ssl: refactoring ProcessBuffer to reduce stack usage:

--- variable password moved to the heap (80 bytes saved)
--- variable key moved to the heap (32 bytes saved)
--- variable iv moved to the heap (16 bytes saved)
--- variable Des moved to the heap (sizeof(Des) saved)
--- variable Des3 moved to the heap (sizeof(Des3) saved)
--- variable Aes moved to the heap (sizeof(Aes) saved)
--- variable RsaKey moved to the heap (sizeof(RsaKey) saved)

Utility functions added to Des, Des3 and Aes for easier decryption.

ctaocrypt/src/aes.c

@@ -1575,6 +1575,34 @@ int AesSetIV(Aes* aes, const byte* iv)
 }
 
 
+int AesCbcDecryptWithKey(byte* out, const byte* in, word32 inSz,
+                                  const byte* key, word32 keySz, const byte* iv)
+{
+    int  ret = 0;
+#ifdef CYASSL_SMALL_STACK
+    Aes* aes = NULL;
+#else
+    Aes  aes[1];
+#endif
+
+#ifdef CYASSL_SMALL_STACK
+    aes = (Aes*)XMALLOC(sizeof(Aes), NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    if (aes == NULL)
+        return MEMORY_E;
+#endif
+
+    ret = AesSetKey(aes, key, keySz, iv, AES_DECRYPTION);
+    if (ret == 0)
+        ret = AesCbcDecrypt(aes, out, in, inSz); 
+
+#ifdef CYASSL_SMALL_STACK
+    XFREE(aes, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+#endif
+
+    return ret;
+}
+
+
 /* AES-DIRECT */
 #if defined(CYASSL_AES_DIRECT)
     #if defined(FREESCALE_MMCAU)

ctaocrypt/src/des3.c

@@ -1389,6 +1389,34 @@ void Des_SetIV(Des* des, const byte* iv)
 }
 
 
+int Des_CbcDecryptWithKey(byte* out, const byte* in, word32 sz,
+                                                const byte* key, const byte* iv)
+{
+    int ret  = 0;
+#ifdef CYASSL_SMALL_STACK
+    Des* des = NULL;
+#else
+    Des  des[1];
+#endif
+
+#ifdef CYASSL_SMALL_STACK
+    des = (Des*)XMALLOC(sizeof(Des), NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    if (des == NULL)
+        return MEMORY_E;
+#endif
+
+    ret = Des_SetKey(des, key, iv, DES_DECRYPTION);
+    if (ret == 0)
+        ret = Des_CbcDecrypt(des, out, in, sz); 
+
+#ifdef CYASSL_SMALL_STACK
+    XFREE(des, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+#endif
+
+    return ret;
+}
+
+
 int Des3_SetIV(Des3* des, const byte* iv)
 {
     if (des && iv)
@@ -1400,6 +1428,34 @@ int Des3_SetIV(Des3* des, const byte* iv)
 }
 
 
+int Des3_CbcDecryptWithKey(byte* out, const byte* in, word32 sz,
+                                                const byte* key, const byte* iv)
+{
+    int ret    = 0;
+#ifdef CYASSL_SMALL_STACK
+    Des3* des3 = NULL;
+#else
+    Des3  des3[1];
+#endif
+
+#ifdef CYASSL_SMALL_STACK
+    des3 = (Des3*)XMALLOC(sizeof(Des3), NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    if (des3 == NULL)
+        return MEMORY_E;
+#endif
+
+    ret = Des3_SetKey(des3, key, iv, DES_DECRYPTION);
+    if (ret == 0)
+        ret = Des3_CbcDecrypt(des3, out, in, sz); 
+
+#ifdef CYASSL_SMALL_STACK
+    XFREE(des3, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+#endif
+
+    return ret;
+}
+
+
 #ifdef HAVE_CAVIUM
 
