Function extract_first_bitstring

src/pem/decoder.rs:188–207

This really just finds and returns the first bitstring or octet string Which is the x coordinate for EC public keys And the DER contents of an RSA key Though PKCS#11 keys shouldn't have anything else. It will get confusing with certificates.

(asn1: &[simple_asn1::ASN1Block])

// Though PKCS#11 keys shouldn't have anything else.
// It will get confusing with certificates.
fn extract_first_bitstring(asn1: &[simple_asn1::ASN1Block]) -> Result<&[u8]> {
    for asn1_entry in asn1 {
        match asn1_entry {
            simple_asn1::ASN1Block::Sequence(_, entries) => {
                if let Ok(result) = extract_first_bitstring(entries) {
                    return Ok(result);
                }
            }
            simple_asn1::ASN1Block::BitString(_, _, value) => {
                return Ok(value.as_ref());
            }
            simple_asn1::ASN1Block::OctetString(_, value) => {
                return Ok(value.as_ref());
            }
            _ => (),
        }
    }

    Err(ErrorKind::InvalidEcdsaKey.into())
}

/// Find whether this is EC, RSA, or Ed
/// Note: Ed448 keys are not supported