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authorKing Kévin <kingkevin@cuvoodoo.info>2015-11-10 13:44:17 +0100
committerKing Kévin <kingkevin@cuvoodoo.info>2015-11-10 13:44:17 +0100
commitd72a952f878030b490779e44d87d68443edffcd4 (patch)
treeb722d803fe234df6b26f3d3d269d8362e8dc76f9
parent7922e14807d0f9a97065bc799ae267c5bee4fbcd (diff)
add AES decryption to receiver using tiny-AES128-C library
-rw-r--r--rpi/Makefile19
-rw-r--r--rpi/aes.c583
-rw-r--r--rpi/aes.h40
-rw-r--r--rpi/spark_counter_receiver.cpp60
4 files changed, 649 insertions, 53 deletions
diff --git a/rpi/Makefile b/rpi/Makefile
index 03a6cc7..2d02902 100644
--- a/rpi/Makefile
+++ b/rpi/Makefile
@@ -9,22 +9,15 @@ CCFLAGS=-Ofast -mfpu=vfp -mfloat-abi=hard -march=armv6zk -mtune=arm1176jzf-s
endif
# define all programs
-PROGRAMS = spark_counter_receiver
-SOURCES = ${PROGRAMS:=.cpp}
+PROGRAM = spark_counter_receiver
+SOURCES = ${PROGRAM:=.cpp} aes.c
-all: ${PROGRAMS}
+all: ${PROGRAM}
-${PROGRAMS}: ${SOURCES}
- g++ ${CCFLAGS} -Wall -I../ -lrf24-bcm -lcurl -o $@ $<
+${PROGRAM}: ${SOURCES}
+ g++ ${CCFLAGS} -Wall -I. -lrf24-bcm -lcurl -o $@ $^
clean:
- rm -rf $(PROGRAMS)
-
-install: all
- test -d $(prefix) || mkdir $(prefix)
- test -d $(prefix)/bin || mkdir $(prefix)/bin
- for prog in $(PROGRAMS); do \
- install -m 0755 $$prog $(prefix)/bin; \
- done
+ rm -rf $(PROGRAM)
.PHONY: install
diff --git a/rpi/aes.c b/rpi/aes.c
new file mode 100644
index 0000000..38ec132
--- /dev/null
+++ b/rpi/aes.c
@@ -0,0 +1,583 @@
+/*
+
+This is an implementation of the AES128 algorithm, specifically ECB and CBC mode.
+
+The implementation is verified against the test vectors in:
+ National Institute of Standards and Technology Special Publication 800-38A 2001 ED
+
+ECB-AES128
+----------
+
+ plain-text:
+ 6bc1bee22e409f96e93d7e117393172a
+ ae2d8a571e03ac9c9eb76fac45af8e51
+ 30c81c46a35ce411e5fbc1191a0a52ef
+ f69f2445df4f9b17ad2b417be66c3710
+
+ key:
+ 2b7e151628aed2a6abf7158809cf4f3c
+
+ resulting cipher
+ 3ad77bb40d7a3660a89ecaf32466ef97
+ f5d3d58503b9699de785895a96fdbaaf
+ 43b1cd7f598ece23881b00e3ed030688
+ 7b0c785e27e8ad3f8223207104725dd4
+
+
+NOTE: String length must be evenly divisible by 16byte (str_len % 16 == 0)
+ You should pad the end of the string with zeros if this is not the case.
+
+*/
+
+
+/*****************************************************************************/
+/* Includes: */
+/*****************************************************************************/
+#include <stdint.h>
+#include <string.h> // CBC mode, for memset
+#include "aes.h"
+
+
+/*****************************************************************************/
+/* Defines: */
+/*****************************************************************************/
+// The number of columns comprising a state in AES. This is a constant in AES. Value=4
+#define Nb 4
+// The number of 32 bit words in a key.
+#define Nk 4
+// Key length in bytes [128 bit]
+#define KEYLEN 16
+// The number of rounds in AES Cipher.
+#define Nr 10
+
+// jcallan@github points out that declaring Multiply as a function
+// reduces code size considerably with the Keil ARM compiler.
+// See this link for more information: https://github.com/kokke/tiny-AES128-C/pull/3
+#ifndef MULTIPLY_AS_A_FUNCTION
+ #define MULTIPLY_AS_A_FUNCTION 0
+#endif
+
+
+/*****************************************************************************/
+/* Private variables: */
+/*****************************************************************************/
+// state - array holding the intermediate results during decryption.