 #include "cavium_common.h"

cyassl/ctaocrypt/aes.h

@@ -110,6 +110,8 @@ CYASSL_API int  AesSetKey(Aes* aes, const byte* key, word32 len, const byte* iv,
 CYASSL_API int  AesSetIV(Aes* aes, const byte* iv);
 CYASSL_API int  AesCbcEncrypt(Aes* aes, byte* out, const byte* in, word32 sz);
 CYASSL_API int  AesCbcDecrypt(Aes* aes, byte* out, const byte* in, word32 sz);
+CYASSL_API int  AesCbcDecryptWithKey(byte* out, const byte* in, word32 inSz,
+                                 const byte* key, word32 keySz, const byte* iv);
 CYASSL_API void AesCtrEncrypt(Aes* aes, byte* out, const byte* in, word32 sz);
 CYASSL_API void AesEncryptDirect(Aes* aes, byte* out, const byte* in);
 CYASSL_API void AesDecryptDirect(Aes* aes, byte* out, const byte* in);

cyassl/ctaocrypt/des3.h

@@ -85,11 +85,15 @@ CYASSL_API void Des_SetIV(Des* des, const byte* iv);
 CYASSL_API int  Des_CbcEncrypt(Des* des, byte* out, const byte* in, word32 sz);
 CYASSL_API int  Des_CbcDecrypt(Des* des, byte* out, const byte* in, word32 sz);
 CYASSL_API int  Des_EcbEncrypt(Des* des, byte* out, const byte* in, word32 sz);
+CYASSL_API int  Des_CbcDecryptWithKey(byte* out, const byte* in, word32 sz,
+                                               const byte* key, const byte* iv);
 
 CYASSL_API int  Des3_SetKey(Des3* des, const byte* key, const byte* iv,int dir);
 CYASSL_API int  Des3_SetIV(Des3* des, const byte* iv);
 CYASSL_API int  Des3_CbcEncrypt(Des3* des, byte* out, const byte* in,word32 sz);
 CYASSL_API int  Des3_CbcDecrypt(Des3* des, byte* out, const byte* in,word32 sz);
+CYASSL_API int  Des3_CbcDecryptWithKey(byte* out, const byte* in, word32 sz,
+                                               const byte* key, const byte* iv);
 
 
 #ifdef HAVE_CAVIUM

src/ssl.c

@@ -2183,14 +2183,34 @@ static int ProcessBuffer(CYASSL_CTX* ctx, const unsigned char* buff,
 #if defined(OPENSSL_EXTRA) || defined(HAVE_WEBSERVER)
     if (info->set) {
         /* decrypt */
-        char password[80];
+        int   passwordSz;
-        int  passwordSz;
+#ifdef CYASSL_SMALL_STACK
-
+        char* password = NULL;
-        byte key[AES_256_KEY_SIZE];
+        byte* key      = NULL;
+        byte* iv       = NULL;
+#else
+        char  password[80];
+        byte  key[AES_256_KEY_SIZE];
         byte  iv[AES_IV_SIZE];
+#endif
 
+    #ifdef CYASSL_SMALL_STACK
+        password = (char*)XMALLOC(80, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+        key      = (byte*)XMALLOC(AES_256_KEY_SIZE, NULL,
+                                                   DYNAMIC_TYPE_TMP_BUFFER);
+        iv       = (byte*)XMALLOC(AES_IV_SIZE, NULL, 
+                                                   DYNAMIC_TYPE_TMP_BUFFER);
+
+        if (password == NULL || key == NULL || iv == NULL) {
+            XFREE(password, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+            XFREE(key,      NULL, DYNAMIC_TYPE_TMP_BUFFER);
+            XFREE(iv,       NULL, DYNAMIC_TYPE_TMP_BUFFER);
+            ret = MEMORY_E;
+        }
+        else
+    #endif
         if (!ctx || !ctx->passwd_cb) {
-            return NO_PASSWORD;
+            ret = NO_PASSWORD;
         }
         else {
             passwordSz = ctx->passwd_cb(password, sizeof(password), 0,
@@ -2206,50 +2226,36 @@ static int ProcessBuffer(CYASSL_CTX* ctx, const unsigned char* buff,
                 /* empty */
             }
             else if (XSTRNCMP(info->name, "DES-CBC", 7) == 0) {
-                Des enc;
+                ret = Des_CbcDecryptWithKey(der.buffer, der.buffer, der.length,
-
+                                                                 key, info->iv);
-                ret = Des_SetKey(&enc, key, info->iv, DES_DECRYPTION);
-                if (ret == 0)
-                    Des_CbcDecrypt(&enc, der.buffer, der.buffer,
-                                                                    der.length);
             }
             else if (XSTRNCMP(info->name, "DES-EDE3-CBC", 13) == 0) {
-                Des3 enc;
+                ret = Des3_CbcDecryptWithKey(der.buffer, der.buffer, der.length,
-
+                                                                 key, info->iv);
-                ret = Des3_SetKey(&enc, key, info->iv, DES_DECRYPTION);
-                if (ret == 0)
-                    ret = Des3_CbcDecrypt(&enc, der.buffer, der.buffer,
-                                                                    der.length);
             }
             else if (XSTRNCMP(info->name, "AES-128-CBC", 13) == 0) {
-                Aes enc;
+                ret = AesCbcDecryptWithKey(der.buffer, der.buffer, der.length,
-                ret = AesSetKey(&enc, key, AES_128_KEY_SIZE, info->iv,
+                                               key, AES_128_KEY_SIZE, info->iv);
-                                                                AES_DECRYPTION);
-                if (ret == 0)
-                    ret = AesCbcDecrypt(&enc, der.buffer, der.buffer,
-                                                                    der.length);
             }
             else if (XSTRNCMP(info->name, "AES-192-CBC", 13) == 0) {
-                Aes enc;
+                ret = AesCbcDecryptWithKey(der.buffer, der.buffer, der.length,
-                ret = AesSetKey(&enc, key, AES_192_KEY_SIZE, info->iv,
+                                               key, AES_192_KEY_SIZE, info->iv);
-                                                                AES_DECRYPTION);
-                if (ret == 0)
-                    ret = AesCbcDecrypt(&enc, der.buffer, der.buffer,
-                                                                    der.length);
             }
             else if (XSTRNCMP(info->name, "AES-256-CBC", 13) == 0) {
-                Aes enc;
+                ret = AesCbcDecryptWithKey(der.buffer, der.buffer, der.length,
-                ret = AesSetKey(&enc, key, AES_256_KEY_SIZE, info->iv,
+                                               key, AES_256_KEY_SIZE, info->iv);
-                                                                AES_DECRYPTION);
-                if (ret == 0)
-                    ret = AesCbcDecrypt(&enc, der.buffer, der.buffer,
-                                                                    der.length);
             }
             else {
                 ret = SSL_BAD_FILE;
             }
         }
 
