pgpainless/docs/source/pgpainless-cli/usage.md

# User Guide PGPainless-CLI

The module `pgpainless-cli` contains a command line application which conforms to the
[Stateless OpenPGP Command Line Interface](https://datatracker.ietf.org/doc/draft-dkg-openpgp-stateless-cli/).

You can use it to generate keys, encrypt, sign and decrypt messages, as well as verify signatures.

## Implementation

Essentially, `pgpainless-cli` is just a very small composing module, which injects `pgpainless-sop` as a
concrete implementation of `sop-java` into `sop-java-picocli`.

## Install

The `pgpainless-cli` command line application is available in Debian unstable / Ubuntu 22.10 and can be installed via APT:
```shell
$ sudo apt install pgpainless-cli
```

This method comes with man-pages:
```shell
$ man pgpainless-cli
```

## Build

To build a standalone *fat*-jar:
```shell
$ cd pgpainless-cli/
$ gradle shadowJar
```

The fat-jar can afterwards be found in `build/libs/`.

To build a [distributable](https://docs.gradle.org/current/userguide/distribution_plugin.html):

```shell
$ cd pgpainless-cli/
$ gradle installDist
```

Afterwards, an uncompressed distributable is installed in `build/install/`.
To execute the application, you can call `build/install/bin/pgpainless-cli{.bat}`

Building / updating man pages is a two-step process.
The contents of the man pages is largely defined by the `sop-java-picocli` source code.

In order to generate a fresh set of man pages from the `sop-java-picocli` source, you need to clone that repository
next to the `pgpainless` repository:
```shell
$ ls
pgpainless
$ git clone https://github.com/pgpainless/sop-java.git
$ ls
pgpainless  sop-java
```

Next, you need to execute the `asciiDoctor` gradle task inside the sop-java repository:
```shell
$ cd sop-java
$ gradle asciiDoctor
```

This will generate generic sop manpages in `sop-java-picocli/build/docs/manpage/`.

Next, you need to execute a script for converting the `sop` manpages to fit the `pgpainless-cli` command with the help
of a script in the `pgpainless` repository:
```shell
$ cd ../pgpainless/pgpainless-cli
$ ./rewriteManPages.sh
```

The resulting updated man pages are placed in `packaging/man/`.

## Usage

Hereafter, the program will be referred to as `pgpainless-cli`.

```
$ pgpainless-cli help
Stateless OpenPGP Protocol
Usage: pgpainless-cli [--stacktrace] [COMMAND]

Options:
      --stacktrace   Print Stacktrace

Commands:
  help           Display usage information for the specified subcommand
  armor          Add ASCII Armor to standard input
  dearmor        Remove ASCII Armor from standard input
  decrypt        Decrypt a message from standard input
  inline-detach  Split signatures from a clearsigned message
  encrypt        Encrypt a message from standard input
  extract-cert   Extract a public key certificate from a secret key from
                   standard input
  generate-key   Generate a secret key
  sign           Create a detached signature on the data from standard input
  verify         Verify a detached signature over the data from standard input
  inline-sign    Create an inline-signed message from data on standard input
  inline-verify  Verify inline-signed data from standard input
  version        Display version information about the tool

Exit Codes:
   0   Successful program execution
   1   Generic program error
   3   Verification requested but no verifiable signature found
  13   Unsupported asymmetric algorithm
  17   Certificate is not encryption capable
  19   Usage error: Missing argument
  23   Incomplete verification instructions
  29   Unable to decrypt
  31   Password is not human-readable
  37   Unsupported Option
  41   Invalid data or data of wrong type encountered
  53   Non-text input received where text was expected
  59   Output file already exists
  61   Input file does not exist
  67   Cannot unlock password protected secret key
  69   Unsupported subcommand
  71   Unsupported special prefix (e.g. "@ENV/@FD") of indirect parameter
  73   Ambiguous input (a filename matching the designator already exists)
  79   Key is not signing capable
```

To get help on a subcommand, e.g. `encrypt`, just call the help subcommand followed by the subcommand you
are interested in (e.g. `pgpainless-cli help encrypt`).

## Examples
```shell
$ # Generate a key
$ pgpainless-cli generate-key "Alice <alice@pgpainless.org>" > key.asc
$ # Extract a certificate from a key
$ cat key.asc | pgpainless-cli extract-cert > cert.asc
$ # Create an encrypted signed message
$ echo "Hello, World!" | pgpainless-cli encrypt cert.asc --sign-with key.asc > msg.asc
$ # Decrypt an encrypted message and verify the signature
$ cat msg.asc | pgpainless-cli decrypt key.asc --verify-with cert.asc --verifications-out verifications.txt
Hello, World!
$ cat verifications.txt
2022-11-15T21:25:48Z 4FF67C69150209ED8139DE22578CB2FABD5D7897 9000235358B8CEA6A368EC86DE56DC2D942ACAA4
```

## Indirect Data Types

Some commands take options whose arguments are indirect data types. Those are arguments which are not used directly,
but instead they point to a place where the argument value can be sourced from, such as a file, an environment variable
or a file descriptor.

It is important to keep in mind, that options like `--with-password` or `--with-key-password` are examples for such
indirect data types. If you want to unlock a key whose password is `sw0rdf1sh`, you *cannot* provide the password
like `--with-key-password sw0rdf1sh`, but instead you have to either write out the password into a file and provide
the file's path (e.g. `--with-key-password /path/to/file`), store the password in an environment variable and pass that
(e.g. `--with-key-password @ENV:myvar`), or provide a numbered file descriptor from which the password can be read
(e.g. `--with-key-password @FD:4`).

Note, that environment variables and file descriptors can only be used to pass input data to the program.
For output parameters (e.g. `--verifications-out`) only file paths are allowed.