+typedef uint8_t state_t[4][4];
+static state_t* state;
+
+// The array that stores the round keys.
+static uint8_t RoundKey[176];
+
+// The Key input to the AES Program
+static const uint8_t* Key;
+
+#if defined(CBC) && CBC
+ // Initial Vector used only for CBC mode
+ static uint8_t* Iv;
+#endif
+
+// The lookup-tables are marked const so they can be placed in read-only storage instead of RAM
+// The numbers below can be computed dynamically trading ROM for RAM -
+// This can be useful in (embedded) bootloader applications, where ROM is often limited.
+static const uint8_t sbox[256] = {
+ //0 1 2 3 4 5 6 7 8 9 A B C D E F
+ 0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
+ 0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
+ 0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
+ 0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
+ 0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
+ 0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
+ 0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
+ 0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
+ 0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
+ 0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
+ 0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
+ 0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
+ 0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
+ 0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
+ 0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
+ 0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16 };
+
+static const uint8_t rsbox[256] =
+{ 0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
+ 0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
+ 0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
+ 0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
+ 0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
+ 0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
+ 0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
+ 0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
+ 0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
+ 0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
+ 0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
+ 0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
+ 0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
+ 0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
+ 0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
+ 0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d };
+
+
+// The round constant word array, Rcon[i], contains the values given by
+// x to th e power (i-1) being powers of x (x is denoted as {02}) in the field GF(2^8)
+// Note that i starts at 1, not 0).
+static const uint8_t Rcon[255] = {
+ 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a,
+ 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39,
+ 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a,
+ 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8,
+ 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef,
+ 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc,
+ 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b,
+ 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3,
+ 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94,
+ 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20,
+ 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35,
+ 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f,
+ 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04,
+ 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63,
+ 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd,
+ 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb };
+
+
+/*****************************************************************************/
+/* Private functions: */
+/*****************************************************************************/
+static uint8_t getSBoxValue(uint8_t num)
+{
+ return sbox[num];
+}
+
+static uint8_t getSBoxInvert(uint8_t num)
+{
+ return rsbox[num];
+}
+
+// This function produces Nb(Nr+1) round keys. The round keys are used in each round to decrypt the states.
+static void KeyExpansion(void)
+{
+ uint32_t i, j, k;
+ uint8_t tempa[4]; // Used for the column/row operations
+
+ // The first round key is the key itself.
+ for(i = 0; i < Nk; ++i)
+ {
+ RoundKey[(i * 4) + 0] = Key[(i * 4) + 0];
+ RoundKey[(i * 4) + 1] = Key[(i * 4) + 1];
+ RoundKey[(i * 4) + 2] = Key[(i * 4) + 2];
+ RoundKey[(i * 4) + 3] = Key[(i * 4) + 3];
+ }
+
+ // All other round keys are found from the previous round keys.
+ for(; (i < (Nb * (Nr + 1))); ++i)
+ {
+ for(j = 0; j < 4; ++j)
+ {
+ tempa[j]=RoundKey[(i-1) * 4 + j];
+ }
+ if (i % Nk == 0)
+ {
+ // This function rotates the 4 bytes in a word to the left once.
+ // [a0,a1,a2,a3] becomes [a1,a2,a3,a0]
+
+ // Function RotWord()
+ {
+ k = tempa[0];
+ tempa[0] = tempa[1];
+ tempa[1] = tempa[2];
+ tempa[2] = tempa[3];
+ tempa[3] = k;
+ }
+
+ // SubWord() is a function that takes a four-byte input word and
+ // applies the S-box to each of the four bytes to produce an output word.
+
+ // Function Subword()
+ {
+ tempa[0] = getSBoxValue(tempa[0]);
+ tempa[1] = getSBoxValue(tempa[1]);
+ tempa[2] = getSBoxValue(tempa[2]);
+ tempa[3] = getSBoxValue(tempa[3]);
+ }
+
+ tempa[0] = tempa[0] ^ Rcon[i/Nk];
+ }
+ else if (Nk > 6 && i % Nk == 4)
+ {
+ // Function Subword()
+ {
+ tempa[0] = getSBoxValue(tempa[0]);
+ tempa[1] = getSBoxValue(tempa[1]);
+ tempa[2] = getSBoxValue(tempa[2]);
+ tempa[3] = getSBoxValue(tempa[3]);
+ }
+ }
+ RoundKey[i * 4 + 0] = RoundKey[(i - Nk) * 4 + 0] ^ tempa[0];
+ RoundKey[i * 4 + 1] = RoundKey[(i - Nk) * 4 + 1] ^ tempa[1];
+ RoundKey[i * 4 + 2] = RoundKey[(i - Nk) * 4 + 2] ^ tempa[2];
+ RoundKey[i * 4 + 3] = RoundKey[(i - Nk) * 4 + 3] ^ tempa[3];
+ }
+}
+
+// This function adds the round key to state.
