initial commit

Author: ianopolous

.gitignore

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+*.class
+
+build/**
+dist/**
+.idea/**
+
+# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
+hs_err_pid*

LICENSE

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+MIT License
+
+Copyright (c) 2015 Ian Preston
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# java-multihash
+A Java implementation of Multibase
+
+## Usage
+Multihash m = Multihash.fromBase58("QmatmE9msSfkKxoffpHwNLNKgwZG8eT9Bud6YoPab52vpy");
+
+## Compilation
+To compile just run ant.

build.xml

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+<project name="java-multibase" default="dist" basedir=".">
+  <description>
+    Java Multibase
+  </description>
+
+  <property name="src" location="src"/>
+  <property name="build" location="build"/>
+  <property name="dist" location="dist"/>
+
+  <path id="dep.runtime">
+    <fileset dir="./lib">
+        <include name="**/*.jar" />
+    </fileset>
+  </path>
+
+  <target name="init">
+    <mkdir dir="${build}"/>
+  </target>
+
+  <target name="compile" depends="init" description="compile the source">
+    <javac includeantruntime="false" srcdir="${src}" destdir="${build}" debug="true" debuglevel="lines,vars,source">
+      <classpath>
+	<fileset dir="lib">
+          <include name="**/*.jar" />
+        </fileset>
+      </classpath>
+    </javac>
+  </target>
+
+  <target name="dist" depends="compile" description="generate the distribution">
+    <mkdir dir="${dist}/lib"/>
+    <copy todir="${dist}/lib">
+      <fileset dir="lib"/>
+    </copy>
+    <manifestclasspath property="manifest_cp" jarfile="myjar.jar">
+      <classpath refid="dep.runtime" />
+    </manifestclasspath>
+    <jar jarfile="${dist}/multibase.jar" basedir="${build}">
+      <manifest>
+	  <attribute name="Class-Path" value="${manifest_cp}"/>
+      </manifest>
+    </jar>
+    <copy todir=".">
+      <fileset file="${dist}/multibase.jar"/>
+    </copy>
+  </target>
+
+
+  <target name="test" depends="compile,dist">
+    <junit printsummary="yes" fork="true" haltonfailure="yes">
+      <jvmarg value="-Xmx1g"/>
+      <classpath>
+	<pathelement location="lib/junit-4.11.jar" />
+	<pathelement location="lib/hamcrest-core-1.3.jar" />
+	<pathelement location="multibase.jar" />
+      </classpath>
+      <test name="io.ipfs.api.MultibaseTests" haltonfailure="yes">
+	<formatter type="plain"/>
+	<formatter type="xml"/>
+      </test>
+      </junit>
+  </target>
+
+  <target name="clean" description="clean up">
+    <delete dir="${build}"/>
+    <delete dir="${dist}"/>
+  </target>
+</project>

lib/hamcrest-core-1.3.jar

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+package io.ipfs.multibase;
+
+public class Base16 {
+    public static byte[] decode(String hex)
+    {
+        byte[] res = new byte[hex.length()/2];
+        for (int i=0; i < res.length; i++)
+            res[i] = (byte) Integer.parseInt(hex.substring(2*i, 2*i+2), 16);
+        return res;
+    }
+
+    public static String encode(byte[] data)
+    {
+        StringBuilder s = new StringBuilder();
+        for (byte b : data)
+            s.append(String.format("%02x", b & 0xFF));
+        return s.toString();
+    }
+}

