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use crate::error::*;
use asn1_rs::FromDer;
use der_parser::{
der::{parse_der_integer, parse_der_sequence_defined_g},
error::BerResult,
};
/// Public Key value
#[derive(Debug, PartialEq, Eq)]
pub enum PublicKey<'a> {
RSA(RSAPublicKey<'a>),
EC(ECPoint<'a>),
/// DSAPublicKey ::= INTEGER -- public key, Y (RFC 3279)
DSA(&'a [u8]),
/// GostR3410-94-PublicKey ::= OCTET STRING -- public key, Y (RFC 4491)
GostR3410(&'a [u8]),
/// GostR3410-2012-256-PublicKey ::= OCTET STRING (64),
/// GostR3410-2012-512-PublicKey ::= OCTET STRING (128). (RFC 4491-bis)
GostR3410_2012(&'a [u8]),
Unknown(&'a [u8]),
}
impl PublicKey<'_> {
/// Return the key size (in bits) or 0
pub fn key_size(&self) -> usize {
match self {
Self::EC(ec) => ec.key_size(),
Self::RSA(rsa) => rsa.key_size(),
Self::DSA(y) | Self::GostR3410(y) => y.len() * 8,
_ => 0,
}
}
}
/// RSA public Key, defined in rfc3279
#[derive(Debug, PartialEq, Eq)]
pub struct RSAPublicKey<'a> {
/// Raw bytes of the modulus
///
/// This possibly includes a leading 0 if the MSB is 1
pub modulus: &'a [u8],
/// Raw bytes of the exponent
///
/// This possibly includes a leading 0 if the MSB is 1
pub exponent: &'a [u8],
}
impl RSAPublicKey<'_> {
/// Attempt to convert exponent to u64
///
/// Returns an error if integer is too large, empty, or negative
pub fn try_exponent(&self) -> Result<u64, X509Error> {
let mut buf = [0u8; 8];
if self.exponent.is_empty() || self.exponent[0] & 0x80 != 0 || self.exponent.len() > 8 {
return Err(X509Error::InvalidNumber);
}
buf[8_usize.saturating_sub(self.exponent.len())..].copy_from_slice(self.exponent);
let int = <u64>::from_be_bytes(buf);
Ok(int)
}
/// Return the key size (in bits) or 0
pub fn key_size(&self) -> usize {
if !self.modulus.is_empty() && self.modulus[0] & 0x80 == 0 {
// XXX len must substract leading zeroes
let modulus = &self.modulus[1..];
8 * modulus.len()
} else {
0
}
}
}
// helper function to parse with error type BerError
fn parse_rsa_key(bytes: &[u8]) -> BerResult<'_, RSAPublicKey<'_>> {
parse_der_sequence_defined_g(move |i, _| {
let (i, obj_modulus) = parse_der_integer(i)?;
let (i, obj_exponent) = parse_der_integer(i)?;
let modulus = obj_modulus.as_slice()?;
let exponent = obj_exponent.as_slice()?;
let key = RSAPublicKey { modulus, exponent };
Ok((i, key))
})(bytes)
}
impl<'a> FromDer<'a, X509Error> for RSAPublicKey<'a> {
fn from_der(bytes: &'a [u8]) -> X509Result<'a, Self> {
parse_rsa_key(bytes).map_err(|_| nom::Err::Error(X509Error::InvalidSPKI))
}
}
/// Elliptic Curve point, as defined in [RFC5480](https://datatracker.ietf.org/doc/html/rfc5480)
#[derive(Debug, PartialEq, Eq)]
pub struct ECPoint<'a> {
data: &'a [u8],
}
impl<'a> ECPoint<'a> {
/// EC Point content (See Standards for Efficient Cryptography Group (SECG), "SEC1: Elliptic Curve Cryptography")
pub fn data(&'a self) -> &'a [u8] {
self.data
}
/// Return the key size (in bits) or 0
pub fn key_size(&self) -> usize {
match self.data {
[] => {
// empty
0
}
[4, rem @ ..] => {
// uncompressed
rem.len() * 8 / 2
}
[2..=3, rem @ ..] => {
// compressed
rem.len() * 8
}
_ => {
// invalid
0
}
}
}
}
impl<'a> From<&'a [u8]> for ECPoint<'a> {
fn from(data: &'a [u8]) -> Self {
ECPoint { data }
}
}