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Forensic check

HTPBE_PROPRIETARY_SIGNAL

HTPBE_PROPRIETARY_SIGNAL appears on 0.7% of modified results in our corpus. A marker is evidence about the file, not a judgement about the person who sent it.

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Marker profile

Structural Integrity

An additional integrity finding whose method is not disclosed.

Share of modified results
0.7%
Frequency rank
#29
Among the 56 markers seen in modified results
Certain confidence
84.5%
Of results with this marker rated certain rather than high
Fires alone
29.6%
Results where it is the only marker found

Marker profile

What HTPBE_PROPRIETARY_SIGNAL tells you

HTPBE_PROPRIETARY_SIGNAL is one of the named findings returned in modification_markers when a PDF is reported as modified. It belongs to the Structural Integrity group of checks. These checks look at whether the internal layout of the file is consistent with the file having been left untouched since it was finalised.

On 29.6% of the modified results that carry HTPBE_PROPRIETARY_SIGNAL it is the only marker. A result with this marker carries 3.4 markers on average. It is most often found together with HTPBE_DATES_DISAGREE, on 47.9% of these results.

Example API response

How it appears in a result

When a PDF is reported as modified, HTPBE_PROPRIETARY_SIGNAL is listed in modification_markers next to the verdict and its confidence. Each marker is a named, actionable finding – not a score.

GET /api/v1/result/{id}
{
  "id": "9f3a2c1d-8b47-4e6f-a012-3d5e7f890123",
  "status": "modified",
  "modification_confidence": "high",
  "modification_markers": [
    "HTPBE_PROPRIETARY_SIGNAL"
  ],
  "creator": "Adobe Acrobat Pro DC",
  "has_incremental_updates": true,
  "page_count": 3
}

Full schema in the API reference →

Distributions

What ships alongside HTPBE_PROPRIETARY_SIGNAL

The tools, formats and document traits that appear on the modified results carrying this marker. Shares are of those results.

Common Producers

iText writes 14.1% of these results – and 1.0% of all modified results naming it carry this marker.

iText1.0% of its modified14.1%
Adobe Acrobat6.6% of its modified12.7%
Adobe PDF Library2.4% of its modified9.9%
PDFOUT3.0% of its modified5.6%
Acrobat Distiller1.5% of its modified4.2%
Microsoft Reporting Services3.2% of its modified4.2%
Microsoft Word0.4% of its modified4.2%

Common Creators

Microsoft Word is the Creator on 18.3% of these results.

Microsoft Word1.2% of its modified18.3%
Adobe Acrobat6.9% of its modified12.7%
Acrobat PDFMaker13.2% of its modified9.9%
ADP3.5% of its modified7.0%
Adobe Photoshop10.8% of its modified5.6%
JasperReports2.3% of its modified4.2%
Microsoft Reporting Services0.9% of its modified4.2%
PScript51.8% of its modified4.2%

Often found together with

HTPBE_DATES_DISAGREE sits next to HTPBE_PROPRIETARY_SIGNAL more often than any other marker.

Document origin

Institutional57.7%
Consumer software31.0%
Scanned5.6%
Unknown4.2%

Creator → Producer pairs

Adobe Acrobat → Adobe Acrobat12.7%
Acrobat PDFMaker → Adobe PDF Library9.9%
ADP → PDFOUT5.6%
Microsoft Reporting Services → Microsoft Reporting Services4.2%
Microsoft Word → Microsoft Word4.2%
PScript5 → Acrobat Distiller4.2%

Detected origin software

Microsoft Word18.3%
Adobe Photoshop5.6%

Confidence of the verdict

Certain84.5%
High15.5%

When these results were checked

June 20267.0%
July 202639.4%
August 20267.0%
September 20268.5%
October 202638.0%

Document length

1 page53.5%
2–5 pages45.1%
21–100 pages1.4%

File size

Under 100 KB25.4%
100 KB – 1 MB71.8%
1 – 5 MB2.8%

PDF versions

PDF 1.638.0%
PDF 1.732.4%
PDF 1.419.7%
PDF 1.55.6%
PDF 1.34.2%

Year the document says it was created

202691.5%

Long tail

Notable observations

Smaller cuts of the results carrying HTPBE_PROPRIETARY_SIGNAL – useful context, but treat each row as a single data point rather than a strong signal.

Digitally signed
5.6%

Of files carry at least one digital signature

Saved revisions
29.6%

Of files contain earlier saved revisions

Embedded JavaScript
0%

Of files contain JavaScript code

Embedded files
7.0%

Of files have attachments inside

Avg pages per document
2.1
Markers per result
3.4

Average number of markers on these results

Related checks

Other Structural Integrity checks

Checks from the same group. Each card links to its own reference page.

HTPBE_NAVIGATION_TABLE_MISMATCHInternal file structure showing signs of tampering
Share of modified0.5%
HTPBE_DECLARED_SIZE_MISMATCHFile layout altered after the file was finalised
Share of modified0.8%
Seen together26.8%
HTPBE_TRAILING_BYTES_AFTER_EOFUnexplained data added to the file after it was finalised
Share of modified0.2%

FAQ

HTPBE_PROPRIETARY_SIGNAL: common questions

What does HTPBE_PROPRIETARY_SIGNAL mean?

HTPBE_PROPRIETARY_SIGNAL is a named finding in an HTPBE? result: an additional integrity finding whose method is not disclosed. It is returned in the modification_markers list of a modified result and belongs to the Structural Integrity group of checks.

Does HTPBE_PROPRIETARY_SIGNAL mean the document is fake?

No. A marker is evidence about the file, not a judgement about the person who sent it. It records that the file shows this pattern; it does not say why, and it does not assess what the document states. Read it together with the verdict and any other markers on the same result.

What should I do when a result contains HTPBE_PROPRIETARY_SIGNAL?

Ask the sender for the original file straight from the issuing system, or request a fresh copy from the issuer. Check whether the document went through a later step such as re-saving, merging or converting, and verify it with the issuer before relying on it for a decision.

How common is HTPBE_PROPRIETARY_SIGNAL?

HTPBE_PROPRIETARY_SIGNAL appears on 0.7% of the modified results in the HTPBE? corpus. The corpus consists of PDFs people chose to submit for checking, so it skews towards documents someone had a reason to doubt and is not a sample of all PDFs.

Where do I see HTPBE_PROPRIETARY_SIGNAL?

In the modification_markers list of the result returned by the HTPBE? API, and on the result page of a modified document. Other checks in the Structural Integrity group are listed below on this page; all 63 checks are listed on the how-it-works page.

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