nettle 5.0.1

Rust bindings for the Nettle cryptographic library
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use nettle_sys::{
    __gmpz_init_set, dsa_signature, nettle_dsa_signature_clear,
    nettle_dsa_signature_init,
};
use std::mem::zeroed;

use crate::helper::{convert_buffer_to_gmpz, convert_gmpz_to_buffer};

/// (EC)DSA signature.
pub struct Signature {
    pub(crate) signature: dsa_signature,
}

impl Signature {
    /// Create a new signature structure. Both `r` and `s` need to be big endian integer.
    pub fn new(r: &[u8], s: &[u8]) -> Signature {
        unsafe {
            let mut ret = zeroed();

            nettle_dsa_signature_init(&mut ret);
            ret.r[0] = convert_buffer_to_gmpz(r);
            ret.s[0] = convert_buffer_to_gmpz(s);

            Signature { signature: ret }
        }
    }

    /// Returns `r` as big endian integer.
    pub fn r(&self) -> Box<[u8]> {
        convert_gmpz_to_buffer(self.signature.r[0])
    }

    /// Returns `s` as big endian integer.
    pub fn s(&self) -> Box<[u8]> {
        convert_gmpz_to_buffer(self.signature.s[0])
    }
}

impl Clone for Signature {
    fn clone(&self) -> Self {
        unsafe {
            let mut ret = zeroed();

            nettle_dsa_signature_init(&mut ret);
            __gmpz_init_set(&mut ret.r[0], &self.signature.r[0]);
            __gmpz_init_set(&mut ret.s[0], &self.signature.s[0]);

            Signature { signature: ret }
        }
    }
}

impl Drop for Signature {
    fn drop(&mut self) {
        unsafe {
            nettle_dsa_signature_clear(&mut self.signature as *mut _);
        }
    }
}