openpgp: Make digest computation more robust.justus/fix-615

1 files changed, 2 insertions, 1 deletions

diff --git a/openpgp/src/crypto/backend/cng/hash.rs b/openpgp/src/crypto/backend/cng/hash.rs
index 73121c23..5b5559f1 100644
--- a/openpgp/src/crypto/backend/cng/hash.rs
+++ b/openpgp/src/crypto/backend/cng/hash.rs
@@ -33,7 +33,8 @@ impl Digest for Mutex<cng::Hash> {
         let buffer = old.finish()
             .expect("CNG to not fail internally");
 
-        digest.copy_from_slice(&buffer.as_slice()[..digest.len()]);
+        let l = buffer.len().min(digest.len());
+        mut digest[..l].copy_from_slice(&buffer.as_slice()[..l]);
         Ok(())
     }
 }