update CFB mode to handle partial AES block sizes

wolfcrypt/src/aes.c

@@ -1828,7 +1828,7 @@ static void wc_AesDecrypt(Aes* aes, const byte* inBlock, byte* outBlock)
     #ifndef WOLFSSL_STM32_CUBEMX
         ByteReverseWords(rk, rk, keylen);
     #endif
-    #ifdef WOLFSSL_AES_COUNTER
+    #if defined(HAVE_AES_CFB) || defined(WOLFSSL_AES_COUNTER)
         aes->left = 0;
     #endif
 
@@ -1901,6 +1901,10 @@ static void wc_AesDecrypt(Aes* aes, const byte* inBlock, byte* outBlock)
         if (iv)
             XMEMCPY(aes->reg, iv, AES_BLOCK_SIZE);
 
+    #if defined(HAVE_AES_CFB) || defined(WOLFSSL_AES_COUNTER)
+        aes->left = 0;
+    #endif
+
         return 0;
     }
 #elif defined(FREESCALE_LTC)
@@ -1912,7 +1916,8 @@ static void wc_AesDecrypt(Aes* aes, const byte* inBlock, byte* outBlock)
 
         aes->rounds = keylen/4 + 6;
         XMEMCPY(aes->key, userKey, keylen);
-    #ifdef WOLFSSL_AES_COUNTER
+
+    #if defined(HAVE_AES_CFB) || defined(WOLFSSL_AES_COUNTER)
         aes->left = 0;
     #endif
 
@@ -1939,10 +1944,10 @@ static void wc_AesDecrypt(Aes* aes, const byte* inBlock, byte* outBlock)
         if (rk == NULL)
             return BAD_FUNC_ARG;
 
-    #ifdef WOLFSSL_AES_COUNTER
+    #if defined(HAVE_AES_CFB) || defined(WOLFSSL_AES_COUNTER)
         aes->left = 0;
     #endif
-        aes->keylen = keylen;
+
         aes->rounds = keylen/4 + 6;
 
         ret = wolfSSL_CryptHwMutexLock();
@@ -1982,6 +1987,10 @@ static void wc_AesDecrypt(Aes* aes, const byte* inBlock, byte* outBlock)
         aes->rounds = keylen/4 + 6;
         ret = nrf51_aes_set_key(userKey);
 
+    #if defined(HAVE_AES_CFB) || defined(WOLFSSL_AES_COUNTER)
+        aes->left = 0;
+    #endif
+
         return ret;
     }
 
@@ -2004,12 +2013,12 @@ static void wc_AesDecrypt(Aes* aes, const byte* inBlock, byte* outBlock)
         unsigned int i = 0;
     #endif
 
-    #ifdef WOLFSSL_AESNI
+        #ifdef WOLFSSL_AESNI
-        aes->use_aesni = 0;
+            aes->use_aesni = 0;
-    #endif /* WOLFSSL_AESNI */
+        #endif /* WOLFSSL_AESNI */
-    #ifdef WOLFSSL_AES_COUNTER
+        #if defined(HAVE_AES_CFB) || defined(WOLFSSL_AES_COUNTER)
-        aes->left = 0;
+            aes->left = 0;
-    #endif /* WOLFSSL_AES_COUNTER */
+        #endif
 
         aes->keylen = keylen;
         aes->rounds = (keylen/4) + 6;
@@ -3053,7 +3062,8 @@ int wc_AesSetIV(Aes* aes, const byte* iv)
 /* CFB 128 */
 int wc_AesCfbEncrypt(Aes* aes, byte* out, const byte* in, word32 sz)
 {
-    word32 blocks = sz / AES_BLOCK_SIZE;
+    byte*  reg = NULL;
+    byte*  tmp;
 
     WOLFSSL_ENTER("wc_AesCfbEncrypt");
 
@@ -3061,12 +3071,39 @@ int wc_AesCfbEncrypt(Aes* aes, byte* out, const byte* in, word32 sz)
         return BAD_FUNC_ARG;
     }
 
-    while (blocks--) {
+    if (aes->left && sz) {
+        reg = (byte*)aes->reg + AES_BLOCK_SIZE - aes->left;
+    }
+
+    /* consume any unused bytes left in aes->tmp */
+    tmp = (byte*)aes->tmp + AES_BLOCK_SIZE - aes->left;
+    while (aes->left && sz) {
+        *(out++) = *(reg++) = *(in++) ^ *(tmp++);
+        aes->left--;
+        sz--;
+    }
+
+    while (sz >= AES_BLOCK_SIZE) {
         wc_AesEncrypt(aes, (byte*)aes->reg, out);
         xorbuf(out, in, AES_BLOCK_SIZE);
         XMEMCPY(aes->reg, out, AES_BLOCK_SIZE);
         out += AES_BLOCK_SIZE;
         in  += AES_BLOCK_SIZE;
+        sz  -= AES_BLOCK_SIZE;
+        aes->left = 0;
+    }
+
+    /* encrypt left over data */
+    if (sz) {
+        wc_AesEncrypt(aes, (byte*)aes->reg, (byte*)aes->tmp);
+        aes->left = AES_BLOCK_SIZE;
+        tmp = (byte*)aes->tmp;
+        reg = (byte*)aes->reg;
+
+        while (sz--) {
+            *(out++) = *(reg++) = *(in++) ^ *(tmp++);
+            aes->left--;
+        }
     }
 
     return 0;
@@ -3076,7 +3113,7 @@ int wc_AesCfbEncrypt(Aes* aes, byte* out, const byte* in, word32 sz)
 #ifdef HAVE_AES_DECRYPT
 int wc_AesCfbDecrypt(Aes* aes, byte* out, const byte* in, word32 sz)
 {
-    word32 blocks = sz / AES_BLOCK_SIZE;
+    byte*  tmp;
 
