Creating CBT Files

Creating CBT Files

This guide covers multiple methods for creating CBT (Comic Book TAR) files with or without encryption.

Method 1: Using the cbt.sh Bash Script (Recommended)

Prerequisites

• Bash shell (Linux/Mac/WSL)
• OpenSSL
• Standard Unix tools (tar, sha256sum, xxd)

Installation

The cbt.sh script is included in the scripts-bash/comic-scripts/ directory:

chmod +x scripts-bash/comic-scripts/cbt.sh

Creating Unencrypted CBT

./scripts-bash/comic-scripts/cbt.sh create -i /path/to/comic/images -o mycomic.cbt

Example:

./scripts-bash/comic-scripts/cbt.sh create -i ./my-comic-pages-folder -o amazing-comic.cbt

This will:

1. Create a TAR archive from all files in the directory
2. Save it as amazing-comic.cbt
3. Display list of files added

Creating Encrypted CBT

./scripts-bash/comic-scripts/cbt.sh create -i /path/to/comic/images -o mycomic.cbt -p "your-password"

Example:

./scripts-bash/comic-scripts/cbt.sh create -i ./my-comic-pages-folder -o secret-comic.cbt -p "super-secret-123"

This will:

1. Create a TAR archive
2. Encrypt it using AES-256-CFB
3. Save the encrypted CBT file

Extracting CBT Files

Unencrypted:

./scripts-bash/comic-scripts/cbt.sh extract -i mycomic.cbt -o ./extracted

Encrypted:

./scripts-bash/comic-scripts/cbt.sh extract -i secret-comic.cbt -o ./extracted -p "your-password"

Script Options

Usage:
  Create:  cbt.sh create -i <input_directory> -o <output_file> [-p <password>]
  Extract: cbt.sh extract -i <input_file> -o <output_directory> [-p <password>]

Options:
  -i    Input directory/file
  -o    Output file/directory
  -p    Password for encryption/decryption (optional)

Method 2: Using the cbt.go Program

Prerequisites

• Go 1.25.2 or higher

Building the Tool

go build -o cbt scripts-go/cbt.go

Creating Unencrypted CBT

./cbt -input /path/to/images -output mycomic.cbt

Example:

./cbt -input ./comic-pages-folder -output "My Amazing Comic.cbt"

Creating Encrypted CBT

./cbt -input /path/to/images -output mycomic.cbt -password "your-password"

Example:

./cbt -input ./comic-pages-folder -output "Secret Comic.cbt" -password "super-secret-123"

Program Options

Usage: cbt -input <directory> -output <file.cbt> [-password <password>]

Flags:
  -input string
        Input directory containing comic files
  -output string
        Output .cbt file
  -password string
        Password for encryption (leave empty for no encryption)

Method 3: Manual Creation with TAR

Creating Unencrypted CBT

cd /path/to/comic/images
tar -cf ../mycomic.cbt *

Creating Encrypted CBT Manually

1. Create TAR archive:

   tar -cf temp.tar *

2. Encrypt using OpenSSL:

   # Generate key from password
   KEY=$(echo -n "your-password" | sha256sum | cut -d' ' -f1)
   
   # Generate random IV
   openssl rand -out iv.bin 16
   
   # Encrypt
   openssl enc -aes-256-cfb -K "$KEY" -iv $(xxd -p -c 256 iv.bin) -in temp.tar -out temp.enc
   
   # Combine IV and encrypted data
   cat iv.bin temp.enc > mycomic.cbt
   
   # Cleanup
   rm temp.tar iv.bin temp.enc

Directory Structure Best Practices

Recommended Structure

comic-pages/
├── 001.jpg
├── 002.jpg
├── 003.jpg
├── ...
└── ComicInfo.xml

File Naming

Use zero-padded numbers for proper sorting:

• ✅ 001.jpg, 002.jpg, 003.jpg
• ❌ 1.jpg, 2.jpg, 3.jpg

Including ComicInfo.xml

Always include metadata for best results:

<?xml version="1.0" encoding="utf-8"?>
<ComicInfo>
    <Title>My Comic Title</Title>
    <Series>My Series</Series>
    <Number>1</Number>
    <Writer>Author Name</Writer>
    <Artist>Artist Name</Artist>
    <Publisher>Publisher</Publisher>
    <Genre>Action, Adventure</Genre>
    <Year>2024</Year>
    <PageCount>24</PageCount>
</ComicInfo>

Automated Workflow Scripts

Batch Creation Script

Create batch-cbt.sh:

#!/bin/bash

PASSWORD="your-default-password"

for dir in */; do
    dirname="${dir%/}"
    echo "Processing: $dirname"
    ./cbt.sh create -i "$dir" -o "${dirname}.cbt" -p "$PASSWORD"
done

echo "Batch creation complete!"

Usage:

chmod +x batch-cbt.sh
./batch-cbt.sh

Using with GPG-Encrypted Passwords

Store passwords securely with GPG:

#!/bin/bash

# Store password encrypted
echo "my-secret-password" | gpg -e -r your@email.com > password.gpg

# Use in script
PASSWORD=$(gpg -qd password.gpg)
./cbt.sh create -i ./comic -o comic.cbt -p "$PASSWORD"

Testing Your CBT Files

Test with Gopherbook

1. Upload to Gopherbook via web UI
2. Or place in watch folder:

   cp mycomic.cbt ./watch/[username]/

Test Encryption

# Should fail if encrypted
tar -tf mycomic.cbt

# Should succeed if unencrypted
tar -tf mycomic.cbt

Test Extraction

./cbt.sh extract -i mycomic.cbt -o test-extract -p "password"
ls test-extract/

Integration with Comic Creation Tools

ImageMagick Conversion

Convert PDF or images to comic pages:

# Convert PDF to images
magick convert -density 300 comic.pdf page-%03d.jpg

# Create CBT
./cbt.sh create -i . -o comic.cbt

Optimize Images Before Packing

# Optimize JPEGs
for img in *.jpg; do
    mogrify -quality 85 -strip "$img"
done

# Create optimized CBT
./cbt.sh create -i . -o optimized-comic.cbt -p "password"

Troubleshooting

"Permission Denied" Error

chmod +x scripts-bash/cbt.sh

"Command Not Found" Errors

Ensure required tools are installed:

# Ubuntu/Debian
sudo apt install tar openssl xxd coreutils

# Fedora
sudo dnf install tar openssl vim-common coreutils

# macOS
brew install gnu-tar openssl

Encryption Issues

Verify OpenSSL version:

openssl version

Should be OpenSSL 1.1.1 or higher.

Related Pages

• CBT File Format - Technical details

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Tip: Use the bash script for simplicity, or the Go program for cross-platform compatibility.