Merge pull request #738 from seadowg/extract-signed

Add `extract-signed`

build.gradle

@@ -168,6 +168,7 @@ dependencies {
     implementation 'commons-io:commons-io:2.5'
 
     implementation 'org.jetbrains.kotlin:kotlin-stdlib:1.6.10'
+    implementation 'org.bouncycastle:bcprov-jdk18on:1.77'
 
     compileOnly 'net.sf.kxml:kxml2:2.3.0'
 

pom.xml

@@ -81,6 +81,11 @@
       <artifactId>slf4j-api</artifactId>
       <version>1.7.33</version>
     </dependency>
+    <dependency>
+       <groupId>org.bouncycastle</groupId>
+       <artifactId>bcprov-jdk18on</artifactId>
+       <version>1.77</version>
+    </dependency>
     <dependency>
       <groupId>ch.qos.logback</groupId>
       <artifactId>logback-classic</artifactId>

src/main/java/org/javarosa/core/util/Base64.java

@@ -0,0 +1,88 @@
+package org.javarosa.core.util;
+
+import java.nio.charset.StandardCharsets;
+import java.util.Arrays;
+
+// Copied from: https://github.com/brsanthu/migbase64/blob/master/src/main/java/com/migcomponents/migbase64/Base64.java
+// Irrelevant after Java8
+public class Base64 {
+
+    private static final char[] BASE_64_TBL = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();
+    private static final int[] IA = new int[256];
+    static {
+        Arrays.fill(IA, -1);
+        for (int i = 0, iS = BASE_64_TBL.length; i < iS; i++)
+            IA[BASE_64_TBL[i]] = i;
+        IA['='] = 0;
+    }
+
+    public static String encode(byte[] sArr) {
+        int sLen = sArr.length;
+        int sOff = 0;
+
+        if (sLen == 0)
+            return "";
+
+        int eLen = (sLen / 3) * 3;
+        int dLen = ((sLen - 1) / 3 + 1) << 2;
+        byte[] dArr = new byte[dLen];
+
+        for (int s = sOff, d = 0; s < sOff + eLen; ) {
+            int i = (sArr[s++] & 0xff) << 16 | (sArr[s++] & 0xff) << 8 | (sArr[s++] & 0xff);
+            dArr[d++] = (byte) BASE_64_TBL[(i >>> 18) & 0x3f];
+            dArr[d++] = (byte) BASE_64_TBL[(i >>> 12) & 0x3f];
+            dArr[d++] = (byte) BASE_64_TBL[(i >>> 6) & 0x3f];
+            dArr[d++] = (byte) BASE_64_TBL[i & 0x3f];
+        }
+
+        int left = sLen - eLen;
+        if (left > 0) {
+            int i = ((sArr[sOff + eLen] & 0xff) << 10) | (left == 2 ? ((sArr[sOff + sLen - 1] & 0xff) << 2) : 0);
+            dArr[dLen - 4] = (byte) BASE_64_TBL[i >> 12];
+            dArr[dLen - 3] = (byte) BASE_64_TBL[(i >>> 6) & 0x3f];
+            dArr[dLen - 2] = left == 2 ? (byte) BASE_64_TBL[i & 0x3f] : (byte) '=';
+            dArr[dLen - 1] = '=';
+        }
+
+        return new String(dArr, StandardCharsets.UTF_8);
+    }
+
+    public static byte[] decode(byte[] sArr) {
+        int sepCnt = 0;
+        for (byte b : sArr)
+            if (IA[b & 0xff] < 0)
+                sepCnt++;
+
+        if ((sArr.length - sepCnt) % 4 != 0)
+            return new byte[0];
+
+        int pad = 0;
+        for (int i = sArr.length; i > 1 && IA[sArr[--i] & 0xff] <= 0; )
+            if (sArr[i] == '=')
+                pad++;
+
+        int len = ((sArr.length - sepCnt) * 6 >> 3) - pad;
+
+        byte[] dArr = new byte[len];
+
+        for (int s = 0, d = 0; d < len; ) {
+            int i = 0;
+            for (int j = 0; j < 4; j++) {
+                int c = IA[sArr[s++] & 0xff];
+                if (c >= 0)
+                    i |= c << (18 - j * 6);
+                else
+                    j--;
+            }
+
+            dArr[d++] = (byte) (i >> 16);
+            if (d < len) {
+                dArr[d++] = (byte) (i >> 8);
+                if (d < len)
+                    dArr[d++] = (byte) i;
+            }
+        }
+
+        return dArr;
+    }
+}

