Package com.nettgryppa.security

Class HashCash

java.lang.Object
com.nettgryppa.security.HashCash
All Implemented Interfaces:
Comparable<HashCash>
public class HashCash extends Object implements Comparable<HashCash>
Class for generation and parsing of HashCash
Copyright 2006 Gregory Rubin grrubin@gmail.com
Permission is given to use, modify, and or distribute this code so long as this message remains attached
Please see the spec at: http://www.hashcash.org/
Version:
1.1
Author:
grrubin@gmail.com

  • Field Details

  • Constructor Details

  • Method Details

    • mintCash

      public static HashCash mintCash(String resource, int value) throws NoSuchAlgorithmException
      Mints a version 1 HashCash using now as the date
      Parameters:
      resource - the string to be encoded in the HashCash
      Throws:
      NoSuchAlgorithmException - If SHA1 is not a supported Message Digest

    • mintCash

      public static HashCash mintCash(String resource, int value, int version) throws NoSuchAlgorithmException
      Mints a HashCash using now as the date
      Parameters:
      resource - the string to be encoded in the HashCash
      version - Which version to mint. Only valid values are 0 and 1
      Throws:
      NoSuchAlgorithmException - If SHA1 is not a supported Message Digest

    • mintCash

      public static HashCash mintCash(String resource, Calendar date, int value) throws NoSuchAlgorithmException
      Mints a version 1 HashCash
      Parameters:
      resource - the string to be encoded in the HashCash
      Throws:
      NoSuchAlgorithmException - If SHA1 is not a supported Message Digest

    • mintCash

      public static HashCash mintCash(String resource, Calendar date, int value, int version) throws NoSuchAlgorithmException
      Mints a HashCash
      Parameters:
      resource - the string to be encoded in the HashCash
      version - Which version to mint. Only valid values are 0 and 1
      Throws:
      NoSuchAlgorithmException - If SHA1 is not a supported Message Digest

    • mintCash

      public static HashCash mintCash(String resource, Map<String,List<String>> extensions, int value) throws NoSuchAlgorithmException
      Mints a version 1 HashCash using now as the date
      Parameters:
      resource - the string to be encoded in the HashCash
      extensions - Extra data to be encoded in the HashCash
      Throws:
      NoSuchAlgorithmException - If SHA1 is not a supported Message Digest

    • mintCash

      public static HashCash mintCash(String resource, Map<String,List<String>> extensions, int value, int version) throws NoSuchAlgorithmException
      Mints a HashCash using now as the date
      Parameters:
      resource - the string to be encoded in the HashCash
      extensions - Extra data to be encoded in the HashCash
      version - Which version to mint. Only valid values are 0 and 1
      Throws:
      NoSuchAlgorithmException - If SHA1 is not a supported Message Digest

    • mintCash

      public static HashCash mintCash(String resource, Map<String,List<String>> extensions, Calendar date, int value) throws NoSuchAlgorithmException
      Mints a version 1 HashCash
      Parameters:
      resource - the string to be encoded in the HashCash
      extensions - Extra data to be encoded in the HashCash
      Throws:
      NoSuchAlgorithmException - If SHA1 is not a supported Message Digest

    • mintCash

      public static HashCash mintCash(String resource, Map<String,List<String>> extensions, Calendar date, int value, int version) throws NoSuchAlgorithmException
      Mints a HashCash
      Parameters:
      resource - the string to be encoded in the HashCash
      extensions - Extra data to be encoded in the HashCash
      version - Which version to mint. Only valid values are 0 and 1
      Throws:
      NoSuchAlgorithmException - If SHA1 is not a supported Message Digest

    • equals

      public boolean equals(Object obj)
      Two objects are considered equal if they are both of type HashCash and have an identical string representation
      Overrides:
      equals in class Object

    • hashCode

      public int hashCode()
      Implemented based on definition of equals()
      Overrides:
      hashCode in class Object

    • toString

      public String toString()
      Returns the canonical string representation of the HashCash
      Overrides:
      toString in class Object

    • getExtensions

      public Map<String,List<String>> getExtensions()
      Extra data encoded in the HashCash

    • getResource

      public String getResource()
      The primary resource being protected

    • getDate

      public Calendar getDate()
      The minting date

    • getValue

      public int getValue()
      The value of the HashCash (e.g. how many leading zero bits it has)

    • getVersion

      public int getVersion()
      Which version of HashCash is used here

    • estimateTime

      public static long estimateTime(int value) throws NoSuchAlgorithmException
      Estimates how many milliseconds it would take to mint a cash of the specified value.
      • NOTE1: Minting time can vary greatly in fact, half of the time it will take half as long)
      • NOTE2: The first time that an estimation function is called it is expensive (on the order of seconds). After that, it is very quick.
      Throws:
      NoSuchAlgorithmException - If SHA1 is not a supported Message Digest

    • estimateValue

      public static int estimateValue(int secs) throws NoSuchAlgorithmException
      Estimates what value (e.g. how many bits of collision) are required for the specified length of time.
      • NOTE1: Minting time can vary greatly in fact, half of the time it will take half as long)
      • NOTE2: The first time that an estimation function is called it is expensive (on the order of seconds). After that, it is very quick.
      Throws:
      NoSuchAlgorithmException - If SHA1 is not a supported Message Digest

    • compareTo

      public int compareTo(HashCash other)
      Compares the value of two HashCashes
      Specified by:
      compareTo in interface Comparable<HashCash>
      Parameters:
      other -
      See Also: