From bc1cb4ead842ab6b82aa4a2eedb451aaa4685619 Mon Sep 17 00:00:00 2001
From: David Garske <david@wolfssl.com>
Date: Tue, 7 Jan 2020 18:58:26 -0800
Subject: [PATCH] Fix to keep existing behavior where AAD is optional for
 `wc_ChaCha20Poly1305_Encrypt` and `wc_ChaCha20Poly1305_Decrypt`.

---
 wolfcrypt/src/chacha20_poly1305.c | 6 +++---
 wolfcrypt/src/poly1305.c          | 3 +++
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/wolfcrypt/src/chacha20_poly1305.c b/wolfcrypt/src/chacha20_poly1305.c
index ddd3a576f..b59495753 100644
--- a/wolfcrypt/src/chacha20_poly1305.c
+++ b/wolfcrypt/src/chacha20_poly1305.c
@@ -176,7 +176,7 @@ int wc_ChaCha20Poly1305_UpdateAad(ChaChaPoly_Aead* aead,
 {
     int ret = 0;
 
-    if (aead == NULL || inAAD == NULL) {
+    if (aead == NULL || (inAAD == NULL && inAADLen > 0)) {
         return BAD_FUNC_ARG;
     }
     if (aead->state != CHACHA20_POLY1305_STATE_READY &&
@@ -184,7 +184,7 @@ int wc_ChaCha20Poly1305_UpdateAad(ChaChaPoly_Aead* aead,
         return BAD_STATE_E;
     }
 
-    if (inAADLen > 0) {
+    if (inAAD && inAADLen > 0) {
         ret = wc_Poly1305Update(&aead->poly, inAAD, inAADLen);
         if (ret == 0) {
             aead->aadLen += inAADLen;
@@ -218,7 +218,7 @@ int wc_ChaCha20Poly1305_UpdateData(ChaChaPoly_Aead* aead,
     /* advance state */
     aead->state = CHACHA20_POLY1305_STATE_DATA;
 
-    /* Perform ChaCha20 encrypt or decrypt inline and Poly1305 auth calc */
+    /* Perform ChaCha20 encrypt/decrypt and Poly1305 auth calc */
     if (ret == 0) {
         if (aead->isEncrypt) {
             ret = wc_Chacha_Process(&aead->chacha, outData, inData, dataLen);
diff --git a/wolfcrypt/src/poly1305.c b/wolfcrypt/src/poly1305.c
index c43b7ba55..797785b8d 100644
--- a/wolfcrypt/src/poly1305.c
+++ b/wolfcrypt/src/poly1305.c
@@ -770,6 +770,9 @@ int wc_Poly1305_Pad(Poly1305* ctx, word32 lenToPad)
     if (ctx == NULL) {
         return BAD_FUNC_ARG;
     }
+    if (lenToPad == 0) {
+        return 0; /* nothing needs to be done */
+    }
 
     XMEMSET(padding, 0, sizeof(padding));