src/main/java/org/javarosa/core/util/Ed25519.java

@@ -0,0 +1,50 @@
+package org.javarosa.core.util;
+
+import org.bouncycastle.crypto.Signer;
+import org.bouncycastle.crypto.params.Ed25519PublicKeyParameters;
+import org.bouncycastle.crypto.signers.Ed25519Signer;
+import org.jetbrains.annotations.Nullable;
+
+import java.nio.charset.StandardCharsets;
+
+public class Ed25519 {
+
+    private static final int SIGNATURE_LENGTH = 64;
+
+    @Nullable
+    public static String extractSigned(byte[] contents, byte[] publicKey) {
+        if (contents.length < 64) {
+            return null;
+        }
+
+        byte[] signature = new byte[SIGNATURE_LENGTH];
+        System.arraycopy(contents, 0, signature, 0, SIGNATURE_LENGTH);
+
+        int messageLength = contents.length - SIGNATURE_LENGTH;
+        byte[] message = new byte[messageLength];
+        System.arraycopy(contents, SIGNATURE_LENGTH, message, 0, messageLength);
+
+        if (verify(publicKey, signature, message)) {
+            return new String(message, StandardCharsets.UTF_8);
+        } else {
+            return null;
+        }
+    }
+
+    private static boolean verify(byte[] publicKey, byte[] signature, byte[] message) {
+        try {
+            Ed25519PublicKeyParameters publicKeyParameters = new Ed25519PublicKeyParameters(publicKey, 0);
+            Signer signer = new Ed25519Signer();
+            signer.init(false, publicKeyParameters);
+            signer.update(message, 0, message.length);
+
+            return signer.verifySignature(signature);
+        } catch (ArrayIndexOutOfBoundsException e) {
+            // The key was too small
+            return false;
+        } catch (IllegalArgumentException e) {
+            // The key was invalid
+            return false;
+        }
+    }
+}

src/main/java/org/javarosa/xpath/expr/Encoding.java

@@ -15,8 +15,7 @@
  */
 package org.javarosa.xpath.expr;
 
-import java.nio.charset.StandardCharsets;
-import java.util.Arrays;
+import org.javarosa.core.util.Base64;
 import org.javarosa.xpath.XPathUnsupportedException;
 
 /**
@@ -46,78 +45,14 @@ byte[] decode(byte[] bytes) {
         }
     },
     BASE64("base64") {
-        // Copied from: https://github.com/brsanthu/migbase64/blob/master/src/main/java/com/migcomponents/migbase64/Base64.java
-        // Irrelevant after Java8
         @Override
         String encode(byte[] sArr) {
-            int sLen = sArr.length;
-            int sOff = 0;
-
-            if (sLen == 0)
-                return "";
-
-            int eLen = (sLen / 3) * 3;
-            int dLen = ((sLen - 1) / 3 + 1) << 2;
-            byte[] dArr = new byte[dLen];
-
-            for (int s = sOff, d = 0; s < sOff + eLen; ) {
-                int i = (sArr[s++] & 0xff) << 16 | (sArr[s++] & 0xff) << 8 | (sArr[s++] & 0xff);
-                dArr[d++] = (byte) BASE_64_TBL[(i >>> 18) & 0x3f];
-                dArr[d++] = (byte) BASE_64_TBL[(i >>> 12) & 0x3f];
-                dArr[d++] = (byte) BASE_64_TBL[(i >>> 6) & 0x3f];
-                dArr[d++] = (byte) BASE_64_TBL[i & 0x3f];
-            }
-
-            int left = sLen - eLen;
-            if (left > 0) {
-                int i = ((sArr[sOff + eLen] & 0xff) << 10) | (left == 2 ? ((sArr[sOff + sLen - 1] & 0xff) << 2) : 0);
-                dArr[dLen - 4] = (byte) BASE_64_TBL[i >> 12];
-                dArr[dLen - 3] = (byte) BASE_64_TBL[(i >>> 6) & 0x3f];
-                dArr[dLen - 2] = left == 2 ? (byte) BASE_64_TBL[i & 0x3f] : (byte) '=';
-                dArr[dLen - 1] = '=';
-            }
-
-            return new String(dArr, StandardCharsets.UTF_8);
+            return Base64.encode(sArr);
         }
 
