utils/imxtools/aes128.c

   1 // Simple, thoroughly commented implementation of 128-bit AES / Rijndael using C
   2 // Chris Hulbert - chris.hulbert@gmail.com - http://splinter.com.au/blog
   3 // References:
   4 // http://en.wikipedia.org/wiki/Advanced_Encryption_Standard
   5 // http://en.wikipedia.org/wiki/Rijndael_key_schedule
   6 // http://en.wikipeia.org/wiki/Rijndael_mix_columns
   7 // http://en.wikipedia.org/wiki/Rijndael_S-box
   8 // This code is public domain, or any OSI-approved license, your choice. No warranty.
   9 #include "crypto.h"
  10
  11 // Here are all the lookup tables for the row shifts, rcon, s-boxes, and galois field multiplications
  12 byte shift_rows_table[]     = {0,5,10,15,4,9,14,3,8,13,2,7,12,1,6,11};
  13 byte shift_rows_table_inv[] = {0,13,10,7,4,1,14,11,8,5,2,15,12,9,6,3};
  14 byte lookup_rcon[]={0x8d,0x01,0x02,0x04,0x08,0x10,0x20,0x40,0x80,0x1b,0x36,0x6c,0xd8,0xab,0x4d,0x9a};
  15 byte lookup_sbox[]={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};
  16 byte lookup_sbox_inv[]={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};
  17 byte lookup_g2  []={0x00,0x02,0x04,0x06,0x08,0x0a,0x0c,0x0e,0x10,0x12,0x14,0x16,0x18,0x1a,0x1c,0x1e,0x20,0x22,0x24,0x26,0x28,0x2a,0x2c,0x2e,0x30,0x32,0x34,0x36,0x38,0x3a,0x3c,0x3e,0x40,0x42,0x44,0x46,0x48,0x4a,0x4c,0x4e,0x50,0x52,0x54,0x56,0x58,0x5a,0x5c,0x5e,0x60,0x62,0x64,0x66,0x68,0x6a,0x6c,0x6e,0x70,0x72,0x74,0x76,0x78,0x7a,0x7c,0x7e,0x80,0x82,0x84,0x86,0x88,0x8a,0x8c,0x8e,0x90,0x92,0x94,0x96,0x98,0x9a,0x9c,0x9e,0xa0,0xa2,0xa4,0xa6,0xa8,0xaa,0xac,0xae,0xb0,0xb2,0xb4,0xb6,0xb8,0xba,0xbc,0xbe,0xc0,0xc2,0xc4,0xc6,0xc8,0xca,0xcc,0xce,0xd0,0xd2,0xd4,0xd6,0xd8,0xda,0xdc,0xde,0xe0,0xe2,0xe4,0xe6,0xe8,0xea,0xec,0xee,0xf0,0xf2,0xf4,0xf6,0xf8,0xfa,0xfc,0xfe,0x1b,0x19,0x1f,0x1d,0x13,0x11,0x17,0x15,0x0b,0x09,0x0f,0x0d,0x03,0x01,0x07,0x05,0x3b,0x39,0x3f,0x3d,0x33,0x31,0x37,0x35,0x2b,0x29,0x2f,0x2d,0x23,0x21,0x27,0x25,0x5b,0x59,0x5f,0x5d,0x53,0x51,0x57,0x55,0x4b,0x49,0x4f,0x4d,0x43,0x41,0x47,0x45,0x7b,0x79,0x7f,0x7d,0x73,0x71,0x77,0x75,0x6b,0x69,0x6f,0x6d,0x63,0x61,0x67,0x65,0x9b,0x99,0x9f,0x9d,0x93,0x91,0x97,0x95,0x8b,0x89,0x8f,0x8d,0x83,0x81,0x87,0x85,0xbb,0xb9,0xbf,0xbd,0xb3,0xb1,0xb7,0xb5,0xab,0xa9,0xaf,0xad,0xa3,0xa1,0xa7,0xa5,0xdb,0xd9,0xdf,0xdd,0xd3,0xd1,0xd7,0xd5,0xcb,0xc9,0xcf,0xcd,0xc3,0xc1,0xc7,0xc5,0xfb,0xf9,0xff,0xfd,0xf3,0xf1,0xf7,0xf5,0xeb,0xe9,0xef,0xed,0xe3,0xe1,0xe7,0xe5};