+// The round key is added to the state by an XOR function.
+static void AddRoundKey(uint8_t round)
+{
+ uint8_t i,j;
+ for(i=0;i<4;++i)
+ {
+ for(j = 0; j < 4; ++j)
+ {
+ (*state)[i][j] ^= RoundKey[round * Nb * 4 + i * Nb + j];
+ }
+ }
+}
+
+// The SubBytes Function Substitutes the values in the
+// state matrix with values in an S-box.
+static void SubBytes(void)
+{
+ uint8_t i, j;
+ for(i = 0; i < 4; ++i)
+ {
+ for(j = 0; j < 4; ++j)
+ {
+ (*state)[j][i] = getSBoxValue((*state)[j][i]);
+ }
+ }
+}
+
+// The ShiftRows() function shifts the rows in the state to the left.
+// Each row is shifted with different offset.
+// Offset = Row number. So the first row is not shifted.
+static void ShiftRows(void)
+{
+ uint8_t temp;
+
+ // Rotate first row 1 columns to left
+ temp = (*state)[0][1];
+ (*state)[0][1] = (*state)[1][1];
+ (*state)[1][1] = (*state)[2][1];
+ (*state)[2][1] = (*state)[3][1];
+ (*state)[3][1] = temp;
+
+ // Rotate second row 2 columns to left
+ temp = (*state)[0][2];
+ (*state)[0][2] = (*state)[2][2];
+ (*state)[2][2] = temp;
+
+ temp = (*state)[1][2];
+ (*state)[1][2] = (*state)[3][2];
+ (*state)[3][2] = temp;
+
+ // Rotate third row 3 columns to left
+ temp = (*state)[0][3];
+ (*state)[0][3] = (*state)[3][3];
+ (*state)[3][3] = (*state)[2][3];
+ (*state)[2][3] = (*state)[1][3];
+ (*state)[1][3] = temp;
+}
+
+static uint8_t xtime(uint8_t x)
+{
+ return ((x<<1) ^ (((x>>7) & 1) * 0x1b));
+}
+
+// MixColumns function mixes the columns of the state matrix
+static void MixColumns(void)
+{
+ uint8_t i;
+ uint8_t Tmp,Tm,t;
+ for(i = 0; i < 4; ++i)
+ {
+ t = (*state)[i][0];
+ Tmp = (*state)[i][0] ^ (*state)[i][1] ^ (*state)[i][2] ^ (*state)[i][3] ;
+ Tm = (*state)[i][0] ^ (*state)[i][1] ; Tm = xtime(Tm); (*state)[i][0] ^= Tm ^ Tmp ;
+ Tm = (*state)[i][1] ^ (*state)[i][2] ; Tm = xtime(Tm); (*state)[i][1] ^= Tm ^ Tmp ;
+ Tm = (*state)[i][2] ^ (*state)[i][3] ; Tm = xtime(Tm); (*state)[i][2] ^= Tm ^ Tmp ;
+ Tm = (*state)[i][3] ^ t ; Tm = xtime(Tm); (*state)[i][3] ^= Tm ^ Tmp ;
+ }
+}
+
+// Multiply is used to multiply numbers in the field GF(2^8)
+#if MULTIPLY_AS_A_FUNCTION
+static uint8_t Multiply(uint8_t x, uint8_t y)
+{
+ return (((y & 1) * x) ^
+ ((y>>1 & 1) * xtime(x)) ^
+ ((y>>2 & 1) * xtime(xtime(x))) ^
+ ((y>>3 & 1) * xtime(xtime(xtime(x)))) ^
+ ((y>>4 & 1) * xtime(xtime(xtime(xtime(x))))));
+ }
+#else
+#define Multiply(x, y) \
+ ( ((y & 1) * x) ^ \
+ ((y>>1 & 1) * xtime(x)) ^ \
+ ((y>>2 & 1) * xtime(xtime(x))) ^ \
+ ((y>>3 & 1) * xtime(xtime(xtime(x)))) ^ \
+ ((y>>4 & 1) * xtime(xtime(xtime(xtime(x)))))) \
+
+#endif
+
+// MixColumns function mixes the columns of the state matrix.