+    #ifdef CYASSL_SMALL_STACK
+        XFREE(password, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+        XFREE(key,      NULL, DYNAMIC_TYPE_TMP_BUFFER);
+        XFREE(iv,       NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    #endif
+
         if (ret != 0) {
         #ifdef CYASSL_SMALL_STACK
             XFREE(info, NULL, DYNAMIC_TYPE_TMP_BUFFER);
@@ -2308,25 +2314,44 @@ static int ProcessBuffer(CYASSL_CTX* ctx, const unsigned char* buff,
     #ifndef NO_RSA
         if (!eccKey) {
             /* make sure RSA key can be used */
-            RsaKey key;
             word32 idx = 0;
+        #ifdef CYASSL_SMALL_STACK
+            RsaKey* key = NULL;
+        #else
+            RsaKey  key[1];
+        #endif
 
-            ret = InitRsaKey(&key, 0);
+        #ifdef CYASSL_SMALL_STACK
-            if (ret != 0) return ret;
+            key = (RsaKey*)XMALLOC(sizeof(RsaKey), NULL,
-            if (RsaPrivateKeyDecode(der.buffer,&idx,&key,der.length) != 0) {
+                                                       DYNAMIC_TYPE_TMP_BUFFER);
-            #ifdef HAVE_ECC
+            if (key == NULL)
-                /* could have DER ECC (or pkcs8 ecc), no easy way to tell */
+                return MEMORY_E;
-                eccKey = 1;  /* so try it out */
+        #endif
-            #endif
+
-                if (!eccKey) {
+            ret = InitRsaKey(key, 0);
-                    FreeRsaKey(&key);
+            if (ret == 0) {
-                    return SSL_BAD_FILE;
+                if (RsaPrivateKeyDecode(der.buffer, &idx, key, der.length) !=
+                                                                            0) {
+                #ifdef HAVE_ECC
+                    /* could have DER ECC (or pkcs8 ecc), no easy way to tell */
+                    eccKey = 1;  /* so try it out */
+                #endif
+                    if (!eccKey)
+                        ret = SSL_BAD_FILE;
+                } else {
+                    rsaKey = 1;
+                    (void)rsaKey;  /* for no ecc builds */
                 }
-            } else {
-                rsaKey = 1;
-                (void)rsaKey;  /* for no ecc builds */
             }
-            FreeRsaKey(&key);
+
+            FreeRsaKey(key);
+
+        #ifdef CYASSL_SMALL_STACK
+            XFREE(key, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+        #endif
+
+            if (ret != 0)
+                return ret;
         }
     #endif
     #ifdef HAVE_ECC