  18 byte lookup_g3  []={0x00,0x03,0x06,0x05,0x0c,0x0f,0x0a,0x09,0x18,0x1b,0x1e,0x1d,0x14,0x17,0x12,0x11,0x30,0x33,0x36,0x35,0x3c,0x3f,0x3a,0x39,0x28,0x2b,0x2e,0x2d,0x24,0x27,0x22,0x21,0x60,0x63,0x66,0x65,0x6c,0x6f,0x6a,0x69,0x78,0x7b,0x7e,0x7d,0x74,0x77,0x72,0x71,0x50,0x53,0x56,0x55,0x5c,0x5f,0x5a,0x59,0x48,0x4b,0x4e,0x4d,0x44,0x47,0x42,0x41,0xc0,0xc3,0xc6,0xc5,0xcc,0xcf,0xca,0xc9,0xd8,0xdb,0xde,0xdd,0xd4,0xd7,0xd2,0xd1,0xf0,0xf3,0xf6,0xf5,0xfc,0xff,0xfa,0xf9,0xe8,0xeb,0xee,0xed,0xe4,0xe7,0xe2,0xe1,0xa0,0xa3,0xa6,0xa5,0xac,0xaf,0xaa,0xa9,0xb8,0xbb,0xbe,0xbd,0xb4,0xb7,0xb2,0xb1,0x90,0x93,0x96,0x95,0x9c,0x9f,0x9a,0x99,0x88,0x8b,0x8e,0x8d,0x84,0x87,0x82,0x81,0x9b,0x98,0x9d,0x9e,0x97,0x94,0x91,0x92,0x83,0x80,0x85,0x86,0x8f,0x8c,0x89,0x8a,0xab,0xa8,0xad,0xae,0xa7,0xa4,0xa1,0xa2,0xb3,0xb0,0xb5,0xb6,0xbf,0xbc,0xb9,0xba,0xfb,0xf8,0xfd,0xfe,0xf7,0xf4,0xf1,0xf2,0xe3,0xe0,0xe5,0xe6,0xef,0xec,0xe9,0xea,0xcb,0xc8,0xcd,0xce,0xc7,0xc4,0xc1,0xc2,0xd3,0xd0,0xd5,0xd6,0xdf,0xdc,0xd9,0xda,0x5b,0x58,0x5d,0x5e,0x57,0x54,0x51,0x52,0x43,0x40,0x45,0x46,0x4f,0x4c,0x49,0x4a,0x6b,0x68,0x6d,0x6e,0x67,0x64,0x61,0x62,0x73,0x70,0x75,0x76,0x7f,0x7c,0x79,0x7a,0x3b,0x38,0x3d,0x3e,0x37,0x34,0x31,0x32,0x23,0x20,0x25,0x26,0x2f,0x2c,0x29,0x2a,0x0b,0x08,0x0d,0x0e,0x07,0x04,0x01,0x02,0x13,0x10,0x15,0x16,0x1f,0x1c,0x19,0x1a};
  19 byte lookup_g9  []={0x00,0x09,0x12,0x1b,0x24,0x2d,0x36,0x3f,0x48,0x41,0x5a,0x53,0x6c,0x65,0x7e,0x77,0x90,0x99,0x82,0x8b,0xb4,0xbd,0xa6,0xaf,0xd8,0xd1,0xca,0xc3,0xfc,0xf5,0xee,0xe7,0x3b,0x32,0x29,0x20,0x1f,0x16,0x0d,0x04,0x73,0x7a,0x61,0x68,0x57,0x5e,0x45,0x4c,0xab,0xa2,0xb9,0xb0,0x8f,0x86,0x9d,0x94,0xe3,0xea,0xf1,0xf8,0xc7,0xce,0xd5,0xdc,0x76,0x7f,0x64,0x6d,0x52,0x5b,0x40,0x49,0x3e,0x37,0x2c,0x25,0x1a,0x13,0x08,0x01,0xe6,0xef,0xf4,0xfd,0xc2,0xcb,0xd0,0xd9,0xae,0xa7,0xbc,0xb5,0x8a,0x83,0x98,0x91,0x4d,0x44,0x5f,0x56,0x69,0x60,0x7b,0x72,0x05,0x0c,0x17,0x1e,0x21,0x28,0x33,0x3a,0xdd,0xd4,0xcf,0xc6,0xf9,0xf0,0xeb,0xe2,0x95,0x9c,0x87,0x8e,0xb1,0xb8,0xa3,0xaa,0xec,0xe5,0xfe,0xf7,0xc8,0xc1,0xda,0xd3,0xa4,0xad,0xb6,0xbf,0x80,0x89,0x92,0x9b,0x7c,0x75,0x6e,0x67,0x58,0x51,0x4a,0x43,0x34,0x3d,0x26,0x2f,0x10,0x19,0x02,0x0b,0xd7,0xde,0xc5,0xcc,0xf3,0xfa,0xe1,0xe8,0x9f,0x96,0x8d,0x84,0xbb,0xb2,0xa9,0xa0,0x47,0x4e,