From 665fb3076ce9b8a6f26c50a422570252f8a24849 Mon Sep 17 00:00:00 2001
From: Jacob Barthelmeh <jacob@wolfssl.com>
Date: Mon, 4 Apr 2016 17:47:11 -0600
Subject: [PATCH] add trailing zero enum and correct call for export key size

---
 wolfcrypt/src/asn.c     | 28 +++++++++++++++++-----------
 wolfssl/wolfcrypt/asn.h |  3 ++-
 2 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/wolfcrypt/src/asn.c b/wolfcrypt/src/asn.c
index 53c84c198..c68d5c645 100644
--- a/wolfcrypt/src/asn.c
+++ b/wolfcrypt/src/asn.c
@@ -5883,7 +5883,7 @@ static int SetSerial(const byte* serial, byte* output)
 /* Write a public ECC key to output */
 static int SetEccPublicKey(byte* output, ecc_key* key, int with_header)
 {
-    byte len[MAX_LENGTH_SZ + 1];  /* trailing 0 */
+    byte len[MAX_LENGTH_SZ + TRAILING_ZERO];
     int  algoSz;
     int  curveSz;
     int  lenSz;
@@ -5941,7 +5941,7 @@ static int SetEccPublicKey(byte* output, ecc_key* key, int with_header)
 #endif
         algoSz  = SetAlgoID(ECDSAk, algo, oidKeyType, curveSz);
 
-        lenSz   = SetLength(pubSz + 1, len);
+        lenSz   = SetLength(pubSz + TRAILING_ZERO, len);
         len[lenSz++] = 0;   /* trailing 0 */
 
         /* write, 1 is for ASN_BIT_STRING */
@@ -5985,24 +5985,30 @@ int wc_EccPublicKeyToDer(ecc_key* key, byte* output, word32 inLen,
                                                               int with_AlgCurve)
 {
     word32 infoSz = 0;
+    word32 keySz  = 0;
+    int ret;
 
     if (output == NULL || key == NULL) {
         return BAD_FUNC_ARG;
     }
 
     if (with_AlgCurve) {
-        int maxSetLength = 4; /* max buffer space needed for SetLength        */
-        int asnBit = 1;       /* buffer space needed for asn bit string macro */
+        /* buffer space for algorithm/curve */
+        infoSz += MAX_SEQ_SZ;
+        infoSz += 2 * MAX_ALGO_SZ;
 
-        infoSz += asnBit;
-        infoSz += maxSetLength + asnBit; /* SetSequence buffer needed        */
-        infoSz += 2 * MAX_ALGO_SZ;       /* buffer space for algorithm/curve */
-        infoSz += asnBit;
-        infoSz += maxSetLength;
+        /* buffer space for public key sequence */
+        infoSz += MAX_SEQ_SZ;
+        infoSz += TRAILING_ZERO;
     }
 
-    if (inLen < wc_ecc_size(key) + infoSz) {
-        return BAD_FUNC_ARG;
+    if ((ret = wc_ecc_export_x963(key, NULL, &keySz)) != LENGTH_ONLY_E) {
+        WOLFSSL_MSG("Error in getting ECC public key size");
+        return ret;
+    }
+
+    if (inLen < keySz + infoSz) {
+        return BUFFER_E;
     }
 
     return SetEccPublicKey(output, key, with_AlgCurve);
diff --git a/wolfssl/wolfcrypt/asn.h b/wolfssl/wolfcrypt/asn.h
index 50d0c6c4f..dd54ffb5b 100644
--- a/wolfssl/wolfcrypt/asn.h
+++ b/wolfssl/wolfcrypt/asn.h
@@ -195,7 +195,8 @@ enum Misc_ASN {
     EIGHTK_BUF          = 8192,    /* Tmp buffer size           */
     MAX_PUBLIC_KEY_SZ   = MAX_NTRU_ENC_SZ + MAX_ALGO_SZ + MAX_SEQ_SZ * 2,
                                    /* use bigger NTRU size */
-    HEADER_ENCRYPTED_KEY_SIZE = 88 /* Extra header size for encrypted key */
+    HEADER_ENCRYPTED_KEY_SIZE = 88,/* Extra header size for encrypted key */
+    TRAILING_ZERO       = 1        /* Used for size of zero pad */
 };