# README

git-caesar

This command encrypts and decrypts files using the public key registered on GitHub and your own private key.

Installation

go install github.com/yoshi389111/git-caesar@latest

Requires go 1.20 or higher

See below for how to uninstall

go clean -i github.com/yoshi389111/git-caesar

Usage

Usage:

  git-caesar [options]

Application Options:

  -h, --help                    print help and exit.
  -v, --version                 print version and exit.
  -u, --public=<target>         github account, url or file.
  -k, --private=<id_file>       ssh private key file.
  -i, --input=<input_file>      the path of the file to read. default: stdin
  -o, --output=<output_file>    the path of the file to write. default: stdout
  -d, --decrypt                 decryption mode.

-u specifies the location of the peer's public key. Get from https://github.com/USER_NAME.keys if the one specified looks like a GitHub username. If it starts with http: or https:, it will be fetched from the web. Otherwise, it will be determined as a file path. If you specify a file that looks like GitHub username, specify it with a path (e.g. -u ./octacat). Required for encryption. For decryption, perform signature verification if specified.
-k Specify your private key. If not specified, it searches ~/.ssh/id_ecdsa, ~/.ssh/id_ed25519, ~/.ssh/id_rsa in order and uses the first one found.
-i Input file. Plaintext file to be encrypted when encrypting. When decrypting, please specify the ciphertext file to be decrypted. If no options are specified, it reads from standard input.
-o output file. Outputs to standard output if no option is specified.
Specify -d for decrypt mode. Encrypted mode if not specified.

Supported algorithms

List of supported public key prefixes:

ssh-rsa -- Key length is 1024 bits or more
ecdsa-sha2-nistp256
ecdsa-sha2-nistp384
ecdsa-sha2-nistp521
ssh-ed25519

Unsupported public key prefix list:

ssh-dss -- DSA
ssh-rsa -- Key length is less than 1024 bits
[email protected]
[email protected]

Example of use

Encrypt your file secret.txt for GitHub user octacat and save it as sceret.zip.

git-caesar -u octacat -i secret.txt -o secret.zip

In the same situation, the private key uses ~/.ssh/id_secret.

git-caesar -u octacat -i secret.txt -o secret.zip -k ~/.ssh/id_secret

Decrypt GitLab user tanuki's file secret.zip and save it as sceret.txt.

git-caesar -d -u https://gitlab.com/tanuki.keys -i secret.zip -o secret.txt

Same situation, no signature verification.

git-caesar -d -i secret.zip -o secret.txt