From fd0d1c7d603ff33c65a596c005aa2408481ae52c Mon Sep 17 00:00:00 2001
From: Jack Grigg <jack@z.cash>
Date: Thu, 8 Jun 2017 16:07:49 +1200
Subject: [PATCH] Ensure that ECDSA constant sizes are correctly-sized

---
 src/key.cpp  | 3 +++
 src/pubkey.h | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/src/key.cpp b/src/key.cpp
index 9da5ec891..a43131613 100644
--- a/src/key.cpp
+++ b/src/key.cpp
@@ -92,6 +92,9 @@ static int ec_privkey_import_der(const secp256k1_context* ctx, unsigned char *ou
  */
 static int ec_privkey_export_der(const secp256k1_context *ctx, unsigned char *privkey, size_t *privkeylen, const unsigned char *key32, int compressed) {
     assert(*privkeylen >= PRIVATE_KEY_SIZE);
+    static_assert(
+        PRIVATE_KEY_SIZE >= COMPRESSED_PRIVATE_KEY_SIZE,
+        "COMPRESSED_PRIVATE_KEY_SIZE is larger than PRIVATE_KEY_SIZE");
     secp256k1_pubkey pubkey;
     size_t pubkeylen = 0;
     if (!secp256k1_ec_pubkey_create(ctx, &pubkey, key32)) {
diff --git a/src/pubkey.h b/src/pubkey.h
index fb1352266..fcfa019cf 100644
--- a/src/pubkey.h
+++ b/src/pubkey.h
@@ -46,6 +46,9 @@ private:
      * Its length can very cheaply be computed from the first byte.
      */
     unsigned char vch[PUBLIC_KEY_SIZE];
+    static_assert(
+        PUBLIC_KEY_SIZE >= COMPRESSED_PUBLIC_KEY_SIZE,
+        "COMPRESSED_PUBLIC_KEY_SIZE is larger than PUBLIC_KEY_SIZE");
 
     //! Compute the length of a pubkey with a given first byte.
     unsigned int static GetLen(unsigned char chHeader)