icf-reader/README.md

# icf-reader

Tools for decoding, decrypting and encrypting ICFs

## Usage
```shell
Usage: icf-reader.exe <COMMAND>

Commands:
  encrypt  Fixes some common ICF errors, then encrypt the given ICF
  decrypt  Decrypts the given ICF
  decode   Decodes the given ICF (optionally to a JSON file)
  encode   Encodes a JSON file from the decode subcommand to an ICF
  help     Print this message or the help of the given subcommand(s)

Options:
  -h, --help  Print help
```

Encrypting the ICF will also correct CRC checksums, so worrying about the
correct checksum is not needed.

## Creating an ICF file from JSON
The JSON file is an array of `IcfData`, which follows the format below:
```typescript
interface Version {
    major: number;
    minor: number;
    build: number;
}

interface IcfInnerData {
    type: "System" | "App",
    id: string, // Must be 3 characters for "System" and 4 characters for "App"
    version: Version,
    required_system_version: Version,
    datetime: string, // ISO8601 string yyyy-MM-dd'T'HH:mm:ss
}

interface IcfOptionData {
    type: "Option",
    option_id: string, // Must be 4 characters
    datetime: string, // ISO8601 string yyyy-MM-dd'T'HH:mm:ss
}

interface IcfPatchData {
    type: "Patch",
    
    sequence_number: number, // Incremented for every patch, starting from 1
    
    source_version: Version,
    source_datetime: string, // ISO8601 string yyyy-MM-dd'T'HH:mm:ss
    source_required_system_version: Version,
    
    target_version: Version,
    target_datetime: string, // ISO8601 string yyyy-MM-dd'T'HH:mm:ss
    target_required_system_version: Version,
}

type IcfData = IcfInnerData | IcfOptionData | IcfPatchData;
```

At least one entry of type `System` and `App` must be specified.

When done, create your ICF using `icf-reader.exe encode input.json output.icf`.

## Building
```
ICF_KEY=<key> ICF_IV=<iv> cargo build --release

ls target/release/icf-reader.exe
```