PaperCrypt

Printable Backup Documents

---

PaperCrypt is a Go-based command-line tool designed to enhance the security of your sensitive data through the generation of printable backup documents. These documents, referred to as "PaperCrypt" Documents, combine the robust encryption capabilities of the OpenPGP with the resilience and simplicity of a physical hardcopy. This ensures the confidentiality and integrity of your data, while also providing a physical backup that 's not susceptible to digital threats.

Please note that to decrypt the data from a PaperCrypt Document, you will need the original passphrase used during the encryption process. Treat this passphrase with care; if it is lost, the data will be irrecoverable.

Features

• Encryption: PaperCrypt utilizes the GopenPGP library to apply advanced cryptographic techniques, securing your data with industry-standard algorithms.

• PDF Generation: PaperCrypt can output PDF documents ready for printing, that include all the information needed to recover the encrypted data.

• Data Integrity: To verify the integrity of the data, PaperCrypt embeds checksums within the encrypted data section of its documents. This ensures that the data remains unaltered during backup and restoration processes.

• Offline Security: By generating printable backup documents, PaperCrypt offers an offline solution to safeguard your sensitive data against online threats, as well as an option to store your data in an off-site location. This provides a layer of security, as it ensures that your data remains safe and accessible even in the event of a catastrophic failure, malicious attack, or natural disaster.

Installation

Pre-built binaries

Pre-built binaries for PaperCrypt are available for download from the releases page.

The pre-built binaries are preferred over manual installation, as they include version information. The GitHub releases also included signatures for the binaries.

Homebrew (Linux, macOS)

brew tap TMUniversal/homebrew-tap
brew install papercrypt

Scoop (Windows)

Make sure you have scoop installed, alongside git (scoop install git) to be able to add the bucket.

scoop bucket add tmuniversal https://github.com/tmuniversal/scoop-bucket.git
scoop install papercrypt

From source (manual)

1. Install Go: Ensure you have Go installed. If not, you can download it from here.

2. Clone the Repository: Clone the repository to your local machine:

git clone https://github.com/TMUniversal/papercrypt.git

3. Navigate to the Directory:

cd papercrypt

4. Build the binary:

Build using task:

task build

or through goreleaser:

goreleaser build --snapshot --clean --single-target

From source (go install)

This method is not recommended, as it won't include the version information in the binary.

1. Ensure Go is installed: See step 1 from manual installation.
2. Install PaperCrypt: Run the following command to install PaperCrypt:

go install github.com/tmuniversal/papercrypt/v2@latest

Running with Docker

You can also run PaperCrypt using Docker, with the following command:

docker run --rm -it -v $(pwd):/data ghcr.io/tmuniversal/papercrypt:latest

With -v $(pwd):/data mounting the current working directory as /data in the container, allowing the container to read and write to host storage.

On Windows, the command is slightly different:

docker run --rm -it -v ${PWD}:/data ghcr.io/tmuniversal/papercrypt:latest

Note that -t is required so that the program can prompt for a passphrase.

Verifying artifacts

First, you'll need to download the archive and signature file (.sig) for your version from the releases page, pay attention to the version (papercrypt version), your OS and architecture. You will also need the public key (cosign.pub).

The pre-built binaries are signed through cosign.

To verify the signature, you can run the following command:

cosign verify-blob \
  --key cosign.pub \
  --signature papercrypt_$(uname -s)_$(uname -m).tar.gz.sig \
  papercrypt_$(uname -s)_$(uname -m).tar.gz

and for Windows:

cosign verify-blob \
  --key cosign.pub \
  --signature papercrypt_Windows_x86_64.zip.sig \
  papercrypt_Windows_x86_64.zip

Usage

General notes:

• --in and --out can be omitted, in which case stdin and stdout are used.
• This means papercrypt decode --in - --out - < qr.txt > data.json is equivalent to papercrypt decode < qr.txt > data.json
• Commands, as well as their flags, can be abbreviated to their shortest unique prefix:
  • papercrypt generate can be abbreviated to papercrypt g
• that is papercrypt generate --in data.json --out output.pdf can be abbreviated to papercrypt g -i data.json -o output.pdf

Generating a key phrase

A 24 word mnemonic phrase is suitable for real-world use, but you can use any string of words or characters.

Generate one with your tool of choice, you can run:

papercrypt generate-key --words 24 --out mnemonic.txt

to generate a 24 word mnemonic phrase.

The passphrase sheet

PaperCrypt is able to generate a printable Phrase Sheet, which is a two-page document containing 135 words from the EFF large word list, chosen with a seeded random number generator.

If no seed is passed to the command, one will be generated using the system's entropy source.

Example:

papercrypt phrase-sheet --out phrase-sheet.pdf ExampleAbcA=

Here, ExampleAbcA= is the base64-encoded seed, which is used to generate the word list. The seed will is also present on the generated PDF document, so you can regenerate the same word list later, even if you allowed the seed to be chosen at random.

Using the phrase sheet, you can select a number of words from to form your mnemonic phrase.