0x55,0x5c,0x63,0x6a,0x71,0x78,0x0f,0x06,0x1d,0x14,0x2b,0x22,0x39,0x30,0x9a,0x93,0x88,0x81,0xbe,0xb7,0xac,0xa5,0xd2,0xdb,0xc0,0xc9,0xf6,0xff,0xe4,0xed,0x0a,0x03,0x18,0x11,0x2e,0x27,0x3c,0x35,0x42,0x4b,0x50,0x59,0x66,0x6f,0x74,0x7d,0xa1,0xa8,0xb3,0xba,0x85,0x8c,0x97,0x9e,0xe9,0xe0,0xfb,0xf2,0xcd,0xc4,0xdf,0xd6,0x31,0x38,0x23,0x2a,0x15,0x1c,0x07,0x0e,0x79,0x70,0x6b,0x62,0x5d,0x54,0x4f,0x46};
  20 byte lookup_g11 []={0x00,0x0b,0x16,0x1d,0x2c,0x27,0x3a,0x31,0x58,0x53,0x4e,0x45,0x74,0x7f,0x62,0x69,0xb0,0xbb,0xa6,0xad,0x9c,0x97,0x8a,0x81,0xe8,0xe3,0xfe,0xf5,0xc4,0xcf,0xd2,0xd9,0x7b,0x70,0x6d,0x66,0x57,0x5c,0x41,0x4a,0x23,0x28,0x35,0x3e,0x0f,0x04,0x19,0x12,0xcb,0xc0,0xdd,0xd6,0xe7,0xec,0xf1,0xfa,0x93,0x98,0x85,0x8e,0xbf,0xb4,0xa9,0xa2,0xf6,0xfd,0xe0,0xeb,0xda,0xd1,0xcc,0xc7,0xae,0xa5,0xb8,0xb3,0x82,0x89,0x94,0x9f,0x46,0x4d,0x50,0x5b,0x6a,0x61,0x7c,0x77,0x1e,0x15,0x08,0x03,0x32,0x39,0x24,0x2f,0x8d,0x86,0x9b,0x90,0xa1,0xaa,0xb7,0xbc,0xd5,0xde,0xc3,0xc8,0xf9,0xf2,0xef,0xe4,0x3d,0x36,0x2b,0x20,0x11,0x1a,0x07,0x0c,0x65,0x6e,0x73,0x78,0x49,0x42,0x5f,0x54,0xf7,0xfc,0xe1,0xea,0xdb,0xd0,0xcd,0xc6,0xaf,0xa4,0xb9,0xb2,0x83,0x88,0x95,0x9e,0x47,0x4c,0x51,0x5a,0x6b,0x60,0x7d,0x76,0x1f,0x14,0x09,0x02,0x33,0x38,0x25,0x2e,0x8c,0x87,0x9a,0x91,0xa0,0xab,0xb6,0xbd,0xd4,0xdf,0xc2,0xc9,0xf8,0xf3,0xee,0xe5,0x3c,0x37,0x2a,0x21,0x10,0x1b,0x06,0x0d,0x64,0x6f,0x72,0x79,0x48,0x43,0x5e,0x55,0x01,0x0a,0x17,0x1c,0x2d,0x26,0x3b,0x30,0x59,0x52,0x4f,0x44,0x75,0x7e,0x63,0x68,0xb1,0xba,0xa7,0xac,0x9d,0x96,0x8b,0x80,0xe9,0xe2,0xff,0xf4,0xc5,0xce,0xd3,0xd8,0x7a,0x71,0x6c,0x67,0x56,0x5d,0x40,0x4b,0x22,0x29,0x34,0x3f,0x0e,0x05,0x18,0x13,0xca,0xc1,0xdc,0xd7,0xe6,0xed,0xf0,0xfb,0x92,0x99,0x84,0x8f,0xbe,0xb5,0xa8,0xa3};
  21 byte lookup_g13 []={0x00,0x0d,0x1a,0x17,0x34,0x39,0x2e,0x23,0x68,0x65,0x72,0x7f,0x5c,0x51,0x46,0x4b,0xd0,0xdd,0xca,0xc7,0xe4,0xe9,0xfe,0xf3,0xb8,0xb5,0xa2,0xaf,0x8c,0x81,0x96,0x9b,0xbb,0xb6,0xa1,0xac,0x8f,0x82,0x95,0x98,0xd3,0xde,0xc9,0xc4,0xe7,0xea,0xfd,0xf0,0x6b,0x66,0x71,0x7c,0x5f,0x52,0x45,0x48,0x03,0x0e,0x19,0x14,0x37,0x3a,0x2d,0x20,0x6d,0x60,0x77,0x7a,0x59,0x54,0x43,0x4e,0x05,0x08,0x1f,0x12,0x31,0x3c,0x2b,0x26,0xbd,0xb0,0xa7,0xaa,0x89,0x84,0x93,0x9e,0xd5,0xd8,0xcf,0xc2,0xe1,0xec,0xfb,0xf6,0xd6,0xdb,0xcc,0xc1,0xe2,0xef,0xf8,0xf5,0xbe,0xb3,0xa4,0xa9,0x8a,0x87,0x90,0x9d,0x06,0x0b,0x1c,0x11,0x32,0x3f