solana/zk-token-sdk/src/zk_token_elgamal/decryption.rs

#[cfg(not(target_arch = "bpf"))]
use crate::{
    encryption::elgamal::{ElGamalCiphertext, ElGamalSecretKey},
    zk_token_elgamal::pod,
};

#[cfg(not(target_arch = "bpf"))]
impl pod::ElGamalCiphertext {
    pub fn decrypt(self, secret_key: &ElGamalSecretKey) -> Option<u64> {
        let deserialized_ciphertext: Option<ElGamalCiphertext> = self.try_into().ok();
        if let Some(ciphertext) = deserialized_ciphertext {
            ciphertext.decrypt_u32(secret_key)
        } else {
            None
        }
    }
}

#[cfg(test)]
mod tests {
    use {super::*, crate::encryption::elgamal::ElGamalKeypair};

    #[test]
    fn test_pod_decryption() {
        let keypair = ElGamalKeypair::new_rand();

        let pod_ciphertext = pod::ElGamalCiphertext([0u8; 64]);
        assert_eq!(pod_ciphertext.decrypt(&keypair.secret).unwrap(), 0);

        let amount = 55_u64;
        let ciphertext = keypair.public.encrypt(amount);
        let pod_ciphertext: pod::ElGamalCiphertext = ciphertext.into();
        assert_eq!(pod_ciphertext.decrypt(&keypair.secret).unwrap(), 55);
    }
}