+// The method used to multiply may be difficult to understand for the inexperienced.
+// Please use the references to gain more information.
+static void InvMixColumns(void)
+{
+ int i;
+ uint8_t a,b,c,d;
+ for(i=0;i<4;++i)
+ {
+ a = (*state)[i][0];
+ b = (*state)[i][1];
+ c = (*state)[i][2];
+ d = (*state)[i][3];
+
+ (*state)[i][0] = Multiply(a, 0x0e) ^ Multiply(b, 0x0b) ^ Multiply(c, 0x0d) ^ Multiply(d, 0x09);
+ (*state)[i][1] = Multiply(a, 0x09) ^ Multiply(b, 0x0e) ^ Multiply(c, 0x0b) ^ Multiply(d, 0x0d);
+ (*state)[i][2] = Multiply(a, 0x0d) ^ Multiply(b, 0x09) ^ Multiply(c, 0x0e) ^ Multiply(d, 0x0b);
+ (*state)[i][3] = Multiply(a, 0x0b) ^ Multiply(b, 0x0d) ^ Multiply(c, 0x09) ^ Multiply(d, 0x0e);
+ }
+}
+
+
+// The SubBytes Function Substitutes the values in the
+// state matrix with values in an S-box.
+static void InvSubBytes(void)
+{
+ uint8_t i,j;
+ for(i=0;i<4;++i)
+ {
+ for(j=0;j<4;++j)
+ {
+ (*state)[j][i] = getSBoxInvert((*state)[j][i]);
+ }
+ }
+}
+
+static void InvShiftRows(void)
+{
+ uint8_t temp;
+
+ // Rotate first row 1 columns to right
+ temp=(*state)[3][1];
+ (*state)[3][1]=(*state)[2][1];
+ (*state)[2][1]=(*state)[1][1];
+ (*state)[1][1]=(*state)[0][1];
+ (*state)[0][1]=temp;
+
+ // Rotate second row 2 columns to right
+ temp=(*state)[0][2];
+ (*state)[0][2]=(*state)[2][2];
+ (*state)[2][2]=temp;
+
+ temp=(*state)[1][2];
+ (*state)[1][2]=(*state)[3][2];
+ (*state)[3][2]=temp;
+
+ // Rotate third row 3 columns to right
+ temp=(*state)[0][3];
+ (*state)[0][3]=(*state)[1][3];
+ (*state)[1][3]=(*state)[2][3];
+ (*state)[2][3]=(*state)[3][3];
+ (*state)[3][3]=temp;
+}
+
+
+// Cipher is the main function that encrypts the PlainText.
+static void Cipher(void)
+{
+ uint8_t round = 0;
+
+ // Add the First round key to the state before starting the rounds.
+ AddRoundKey(0);
+
+ // There will be Nr rounds.
+ // The first Nr-1 rounds are identical.
+ // These Nr-1 rounds are executed in the loop below.
+ for(round = 1; round < Nr; ++round)
+ {
+ SubBytes();
+ ShiftRows();
+ MixColumns();
+ AddRoundKey(round);
+ }
+
+ // The last round is given below.
+ // The MixColumns function is not here in the last round.
+ SubBytes();
+ ShiftRows();
+ AddRoundKey(Nr);
+}
+
+static void InvCipher(void)
+{
+ uint8_t round=0;
+
+ // Add the First round key to the state before starting the rounds.
+ AddRoundKey(Nr);
+
+ // There will be Nr rounds.
+ // The first Nr-1 rounds are identical.
+ // These Nr-1 rounds are executed in the loop below.
+ for(round=Nr-1;round>0;round--)
+ {
+ InvShiftRows();
+ InvSubBytes();
+ AddRoundKey(round);
+ InvMixColumns();
+ }
+
+ // The last round is given below.
+ // The MixColumns function is not here in the last round.
+ InvShiftRows();
+ InvSubBytes();
+ AddRoundKey(0);
+}
+
+static void BlockCopy(uint8_t* output, uint8_t* input)
+{
+ uint8_t i;
+ for (i=0;i<KEYLEN;++i)
+ {
+ output[i] = input[i];
+ }
+}
+
+
+
+/*****************************************************************************/
+/* Public functions: */
+/*****************************************************************************/
+#if defined(ECB) && ECB
+
+
+void AES128_ECB_encrypt(uint8_t* input, const uint8_t* key, uint8_t* output)
+{
+ // Copy input to output, and work in-memory on output
+ BlockCopy(output, input);
+ state = (state_t*)output;
+
+ Key = key;
+ KeyExpansion();
+
+ // The next function call encrypts the PlainText with the Key using AES algorithm.
