  Tries to resolve the best type of CPU that we have an optimized jbigi-dll/so for.

  Returns:

  A string containing the CPU-type or null if CPU type is unknown

• nativeModPow

  private static byte[] nativeModPow(byte[] base, byte[] exponent, byte[] modulus)

  Calculate (base ^ exponent) % modulus.

  Parameters:

  base - big endian twos complement representation of the base (but it must be positive)

  exponent - big endian twos complement representation of the exponent

  modulus - big endian twos complement representation of the modulus

  Returns:

  big endian twos complement representation of (base ^ exponent) % modulus

  Throws:

  ArithmeticException - if modulus <= 0 (since libjbigi version 3)

• nativeModPowCT

  private static byte[] nativeModPowCT(byte[] base, byte[] exponent, byte[] modulus)

  Calculate (base ^ exponent) % modulus. Constant Time.

  Parameters:

  base - big endian twos complement representation of the base (but it must be positive)

  exponent - big endian twos complement representation of the exponent

  modulus - big endian twos complement representation of the modulus

  Returns:

  big endian twos complement representation of (base ^ exponent) % modulus

  Throws:

  ArithmeticException - if modulus <= 0

• nativeModInverse

  private static byte[] nativeModInverse(byte[] base, byte[] d)

  Compute the modular inverse of base modulo d.

  Parameters:

  base - big endian twos complement representation of the number to invert

  d - big endian twos complement representation of the modulus

  Returns:

  big endian twos complement representation of the inverse

  Throws:

  ArithmeticException - if the modulus is not positive or the inverse does not exist

• nativeJbigiVersion

  private static int nativeJbigiVersion()

  The jbigi version, only available since jbigi version 3.

  Returns:

  the version number reported by the loaded native library

• nativeGMPMajorVersion

  private static int nativeGMPMajorVersion()

  The libmp major version, only available since jbigi version 3.

  Returns:

  the major version number of the libmp the native library links against

• nativeGMPMinorVersion

  private static int nativeGMPMinorVersion()

  The libmp minor version, only available since jbigi version 3.

  Returns:

  the minor version number of the libmp the native library links against

• nativeGMPPatchVersion

  private static int nativeGMPPatchVersion()

  The libmp patch version, only available since jbigi version 3.

  Returns:

  the patch version number of the libmp the native library links against

• fetchJbigiVersion

  private static int fetchJbigiVersion()

  The jbigi version, fetched from the native library.

  Returns:

  0 if no jbigi available, 2 if version not supported

• setVersions

  private static void setVersions()

  Store the jbigi and libgmp versions. Call after loading. Sets _jbigiVersion, _nativeOk3, and _libGMPVersion.

• getJbigiVersion

  public static int getJbigiVersion()

  The jbigi version, fetched from the native library.

  Returns:

  0 if no jbigi available, 2 if version info not supported

• getLibGMPVersion

  public static String getLibGMPVersion()

  The libgmp version string.

  Returns:

  "unknown" if no jbigi available or if version not supported

• modPow

  public BigInteger modPow(BigInteger exponent, BigInteger m)

  Compute base^exponent mod m using the native library.

  Overrides:

  modPow in class BigInteger

  Parameters:

  exponent - must be positive

  m - must be positive

  Throws:

  ArithmeticException - if m <= 0 or exponent <=0

• modPowCT

  public BigInteger modPowCT(BigInteger exponent, BigInteger m)

  Compute base^exponent mod m in constant time using the native library.

  Parameters:

  exponent - must be positive

  m - must be positive and odd

  Returns:

  this value raised to the exponent modulo m, falling back to the variable-time computation when constant-time native code is unavailable

  Throws:

  ArithmeticException - if m <= 0 or m is even or exponent <=0

• modInverse

  public BigInteger modInverse(BigInteger m)

  Compute the modular inverse of this value modulo m using the native library.

  Overrides:

  modInverse in class BigInteger

  Throws:

  ArithmeticException - if not coprime with m, or m <= 0

• toByteArray

  public byte[] toByteArray()

  Cached byte array representation, filled in on first call.

  Overrides:

  toByteArray in class BigInteger

• isNative

  public static boolean isNative()

  Whether native methods will be used by this class.

  Returns:

  True iff native methods will be used by this class

• loadStatus

  public static String loadStatus()

  Human-readable status of the native library load.

  Returns:

  A string suitable for display to the user

• getLoadedResourceName

  public static String getLoadedResourceName()

  The name of the library loaded, if known. Null if unknown or not loaded. Currently non-null only if extracted from jbigi.jar.

  Returns:

  the loaded resource name

• cpuType

  public static String cpuType()

  Detected CPU type for jbigi optimization.

