Digital Signature
PDF Digital Signature
A cryptographic mechanism embedded in a PDF to verify document authenticity and integrity.
Technical Detail
In the PDF specification (ISO 32000-2:2020), digital signature is implemented as a specialized object within the document's object graph. PDF files use a cross-reference table to index every object by byte offset, enabling random access without sequential parsing. This architecture allows digital signature to be read, modified, or extracted independently of other document elements. The binary structure supports incremental saves, where changes append to the file without rewriting existing content.
Example
```javascript
// Digital Signature: PDF manipulation example
import { PDFDocument } from 'pdf-lib';
const pdfDoc = await PDFDocument.load(fileBytes);
const pages = pdfDoc.getPages();
console.log(`Pages: ${pages.length}`);
```
Related Formats
Related Tools
M
Merge PDF
S
Split PDF
C
Compress PDF
R
Rotate PDF
A
Add Page Numbers
P
PDF to JPG
W
Watermark PDF
R
Reorder PDF Pages
F
Flatten PDF
E
Edit PDF Metadata
S
Sign PDF
J
JPG to PDF
E
Extract Text from PDF
D
Delete PDF Pages
R
Reverse PDF
E
Extract PDF Pages
E
Extract Odd/Even Pages
R
Resize PDF Pages
C
Crop PDF
I
Insert Blank Pages
D
Duplicate PDF Pages
P
PDF to PNG
A
Add Header & Footer
A
Add Text to PDF
A
Add Image to PDF
Related Terms
AcroForm
Annotation
Bates Numbering
Bookmark
Color Management (PDF)
Content Stream
Cross-Reference Table
Document Catalog
Encryption
File Signature
Flattening
Font Embedding
Form Field
Incremental Save
Linearization
OCR
Page Tree
PDF
PDF/A
PDF/E
PDF Layers
PDF Optimizer
PDF Portfolio
PDF Redaction
PDF Signature
PDF/UA
PDF/VT
PDF/X
Redaction
Tagged PDF
Watermark
XFA