Evals / pdf / Security and redaction

Remove a password I know

locked.pdf has the password hunter2. Save an unprotected copy as unlocked.pdf.

normaledgeencrypteddeft pdf decrypt

The task

The reference answer shows the job can be done with deft. It is not an agent run.

deft pdf decrypt locked.pdf --password hunter2 -o unlocked.pdf

Input

locked.pdf 1020 B

This PDF has no preview: it needs a password or cannot be read.

Reference output

unlocked.pdf 940 B · 2 pages
Page 1Page 2
How a result is judged (2 checks)
  • pdf_pages: file = "unlocked.pdf", pages = 2
  • pdf_encrypted: file = "unlocked.pdf", encrypted = false

Runs

CodexWithout deftPassed2026-11-07

Time
13s
New tokens
6.5k
Total input
54.1k
Output tokens
0.4k
Commands
3
Failed
1

Trace

  1. I’ll decrypt `locked.pdf` with the supplied password and write `unlocked.pdf` in the current directory.

  2. pwd && ls -l locked.pdf && (qpdf --password='hunter2' --decrypt locked.pdf unlocked.pdf || pdftk locked.pdf input_pw hunter2 output unlocked.pdf) (exit 127)
    output
    -rw-r--r--@ 1 user  staff  1020 Nov  5 21:11 locked.pdf
zsh:1: command not found: qpdf
zsh:1: command not found: pdftk
  3. file locked.pdf && which gs mutool python3 openssl || true && python3 -c \"import importlib.util; print({m: bool(importlib.util.find_spec(m)) for m in ['pypdf','PyPDF2','fitz']})\" && ls -l
    output
    locked.pdf: PDF document, version 1.7, 2 pages
/usr/local/bin/gs
mutool not found
/usr/local/bin/python3
/usr/bin/openssl
{'pypdf': False, 'PyPDF2': False, 'fitz': False}
total 8
-rw-r--r--@ 1 user  staff  1020 Nov  5 21:11 locked.pdf

  4. `qpdf` and `pdftk` aren’t installed, so I’m using the available Ghostscript PDF writer to create the decrypted copy.

  5. gs -q -dBATCH -dNOPAUSE -sDEVICE=pdfwrite -sPDFPassword=hunter2 -sOutputFile=unlocked.pdf locked.pdf && ls -l unlocked.pdf && file unlocked.pdf
    output
    -rw-r--r--@ 1 user  staff  2805 Nov  6 17:23 unlocked.pdf
unlocked.pdf: PDF document, version 1.7, 2 pages

  6. Created the unprotected copy at [unlocked.pdf](unlocked.pdf).

Output

unlocked.pdf 2.7 KB · 2 pages
Page 1Page 2

CodexWith deft, skill installedPassedRead the skillUsed deft2026-11-07

Time
15s
New tokens
5.4k
Total input
72.7k
Output tokens
0.5k
Commands
4
Failed
0

Trace

  1. I’ll use the `deft` skill for this PDF file operation, then save the unlocked copy in the current directory.

  2. cat .agents/skills/deft/SKILL.md 2>/dev/null || cat ../.agents/skills/deft/SKILL.md 2>/dev/null || true pwd rg --files -g 'locked.pdf' -g 'unlocked.pdf' -g 'AGENTS.md' -g 'SKILL.md' .
    output
    ---
name: deft
description: "Use deft instead of writing a script for file jobs: PDF merge/split/compress/watermark, image resize/convert/compress, video and audio trim/convert/compress, spreadsheets, Markdown to PDF/HTML, and YouTube downloads and subtitles."
---

# deft

One local command for file jobs. Prefer it over writing Python or shell scripts.

