Add XTEA encryption support in libavutil

Signed-off-by: Martin Storsjö <martin@martin.st>

4 files changed, 230 insertions, 1 deletions

diff --git a/libavutil/Makefile b/libavutil/Makefile
index ea8139f522..4eabcd046a 100644
--- a/libavutil/Makefile
+++ b/libavutil/Makefile
@@ -38,6 +38,7 @@ HEADERS = adler32.h                                                     \
           samplefmt.h                                                   \
           sha.h                                                         \
           time.h                                                        \
+          xtea.h                                                        \
 
 ARCH_HEADERS = bswap.h                                                  \
                intmath.h                                                \
@@ -83,6 +84,7 @@ OBJS = adler32.o                                                        \
        time.o                                                           \
        tree.o                                                           \
        utils.o                                                          \
+       xtea.o                                                           \
 
 TESTPROGS = adler32                                                     \
             aes                                                         \
@@ -101,3 +103,4 @@ TESTPROGS = adler32                                                     \
             parseutils                                                  \
             sha                                                         \
             tree                                                        \
+            xtea                                                        \
diff --git a/libavutil/avutil.h b/libavutil/avutil.h
index 31811528b6..fc1841785e 100644
--- a/libavutil/avutil.h
+++ b/libavutil/avutil.h
@@ -152,7 +152,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR 51
-#define LIBAVUTIL_VERSION_MINOR 35
+#define LIBAVUTIL_VERSION_MINOR 36
 #define LIBAVUTIL_VERSION_MICRO  0
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
diff --git a/libavutil/xtea.c b/libavutil/xtea.c
new file mode 100644
index 0000000000..138657f88b
--- /dev/null
+++ b/libavutil/xtea.c
@@ -0,0 +1,165 @@
+/*
+ * A 32-bit implementation of the XTEA algorithm
+ * Copyright (c) 2012 Samuel Pitoiset
+ *
+ * loosely based on the implementation of David Wheeler and Roger Needham
+ *
+ * This file is part of Libav.
+ *
+ * Libav 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.
+ *
+ * Libav 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 Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavutil/intreadwrite.h"
+
+#include "avutil.h"
+#include "common.h"
+#include "xtea.h"
+
+void av_xtea_init(AVXTEA *ctx, const uint8_t key[16])
+{
+    int i;
+
+    for (i = 0; i < 4; i++)
+        ctx->key[i] = AV_RB32(key + (i << 2));
+}
+
+static void xtea_crypt_ecb(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
+                           int decrypt)
+{
+    uint32_t v0, v1;
+    int i;
+
+    v0 = AV_RB32(src);
+    v1 = AV_RB32(src + 4);
+
+    if (decrypt) {
+        uint32_t delta = 0x9E3779B9, sum = delta * 32;
+
+        for (i = 0; i < 32; i++) {
+            v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
+            sum -= delta;
+            v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
+        }
+    } else {
+        uint32_t sum = 0, delta = 0x9E3779B9;
+
+        for (i = 0; i < 32; i++) {
+            v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
+            sum += delta;
+            v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
+        }
+    }
+
+    AV_WB32(dst, v0);
+    AV_WB32(dst + 4, v1);
+}
+
+void av_xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
+                   uint8_t *iv, int decrypt)
+{
+    int i;
+
+    while (count > 0) {
+        if (decrypt) {
+            xtea_crypt_ecb(ctx, dst, src, decrypt);
+
+            if (iv) {
+                for (i = 0; i < 8; i++)
