main.rs

const EC_PUBLIC_KEY_OID: asn1::ObjectIdentifier = asn1::oid!(1, 2, 840, 10045, 2, 1);

const P256_OID: asn1::ObjectIdentifier = asn1::oid!(1, 2, 840, 10045, 3, 1, 7);

#[derive(asn1::Asn1Read)]
struct SubjectPublicKeyInfo<'a> {
    algorithm: AlgorithmIdentifier<'a>,
    subject_public_key: asn1::BitString<'a>,
}

#[derive(asn1::Asn1Read)]
struct AlgorithmIdentifier<'a> {
    algorithm: asn1::ObjectIdentifier,
    params: Option<asn1::Tlv<'a>>,
}

fn parse_key(
    data: &[u8],
) -> Result<openssl::pkey::PKey<openssl::pkey::Public>, openssl::error::ErrorStack> {
    let spki = asn1::parse_single::<SubjectPublicKeyInfo>(data).unwrap();

    return match spki.algorithm.algorithm {
        EC_PUBLIC_KEY_OID => {
            let curve_oid = spki
                .algorithm
                .params
                .unwrap()
                .parse::<asn1::ObjectIdentifier>()
                .unwrap();
            let curve_nid = match curve_oid {
                P256_OID => openssl::nid::Nid::X9_62_PRIME256V1,
                _ => panic!("Unrecognized curve OID"),
            };
            let group = openssl::ec::EcGroup::from_curve_name(curve_nid)?;
            let mut bn_ctx = openssl::bn::BigNumContext::new()?;
            let ec_point = openssl::ec::EcPoint::from_bytes(
                &group,
                spki.subject_public_key.as_bytes(),
                &mut bn_ctx,
            )?;
            let ec_key = openssl::ec::EcKey::from_public_key(&group, &ec_point)?;

            openssl::pkey::PKey::from_ec_key(ec_key)
        }
        _ => panic!("Unrecognized key algorithm OID"),
    };
}

fn main() {
    const KEY_BYTES: &[u8] = b"0Y0\x13\x06\x07*\x86H\xce=\x02\x01\x06\x08*\x86H\xce=\x03\x01\x07\x03B\x00\x04)'\xb1\x05\x12\xba\xe3\xed\xdc\xfeFx(\x12\x8b\xad)\x03&\x99\x19\xf7\x08`i\xc8\xc4\xdfls(8\xc7xyd\xea\xac\x00\xe5\x92\x1f\xb1I\x8a`\xf4`gf\xb3\xd9hP\x01U\x8d\x1a\x97NsAQ>";

    for i in 0..10240 {
        let pkey = parse_key(KEY_BYTES).unwrap();
        pkey.ec_key().unwrap();
    }
}