alice-auth 0.5.0

Ed25519 ZKP auth for ALICE
Documentation 
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//! identity.

use crate::errors::*;
use crate::random::*;
use crate::types::*;
use ed25519_dalek::{Signer, SigningKey, VerifyingKey};
use zeroize::Zeroize;

// Identity
// ============================================================================

/// Ed25519 signing identity. Secret key is zeroized on drop.
pub struct Identity {
    sk: SigningKey,
    pk: VerifyingKey,
}

impl Drop for Identity {
    fn drop(&mut self) {
        // Overwrite the signing key with zeros to prevent secret key residue in memory.
        // SigningKey::from_bytes overwrites internal state; zeroize the temp buffer.
        let mut zero = [0u8; 32];
        self.sk = SigningKey::from_bytes(&zero);
        zero.zeroize();
    }
}

impl Identity {
    /// # Errors
    /// Returns `AuthError::E5` if the platform RNG fails.
    #[inline(always)]
    pub fn gen() -> Result<Self> {
        Ok(Self::from_seed(&rand()?))
    }
    #[inline(always)]
    #[must_use]
    pub fn from_seed(s: &[u8; 32]) -> Self {
        let sk = SigningKey::from_bytes(s);
        Self {
            pk: VerifyingKey::from(&sk),
            sk,
        }
    }
    #[inline(always)]
    #[must_use]
    pub fn seed(&self) -> [u8; 32] {
        self.sk.to_bytes()
    }
    #[inline(always)]
    #[must_use]
    pub fn id(&self) -> AliceId {
        AliceId(self.pk.to_bytes())
    }
    #[inline(always)]
    #[must_use]
    pub fn sign(&self, m: &[u8]) -> AliceSig {
        AliceSig(self.sk.sign(m).to_bytes())
    }
    #[inline(always)]
    #[must_use]
    pub fn sign32(&self, c: &[u8; 32]) -> AliceSig {
        self.sign(c)
    }
}