         @Override
-        public byte[] decode(byte[] sArr) {
-            int sepCnt = 0;
-            for (byte b : sArr)
-                if (IA[b & 0xff] < 0)
-                    sepCnt++;
-
-            if ((sArr.length - sepCnt) % 4 != 0)
-                return new byte[0];
-
-            int pad = 0;
-            for (int i = sArr.length; i > 1 && IA[sArr[--i] & 0xff] <= 0; )
-                if (sArr[i] == '=')
-                    pad++;
-
-            int len = ((sArr.length - sepCnt) * 6 >> 3) - pad;
-
-            byte[] dArr = new byte[len];
-
-            for (int s = 0, d = 0; d < len; ) {
-                int i = 0;
-                for (int j = 0; j < 4; j++) {
-                    int c = IA[sArr[s++] & 0xff];
-                    if (c >= 0)
-                        i |= c << (18 - j * 6);
-                    else
-                        j--;
-                }
-
-                dArr[d++] = (byte) (i >> 16);
-                if (d < len) {
-                    dArr[d++] = (byte) (i >> 8);
-                    if (d < len)
-                        dArr[d++] = (byte) i;
-                }
-            }
-
-            return dArr;
+        byte[] decode(byte[] sArr) {
+            return Base64.decode(sArr);
         }
     };
 
@@ -137,16 +72,6 @@ static Encoding from(String name) {
 
     private static final char[] HEX_TBL = "0123456789abcdef".toCharArray();
 
-    private static final char[] BASE_64_TBL = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();
-
-    private static final int[] IA = new int[256];
-    static {
-        Arrays.fill(IA, -1);
-        for (int i = 0, iS = BASE_64_TBL.length; i < iS; i++)
-            IA[BASE_64_TBL[i]] = i;
-        IA['='] = 0;
-    }
-
     abstract String encode(byte[] bytes);
 
     abstract byte[] decode(byte[] bytes);

src/main/java/org/javarosa/xpath/expr/XPathFuncExpr.java

@@ -25,6 +25,8 @@
 import org.javarosa.core.model.instance.TreeReference;
 import org.javarosa.core.model.utils.DateUtils;
 import org.javarosa.core.services.PropertyManager;
+import org.javarosa.core.util.Base64;
+import org.javarosa.core.util.Ed25519;
 import org.javarosa.core.util.GeoUtils;
 import org.javarosa.core.util.MathUtils;
 import org.javarosa.core.util.PropertyUtils;
@@ -496,6 +498,9 @@ public Object eval(DataInstance model, EvaluationContext evalContext) {
         } else if (name.equals("base64-decode")) {
             assertArgsCount(name, args, 1);
             return base64Decode(argVals[0]);
+        } else if (name.equals("extract-signed")) {
+            assertArgsCount(name, args, 2);
+            return extractSigned(argVals[0], argVals[1]);
         } else {
             //check for custom handler
             IFunctionHandler handler = funcHandlers.get(name);
@@ -1264,6 +1269,18 @@ private static String base64Decode(Object o1) {
         return new String(decoded, StandardCharsets.UTF_8);
     }
 
+    private static String extractSigned(Object o1, Object o2) {
+        byte[] decodedContents = Base64.decode(toString(o1).getBytes());
+        byte[] decodedPublicKey = Base64.decode(toString(o2).getBytes());
+
+        String extracted = Ed25519.extractSigned(decodedContents, decodedPublicKey);
+        if (extracted != null) {
+            return extracted;
+        } else {
+            return "";
+        }
+    }
+
     private static Object[] subsetArgList(Object[] args, int start) {
         return subsetArgList(args, start, 1);
     }