Enable setting RSA OAEP label in Decrypter

openssl/src/encrypt.rs

@@ -363,6 +363,32 @@ impl<'a> Decrypter<'a> {
         }
     }
 
+    /// Sets the RSA OAEP label.
+    ///
+    /// This is only useful for RSA keys.
+    ///
+    /// This corresponds to [`EVP_PKEY_CTX_set0_rsa_oaep_label`].
+    ///
+    /// [`EVP_PKEY_CTX_set0_rsa_oaep_label`]: https://www.openssl.org/docs/manmaster/man3/EVP_PKEY_CTX_set0_rsa_oaep_label.html
+    #[cfg(any(ossl102, libressl310))]
+    pub fn set_rsa_oaep_label(&mut self, label: &[u8]) -> Result<(), ErrorStack> {
+        unsafe {
+            let p = cvt_p(ffi::OPENSSL_malloc(label.len() as _))?;
+            ptr::copy_nonoverlapping(label.as_ptr(), p as *mut u8, label.len());
+
+            cvt(ffi::EVP_PKEY_CTX_set0_rsa_oaep_label(
+                self.pctx,
+                p as *mut c_void,
+                label.len() as c_int,
+            ))
+            .map(|_| ())
+            .map_err(|e| {
+                ffi::OPENSSL_free(p);
+                e
+            })
+        }
+    }
+
     /// Performs public key decryption.
     ///
     /// In order to know the size needed for the output buffer, use [`decrypt_len`](Decrypter::decrypt_len).
@@ -516,4 +542,37 @@ mod test {
 
         assert_eq!(decoded, &*input);
     }
+
+    #[test]
+    #[cfg(any(ossl102, libressl310))]
+    fn rsa_encrypt_decrypt_oaep_label() {
+        let key = include_bytes!("../test/rsa.pem");
+        let private_key = Rsa::private_key_from_pem(key).unwrap();
+        let pkey = PKey::from_rsa(private_key).unwrap();
+
+        let mut encrypter = Encrypter::new(&pkey).unwrap();
+        encrypter.set_rsa_padding(Padding::PKCS1_OAEP).unwrap();
+        encrypter.set_rsa_oaep_label(b"test_oaep_label").unwrap();
+        let input = Vec::from_hex(INPUT).unwrap();
+        let buffer_len = encrypter.encrypt_len(&input).unwrap();
+        let mut encoded = vec![0u8; buffer_len];
+        let encoded_len = encrypter.encrypt(&input, &mut encoded).unwrap();
+        let encoded = &encoded[..encoded_len];
+
+        let mut decrypter = Decrypter::new(&pkey).unwrap();
+        decrypter.set_rsa_padding(Padding::PKCS1_OAEP).unwrap();
+        decrypter.set_rsa_oaep_label(b"test_oaep_label").unwrap();
+        let buffer_len = decrypter.decrypt_len(encoded).unwrap();
+        let mut decoded = vec![0u8; buffer_len];
+        let decoded_len = decrypter.decrypt(encoded, &mut decoded).unwrap();
+        let decoded = &decoded[..decoded_len];
+
+        assert_eq!(decoded, &*input);
+
+        decrypter.set_rsa_oaep_label(b"wrong_oaep_label").unwrap();
+        let buffer_len = decrypter.decrypt_len(encoded).unwrap();
+        let mut decoded = vec![0u8; buffer_len];
+
+        assert!(decrypter.decrypt(encoded, &mut decoded).is_err());
+    }
 }