1 files changed, 121 insertions, 0 deletions
diff --git a/libavutil/tea.c b/libavutil/tea.c
new file mode 100644
index 0000000000..b138f8bea1
--- /dev/null
+++ b/libavutil/tea.c
@@ -0,0 +1,121 @@
+/*
+ * A 32-bit implementation of the TEA algorithm
+ * Copyright (c) 2015 Vesselin Bontchev
+ *
+ * Loosely based on the implementation of David Wheeler and Roger Needham,
+ * https://en.wikipedia.org/wiki/Tiny_Encryption_Algorithm#Reference_code
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "avutil.h"
+#include "common.h"
+#include "intreadwrite.h"
+#include "tea.h"
+
+typedef struct AVTEA {
+    uint32_t key[16];
+    int rounds;
+} AVTEA;
+
+struct AVTEA *av_tea_alloc(void)
+{
+    return av_mallocz(sizeof(struct AVTEA));
+}
+
+const int av_tea_size = sizeof(AVTEA);
+
+void av_tea_init(AVTEA *ctx, const uint8_t key[16], int rounds)
+{
+    int i;
+
+    for (i = 0; i < 4; i++)
+        ctx->key[i] = AV_RB32(key + (i << 2));
+
+    ctx->rounds = rounds;
+}
+
+static void tea_crypt_ecb(AVTEA *ctx, uint8_t *dst, const uint8_t *src,
+                          int decrypt, uint8_t *iv)
+{
+    uint32_t v0, v1;
+    int rounds = ctx->rounds;
+    uint32_t k0, k1, k2, k3;
+    k0 = ctx->key[0];
+    k1 = ctx->key[1];
+    k2 = ctx->key[2];
+    k3 = ctx->key[3];
+
+    v0 = AV_RB32(src);
+    v1 = AV_RB32(src + 4);
+
+    if (decrypt) {
+        int i;
+        uint32_t delta = 0x9E3779B9U, sum = delta * (rounds / 2);
+
+        for (i = 0; i < rounds / 2; i++) {
+            v1 -= ((v0 << 4) + k2) ^ (v0 + sum) ^ ((v0 >> 5) + k3);
+            v0 -= ((v1 << 4) + k0) ^ (v1 + sum) ^ ((v1 >> 5) + k1);
+            sum -= delta;
+        }
+        if (iv) {
+            v0 ^= AV_RB32(iv);
+            v1 ^= AV_RB32(iv + 4);
+            memcpy(iv, src, 8);
+        }
+    } else {
+        int i;
+        uint32_t sum = 0, delta = 0x9E3779B9U;
+
+        for (i = 0; i < rounds / 2; i++) {
+            sum += delta;
+            v0 += ((v1 << 4) + k0) ^ (v1 + sum) ^ ((v1 >> 5) + k1);
+            v1 += ((v0 << 4) + k2) ^ (v0 + sum) ^ ((v0 >> 5) + k3);
+        }
+    }
+
+    AV_WB32(dst, v0);
+    AV_WB32(dst + 4, v1);
+}
+
+void av_tea_crypt(AVTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
+                  uint8_t *iv, int decrypt)
+{
+    int i;
+
+    if (decrypt) {
+        while (count--) {
+            tea_crypt_ecb(ctx, dst, src, decrypt, iv);
+
+            src   += 8;
+            dst   += 8;
+        }
+    } else {
+        while (count--) {
+            if (iv) {
+                for (i = 0; i < 8; i++)
+                    dst[i] = src[i] ^ iv[i];
+                tea_crypt_ecb(ctx, dst, dst, decrypt, NULL);
+                memcpy(iv, dst, 8);
+            } else {
+                tea_crypt_ecb(ctx, dst, src, decrypt, NULL);
+            }
+            src   += 8;
+            dst   += 8;
+        }
+    }
+}