recrypt 0.12.0

A pure-Rust implementation of Transform Encryption, a Proxy Re-encryption scheme
Documentation 
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use crate::internal::ByteVector;
use arrayvec;
use arrayvec::ArrayVec;
use gridiron::fp_256::Fp256;
use gridiron::fp_480::Fp480;
use quick_error::quick_error;
use std::convert::From;
use std::result::Result;

/// Decode a ByteVector into an implementing type.
/// Inverse of Hashable.
pub trait BytesDecoder
where
    Self: Sized,
{
    /// Expected size (in bytes) of the byte representation of the implementing type
    const ENCODED_SIZE_BYTES: usize;

    /// Decode bytes into Self
    fn decode(bytes: ByteVector) -> Result<Self, DecodeErr>;
}

impl BytesDecoder for gridiron::fp_256::Monty {
    const ENCODED_SIZE_BYTES: usize = 32;
    fn decode(bytes: ByteVector) -> Result<Self, DecodeErr> {
        let byte_arr: ArrayVec<[u8; Self::ENCODED_SIZE_BYTES]> = bytes.into_iter().collect();
        let byte_arr: [u8; Self::ENCODED_SIZE_BYTES] = byte_arr.into_inner()?;
        Result::Ok(Fp256::from(byte_arr).to_monty())
    }
}

impl BytesDecoder for gridiron::fp_480::Monty {
    const ENCODED_SIZE_BYTES: usize = 60;

    fn decode(bytes: Vec<u8>) -> Result<Self, DecodeErr> {
        if bytes.len() == Self::ENCODED_SIZE_BYTES {
            let mut byte_arr: [u8; Self::ENCODED_SIZE_BYTES] = [0u8; Self::ENCODED_SIZE_BYTES];
            byte_arr.copy_from_slice(&bytes);
            Result::Ok(Fp480::from(byte_arr).to_monty())
        } else {
            Result::Err(DecodeErr::BytesNotCorrectLength {
                required_length: Self::ENCODED_SIZE_BYTES,
                bad_bytes: bytes,
            })
        }
    }
}

quick_error! {
    #[derive(Debug, PartialEq, Eq)]
    pub enum DecodeErr {
        BytesNotCorrectLength {
            required_length: usize,
            bad_bytes: ByteVector,
        } {
        }
        BytesInvalid {
            message: String,
            bad_bytes: ByteVector,
        }{}
    }
}

/// Needed for error handing when ArrayVec.into_inner is called on an instance that is not
/// at capacity.
macro_rules! from_arrayvec_n { ($($n: expr), *) => {
    $(impl From<arrayvec::ArrayVec<[u8; $n]>> for DecodeErr {
        fn from(x: arrayvec::ArrayVec<[u8; $n]>) -> Self {
            DecodeErr::BytesNotCorrectLength {
                required_length: $n,
                bad_bytes: x.to_vec(),
            }
        }
})+
}}

from_arrayvec_n! {32, 128, 384}