Generating a PaperCrypt document

Save your data as a file, data.json, for example:

{
  "prop": "value",
  "another_property": "another_value",
  "a_number": 123,
  "a_boolean": true,
  "an_array": ["a", "b", "c"],
  "an_object": {
    "another_property": "another_value"
  }
}

Then, run

papercrypt generate --in data.json --out output.pdf

to generate the file containing your data, and the decryption instructions.

The program then asks you for an encryption key, for which you can use your mnemonic phrase from earlier.

You can also pass the data through stdin, simply omit the --in flag. The caveat is that, when on Windows, you can't be prompted for your passphrase, so you would have to pass it with the --passphrase flag.

Please see the examples directory for the generated PDF files.

Restoring a PaperCrypt document

To restore your data from a PaperCrypt document, you must first re-construct the document from the printed copy. This can be done either by saving the QR code as an image file, and passing it to the command-line, or by copy-pasting the text from the printed document (would have to run OCR).

Using the QR code

Save the 2D code as an image file (a screenshot should do), for example 2d.png.

Then, run

papercrypt scan --in 2d.png --out data.txt

Decoding from text

Once you have the text from the printed document,

Click to expand

which should look something like this:

# PaperCrypt Version: 2.0.0
# Content Serial: EIPESR
# Purpose: Example Sheet
# Comment: Regular PDF Example
# Date: Thu, 01 Aug 2024 20:38:10.306596100 +0200
# Data Format: PGP
# Content Length: 390
# Content CRC-24: d6f1c0
# Content CRC-32: bc4b3672
# Content SHA-256: NT7wwW5Tq5fk1J82M1tzE82VGxIlad5vpF5cDMzg+yg=
# Header CRC-32: ecded03b


 1: 1F 8B 08 00 00 00 00 00 02 FF 00 6A 01 95 FE C3 2E 04 09 03 08 7A D49E51
 2: 7D 43 1C 18 E4 C9 19 E0 23 B0 2A D5 58 E1 72 93 E0 06 BB F2 7E C8 D183B9
 3: 2F C9 00 C8 90 6D 83 04 E9 22 FB 07 98 BB 4D 68 CE 04 96 D2 C0 77 730736
 4: 01 01 8D 41 D1 46 E3 82 11 09 E7 15 77 1C EB 92 26 FE 5A B2 84 C3 462812
 5: B4 98 DC D2 27 C1 B1 AF 22 B6 3B CB 95 DC D8 4D 0A 4E FF ED 8E A2 0B74A2
 6: DF C1 72 41 7F 08 AF 9C 43 EA 50 9C 43 30 84 4F F8 82 BC 62 4A 0E DFCF21
 7: 27 91 DF 15 9E 1C 3F 37 77 FB D2 E0 4A F1 73 3E 2D 7B 73 47 96 35 E94DF5
 8: 55 F9 A4 D2 7F 4C 24 4A 0B A1 04 1B 49 95 91 5C D0 6B E2 AF 2D AC 361154
 9: 98 E4 22 BB 62 61 BB 93 97 9A 04 4B 7B AC BF 86 7E 7B DE AB B3 83 9DD5D4
10: A9 66 F3 99 D7 94 2E 4E 72 E6 6D 09 35 11 68 A9 B7 6C EE 5E BC 3F E27CAE
11: E6 1B C7 5A 76 B0 B1 E5 DB 7A 56 13 23 DB 9C 23 8F 85 FF 72 60 56 252FD9
12: F4 26 17 EA 2E AE 05 D7 0F 02 78 A5 BE 3A 61 F0 39 EE 31 4F D6 E3 2ECC66
13: 7E 84 E6 99 D1 E7 71 CE 5D 34 6F A2 1D 66 74 1A 09 FC E2 81 91 AB 444B35
14: AC 88 A5 93 14 38 37 FD BA 49 5E B7 3F 33 55 D0 83 D8 2C 48 35 FF AE678F
15: 54 F5 38 85 EC C8 4E 37 03 B9 22 C7 50 58 7F BD 04 0C 8E EE 8B B9 B26C81
16: E4 6B C0 67 C6 18 54 0D F1 20 73 D8 FC 40 D3 D2 90 00 0F 84 7E BD C47477
17: 1D 67 D8 71 AD 2D D3 89 43 54 8A F5 33 CD 0E AF B0 80 08 29 68 59 E37012
18: 53 15 99 01 00 00 FF FF CC 08 E8 C8 6A 01 00 00 2436D9
19: D6F1C0

Note the two empty lines between the header and the data.

Decode and decompress the data:

papercrypt decode --in data.txt --out data.json

The command prompts for the encryption key, which you could specify with --passphrase|-P:

papercrypt decode -i data.txt -o data.json -P "super-secret-key"

Full pipeline

Contributing

Contributions to PaperCrypt are welcomed and encouraged! If you have suggestions for improvements, bug fixes, or new features, please feel free to submit a pull request. Refer to CONTRIBUTING.md for more information.

License

PaperCrypt is licensed under the terms of the GNU Affero General Public License, version 3.0 or later (GNU AGPL-3.0-or-later).

Acknowledgments

PaperCrypt is developed leveraging the power of Go and a suite of dependable open source libraries. We extend our gratitude to the developers behind GopenPGP, GoFPDF, and other foundational components.