+ Cipher();
+}
+
+void AES128_ECB_decrypt(uint8_t* input, const uint8_t* key, uint8_t *output)
+{
+ // Copy input to output, and work in-memory on output
+ BlockCopy(output, input);
+ state = (state_t*)output;
+
+ // The KeyExpansion routine must be called before encryption.
+ Key = key;
+ KeyExpansion();
+
+ InvCipher();
+}
+
+
+#endif // #if defined(ECB) && ECB
+
+
+
+
+
+#if defined(CBC) && CBC
+
+
+static void XorWithIv(uint8_t* buf)
+{
+ uint8_t i;
+ for(i = 0; i < KEYLEN; ++i)
+ {
+ buf[i] ^= Iv[i];
+ }
+}
+
+void AES128_CBC_encrypt_buffer(uint8_t* output, uint8_t* input, uint32_t length, const uint8_t* key, const uint8_t* iv)
+{
+ uintptr_t i;
+ uint8_t remainders = length % KEYLEN; /* Remaining bytes in the last non-full block */
+
+ BlockCopy(output, input);
+ state = (state_t*)output;
+
+ // Skip the key expansion if key is passed as 0
+ if(0 != key)
+ {
+ Key = key;
+ KeyExpansion();
+ }
+
+ if(iv != 0)
+ {
+ Iv = (uint8_t*)iv;
+ }
+
+ for(i = 0; i < length; i += KEYLEN)
+ {
+ XorWithIv(input);
+ BlockCopy(output, input);
+ state = (state_t*)output;
+ Cipher();
+ Iv = output;
+ input += KEYLEN;
+ output += KEYLEN;
+ }
+
+ if(remainders)
+ {
+ BlockCopy(output, input);
+ memset(output + remainders, 0, KEYLEN - remainders); /* add 0-padding */
+ state = (state_t*)output;
+ Cipher();
+ }
+}
+
+void AES128_CBC_decrypt_buffer(uint8_t* output, uint8_t* input, uint32_t length, const uint8_t* key, const uint8_t* iv)
+{
+ uintptr_t i;
+ uint8_t remainders = length % KEYLEN; /* Remaining bytes in the last non-full block */
+
+ BlockCopy(output, input);
+ state = (state_t*)output;
+
+ // Skip the key expansion if key is passed as 0
+ if(0 != key)
+ {
+ Key = key;
+ KeyExpansion();
+ }
+
+ // If iv is passed as 0, we continue to encrypt without re-setting the Iv
+ if(iv != 0)
+ {
+ Iv = (uint8_t*)iv;
+ }
+
+ for(i = 0; i < length; i += KEYLEN)
+ {
+ BlockCopy(output, input);
+ state = (state_t*)output;
+ InvCipher();
+ XorWithIv(output);
+ Iv = input;
+ input += KEYLEN;
+ output += KEYLEN;
+ }
+
+ if(remainders)
+ {
+ BlockCopy(output, input);
+ memset(output+remainders, 0, KEYLEN - remainders); /* add 0-padding */
+ state = (state_t*)output;
+ InvCipher();
+ }
+}
+
+
+#endif // #if defined(CBC) && CBC
+
+
diff --git a/rpi/aes.h b/rpi/aes.h
new file mode 100644
index 0000000..708a09c
--- /dev/null
+++ b/rpi/aes.h
@@ -0,0 +1,40 @@
+#ifndef _AES_H_
+#define _AES_H_
+
+#include <stdint.h>
+
+
+// #define the macros below to 1/0 to enable/disable the mode of operation.
+//
+// CBC enables AES128 encryption in CBC-mode of operation and handles 0-padding.
+// ECB enables the basic ECB 16-byte block algorithm. Both can be enabled simultaneously.
+
+// The #ifndef-guard allows it to be configured before #include'ing or at compile time.
