vendor/spki/src/fingerprint.rs

   1 //! SPKI fingerprint support.
   2
   3 use der::Writer;
   4 use sha2::{Digest, Sha256};
   5
   6 /// Size of a SHA-256 SPKI fingerprint in bytes.
   7 pub(crate) const SIZE: usize = 32;
   8
   9 /// Raw bytes of a SPKI fingerprint i.e. SHA-256 digest of
  10 /// `SubjectPublicKeyInfo`'s DER encoding.
  11 ///
  12 /// See [RFC7469 § 2.1.1] for more information.
  13 ///
  14 /// [RFC7469 § 2.1.1]: https://datatracker.ietf.org/doc/html/rfc7469#section-2.1.1
  15 pub type FingerprintBytes = [u8; SIZE];
  16
  17 /// Writer newtype which accepts DER being serialized on-the-fly and computes a
  18 /// hash of the contents.
  19 #[derive(Clone, Default)]
  20 pub(crate) struct Builder {
  21     /// In-progress digest being computed from streaming DER.
  22     digest: Sha256,
  23 }
  24
  25 impl Builder {
  26     /// Create a new fingerprint builder.
  27     pub fn new() -> Self {
  28         Self::default()
  29     }
  30
  31     /// Finish computing a fingerprint, returning the computed digest.
  32     pub fn finish(self) -> FingerprintBytes {
  33         self.digest.finalize().into()
  34     }
  35 }
  36
  37 impl Writer for Builder {
  38     fn write(&mut self, der_bytes: &[u8]) -> der::Result<()> {
  39         self.digest.update(der_bytes);
  40         Ok(())
  41     }
  42 }