Syntax: `deft <group> <command> [inputs] [-o output] [--options]`

Groups:
- `pdf`: Merge, split, compress, encrypt, forms, OCR, compare, convert
- `image`: Resize, crop, convert, compress, filters, montage, OCR
- `video`: Trim, crop, speed, convert, compress, GIF, frames (ffmpeg)
- `audio`: Convert, trim, merge, fade, speed, tag, normalize (ffmpeg)
- `doc`: Word/ODT/RTF: to text, Markdown, HTML, PDF; find and replace
- `slides`: PowerPoint: extract text, Markdown outline, PDF handout
- `data`: JSON/YAML/TOML/XML: convert, query with jq syntax, merge, diff
- `sheet`: Excel/CSV/ODS tables: filter, sort, join, pivot, convert
- `md`: Markdown to PDF, HTML, Word, EPUB; table of contents
- `html`: HTML to Markdown, text, Word, PDF; screenshots
- `epub`: E-books: info, to text, Markdown and PDF
- `email`: EML files: headers, text, attachments
- `contact`: VCF address books: to and from CSV
- `calendar`: ICS calendars: to and from CSV
- `gps`: GPX and KML tracks: convert, distance and time
- `youtube`: Info, download, audio, subtitles, thumbnail (yt-dlp)
- `file`: Any file: hash, duplicates, batch rename, base64, encoding
- `qr`: Cre
… 742 more characters
  3. deft pdf
    output
    deft pdf - commands (input -> output)
  info            pdf -> report       Pages, size, metadata, fonts, images
  compare         pdf... -> report    Compare two PDFs: text and pixels
  compress        pdf -> pdf          Make smaller: --level, --target-size 2MB
  crop            pdf -> pdf          Trim pages: --margin, --box, --auto
  decrypt         pdf -> pdf          Remove a password you know
  delete          pdf -> pdf          Remove pages: --pages 2,5-7
  encrypt         pdf -> pdf          Protect with a password (AES-256)
  extract-images  pdf -> image...     Save embedded pictures, unchanged
  extract-sheets  pdf -> csv|xlsx...  Save each table apart [beta]
  fields          pdf -> report       List form fields
  fill            pdf -> pdf          Fill a form from JSON: --data values.json
  flatten         pdf -> pdf          Bake forms into pages
  from-images     image... -> pdf     One page per image
  from-md         md -> pdf           Typeset Markdown as PDF
  grayscale       pdf -> pdf          Remove colour (Ghostscript)
  merge           pdf... -> pdf       Join PDFs in the given order
  meta            pdf -> pdf          Read or set metadata and bookmarks
  number          pdf -> pdf          Add page numbers: --format
  ocr             pdf -> pdf|txt      Make a scan searchable
  redact          pdf -> pdf          Black out for good: --box or --text
  repair          pdf -> pdf          Rebuild a damaged PDF (Ghostscript)
  resize          pdf -> p
… 892 more characters
  4. deft pdf decrypt --help
    output
    deft pdf decrypt - Remove a password you know

Usage: deft pdf decrypt <pdf>... [-o <pdf|dir>] [options]
In: pdf (each handled separately)   Out: pdf (default <name>.decrypted.<ext>)
Files with an empty user password need no --password.

Options:
  --password <text>            Password of an encrypted input
Common: -o --force --dry-run --json -j   (deft help common)

Examples:
  deft pdf decrypt report.pdf -o open.pdf
Errors: INPUT_ENCRYPTED
  5. deft pdf decrypt locked.pdf --password hunter2 -o unlocked.pdf
    output
    ok pdf.decrypt locked.pdf -> unlocked.pdf  940B  0.00s

  6. Saved the unprotected copy as [unlocked.pdf](unlocked.pdf).

Output

unlocked.pdf 940 B · 2 pages
Page 1Page 2

CodexWith deft, skill as AGENTS.mdPassed2026-11-05

Time
15s
New tokens
10.5k
Total input
108.6k
Output tokens
0.4k
Commands
6
Failed
2

