Search for embedded object with custom encryption of QR-code signatures

GroupDocs.Signature provides following abilities to search for embedded data objects in QR-code signatures (QrCodeSignature) that were encrypted with custom encryption.  

  • ability to search for embedded custom objects into metadata and decrypt them to original source values
  • ability to search for custom encrypted QR-code signature and decrypt it  

Here are the steps to search and decrypt previously encrypted text of QR-Code and decrypt custom object from QR-Code signature with GroupDocs.Signature API:

Implementation of custom data encryption

This example shows how to specify custom serialization class. This class could be implemented also as Attribute (optional) to specify as class attribute.

public class CustomXOREncryption implements IDataEncryption
{
    /**
     * <p>
     * Gets or sets non empty key for encryption (at least one character)
     * </p>
     */
    public final int getKey(){ return auto_Key; }
    /**
     * <p>
     * Gets or sets non empty key for encryption (at least one character)
     * </p>
     */
    public final void setKey(int value){ auto_Key = value; }
    private int auto_Key;
 
    /**
     * <p>
     * Encode method to encrypt string.
     * </p>
     * @return Returns enccrypted string
     * @param source Source string to encode.
     */
    public final String encode(String source)
    {
        return process(source);
    }
 
    /**
     * <p>
     * Decode method to obtain decrypted string.
     * </p>
     * @return Returns decrypted string
     * @param source Source string to decode.
     */
    public final String decode(String source)
    {
        return process(source);
    }
 
    /**
     * <p>
     * Using XOR operation get encoded / decoded string
     * </p>
     * @return
     * @param source
     */
    private String process(String source)
    {
        StringBuilder src = new StringBuilder(source);
        StringBuilder dst = new StringBuilder(src.length());
        char chTmp;
        for (int index = 0; index < src.length(); ++index)
        {
            chTmp = src.charAt(index);
            chTmp = (char)(chTmp ^ this.getKey());
            dst.append(chTmp);
        }
        return dst.toString();
    }
}

Definition of class

This example shows how to define custom class for serialization.

public static class DocumentSignatureData
{
    public String getID(){ return ID; }
    public void setID(String value){ ID = value; }
    @FormatAttribute(propertyName = "SignID")
    public String ID;
 
 
    public final String getAuthor(){ return Author; }
    public final void setAuthor(String value){ Author = value; }
    @FormatAttribute(propertyName = "SAuth")
    public String Author;
    //JAVA-added public wrapper for internalized property accessor
 
    public final java.util.Date getSigned() {  return Signed; }
    public final void setSigned(java.util.Date value) { Signed = value; }
    @FormatAttribute (propertyName = "SDate",propertyFormat = "yyyy-MM-dd")
    public java.util.Date Signed = new java.util.Date();
 
 
    public final java.math.BigDecimal getDataFactor() { return DataFactor; }
    public final void setDataFactor(java.math.BigDecimal value) { DataFactor = value; }
    @FormatAttribute (propertyName = "SDFact",propertyFormat = "N2")
    public java.math.BigDecimal DataFactor = new java.math.BigDecimal(0.01);
}

Search for embedded custom objects in QR-code signatures

This example shows how to decrypt previously embedded encrypted custom objects into QrCodeSignature contains method getData to retrieve object

Signature signature = new Signature("signed.pdf");
// create data encryption
IDataEncryption encryption = new CustomXOREncryption();
 
QrCodeSearchOptions options = new QrCodeSearchOptions();
 
// specify special pages to search on
options.setAllPages(true);
options.setDataEncryption(encryption);
 
 
// search for signatures in document
List<QrCodeSignature> signatures = signature.search(QrCodeSignature.class,options);
System.out.print("\nSource document contains following signatures:");
for (QrCodeSignature qrCodeSignature : signatures)
{
    System.out.print("QRCode signature found at page "+qrCodeSignature.getPageNumber()+" with type "+ qrCodeSignature.getEncodeType());
    DocumentSignatureData documentSignatureData = qrCodeSignature.getData(DocumentSignatureData.class);
    if (documentSignatureData != null)
    {
        System.out.print("QRCode signature has DocumentSignatureData object:\n ID = " + documentSignatureData.getID() + ", Author = " + documentSignatureData.getAuthor() + ", Signed = " + documentSignatureData.getSigned() + ", DataFactor "+documentSignatureData.getDataFactor());
    }
}

More resources

GitHub Examples 

You may easily run the code above and see the feature in action in our GitHub examples:

Free Online App 

Along with full-featured .NET library we provide simple, but powerful free Apps.
You are welcome to eSign PDF, Word, Excel, PowerPoint documents with free to use online GroupDocs Signature App.

© Aspose Pty Ltd 2001-2022. All Rights Reserved.