Added AES software-based implementation

c8_payloads/CMakeLists.txt

@@ -11,12 +11,17 @@ endif()
 
 set(CMAKE_C_FLAGS "-nostdlib -O")
 
-set(PAYLOADS payload_sync payload_aes payload_sysreg payload_aes_busy)
-add_executable(payload_sync src/sync.c)
+set(PAYLOADS
+        payload_aes
+        payload_aes_busy
+        payload_aes_sw
+        payload_sync
+        payload_sysreg)
 
 add_executable(payload_aes src/aes.c)
 add_executable(payload_aes_busy src/aes_busy.c)
-
+add_executable(payload_aes_sw src/aes_sw.c)
+add_executable(payload_sync src/sync.c)
 add_executable(payload_sysreg src/sysreg.c)
 
 file(MAKE_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/bin/)
@@ -26,7 +31,7 @@ foreach(BINARY ${PAYLOADS})
     add_custom_command(TARGET ${BINARY} POST_BUILD
                         BYPRODUCTS ${CMAKE_CURRENT_SOURCE_DIR}/bin/${BINARY}.bin
                         COMMAND ${CMAKE_OBJCOPY}
-                        ARGS -O binary -j .text -j .payload_text
+                        ARGS -O binary -j .text -j .payload_text -j .payload_data
                             ${CMAKE_CURRENT_BINARY_DIR}/${BINARY}
                             ${CMAKE_CURRENT_SOURCE_DIR}/bin/${BINARY}.bin)
 endforeach(BINARY)

c8_payloads/src/aes_sw.c

@@ -0,0 +1,150 @@
+#include "util.h"
+
+PAYLOAD_SECTION
+void sub_bytes(unsigned char block[16], unsigned char sbox[16][16])
+{
+    int i;
+    unsigned char val;
+
+    for(i = 0; i < 16; i++)
+    {
+        val = block[i];
+        block[i] = sbox[val >> 4u][val & 0xfu];
+    }
+}
+
+PAYLOAD_SECTION
+void shift_rows(unsigned char block[16])
+{
+    unsigned char temp1, temp2;
+
+    temp1 = block[0x1];
+    block[0x1] = block[0x5];
+    block[0x5] = block[0x9];
+    block[0x9] = block[0xd];
+    block[0xd] = temp1;
+
+    temp1 = block[0x2];
+    temp2 = block[0xe];
+    block[0x2] = block[0xa];
+    block[0xe] = block[0x6];
+    block[0xa] = temp1;
+    block[0x6] = temp2;
+
+    temp1 = block[0x3];
+    block[0x3] = block[0xf];
+    block[0xf] = block[0xb];
+    block[0xb] = block[0x7];
+    block[0x7] = temp1;
+}
+
+PAYLOAD_SECTION
+void mix_cols(unsigned char block[16],
+              unsigned char mul2_lookup[256], unsigned char mul3_lookup[256])
+{
+    unsigned char r0, r1, r2, r3;
+    int i;
+
+    for(i = 0; i < 4; i++)
+    {
+        r0 = block[4 * i];
+        r1 = block[4 * i + 1];
+        r2 = block[4 * i + 2];
+        r3 = block[4 * i + 3];
+
+        // no reason for the "+ 0" here but it makes the code look more lined up :)
+        block[4 * i + 0] = mul2_lookup[r0] ^ mul3_lookup[r1] ^ r2 ^ r3;
+        block[4 * i + 1] = r0 ^ mul2_lookup[r1] ^ mul3_lookup[r2] ^ r3;
+        block[4 * i + 2] = r0 ^ r1 ^ mul2_lookup[r2] ^ mul3_lookup[r3];
+        block[4 * i + 3] = mul3_lookup[r0] ^ r1 ^ r2 ^ mul2_lookup[r3];
+    }
+}
+
+PAYLOAD_SECTION
+void add_key(unsigned char block[16], unsigned char key[16])
+{
+    int i;
+    for(i = 0; i < 16; i++)
+    {
+        block[i] = block[i] ^ key[i];
+    }
+}
+
+PAYLOAD_SECTION
+void expand_key(unsigned char key[16], unsigned char key_sched[176], int n,
+                unsigned char sbox[16][16], unsigned char rc_lookup[11])
+{
+    int i, j, prev_key_base, key_base = 0;
+    unsigned char val;
+    for(i = 0; i < 16; i++)
+    {
+        key_sched[i] = key[i];
+    }
+
+    for(i = 1; i < n; i++)
+    {
+        prev_key_base = key_base;
+        key_base = 16 * i;
+
+        for(j = 0; j < 3; j++)
+        {
+            val = key_sched[prev_key_base + 13 + j];
+            key_sched[key_base + j] = sbox[val >> 4u][val & 0xfu];
+        }
+
+        val = key_sched[prev_key_base + 12];
+        key_sched[key_base + 3] = sbox[val >> 4u][val & 0xfu];
+
+        key_sched[key_base] ^= rc_lookup[i - 1];
+
+        for(j = 0; j < 4; j++)
+        {
+            key_sched[key_base + j] = key_sched[key_base + j] ^ key_sched[prev_key_base + j];
+        }
+
+        for(j = 4; j < 16; j++)
+        {
+            key_sched[key_base + j] = key_sched[key_base + j - 4] ^ key_sched[prev_key_base + j];
+        }
+    }
+}
+
+PAYLOAD_SECTION
+void aes128_encrypt_ecb(unsigned char *msg, unsigned int msg_len, unsigned char key[16],
+                        unsigned char sbox[16][16], unsigned char rc_lookup[11],
+                        unsigned char mul2[256], unsigned char mul3[256])
+{
+    unsigned char key_sched[176];
+    expand_key(key, key_sched, 11, sbox, rc_lookup);
+
+    unsigned int num_blocks = msg_len / 16;
+    unsigned char *block;
+
+    unsigned int i, j;
+    for(i = 0; i < num_blocks; i++)
+    {
+        block = &msg[16 * i];
+        add_key(block, key_sched);
+
+        for(j = 0; j < 9; j++)
+        {
+            sub_bytes(block, sbox);
+            shift_rows(block);
+            mix_cols(block, mul2, mul3);
+            add_key(block, &key_sched[16 * (j + 1)]);
+        }
+
+        sub_bytes(block, sbox);
+        shift_rows(block);
+        add_key(block, &key_sched[16 * (j + 1)]);
+    }
+}
+
+TEXT_SECTION
+unsigned int _start(unsigned char *msg, unsigned int msg_len, unsigned char *key,
+                    unsigned char sbox[16][16], unsigned char rc_lookup[11],
+                    unsigned char mul2[256], unsigned char mul3[256])
+{
+    aes128_encrypt_ecb(msg, msg_len, key, sbox, rc_lookup, mul2, mul3);
+    return 0xDEADBEEF;
+}