Trace

  1. I’ll check the local PDF command options, then remove the password protection and save the copy in this directory.

  2. deft pdf --help
    output
    deft pdf - commands (input -> output)
  info         pdf -> report      Pages, size, metadata, fonts, images
  compress     pdf -> pdf         Make a PDF smaller: --level, --target-size 2MB
  delete       pdf -> pdf         Remove pages: --pages 2,5-7
  from-images  image... -> pdf    One page per image, in the given order
  from-md      md -> pdf          Typeset a PDF with headings, tables, code, images
  merge        pdf... -> pdf      Join PDFs in the given order
  number       pdf -> pdf         Add page numbers: --format "{n} of {total}"
  rotate       pdf -> pdf         Turn pages clockwise: --angle 90, --pages
  select       pdf -> pdf         Keep and reorder pages: --pages 3,1-2
  split        pdf -> pdf...      One file per page, or --every N, --ranges 1-3,4-
  to-images    pdf -> png|jpg...  Render pages to images: --dpi, --pages
  to-text      pdf -> txt         Extract text (form feed between pages)
  watermark    pdf -> pdf         Stamp text or an image on pages: --text, --image
More: deft pdf <command> --help
  3. deft find "remove PDF password protection decrypt unlock"
    output
    pdf delete    pdf -> pdf       Remove pages: --pages 2,5-7
image to-pdf  image... -> pdf  One page per image, in the given order
md to-pdf     md -> pdf        Typeset a PDF with headings, tables, code, images
  4. ls -l locked.pdf && command -v qpdf && qpdf --help=--decrypt (exit 1)
    output
    -rw-r--r--@ 1 user  staff  1020 Nov  4 19:32 locked.pdf
  5. command -v pdftk; command -v mutool; command -v gs; python3 -c 'import pypdf; print(pypdf.__version__)' (exit 1)
    output
    /usr/local/bin/gs
Traceback (most recent call last):
  File "<string>", line 1, in <module>
    import pypdf; print(pypdf.__version__)
    ^^^^^^^^^^^^
ModuleNotFoundError: No module named 'pypdf'
  6. gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sPDFPassword=hunter2 -sOutputFile=unlocked.pdf locked.pdf
  7. ls -l unlocked.pdf
    output
    -rw-r--r--@ 1 user  staff  2805 Nov  4 20:02 unlocked.pdf

  8. Saved the unprotected copy as [unlocked.pdf](unlocked.pdf).

Output

Its files were not kept in this run. The last line of the trace is its own report.

Claude Opus 5.5Without deftPassed2026-11-07

Time
113s
New tokens
26.2k
Total input
184.5k
Output tokens
7.6k
Commands
0
Failed
0

Trace

    Output

    decrypt_pdf.py 5.4 KB
    import hashlib, struct, sys

PAD = bytes([0x28,0xBF,0x4E,0x5E,0x4E,0x75,0x8A,0x41,0x64,0x00,0x4E,0x56,0xFF,0xFA,
             0x01,0x08,0x2E,0x2E,0x00,0xB6,0xD0,0x68,0x3E,0x80,0x2F,0x0C,0xA9,0xFE,
             0x64,0x53,0x69,0x7A])

def rc4(key, data):
    S = list(range(256)); j = 0
    for i in range(256):
        j = (j + S[i] + key[i % len(key)]) & 0xff
        S[i], S[j] = S[j], S[i]
    out = bytearray(); i = j = 0
    for b in data:
        i = (i + 1) & 0xff
        j = (j + S[i]) & 0xff
        S[i], S[j] = S[j], S[i]
        out.append(b ^ S[(S[i] + S[j]) & 0xff])
    return bytes(out)

def parse_literal_string(buf, start):
    # buf[start] == ord('(') ; returns (bytes, index_after_closing_paren)
    assert buf[start:start+1] == b'('
    i = start + 1; depth = 1; out = bytearray()
    while i < len(buf):
        c = buf[i]
        if c == 0x5c:  # backslash
            n = buf[i+1]
            simple = {0x6e:0x0a,0x72:0x0d,0x74:0x09,0x62:0x08,0x66:0x0c,
                      0x28:0x28,0x29:0x29,0x5c:0x5c}
            if n in simple:
                out.append(simple[n]); i += 2
            elif 0x30 <= n <= 0x37:  # octal, up to 3 digits
                j = i + 1; oct_digits = b''
                while j < len(buf) and len(oct_digits) < 3 and 0x30 <= buf[j] <= 0x37:
                    oct_digits += buf[j:j+1]; j += 1
                out.append(int(oct_digits, 8) & 0xff); i = j
            elif n in (0x0a,):  # line continuation
                i += 2
            elif n == 0x0d:
                i += 3 if buf[i+2:i+3] == b'\n' else 2
            else:
                out.append(n); i += 2
        elif c == 0x28:
            depth += 1; out.append(c); i += 1
        elif c == 0x29:
            depth -= 1
            if depth == 0:
                return bytes(out), i + 1
            out.append(c); i += 1
        else:
            out.append(c); i += 1
    raise ValueError("unterminated string")

def find_key_string(buf, enc_obj_region, key):
    idx = buf.index(key, *enc_obj_region)
    # skip whitespace to '('
    j = idx + len(key)
    while buf[j:j+1] in (b' ', b'\n', b'\r', b'\t'):
        j += 1
    s, _ = parse_literal_string(buf, j)
    return s

data = open('locked.pdf', 'rb').read()
password = b'hunter2'

