Add support for TEA (Tiny Encryption Algorithm)

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

3 files changed, 287 insertions, 0 deletions

diff --git a/libavutil/Makefile b/libavutil/Makefile
index 6fa810e..70f8bae 100644
--- a/libavutil/Makefile
+++ b/libavutil/Makefile
@@ -63,6 +63,7 @@ HEADERS = adler32.h                                                     \
           twofish.h                                                     \
           version.h                                                     \
           xtea.h                                                        \
+          tea.h                                                         \
 
 HEADERS-$(CONFIG_LZO)                   += lzo.h
 
@@ -135,6 +136,7 @@ OBJS = adler32.o                                                        \
        utils.o                                                          \
        xga_font_data.o                                                  \
        xtea.o                                                           \
+       tea.o                                                            \
 
 OBJS-$(!HAVE_ATOMICS_NATIVE)            += atomic.o                     \
 
@@ -192,6 +194,7 @@ TESTPROGS = adler32                                                     \
             twofish                                                     \
             utf8                                                        \
             xtea                                                        \
+            tea                                                         \
 
 TESTPROGS-$(HAVE_LZO1X_999_COMPRESS) += lzo
 
diff --git a/libavutil/tea.c b/libavutil/tea.c
new file mode 100644
index 0000000..bf76718
--- /dev/null
+++ b/libavutil/tea.c
@@ -0,0 +1,213 @@
+/*
+ * 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;
+        }
+    }
+}
+
+#ifdef TEST
+#include <stdio.h>
+
+#define TEA_NUM_TESTS 4
+
+// https://github.com/logandrews/TeaCrypt/blob/master/tea/tea_test.go
+static const uint8_t tea_test_key[TEA_NUM_TESTS][16] = {
+    { 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, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
+      0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF
+    },
+    { 0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
+      0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF
+    }
+};
+
+static const uint8_t tea_test_pt[TEA_NUM_TESTS][8] = {
+    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
+    { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 },
+    { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 },
+    { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF }
+};
+
+static const uint8_t tea_test_ct[TEA_NUM_TESTS][8] = {
+    { 0x41, 0xEA, 0x3A, 0x0A, 0x94, 0xBA, 0xA9, 0x40 },
+    { 0x6A, 0x2F, 0x9C, 0xF3, 0xFC, 0xCF, 0x3C, 0x55 },
+    { 0xDE, 0xB1, 0xC0, 0xA2, 0x7E, 0x74, 0x5D, 0xB3 },
+    { 0x12, 0x6C, 0x6B, 0x92, 0xC0, 0x65, 0x3A, 0x3E }
+};
+
+static void test_tea(AVTEA *ctx, uint8_t *dst, const uint8_t *src,
+                     const uint8_t *ref, int len, uint8_t *iv, int dir,
+                     const char *test)
+{
+    av_tea_crypt(ctx, dst, src, len, iv, dir);
+    if (memcmp(dst, ref, 8*len)) {
+        int i;
+        printf("%s failed\ngot      ", test);
+        for (i = 0; i < 8*len; i++)
+            printf("%02x ", dst[i]);
+        printf("\nexpected ");
+        for (i = 0; i < 8*len; i++)
+            printf("%02x ", ref[i]);
+        printf("\n");
+        exit(1);
+    }
+}
+
+int main(void)
+{
+    AVTEA *ctx;
+    uint8_t buf[8], iv[8];
+    int i;
+    static const uint8_t src[32] = "HelloWorldHelloWorldHelloWorld";
+    uint8_t ct[32];
+    uint8_t pl[32];
+
+    ctx = av_tea_alloc();
+    if (!ctx)
+        return 1;
+
+    for (i = 0; i < TEA_NUM_TESTS; i++) {
+        av_tea_init(ctx, tea_test_key[i], 64);
+
+        test_tea(ctx, buf, tea_test_pt[i], tea_test_ct[i], 1, NULL, 0, "encryption");
+        test_tea(ctx, buf, tea_test_ct[i], tea_test_pt[i], 1, NULL, 1, "decryption");
+
+        /* encrypt */
+        memcpy(iv, "HALLO123", 8);
+        av_tea_crypt(ctx, ct, src, 4, iv, 0);
+
+        /* decrypt into pl */
+        memcpy(iv, "HALLO123", 8);
+        test_tea(ctx, pl, ct, src, 4, iv, 1, "CBC decryption");
+
+        memcpy(iv, "HALLO123", 8);
+        test_tea(ctx, ct, ct, src, 4, iv, 1, "CBC inplace decryption");
+    }
+
+    printf("Test encryption/decryption success.\n");
+    av_free(ctx);
+
+    return 0;
+}
+
+#endif
diff --git a/libavutil/tea.h b/libavutil/tea.h
new file mode 100644
index 0000000..dd929bd
--- /dev/null
+++ b/libavutil/tea.h
@@ -0,0 +1,71 @@
+/*
+ * A 32-bit implementation of the TEA algorithm
+ * Copyright (c) 2015 Vesselin Bontchev
+ *
+ * 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
+ */
+
+#ifndef AVUTIL_TEA_H
+#define AVUTIL_TEA_H
+
+#include <stdint.h>
+
+/**
+ * @file
+ * @brief Public header for libavutil TEA algorithm
+ * @defgroup lavu_tea TEA
+ * @ingroup lavu_crypto
+ * @{
+ */
+
+extern const int av_tea_size;
+
+struct AVTEA;
+
+/**
+  * Allocate an AVTEA context
+  * To free the struct: av_free(ptr)
+  */
+struct AVTEA *av_tea_alloc(void);
+
+/**
+ * Initialize an AVTEA context.
+ *
+ * @param ctx an AVTEA context
+ * @param key a key of 16 bytes used for encryption/decryption
+ * @param rounds the number of rounds in TEA (64 is the "standard")
+ */
+void av_tea_init(struct AVTEA *ctx, const uint8_t key[16], int rounds);
+
+/**
+ * Encrypt or decrypt a buffer using a previously initialized context.
+ *
+ * @param ctx an AVTEA 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_tea_crypt(struct AVTEA *ctx, uint8_t *dst, const uint8_t *src,
+                  int count, uint8_t *iv, int decrypt);
+
+/**
+ * @}
+ */
+
+#endif /* AVUTIL_TEA_H */