lib/junit-4.12.jar

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+package io.ipfs.multibase;
+
+/**
+ * Copyright 2011 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import java.math.BigInteger;
+
+/**
+ * A custom form of base58 is used to encode BitCoin addresses. Note that this is not the same base58 as used by
+ * Flickr, which you may see reference to around the internet.<p>
+ *
+ * Satoshi says: why base-58 instead of standard base-64 encoding?<p>
+ *
+ * <ul>
+ * <li>Don't want 0OIl characters that look the same in some fonts and
+ *    could be used to create visually identical looking account numbers.</li>
+ * <li>A string with non-alphanumeric characters is not as easily accepted as an account number.</li>
+ * <li>E-mail usually won't line-break if there's no punctuation to break at.</li>
+ * <li>Doubleclicking selects the whole number as one word if it's all alphanumeric.</li>
+ * </ul>
+ */
+public class Base58 {
+    private static final String ALPHABET = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
+    private static final BigInteger BASE = BigInteger.valueOf(58);
+
+    public static String encode(byte[] input) {
+        // TODO: This could be a lot more efficient.
+        BigInteger bi = new BigInteger(1, input);
+        StringBuffer s = new StringBuffer();
+        while (bi.compareTo(BASE) >= 0) {
+            BigInteger mod = bi.mod(BASE);
+            s.insert(0, ALPHABET.charAt(mod.intValue()));
+            bi = bi.subtract(mod).divide(BASE);
+        }
+        s.insert(0, ALPHABET.charAt(bi.intValue()));
+        // Convert leading zeros too.
+        for (byte anInput : input) {
+            if (anInput == 0)
+                s.insert(0, ALPHABET.charAt(0));
+            else
+                break;
+        }
+        return s.toString();
+    }
+
+    public static byte[] decode(String input) {
+        byte[] bytes = decodeToBigInteger(input).toByteArray();
+        // We may have got one more byte than we wanted, if the high bit of the next-to-last byte was not zero. This
+        // is because BigIntegers are represented with twos-compliment notation, thus if the high bit of the last
+        // byte happens to be 1 another 8 zero bits will be added to ensure the number parses as positive. Detect
+        // that case here and chop it off.
+        boolean stripSignByte = bytes.length > 1 && bytes[0] == 0 && bytes[1] < 0;
+        // Count the leading zeros, if any.
+        int leadingZeros = 0;
+        for (int i = 0; input.charAt(i) == ALPHABET.charAt(0); i++) {
+            leadingZeros++;
+        }
+        // Now cut/pad correctly. Java 6 has a convenience for this, but Android can't use it.
+        byte[] tmp = new byte[bytes.length - (stripSignByte ? 1 : 0) + leadingZeros];
+        System.arraycopy(bytes, stripSignByte ? 1 : 0, tmp, leadingZeros, tmp.length - leadingZeros);
+        return tmp;
+    }
+
+    public static BigInteger decodeToBigInteger(String input) {
+        BigInteger bi = BigInteger.valueOf(0);
+        // Work backwards through the string.
+        for (int i = input.length() - 1; i >= 0; i--) {
+            int alphaIndex = ALPHABET.indexOf(input.charAt(i));
+            if (alphaIndex == -1) {
+                throw new IllegalStateException("Illegal character " + input.charAt(i) + " at " + i);
+            }
+            bi = bi.add(BigInteger.valueOf(alphaIndex).multiply(BASE.pow(input.length() - 1 - i)));
+        }
+        return bi;
+    }
+}

src/main/java/io/ipfs/multibase/Base16.java

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+package io.ipfs.multibase;
+
+import java.util.*;
+
+public class Multibase {
+
+    public enum Base {
+        Base1('1'),
+        Base2('0'),
+        Base8('7'),
+        Base10('9'),
+        Base16('f'),
+        Base58Flickr('Z'),
+        Base58BTC('z');
+
+        public char prefix;
+
+        Base(char prefix) {
+            this.prefix = prefix;
+        }
+
+        private static Map<Character, Base> lookup = new TreeMap<>();
+        static {
+            for (Base b: Base.values())
+                lookup.put(b.prefix, b);
+        }
+
+        public static Base lookup(char p) {
+            if (!lookup.containsKey(p))
+                throw new IllegalStateException("Unknown Multibase type: " + p);
+            return lookup.get(p);
+        }
+    }
+
+    public static String encode(Base b, byte[] data) {
+        switch (b) {
+            case Base58BTC:
+                return b.prefix + Base58.encode(data);
+            case Base16:
+                return b.prefix + Base16.encode(data);
+            default:
+                throw new IllegalStateException("Unsupported base encoding: " + b.name());
+        }
+    }
+
+    public static Base encoding(String data) {
+        return Base.lookup(data.charAt(0));
+    }
+
+    public static byte[] decode(String data) {
+        Base b = encoding(data);
+        String rest = data.substring(1);
+        switch (b) {
+            case Base58BTC:
+                return Base58.decode(rest);
+            case Base16:
+                return Base16.decode(rest);
+            default:
+                throw new IllegalStateException("Unsupported base encoding: " + b.name());
+        }
+    }
+}

src/main/java/io/ipfs/multibase/Base58.java

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+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/java" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>