  Returns:

  the detected architecture, or "unrecognized" if it could not be probed

• cpuFamily

  public static String cpuFamily()

  Processor family for the console info page, named the way a reader would expect rather than the way the jbigi library is named. The optimization name is imprecise at the top of the AMD range on purpose - zen3 is the newest tuned build, so a Zen 4 or Zen 5 part resolves to it - and "none" only says that no tuned build matched, which is not a processor to print.

  Returns:

  the family name, or null if the processor could not be classified

• amdFamily

  public static String amdFamily(AMDCPUInfo cpu)

  Microarchitecture name for an AMD CPU, reported at the newest generation its compatibility flags support. The jbigi build stops at zen3, so the library name cannot tell a Zen 3 part from a Zen 4 or Zen 5 one - naming the library here would hide which chip the machine actually has.

  Parameters:

  cpu - the probed CPU, may be null

  Returns:

  the generation name, or null if it is not a Zen CPU

• familyFor

  static String familyFor(String type)

  Display name for a jbigi optimization name, or null when the name carries no information about the processor - "none" only says that no tuned build matched. AMD is named from the CPU flags instead, by amdFamily(AMDCPUInfo). Package visible for testing.

  Parameters:

  type - the optimization name, or null

  Returns:

  the family name, or null if there is nothing useful to show

• cpuModel

  public static String cpuModel()

  CPU model string from CPUID.

  Returns:

  the model name reported by the CPU, or null if it could not be read

• loadNative

  private static final void loadNative()

  Do whatever we can to load up the native library backing this BigInteger's native methods. If it can find a custom built jbigi.dll / libjbigi.so, it'll use that. Otherwise it'll try to look in the classpath for the correct library (see loadFromResource). If the user specifies -Djbigi.enable=false it'll skip all of this.

  Load order (using linux naming with cpu type "xxx")
  - filesystem libjbigi.so
  - jbigi.jar libjbigi-linux-xxx_64.so
  - jbigi.jar libjbigi-linux-yyy_64.so 0 or more other alternates
  - jbigi.jar libjbigi-linux-none_64.so
  

  Only 64-bit native libraries are shipped.

• debug

  private static void debug(String s)

  Log a native math debug message.

  Parameters:

  s - the message to log

• info

  private static void info(String s)

  Logs an informational message about the library load.

  Parameters:

  s - the message to log

• warn

  private static void warn(String s)

  Logs a warning about the library load.

  Parameters:

  s - the message to log

• warn

  private static void warn(String s, Throwable t)

  Log a native math warning.

  Parameters:

  s - the message to log

  t - the cause to print and record, or null

• error

  private static void error(String s)

  Log a native math error.

  Parameters:

  s - the message to log

• error

  private static void error(String s, Throwable t)

  Log a native math error with its cause.

  Parameters:

  s - the message to log

  t - the cause to print and record, or null

• loadGeneric

  private static final boolean loadGeneric(String name)

  Try loading it from an explicitly build jbigi.dll / libjbigi.so first, before looking into a jbigi.jar for any other libraries.

  Parameters:

  name - the library name to load, null means do nothing

  Returns:

  true if it was loaded successfully, else false

• loadFromResource

  private static final boolean loadFromResource(String resourceName)

  Check all of the jars in the classpath for the file specified by the environmental property "jbigi.impl" and load it as the native library implementation. For instance, a windows user on a p4 would define -Djbigi.impl=win-686 if there is a jbigi.jar in the classpath containing the files "win-686", "win-athlon", "freebsd-p4", "linux-p3", where each of those files contain the correct binary file for a native library (e.g. windows DLL, or a *nix .so).

  This is a pretty ugly hack, using the general technique illustrated by the onion FEC libraries. It works by pulling the resource, writing out the byte stream to a temporary file, loading the native library from that file. We then attempt to copy the file from the temporary dir to the base install dir, so we don't have to do this next time - but we don't complain if it fails, so we transparently support read-only base dirs.

  Parameters:

  resourceName - the resource to load, named by the "jbigi.impl" property, null means do nothing

  Returns:

  true if it was loaded successfully, else false

• getResourceList

  private static List<String> getResourceList()

  Generate a list of resources to search for, in-order. See loadNative() comments for more info.

  Returns:

  non-null

• getMiddleName2

  private static final String getMiddleName2(boolean optimized)

  The middle part of the native library name, based on the CPU type.

  Parameters:

  optimized - true to use the detected CPU type, false for the generic "none" library

  Returns:

  may be null if optimized is true

• getMiddleName1

  private static final String getMiddleName1()

  The middle part of the native library name, for a non-optimized library.

  Returns:

  may be null if optimized is true; returns jbigi-xxx-none if optimize is false