Step 1: reading the file
When you drop a file onto the viewer, the browser hands the page a reference to it. The page reads the bytes into memory with the standard File API. Nothing is transmitted; the bytes move from your disk to a browser tab.
Step 2: unpacking the ZIP
An .asice container is a ZIP archive. The viewer reads the archive's directory, finds mimetype and the entries under META-INF, and decompresses individual files only when they are needed. A large PDF is not unpacked until you click it.
Step 3: reading the signatures
Each signatures*.xml file is parsed with the browser's built-in XML parser. From it the viewer extracts:
- the signer's certificate, decoded from its ASN.1 structure to get the name, personal code, issuer and validity period;
- the signing time and, if present, the time stamp;
- the role and place the signer entered;
- the list of signed files with a digest for each.
Step 4: checking integrity
For every signed file the viewer computes a fresh digest (usually SHA-256) through the Web Crypto API and compares it with the value in the signature. A match means the file is exactly what was signed. A mismatch produces a red warning that names the file.
Step 5: rendering the document
| Document type | How it is displayed |
|---|---|
| Rendered page by page onto a canvas | |
| DOCX | Converted to HTML in the browser |
| XLSX, XLS, ODS, CSV | Shown as a table, one tab per sheet |
| Images, audio, video | Native browser elements |
| Text, XML, JSON | Decoded and formatted |
What this design means for you
Because there is no server step, there is no queue, no size quota set by a provider and no copy of your contract on someone else's disk. The limit is your device's memory. The trade-off is that an online viewer cannot do what needs a trusted server or a smart card. See what an online viewer can and cannot do.
Frequently asked questions
Which browsers can run an ASiC-E online viewer?
Any current version of Chrome, Edge, Firefox, Safari, Opera or Samsung Internet. JavaScript must be enabled.
Is the viewer's code loaded from third parties?
No. ASiCE Viewer serves every library from its own domain and sets a content security policy that blocks other sources.