1 files changed, 94 insertions, 0 deletions
diff --git a/pdf-as-common/src/main/java/at/gv/egiz/pdfas/common/utils/PDFUtils.java b/pdf-as-common/src/main/java/at/gv/egiz/pdfas/common/utils/PDFUtils.java
new file mode 100644
index 00000000..155f9cfb
--- /dev/null
+++ b/pdf-as-common/src/main/java/at/gv/egiz/pdfas/common/utils/PDFUtils.java
@@ -0,0 +1,94 @@
+package at.gv.egiz.pdfas.common.utils;
+
+import org.apache.pdfbox.pdmodel.PDDocument;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.ArrayList;
+import java.util.List;
+
+
+public class PDFUtils {
+
+    private static final Logger logger = LoggerFactory.getLogger(PDFUtils.class);
+
+
+    private static final byte[] signature_pattern = new byte[] {
+            (byte) 0x0A, (byte) 0x2F, (byte) 0x43, (byte) 0x6F,   // ./Co
+            (byte) 0x6E, (byte) 0x74, (byte) 0x65, (byte) 0x6E,   // nten
+            (byte) 0x74, (byte) 0x73, (byte) 0x20, (byte) 0x0A,   // ts .
+            (byte) 0x2F, (byte) 0x42, (byte) 0x79, (byte) 0x74,   // /Byt
+            (byte) 0x65, (byte) 0x52, (byte) 0x61, (byte) 0x6E,   // eRan
+            (byte) 0x67, (byte) 0x65, (byte) 0x20, (byte) 0x5B,   // ge [
+
+    };
+
+    private static final byte range_seperation = (byte) 0x20;
+    private static final byte range_end = (byte) 0x5D;
+
+    private static int extractASCIIInteger(byte[] data, int offset) {
+       int nextsepp = nextSeperator(data, offset);
+
+        if(nextsepp < offset) {
+            return -1;
+        }
+
+        String asciiString = new String(data, offset, nextsepp - offset);
+
+        logger.debug("Extracted " + asciiString);
+
+        return Integer.parseInt(asciiString);
+    }
+
+    private static int nextSeperator(byte[] data, int offset) {
+        for(int i = offset; i < data.length; i++) {
+            if(data[i] == range_seperation) {
+                return i;
+            } else if(data[i] == range_end) {
+                return i;
+            }
+        }
+        return -2;
+    }
+
+    public static int[] extractSignatureByteRange(byte[] rawPdfData) {
+        int i = 0;
+        for(i = rawPdfData.length - 1; i >= 0; i--) {
+            if(rawPdfData[i] == signature_pattern[0] &&
+                    i+signature_pattern.length < rawPdfData.length) {
+                boolean match = true;
+                for(int j = 0; j < signature_pattern.length; j++) {
+
+                    if(rawPdfData[i+j] != signature_pattern[j]) {
+                        match = false;
+                        break;
+                    }
+                }
+
+                if(match) {
+
+                    int offset = i + signature_pattern.length;
+                    List<Integer> byteRange = new ArrayList<Integer>();
+                    while(offset > 0) {
+                        byteRange.add(extractASCIIInteger(rawPdfData, offset));
+                        offset = nextSeperator(rawPdfData, offset);
+                        if(rawPdfData[offset] == range_end) {
+                            break;
+                        }
+                        offset++;
+                    }
+                    int[] range = new int[byteRange.size()];
+                    for(int j = 0; j < byteRange.size(); j++) {
+                        range[j] = byteRange.get(j);
+                    }
+                    return range;
+                }
+            }
+        }
+        return null;
+    }
+
+    public static void checkPDFPermissions(PDDocument doc) {
+        // TODO: Check permission for document
+    }
+}