,0x28,0x25,0x6e,0x63,0x74,0x79,0x5a,0x57,0x40,0x4d,0xda,0xd7,0xc0,0xcd,0xee,0xe3,0xf4,0xf9,0xb2,0xbf,0xa8,0xa5,0x86,0x8b,0x9c,0x91,0x0a,0x07,0x10,0x1d,0x3e,0x33,0x24,0x29,0x62,0x6f,0x78,0x75,0x56,0x5b,0x4c,0x41,0x61,0x6c,0x7b,0x76,0x55,0x58,0x4f,0x42,0x09,0x04,0x13,0x1e,0x3d,0x30,0x27,0x2a,0xb1,0xbc,0xab,0xa6,0x85,0x88,0x9f,0x92,0xd9,0xd4,0xc3,0xce,0xed,0xe0,0xf7,0xfa,0xb7,0xba,0xad,0xa0,0x83,0x8e,0x99,0x94,0xdf,0xd2,0xc5,0xc8,0xeb,0xe6,0xf1,0xfc,0x67,0x6a,0x7d,0x70,0x53,0x5e,0x49,0x44,0x0f,0x02,0x15,0x18,0x3b,0x36,0x21,0x2c,0x0c,0x01,0x16,0x1b,0x38,0x35,0x22,0x2f,0x64,0x69,0x7e,0x73,0x50,0x5d,0x4a,0x47,0xdc,0xd1,0xc6,0xcb,0xe8,0xe5,0xf2,0xff,0xb4,0xb9,0xae,0xa3,0x80,0x8d,0x9a,0x97};
  22 byte lookup_g14 []={0x00,0x0e,0x1c,0x12,0x38,0x36,0x24,0x2a,0x70,0x7e,0x6c,0x62,0x48,0x46,0x54,0x5a,0xe0,0xee,0xfc,0xf2,0xd8,0xd6,0xc4,0xca,0x90,0x9e,0x8c,0x82,0xa8,0xa6,0xb4,0xba,0xdb,0xd5,0xc7,0xc9,0xe3,0xed,0xff,0xf1,0xab,0xa5,0xb7,0xb9,0x93,0x9d,0x8f,0x81,0x3b,0x35,0x27,0x29,0x03,0x0d,0x1f,0x11,0x4b,0x45,0x57,0x59,0x73,0x7d,0x6f,0x61,0xad,0xa3,0xb1,0xbf,0x95,0x9b,0x89,0x87,0xdd,0xd3,0xc1,0xcf,0xe5,0xeb,0xf9,0xf7,0x4d,0x43,0x51,0x5f,0x75,0x7b,0x69,0x67,0x3d,0x33,0x21,0x2f,0x05,0x0b,0x19,0x17,0x76,0x78,0x6a,0x64,0x4e,0x40,0x52,0x5c,0x06,0x08,0x1a,0x14,0x3e,0x30,0x22,0x2c,0x96,0x98,0x8a,0x84,0xae,0xa0,0xb2,0xbc,0xe6,0xe8,0xfa,0xf4,0xde,0xd0,0xc2,0xcc,0x41,0x4f,0x5d,0x53,0x79,0x77,0x65,0x6b,0x31,0x3f,0x2d,0x23,0x09,0x07,0x15,0x1b,0xa1,0xaf,0xbd,0xb3,0x99,0x97,0x85,0x8b,0xd1,0xdf,0xcd,0xc3,0xe9,0xe7,0xf5,0xfb,0x9a,0x94,0x86,0x88,0xa2,0xac,0xbe,0xb0,0xea,0xe4,0xf6,0xf8,0xd2,0xdc,0xce,0xc0,0x7a,0x74,0x66,0x68,0x42,0x4c,0x5e,0x50,0x0a,0x04,0x16,0x18,0x32,0x3c,0x2e,0x20,0xec,0xe2,0xf0,0xfe,0xd4,0xda,0xc8,0xc6,0x9c,0x92,0x80,0x8e,0xa4,0xaa,0xb8,0xb6,0x0c,0x02,0x10,0x1e,0x34,0x3a,0x28,0x26,0x7c,0x72,0x60,0x6e,0x44,0x4a,0x58,0x56,0x37,0x39,0x2b,0x25,0x0f,0x01,0x13,0x1d,0x47,0x49,0x5b,0x55,0x7f,0x71,0x63,0x6d,0xd7,0xd9,0xcb,0xc5,0xef,0xe1,0xf3,0xfd,0xa7,0xa9,0xbb,0xb5,0x9f,0x91,0x83,0x8d};
  23
  24 // Xor's all elements in a n byte array a by b
  25 void xor_(byte *a, byte *b, int n) {
  26   int i;
  27   for (i=0;i<n;i++)
  28     a[i] ^= b[i];
  29 }
  30
  31 // Xor the current cipher state by a specific round key
  32 static void xor_round_key(byte *state, byte *keys, int round) {
