| Copyright | (c) 2023-2024 Apotheca Labs (c) 2024-2025 Haskell Foundation |
|---|---|
| License | BSD-3-Clause |
| Maintainer | joris@well-typed.com, leo@apotheca.io |
| Stability | experimental |
| Portability | POSIX |
| Safe Haskell | None |
| Language | GHC2021 |
Botan.Bindings.ZFEC
Description
The ZFEC module provides forward error correction compatible with the zfec library.
Forward error correction takes an input and creates multiple “shares”, such that any K of N shares is sufficient to recover the entire original input.
Note
Specific to the ZFEC format, the first K generated shares are identical to the original input data, followed by N-K shares of error correcting code. This is very different from threshold secret sharing, where having fewer than K shares gives no information about the original input.
Warning
If a corrupted share is provided to the decoding algorithm, the resulting decoding will be invalid. It is recommended to protect shares using a technique such as a MAC or public key signature, if corruption is likely in your application.
ZFEC requires that the input length be exactly divisible by K; if needed define a padding scheme to pad your input to the necessary size.
Synopsis
- botan_zfec_encode :: CSize -> CSize -> ConstPtr Word8 -> CSize -> Ptr (Ptr Word8) -> IO CInt
- botan_zfec_decode :: CSize -> CSize -> ConstPtr CSize -> ConstPtr (ConstPtr Word8) -> CSize -> Ptr (Ptr Word8) -> IO CInt
Documentation
Arguments
| :: CSize | K: the number of shares needed for recovery |
| -> CSize | N: the number of shares generated |
| -> ConstPtr Word8 | input: the data to FEC |
| -> CSize | size: the length in bytes of input, which must be a multiple of K |
| -> Ptr (Ptr Word8) | outputs: An out parameter pointing to a fully allocated array of size [N][size / K]. For all n in range, an encoded block will be written to the memory starting at outputs[n][0]. |
| -> IO CInt | 0 on success, negative on failure |
Encode some bytes with certain ZFEC parameters.
Arguments
| :: CSize | K: the number of shares needed for recovery |
| -> CSize | N: the total number of shares |
| -> ConstPtr CSize | indexes: The index into the encoder's outputs for the corresponding element of the inputs array. Must be of length K. |
| -> ConstPtr (ConstPtr Word8) | inputs: K previously encoded shares to decode |
| -> CSize | shareSize: the length in bytes of each input |
| -> Ptr (Ptr Word8) | outputs: An out parameter pointing to a fully allocated array of size [K][shareSize]. For all k in range, a decoded block will written to the memory starting at outputs[k][0]. |
| -> IO CInt | 0 on success, negative on failure |
Decode some previously encoded shares using certain ZFEC parameters.