Help center
How can we help?
Help with signing PDFs, saved signatures, stamps, and local digital proof on iPhone and iPad.
Contact support
Tell us what happened and which screen you were using. Include your app version, iPhone or iPad model, and iOS version. Send a screenshot with sensitive information hidden; avoid sending private documents or signature images unless needed for the issue.
CachaDigital@outlook.comSign your first PDF
- Create your signature. Open My signatures → New signature. Draw with your finger or Apple Pencil, or choose Import image. Enter a name and tap Save signature.
- Choose a document. From Home, tap Sign a document → Choose from Files. Select an unlocked PDF.
- Place your marks. In the editor, choose Signature or Stamp, find the right spot, and tap Place here. You can move, resize, and rotate placed elements, or add text and dates.
- Sign and save. Tap Sign and authenticate and authorize with Face ID, Touch ID, or your device passcode. The signed copy appears in Documents.
- Share the result. Open the saved document and use the share menu. Choose the PDF alone for its visual appearance, or PDF and digital proof so the recipient can verify integrity.
Frequently asked questions
Do I need an account or internet connection?
No account is required, and signing works locally. Importing a file from a cloud storage provider or sending it through another app may require internet access.
How do I change the language?
Open Settings → Language and choose English, Español, or Device language. The choice is saved. Custom names and existing PDF content are not translated.
Why can’t I open a PDF?
The PDF may be locked, empty, or unsupported. Some PDFs restrict printing, which prevents creating a signed copy. Try an unlocked PDF that permits printing.
Why can’t I sign?
Configure a device passcode and allow authentication. Place at least one signature or stamp. If an element is waiting to be placed, tap Place here or cancel its placement before signing.
How do I verify a received document?
In Settings → Verify PDF and digital proof, choose the PDF and its accompanying .cachasign.json file, then tap Verify integrity. Both files must belong to the same signed result. Editing the PDF after signing makes its original proof no longer match.
What does the digital proof establish?
It checks that the PDF matches its proof and the signing key. The certificate is local and self-signed; it does not establish a person’s identity through an external certificate authority. Compare the certificate fingerprint with the signer through a trusted channel. The date comes from the device, without an external timestamp service. This version does not embed PAdES signatures or import .p12/.pfx certificates.
Does the PDF alone include the digital proof?
No. The PDF retains the visual signatures and stamps. To verify the local digital proof, share and keep the separate .cachasign.json file with the PDF.
Where are my files and signing keys stored?
The library is stored on your device. Cacha Sign provides no server storage or app-managed cloud synchronization. Signing keys are protected by device security and do not migrate to another device. Copies exported to Files or sent through other services are managed separately.
How do I delete signatures, stamps, or documents?
Use Delete in the corresponding library. Deleting an item in Cacha Sign does not remove copies you already exported or shared. Manage those copies in their destination app or service.
Cacha Sign 0.6 · Requires iOS 17 or later.