  33   xor_(state,keys+round*16,16);
  34 }
  35
  36 // Apply and reverse the rijndael s-box to all elements in an array
  37 // http://en.wikipedia.org/wiki/Rijndael_S-box
  38 static void sub_bytes(byte *a,int n) {
  39   int i;
  40   for (i=0;i<n;i++)
  41     a[i] = lookup_sbox[a[i]];
  42 }
  43 static void sub_bytes_inv(byte *a,int n) {
  44   int i;
  45   for (i=0;i<n;i++)
  46     a[i] = lookup_sbox_inv[a[i]];
  47 }
  48
  49 // Perform the core key schedule transform on 4 bytes, as part of the key expansion process
  50 // http://en.wikipedia.org/wiki/Rijndael_key_schedule#Key_schedule_core
  51 static void key_schedule_core(byte *a, int i) {
  52   byte temp = a[0];     // Rotate the output eight bits to the left
  53   a[0]=a[1];
  54   a[1]=a[2];
  55   a[2]=a[3];
  56   a[3]=temp;
  57   sub_bytes(a,4);       // Apply Rijndael's S-box on all four individual bytes in the output word
  58   a[0]^=lookup_rcon[i]; // On just the first (leftmost) byte of the output word, perform the rcon operation with i
  59                         // as the input, and exclusive or the rcon output with the first byte of the output word
  60 }
  61
  62 // Expand the 16-byte key to 11 round keys (176 bytes)
  63 // http://en.wikipedia.org/wiki/Rijndael_key_schedule#The_key_schedule
  64 static void expand_key(byte *key, byte *keys) {
  65   int bytes=16;             // The count of how many bytes we've created so far
  66   int i=1;                  // The rcon iteration value i is set to 1
  67   int j;                    // For repeating the second stage 3 times
  68   byte t[4];                // Temporary working area known as 't' in the Wiki article
  69   memcpy(keys,key,16);      // The first 16 bytes of the expanded key are simply the encryption key
  70
  71   while (bytes<176) {       // Until we have 176 bytes of expanded key, we do the following:
  72     memcpy(t,keys+bytes-4,4);          // We assign the value of the previous four bytes in the expanded key to t
  73     key_schedule_core(t, i);           // We perform the key schedule core on t, with i as the rcon iteration value
  74     i++;                               // We increment i by 1
  75     xor_(t,keys+bytes-16,4);            // We exclusive-or t with the four-byte block 16 bytes before the new expanded key.