     WOLFSSL_ENTER("wc_AesCfbDecrypt");
 
@@ -3084,12 +3121,41 @@ int wc_AesCfbDecrypt(Aes* aes, byte* out, const byte* in, word32 sz)
         return BAD_FUNC_ARG;
     }
 
-    while (blocks--) {
+    /* check if more input needs copied over to aes->reg */
+    if (aes->left && sz) {
+        int size = min(aes->left, sz);
+        XMEMCPY((byte*)aes->reg + AES_BLOCK_SIZE - aes->left, in, size);
+    }
+
+    /* consume any unused bytes left in aes->tmp */
+    tmp = (byte*)aes->tmp + AES_BLOCK_SIZE - aes->left;
+    while (aes->left && sz) {
+        *(out++) = *(in++) ^ *(tmp++);
+        aes->left--;
+        sz--;
+    }
+
+    while (sz > AES_BLOCK_SIZE) {
         wc_AesEncrypt(aes, (byte*)aes->reg, out);
         xorbuf(out, in, AES_BLOCK_SIZE);
         XMEMCPY(aes->reg, in, AES_BLOCK_SIZE);
         out += AES_BLOCK_SIZE;
         in  += AES_BLOCK_SIZE;
+        sz  -= AES_BLOCK_SIZE;
+        aes->left = 0;
+    }
+
+    /* decrypt left over data */
+    if (sz) {
+        wc_AesEncrypt(aes, (byte*)aes->reg, (byte*)aes->tmp);
+        XMEMCPY(aes->reg, in, sz);
+        aes->left = AES_BLOCK_SIZE;
+        tmp = (byte*)aes->tmp;
+
+        while (sz--) {
+            *(out++) = *(in++) ^ *(tmp++);
+            aes->left--;
+        }
     }
 
     return 0;

wolfcrypt/test/test.c

@@ -4454,21 +4454,56 @@ int des3_test(void)
             return -1118;
     #endif
 
+        /* test with data left overs, magic lengths are checking near edges */
         XMEMSET(cipher, 0, sizeof(cipher));
-        ret = wc_AesCfbEncrypt(&enc, cipher, msg3, AES_BLOCK_SIZE * 4);
+        ret = wc_AesCfbEncrypt(&enc, cipher, msg3, 4);
         if (ret != 0)
             return -1119;
 
-        if (XMEMCMP(cipher, cipher3, AES_BLOCK_SIZE * 4))
+        if (XMEMCMP(cipher, cipher3, 4))
             return -1120;
 
-    #ifdef HAVE_AES_DECRYPT
+        ret = wc_AesCfbEncrypt(&enc, cipher + 4, msg3 + 4, 27);
-        ret = wc_AesCfbDecrypt(&dec, plain, cipher, AES_BLOCK_SIZE * 4);
         if (ret != 0)
             return -1121;
 
-        if (XMEMCMP(plain, msg3, AES_BLOCK_SIZE * 4))
+        if (XMEMCMP(cipher + 4, cipher3 + 4, 27))
             return -1122;
+
+        ret = wc_AesCfbEncrypt(&enc, cipher + 31, msg3 + 31,
+                (AES_BLOCK_SIZE * 4) - 31);
+        if (ret != 0)
+            return -1123;
+
+        if (XMEMCMP(cipher, cipher3, AES_BLOCK_SIZE * 4))
+            return -1124;
+
+    #ifdef HAVE_AES_DECRYPT
+        ret = wc_AesCfbDecrypt(&dec, plain, cipher, 4);
+        if (ret != 0)
+            return -1125;
+
+        if (XMEMCMP(plain, msg3, 4))
+            return -1126;
+
+        ret = wc_AesCfbDecrypt(&dec, plain + 4, cipher + 4, 4);
+        if (ret != 0)
+            return -1127;
+
+        ret = wc_AesCfbDecrypt(&dec, plain + 8, cipher + 8, 23);
+        if (ret != 0)
+            return -1128;
+
+        if (XMEMCMP(plain + 4, msg3 + 4, 27))
+            return -1129;
+
+        ret = wc_AesCfbDecrypt(&dec, plain + 31, cipher + 31,
+                (AES_BLOCK_SIZE * 4) - 31);
+        if (ret != 0)
+            return -1130;
+
+        if (XMEMCMP(plain, msg3, AES_BLOCK_SIZE * 4))
+            return -1131;
     #endif /* HAVE_AES_DECRYPT */
 
         return ret;

wolfssl/wolfcrypt/aes.h

@@ -97,7 +97,7 @@ typedef struct Aes {
     word32 asyncIv[AES_BLOCK_SIZE/sizeof(word32)]; /* raw IV */
     WC_ASYNC_DEV asyncDev;
 #endif /* WOLFSSL_ASYNC_CRYPT */
-#ifdef WOLFSSL_AES_COUNTER
+#if defined(WOLFSSL_AES_COUNTER) || defined(HAVE_AES_CFB)
     word32  left;            /* unused bytes left from last call */
 #endif
 #ifdef WOLFSSL_XILINX_CRYPT