+#ifndef CBC
+ #define CBC 1
+#endif
+
+#ifndef ECB
+ #define ECB 1
+#endif
+
+
+
+#if defined(ECB) && ECB
+
+void AES128_ECB_encrypt(uint8_t* input, const uint8_t* key, uint8_t *output);
+void AES128_ECB_decrypt(uint8_t* input, const uint8_t* key, uint8_t *output);
+
+#endif // #if defined(ECB) && ECB
+
+
+#if defined(CBC) && CBC
+
+void AES128_CBC_encrypt_buffer(uint8_t* output, uint8_t* input, uint32_t length, const uint8_t* key, const uint8_t* iv);
+void AES128_CBC_decrypt_buffer(uint8_t* output, uint8_t* input, uint32_t length, const uint8_t* key, const uint8_t* iv);
+
+#endif // #if defined(CBC) && CBC
+
+
+
+#endif //_AES_H_
diff --git a/rpi/spark_counter_receiver.cpp b/rpi/spark_counter_receiver.cpp
index da1d671..ef6fe58 100644
--- a/rpi/spark_counter_receiver.cpp
+++ b/rpi/spark_counter_receiver.cpp
@@ -28,6 +28,7 @@
#include <RF24/RF24.h> // http://tmrh20.github.io/RF24 library to communicate to the nRF24L01+
#include <curl/curl.h> // curl library to send the measurement data to the influxDB.
+#include "aes.h" // AES library (from tiny-AES128-C)
// Setup for RPi B1 GPIO 22 CE and CE0 CSN with SPI Speed @ 8Mhz
RF24 radio(RPI_V2_GPIO_P1_22, BCM2835_SPI_CS0, BCM2835_SPI_SPEED_8MHZ);
@@ -38,6 +39,10 @@ const uint8_t rx_addr[] = {0,'h','o','m','e'};
CURL *curl; // curl handle to post data to influxbd using the HTTP API
+// key material
+const uint8_t key[16] = {0x00,0x11,0x22,0x33,0x44,0x55,0x66,0x77,0x88,0x99,0xaa,0xbb,0xcc,0xdd,0xee,0xff};
+uint8_t iv[16] = {0xff,0xee,0xdd,0xcc,0xbb,0xaa,0x99,0x88,0x77,0x66,0x55,0x44,0x33,0x22,0x11,0x00};
+
int main(int argc, char** argv){
// configure influxdb connection
@@ -81,50 +86,25 @@ int main(int argc, char** argv){
*/
// got through payload
- uint8_t id = 0; // the meter id (0 is myself, used for unknown source)
+ if (size!=1+16) {
+ continue;
+ }
+ uint8_t id = payload[0]; // the meter id (0 is myself, used for unknown source)
float voltage, current, power, energy; // the values coming from the meter
- CURLcode res = CURLE_OK; // curl response
- uint8_t i = 0; // index within the data
- while (i+2<size) {
- uint8_t type = payload[i]; // type of IE
- uint8_t length = payload[i+1]; // length of IE
- if (i+1+length<size) { // value is within data
- switch (type) { // read type
- case 0: // id
- if (length==1) {
- id = payload[i+2];
- }
- break;
- case 1: // voltage
- if (length==4) {
- memcpy(&voltage,&payload[i+2],length);
- }
- break;
- case 2: // current
- if (length==4) {
- memcpy(&current,&payload[i+2],length);
- }
- break;
- case 3: // power
- if (length==4) {
- memcpy(&power,&payload[i+2],length);
- }
- break;
- case 4: // energy
- if (length==4) {
- memcpy(&energy,&payload[i+2],length);
- }
- break;
- default:
- printf("unknown type: %d\n",payload[i]);
- }
- i += 2+length; // got to next IE
- } else { // value isn't within data
- i = size; // end the loop
- }
+ uint8_t values[16]; // the encrypted values block
+ AES128_ECB_decrypt(&payload[1], key, values); // decrypt payload
+ for (uint8_t i=0; i<sizeof(values) && i<sizeof(iv); i++) { // use CBC mode
+ values[i] ^= iv[i]; // XOR with last IV
}
+ memcpy(iv,&payload[1],sizeof(iv)); // save next IV
+ memcpy(&voltage,&values[0],4); // read voltage
+ memcpy(&current,&values[4],4); // read current
+ memcpy(&power,&values[8],4); // read power
+ memcpy(&energy,&values[12],4); // read energy
+
printf("meter: %d, voltage: %f V, current: %f A, power: %f W, energy: %f Wh\n",id,voltage,current,power,energy);
if (curl) {
+ CURLcode res = CURLE_OK; // curl response
char post[128*4] = {0}; // string to submit data to DB using POST request
snprintf(post, sizeof(post), "voltage,meter=%d value=%f\ncurrent,meter=%d value=%f\npower,meter=%d value=%f\nenergy,meter=%d value=%f\n", id, voltage, id, current, id, power, id, energy);
curl_easy_setopt(curl, CURLOPT_POSTFIELDS, post);