CFShare

Split and reconstruct your file into/from encrypted shares using the Shamir Secret Sharing technique.

How does it work

In the provided implementation the input file is encrypted using a cipher selected by the user.
The random cipher secret key used for encryption is given as input to a Shamir Secret sharing algorithm in order to produce different secrets.
This encrypted file is copied into T shares paired with one unique Shamir secret and a hash (computed using HMAC and SHA256), which provides the integrity of the original content of the file, into multiple shares.
Based on the user's preferences the encrypted content can be copied into one specific file so that it is not contained in every share.

In order to reconstruct the original file at least M<T shares are required (M and T are chosen by the user in the split phase).
Once the user has the required number of shares, the original file is reconstructed by obtaining the original encryption key from the Shamir secrets in the shares, which is later used to decrypt the encrypted content of the original file. The resulting file is later verified for its authenticity and integrity using the tag produced by HMAC.

Split

You can use "cfshare split " to split a file into multiple encrypted shares.

argument	type	description
-i I	String	Original file relative path
-o O	String	Relative path of the output files
-t T	Int	Total number of shares
-m M	Int	Minimum number of shares required for reconstruction
-c	String	Select Cipher (valid options: AES|ChaCha20|Camellia, default:AES)
-so --sharesonly	-	Output encrypted file and shares as distinctive files (default: off)

Bind

You can use "cfshare bind " to bind multiple encrypted shares and reconstruct the original file.

argument	type	description
-i I	String+	Relative paths to encrypted files
-o O	String	Unencrypted reconstructed output path of the file
-s S	String+	Relative paths to shares (required only if the file was split with "-so" option)

Dependencies

• cryptography