  76     memcpy(keys+bytes,t,4);            // This becomes the next 4 bytes in the expanded key
  77     bytes+=4;                          // Keep track of how many expanded key bytes we've added
  78
  79     // We then do the following three times to create the next twelve bytes
  80     for (j=0;j<3;j++) {
  81       memcpy(t,keys+bytes-4,4);          // We assign the value of the previous 4 bytes in the expanded key to t
  82       xor_(t,keys+bytes-16,4);            // We exclusive-or t with the four-byte block n bytes before
  83       memcpy(keys+bytes,t,4);            // This becomes the next 4 bytes in the expanded key
  84       bytes+=4;                          // Keep track of how many expanded key bytes we've added
  85     }
  86   }
  87 }
  88
  89 // Apply / reverse the shift rows step on the 16 byte cipher state
  90 // http://en.wikipedia.org/wiki/Advanced_Encryption_Standard#The_ShiftRows_step
  91 static void shift_rows(byte *state) {
  92   int i;
  93   byte temp[16];
  94   memcpy(temp,state,16);
  95   for (i=0;i<16;i++)
  96     state[i]=temp[shift_rows_table[i]];
  97 }
  98 static void shift_rows_inv(byte *state) {
  99   int i;
 100   byte temp[16];
 101   memcpy(temp,state,16);
 102   for (i=0;i<16;i++)
 103     state[i]=temp[shift_rows_table_inv[i]];
 104 }
 105
 106 // Perform the mix columns matrix on one column of 4 bytes
 107 // http://en.wikipedia.org/wiki/Rijndael_mix_columns
 108 static void mix_col (byte *state) {
 109   byte a0 = state[0];
 110   byte a1 = state[1];
 111   byte a2 = state[2];
 112   byte a3 = state[3];
 113   state[0] = lookup_g2[a0] ^ lookup_g3[a1] ^ a2 ^ a3;
 114   state[1] = lookup_g2[a1] ^ lookup_g3[a2] ^ a3 ^ a0;
 115   state[2] = lookup_g2[a2] ^ lookup_g3[a3] ^ a0 ^ a1;
 116   state[3] = lookup_g2[a3] ^ lookup_g3[a0] ^ a1 ^ a2;
 117 }
 118
 119 // Perform the mix columns matrix on each column of the 16 bytes
 120 static void mix_cols (byte *state) {
 121   mix_col(state);
 122   mix_col(state+4);
 123   mix_col(state+8);
 124   mix_col(state+12);
 125 }
 126
 127 // Perform the inverse mix columns matrix on one column of 4 bytes
 128 // http://en.wikipedia.org/wiki/Rijndael_mix_columns
 129 static void mix_col_inv (byte *state) {
 130   byte a0 = state[0];
 131   byte a1 = state[1];
 132   byte a2 = state[2];
 133   byte a3 = state[3];
 134   state[0] = lookup_g14[a0] ^ lookup_g9[a3] ^ lookup_g13[a2] ^ lookup_g11[a1];
 135   state[1] = lookup_g14[a1] ^ lookup_g9[a0] ^ lookup_g13[a3] ^ lookup_g11[a2];
 136   state[2] = lookup_g14[a2] ^ lookup_g9[a1] ^ lookup_g13[a0] ^ lookup_g11[a3];
 137   state[3] = lookup_g14[a3] ^ lookup_g9[a2] ^ lookup_g13[a1] ^ lookup_g11[a0];
 138 }
 139
 140 // Perform the inverse mix columns matrix on each column of the 16 bytes
 141 static void mix_cols_inv (byte *state) {
 142   mix_col_inv(state);
 143   mix_col_inv(state+4);
 144   mix_col_inv(state+8);
 145   mix_col_inv(state+12);
 146 }
 147
 148 // Encrypt a single 128 bit block by a 128 bit key using AES
 149 // http://en.wikipedia.org/wiki/Advanced_Encryption_Standard
 150 void EncryptAES(byte *msg, byte *key, byte *c) {
 151   int i; // To count the rounds
 152
 153   // Key expansion
 154   byte keys[176];
 155   expand_key(key,keys);
 156
 157   // First Round
 158   memmove(c, msg, 16);
 159   xor_round_key(c,keys,0);
 160
 161   // Middle rounds
 162   for(i=0; i<9; i++) {
 163     sub_bytes(c,16);
 164     shift_rows(c);
 165     mix_cols(c);
 166     xor_round_key(c, keys, i+1);
