crypto_api_chachapoly 0.5.0

An implementation of ChaCha20-IETF, Poly1305 and ChachaPoly-IETF for `crypto_api`
Documentation 
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/// A `usize` extension to use `usize`s as constrainable values
pub trait UsizeExt {
    /// Get the constrainable value
    fn _cv(&self) -> usize;
}
impl UsizeExt for usize {
    fn _cv(&self) -> usize {
        *self
    }
}
/// A slice extension to use slice as constrainable values
pub trait SliceExt {
    /// Get the constrainable value
    fn _cv(&self) -> usize;
}
impl<T: AsRef<[u8]>> SliceExt for T {
    fn _cv(&self) -> usize {
        self.as_ref().len()
    }
}


/// Verifies that
///  - `$buf` is can hold *exactly* `$size` bytes
macro_rules! vfy_keygen {
    ($size:expr => $buf:expr) => ({
        #[allow(unused_imports)]
        use $crate::verify_input::{ UsizeExt, SliceExt };
        
        let error = match true {
            _ if $buf._cv() != $size => Err("Invalid buffer size"),
            _ => Ok(())
        };
        error.map_err(|e| $crate::ChachaPolyError::ApiMisuse(e))?;
    });
}


/// Verifies the encryption parameters
macro_rules! vfy_enc {
    ($key:expr => [$key_size:expr], $nonce:expr => [$nonce_size:expr],
        $plaintext:expr => [$buf:expr, $plaintext_limit:expr]) =>
    ({
        #[allow(unused_imports)]
        use $crate::verify_input::{ UsizeExt, SliceExt };
        
        let error = match true {
            _ if $key._cv() != $key_size => Err("Invalid key length"),
            _ if $nonce._cv() != $nonce_size => Err("Invalid nonce length"),
            _ if $plaintext._cv() > $plaintext_limit => Err("Too much data"),
            _ if $plaintext._cv() > $buf._cv() => Err("Buffer is too small"),
            _ => Ok(())
        };
        error.map_err(|e| $crate::ChachaPolyError::ApiMisuse(e))?;
    })
    
}
/// Verifies the decryption parameters
macro_rules! vfy_dec {
    ($key:expr => [$key_size:expr], $nonce:expr => [$nonce_size:expr],
        $ciphertext:expr => [$buf:expr, $ciphertext_limit:expr]) =>
    ({
        #[allow(unused_imports)]
        use $crate::verify_input::{ UsizeExt, SliceExt };
        
        let error = match true {
            _ if $key._cv() != $key_size => Err("Invalid key length"),
            _ if $nonce._cv() != $nonce_size => Err("Invalid nonce length"),
            _ if $ciphertext._cv() > $ciphertext_limit => Err("Too much data"),
            _ if $ciphertext._cv() > $buf._cv() => Err("Buffer is too small"),
            _ => Ok(())
        };
        error.map_err(|e| $crate::ChachaPolyError::ApiMisuse(e))?;
    })
}


/// Verifies the authentication parameters
macro_rules! vfy_auth {
    ($key:expr => [$key_size:expr], => [$buf:expr, $tag_size:expr]) => ({
        #[allow(unused_imports)]
        use $crate::verify_input::{ UsizeExt, SliceExt };
        
        let error = match true {
            _ if $key._cv() != $key_size => Err("Invalid key length"),
            _ if $buf._cv() < $tag_size => Err("Buffer is too small"),
            _ => Ok(())
        };
        error.map_err(|e| $crate::ChachaPolyError::ApiMisuse(e))?;
    })
}


/// Verifies the sealing parameters
macro_rules! vfy_seal {
    ($key:expr => [$key_size:expr], $nonce:expr => [$nonce_const:expr],
        $plaintext:expr => [$buf:expr, $plaintext_limit:expr]) =>
    ({
        #[allow(unused_imports)]
        use $crate::verify_input::{ UsizeExt, SliceExt };
        
        let error = match true {
            _ if $key._cv() != $key_size => Err("Invalid key length"),
            _ if $nonce._cv() != $nonce_const => Err("Invalid nonce length"),
            _ if $plaintext._cv() > $plaintext_limit => Err("Too much data"),
            _ if $buf._cv() < $plaintext._cv() + CHACHAPOLY_TAG => Err("Buffer is too small"),
            _ => Ok(())
        };
        error.map_err(|e| $crate::ChachaPolyError::ApiMisuse(e))?;
    })
}
/// Verifies the parameters for opening in place
macro_rules! vfy_open {
    ($key:expr => [$key_size:expr], $nonce:expr => [$nonce_size:expr],
        $ciphertext:expr => [$buf:expr, $tag_size:expr, $ciphertext_limit:expr]) =>
    ({
        #[allow(unused_imports)]
        use $crate::verify_input::{ UsizeExt, SliceExt };
    
        let error = match true {
            _ if $key._cv() != $key_size => Err("Invalid key length"),
            _ if $nonce._cv() != $nonce_size => Err("Invalid nonce length"),
            _ if $ciphertext._cv() > $ciphertext_limit => Err("Too much data"),
            _ if $ciphertext._cv() < $tag_size => Err($crate::ChachaPolyError::InvalidData)?,
            _ if $buf._cv() + $tag_size < $ciphertext._cv() => Err("Buffer is too small"),
            _ => Ok(())
        };
        error.map_err(|e| $crate::ChachaPolyError::ApiMisuse(e))?;
    })
}