# Locate Encrypt object (10 0 obj)
enc_start = data.index(b'10 0 obj')
enc_end = data.index(b'endobj', enc_start)
O = find_key_string(data, (enc_start, enc_end), b'/O')
U = find_key_string(data, (enc_start, enc_end), b'/U')
# P value
p_idx = data.index(b'/P', enc_start, enc_end)
p_str = data[p_idx+2:enc_end].split(b'>>')[0].strip().split()[0]
P = int(p_str)
assert len(O) == 32, len(O)

# File ID (first element of /ID array in trailer / xref stream dict)
id_idx = data.index(b'/ID[')
id1, _ = parse_literal_string(data, data.index(b'(', id_idx))
print("O len", len(O), "U len", len(U), "P", P, "ID1", id1, file=sys.stderr)

n = 128 // 8  # 16
# Algorithm 3.2 (R3)
m = hashlib.md5()
m.update((password + PAD)[:32])
m.update(O)
m.update(
… 2526 more characters
    unlocked.pdf 903 B · 2 pages
    Page 1Page 2

    Claude Opus 5.5With deft, skill installedPassedRead the skillUsed deft2026-11-07

    Time
    12s
    New tokens
    9.9k
    Total input
    59.5k
    Output tokens
    0.4k
    Commands
    0
    Failed
    0

    Trace

      Output

      .claude/skills/deft/SKILL.md 2.1 KB
      ---
name: deft
description: "Use deft first for any simple, direct operation on local files, whatever the type: convert, read, extract, edit, compress, merge, split, compare or inspect. Try it before writing a script or one-liner. If unsure, run deft find; if it says no command does this, use another tool. Not for programming work: to read, write or change source code, skip it."
---

# deft

One local command for file jobs. Prefer it over writing Python or shell scripts.

Syntax: `deft <group> <command> [inputs] [-o output] [--options]`

Groups:
- `pdf`: Merge, split, compress, encrypt, forms, OCR, compare, convert
- `image`: Resize, crop, convert, compress, adjust, montage, OCR
- `video`: Trim, merge, convert, compress, subtitles, GIF, frames (ffmpeg)
- `audio`: Convert, trim, normalize, denoise, cut silence (ffmpeg)
- `doc`: Word/ODT/RTF: to text, Markdown, HTML, PDF; find and replace
- `slides`: PowerPoint: extract text, Markdown outline
- `sheet`: Excel/CSV/ODS tables: SQL query, pivot, merge, split, convert
- `json`: JSON: convert, format, merge, diff, validate
- `toml`: TOML: convert, format, merge, diff, validate
- `xml`: XML: convert, format, merge, diff, validate
- `yaml`: YAML: convert, format, merge, diff, validate
- `md`: Markdown to PDF, HTML, Word, EPUB; table of contents
- `html`: HTML to Markdown, text, Word and PDF
- `epub`: E-books: info, to text, Markdown and PDF
- `gps`: GPX and KML tracks: convert, distance and time
- `qr`: Create QR codes and barcodes; read QR codes

How to use it:
1. Run `deft <group>` to list commands, or `deft find "<what you want>"` to search. If it says `no command does this`, use another tool.
2. Run `deft <group> <command> --help` for options and examples.
3. `deft convert <in> -o <out.ext>` converts between formats by extension.
4. Results are one line starting with `ok`, `partial` or `error`; add `--json` to parse them. Errors include a `hint:` with the fix.

Inputs are never overwritten; pass `--force` or `--in-place` to allow it. Globs and directories work as inputs; several inputs run in parallel.

If `deft` is not installed, ask the user, then follow https://github.com/firstprayer/deft/blob/main/docs/INSTALL.md
      unlocked.pdf 940 B · 2 pages
      Page 1Page 2

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