1 files changed, 80 insertions, 0 deletions
diff --git a/openpgp/src/crypto/backend/rust/hash.rs b/openpgp/src/crypto/backend/rust/hash.rs
new file mode 100644
index 00000000..fa3b9f2c
--- /dev/null
+++ b/openpgp/src/crypto/backend/rust/hash.rs
@@ -0,0 +1,80 @@
+use std::cmp;
+
+use digest::Digest as _;
+
+use crate::{Error, Result};
+use crate::crypto::hash::Digest;
+use crate::types::HashAlgorithm;
+
+macro_rules! impl_digest_for {
+    ($ty:ty, $algo:ident) => {
+        impl Digest for $ty {
+            fn algo(&self) -> HashAlgorithm {
+                HashAlgorithm::$algo
+            }
+
+            fn digest_size(&self) -> usize {
+                Self::output_size()
+            }
+
+            fn update(&mut self, data: &[u8]) {
+                digest::Digest::update(self, data)
+            }
+
+            fn digest(&mut self, digest: &mut [u8]) -> Result<()> {
+                let buf = self.finalize_reset();
+                let n = cmp::min(buf.len(), digest.len());
+                digest[..n].copy_from_slice(&buf[..n]);
+                Ok(())
+            }
+        }
+    }
+}
+
+impl_digest_for!(md5::Md5, MD5);
+impl_digest_for!(ripemd160::Ripemd160, RipeMD);
+impl_digest_for!(sha1::Sha1, SHA1);
+impl_digest_for!(sha2::Sha224, SHA224);
+impl_digest_for!(sha2::Sha256, SHA256);
+impl_digest_for!(sha2::Sha384, SHA384);
+impl_digest_for!(sha2::Sha512, SHA512);
+
+impl HashAlgorithm {
+    /// Whether Sequoia supports this algorithm.
+    pub fn is_supported(self) -> bool {
+        match self {
+            HashAlgorithm::SHA1 => true,
+            HashAlgorithm::SHA224 => true,
+            HashAlgorithm::SHA256 => true,
+            HashAlgorithm::SHA384 => true,
+            HashAlgorithm::SHA512 => true,
+            HashAlgorithm::RipeMD => true,
+            HashAlgorithm::MD5 => true,
+            HashAlgorithm::Private(_) => false,
+            HashAlgorithm::Unknown(_) => false,
+        }
+    }
+
+    /// Creates a new hash context for this algorithm.
+    ///
+    /// # Errors
+    ///
+    /// Fails with `Error::UnsupportedHashAlgorithm` if Sequoia does
+    /// not support this algorithm. See
+    /// [`HashAlgorithm::is_supported`].
+    ///
+    /// [`HashAlgorithm::is_supported`]: #method.is_supported
+    pub(crate) fn new_hasher(self) -> Result<Box<dyn Digest>> {
+        match self {
+            HashAlgorithm::SHA1 => Ok(Box::new(sha1::Sha1::new())),
+            HashAlgorithm::SHA224 => Ok(Box::new(sha2::Sha224::new())),
+            HashAlgorithm::SHA256 => Ok(Box::new(sha2::Sha256::new())),
+            HashAlgorithm::SHA384 => Ok(Box::new(sha2::Sha384::new())),
+            HashAlgorithm::SHA512 => Ok(Box::new(sha2::Sha512::new())),
+            HashAlgorithm::RipeMD => Ok(Box::new(ripemd160::Ripemd160::new())),
+            HashAlgorithm::MD5 => Ok(Box::new(md5::Md5::new())),
+            HashAlgorithm::Private(_) | HashAlgorithm::Unknown(_) =>
+                Err(Error::UnsupportedHashAlgorithm(self).into()),
+        }
+    }
+}