feat(util): Add ARC4 algorithm to util

components/util/src/arc4.c

@@ -0,0 +1,91 @@
+// Copyright 2018-2019 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <sys/errno.h>
+#include <string.h>
+#include "esp_arc4.h"
+#include "ibus_data.h"
+#include "util_assert.h"
+
+/*
+ * ARC4 key schedule
+ */
+void esp_arc4_setup(esp_arc4_context *ctx, const uint8_t *key, uint32_t keylen)
+{
+    int i, j, a;
+    uint32_t k;
+    uint8_t *m;
+
+    util_assert(ctx);
+    util_assert(key);
+
+    ctx->x = 0;
+    ctx->y = 0;
+    m = ctx->m;
+
+    for(i = 0; i < 256; i++)
+        m[i] = (uint8_t) i;
+
+    j = k = 0;
+
+    for(i = 0; i < 256; i++, k++)
+    {
+        if(k >= keylen) k = 0;
+
+        a = m[i];
+        j = (j + a + key[k]) & 0xFF;
+        m[i] = m[j];
+        m[j] = (uint8_t) a;
+    }
+}
+
+/*
+ * ARC4 cipher function
+ */
+int esp_arc4_encrypt(esp_arc4_context *ctx, size_t length, const uint8_t *input, uint8_t *output)
+{
+    int x, y, a, b;
+    size_t i;
+    uint8_t *m;
+
+    util_assert(ctx);
+    util_assert(input);
+    util_assert(output);
+    
+    x = ctx->x;
+    y = ctx->y;
+    m = ctx->m;
+
+    for(i = 0; i < length; i++)
+    {
+        x = (x + 1) & 0xFF; a = m[x];
+        y = (y + a) & 0xFF; b = m[y];
+
+        m[x] = (uint8_t) b;
+        m[y] = (uint8_t) a;
+
+        output[i] = (uint8_t)(input[i] ^ m[(uint8_t)(a + b)]);
+    }
+
+    ctx->x = x;
+    ctx->y = y;
+
+    return 0;
+}
+
+int esp_arc4_decrypt(esp_arc4_context *ctx, size_t length, const uint8_t *input, uint8_t *output)
+{
+    return esp_arc4_encrypt(ctx, length, input, output);
+}
+