+                    dst[i] = dst[i] ^ iv[i];
+                memcpy(iv, src, 8);
+            }
+        } else {
+            if (iv) {
+                for (i = 0; i < 8; i++)
+                    dst[i] = src[i] ^ iv[i];
+                xtea_crypt_ecb(ctx, dst, dst, decrypt);
+                memcpy(iv, dst, 8);
+            } else {
+                xtea_crypt_ecb(ctx, dst, src, decrypt);
+            }
+        }
+
+        src   += 8;
+        dst   += 8;
+        count -= 8;
+    }
+}
+
+#ifdef TEST
+#include <stdio.h>
+#undef printf
+
+#define XTEA_NUM_TESTS 6
+
+static const uint8_t xtea_test_key[XTEA_NUM_TESTS][16] = {
+    { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+      0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
+    { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+      0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
+    { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+      0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
+    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
+    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
+    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
+};
+
+static const uint8_t xtea_test_pt[XTEA_NUM_TESTS][8] = {
+    { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
+    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
+    { 0x5a, 0x5b, 0x6e, 0x27, 0x89, 0x48, 0xd7, 0x7f },
+    { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
+    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
+    { 0x70, 0xe1, 0x22, 0x5d, 0x6e, 0x4e, 0x76, 0x55 }
+};
+
+static const uint8_t xtea_test_ct[XTEA_NUM_TESTS][8] = {
+    { 0x49, 0x7d, 0xf3, 0xd0, 0x72, 0x61, 0x2c, 0xb5 },
+    { 0xe7, 0x8f, 0x2d, 0x13, 0x74, 0x43, 0x41, 0xd8 },
+    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
+    { 0xa0, 0x39, 0x05, 0x89, 0xf8, 0xb8, 0xef, 0xa5 },
+    { 0xed, 0x23, 0x37, 0x5a, 0x82, 0x1a, 0x8c, 0x2d },
+    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 }
+};
+
+int main(void)
+{
+    AVXTEA ctx;
+    uint8_t buf[8];
+    int i;
+
+    for (i = 0; i < XTEA_NUM_TESTS; i++) {
+        av_xtea_init(&ctx, xtea_test_key[i]);
+
+        av_xtea_crypt(&ctx, buf, xtea_test_pt[i], 1, NULL, 0);
+        if (memcmp(buf, xtea_test_ct[i], 8)) {
+            printf("Test encryption failed.\n");
+            return 1;
+        }
+
+        av_xtea_crypt(&ctx, buf, xtea_test_ct[i], 1, NULL, 1);
+        if (memcmp(buf, xtea_test_pt[i], 8)) {
+            printf("Test decryption failed.\n");
+            return 1;
+        }
+    }
+    printf("Test encryption/decryption success.\n");
+
+    return 0;
+}
+
+#endif
diff --git a/libavutil/xtea.h b/libavutil/xtea.h
new file mode 100644
index 0000000000..cf305c6632
--- /dev/null
+++ b/libavutil/xtea.h
@@ -0,0 +1,61 @@
+/*
+ * A 32-bit implementation of the XTEA algorithm
+ *
+ * This file is part of Libav.
+ *
+ * Libav 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.
+ *
+ * Libav 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 Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVUTIL_XTEA_H
+#define AVUTIL_XTEA_H
+
+#include <stdint.h>
+
+/**
+ * @defgroup lavu_xtea XTEA
+ * @ingroup lavu_crypto
+ * @{
+ */
+
+typedef struct AVXTEA {
+    uint32_t key[16];
+} AVXTEA;
+
+/**
+ * Initialize an AVXTEA context.
+ *
+ * @param x an AVXTEA context
+ * @param key a key of 16 bytes used for encryption/decryption
+ */
+void av_xtea_init(struct AVXTEA *ctx, const uint8_t key[16]);
+
+/**
+ * Encrypt or decrypt a buffer using a previously initialized context.
+ *
+ * @param x an AVXTEA context
+ * @param dst destination array, can be equal to src
+ * @param src source array, can be equal to dst
+ * @param count number of 8 byte blocks
+ * @param iv initialization vector for CBC mode, if NULL then ECB will be used
+ * @param decrypt 0 for encryption, 1 for decryption
+ */
+void av_xtea_crypt(struct AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
+                   int count, uint8_t *iv, int decrypt);
+
+/**
+ * @}
+ */
+
+#endif /* AVUTIL_XTEA_H */