 167   }
 168
 169   // Final Round
 170   sub_bytes(c,16);
 171   shift_rows(c);
 172   xor_round_key(c, keys, 10);
 173 }
 174
 175 // Decrypt a single 128 bit block by a 128 bit key using AES
 176 // http://en.wikipedia.org/wiki/Advanced_Encryption_Standard
 177 void DecryptAES(byte *c, byte *key, byte *m) {
 178   int i; // To count the rounds
 179
 180   // Key expansion
 181   byte keys[176];
 182   expand_key(key,keys);
 183
 184   // Reverse the final Round
 185   memcpy(m,c,16);
 186   xor_round_key(m,keys,10);
 187   shift_rows_inv(m);
 188   sub_bytes_inv(m, 16);
 189
 190   // Reverse the middle rounds
 191   for (i=0; i<9; i++) {
 192     xor_round_key(m,keys,9-i);
 193     mix_cols_inv(m);
 194     shift_rows_inv(m);
 195     sub_bytes_inv(m, 16);
 196   }
 197
 198   // Reverse the first Round
 199   xor_round_key(m, keys, 0);
 200 }
 201
 202 /*
 203 // Pretty-print a key (or any smallish buffer) onto screen as hex
 204 void Pretty(byte* b,int len,const char* label)
 205 {
 206   char out[100];
 207   int i;
 208   for (i=0;i<len;i++)
 209     sprintf(out+i*2,"%02x",b[i]);
 210
 211   printf("%s%s",label, out);
 212 }
 213 */
 214
 215 /*
 216 // Test AES
 217 int main(void)
 218 {
 219   byte key[] = {0x12,0x34,0x56,0x12,0x34,0x56,0x12,0x34,0x56,0x12,0x34,0x56,0x12,0x34,0x56,0x12};
 220   byte msg[] = {0xab,0xcd,0xef,0xab,0xcd,0xef,0xab,0xcd,0xef,0xab,0xcd,0xef,0xab,0xcd,0xef,0xab};
 221   byte encrypted[16], decrypted[16];
 222
 223   printf("Test AES\r\n\n");
 224   Pretty(key,16,"Key:         ");
 225   Pretty(msg,16,"Original:    ");
 226
 227   EncryptAES(msg,key,encrypted);
 228   printf("Encrypted should be: 85E5A3D7356A61E29A8AFA559AD67102\r\n");
 229   Pretty(encrypted,16,"Encrypted:   ");
 230
 231   DecryptAES(encrypted,key,decrypted);
 232   Pretty(decrypted,16,"Decrypted:   ");
 233
 234   return 0;
 235 }
 236 */
 237
 238 void cbc_mac(
 239     byte *in_data, /* Input data */
 240     byte *out_data, /* Output data (or NULL) */
 241     int nr_blocks, /* Number of blocks to encrypt/decrypt (one block=16 bytes) */
 242     byte key[16], /* Key */
 243     byte iv[16], /* Initialisation Vector */
 244     byte (*out_cbc_mac)[16], /* CBC-MAC of the result (or NULL) */
 245     int encrypt /* 1 to encrypt, 0 to decrypt */
 246     )
 247 {
 248     byte feedback[16];
 249     memcpy(feedback, iv, 16);
 250
 251     if(encrypt)
 252     {
 253         /* for each block */
 254         for(int i = 0; i < nr_blocks; i++)
 255         {
 256             /* xor it with feedback */
 257             xor_(feedback, &in_data[i * 16], 16);
 258             /* encrypt it using aes */
 259             EncryptAES(feedback, key, feedback);
 260             /* write cipher to output */
 261             if(out_data)
 262                 memcpy(&out_data[i * 16], feedback, 16);
 263         }
 264         if(out_cbc_mac)
 265             memcpy(out_cbc_mac, feedback, 16);
 266     }
 267     else
 268     {
 269         /* nothing to do ? */
 270         if(out_data == NULL)
 271             return;
 272
 273         /* for each block */
 274         for(int i = 0; i < nr_blocks; i++)
 275         {
 276             /* decrypt it using aes */
 277             DecryptAES(&in_data[i * 16], key, &out_data[i * 16]);
 278             /* xor it with iv */
 279             xor_(&out_data[i * 16], feedback, 16);
 280             /* copy cipher to iv */
 281             memcpy(feedback, &in_data[i * 16], 16);
 282         }
 283     }
 284 }