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608 lines
20 KiB
608 lines
20 KiB
/*
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This is an implementation of the AES algorithm, specifically ECB, CTR and CBC mode.
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Block size can be chosen in aes.h - available choices are AES128, AES192, AES256.
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The implementation is verified against the test vectors in:
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National Institute of Standards and Technology Special Publication 800-38A 2001 ED
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ECB-AES128
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----------
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plain-text:
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6bc1bee22e409f96e93d7e117393172a
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ae2d8a571e03ac9c9eb76fac45af8e51
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30c81c46a35ce411e5fbc1191a0a52ef
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f69f2445df4f9b17ad2b417be66c3710
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key:
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2b7e151628aed2a6abf7158809cf4f3c
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resulting cipher
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3ad77bb40d7a3660a89ecaf32466ef97
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f5d3d58503b9699de785895a96fdbaaf
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43b1cd7f598ece23881b00e3ed030688
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7b0c785e27e8ad3f8223207104725dd4
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NOTE: String length must be evenly divisible by 16byte (str_len % 16 == 0)
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You should pad the end of the string with zeros if this is not the case.
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For AES192/256 the key size is proportionally larger.
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*/
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/*****************************************************************************/
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/* Includes: */
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/*****************************************************************************/
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#include <string.h> // CBC mode, for memset
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#include "aes.h"
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/*****************************************************************************/
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/* Defines: */
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/*****************************************************************************/
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// The number of columns comprising a state in AES. This is a constant in AES.
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// Value=4
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#define Nb 4UL
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#if defined(AES256) && (AES256 == 1)
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#define Nk256 8UL
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#define Nr256 14UL
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#endif
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#if defined(AES192) && (AES192 == 1)
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#define Nk192 6UL
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#define Nr192 12UL
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#endif
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#if defined(AES128) && (AES128 == 1)
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#define Nk128 4UL // The number of 32 bit words in a key.
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#define Nr128 10UL // The number of rounds in AES Cipher.
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#endif
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// jcallan@github points out that declaring Multiply as a function reduces code
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// size considerably with the Keil ARM compiler. See this link for more
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// information: https://github.com/kokke/tiny-AES-C/pull/3
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#ifndef MULTIPLY_AS_A_FUNCTION
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#define MULTIPLY_AS_A_FUNCTION 0
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#endif
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/*****************************************************************************/
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/* Private variables: */
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/*****************************************************************************/
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// state - array holding the intermediate results during decryption.
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typedef uint8_t state_t[4][4];
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// The lookup-tables are marked const so they can be placed in read-only storage
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// instead of RAM The numbers below can be computed dynamically trading ROM for
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// RAM - This can be useful in (embedded) bootloader applications, where ROM is
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// often limited.
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static const uint8_t sbox[256] = {
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//0 1 2 3 4 5 6 7 8 9 A B C D E F
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0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
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0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
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0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
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0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
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0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
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0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
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0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
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0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
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0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
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0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
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0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
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0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
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0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
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0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
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0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
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0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16 };
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static const uint8_t rsbox[256] = {
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0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
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0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
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0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
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0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
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0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
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0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
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0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
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0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
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0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
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0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
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0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
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0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
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0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
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0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
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0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
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0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d };
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// The round constant word array, Rcon[i], contains the values given by x to the
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// power (i-1) being powers of x (x is denoted as {02}) in the field GF(2^8)
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static const uint8_t Rcon[11] = {
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0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36 };
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/*
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* Jordan Goulder points out in PR #12
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* (https://github.com/kokke/tiny-AES-C/pull/12), that you can remove most of
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* the elements in the Rcon array, because they are unused.
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*
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* From Wikipedia's article on the Rijndael key schedule @
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* https://en.wikipedia.org/wiki/Rijndael_key_schedule#Rcon
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*
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* "Only the first some of these constants are actually used – up to rcon[10]
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* for AES-128 (as 11 round keys are needed), up to rcon[8] for AES-192, up to
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* rcon[7] for AES-256. rcon[0] is not used in AES algorithm."
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*/
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/*****************************************************************************/
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/* Private functions: */
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/*****************************************************************************/
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static const uint8_t *GetRoundKey(const struct AES_ctx *ctx) {
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switch (ctx->KeyLength) {
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#if defined(AES128) && (AES128 == 1)
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case 16: return ctx->RoundKey128;
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#endif
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#if defined(AES192) && (AES192 == 1)
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case 24: return ctx->RoundKey192;
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#endif
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#if defined(AES256) && (AES256 == 1)
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case 32: return ctx->RoundKey256;
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#endif
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}
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return NULL;
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}
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/*
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static uint8_t getSBoxValue(uint8_t num)
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{
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return sbox[num];
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}
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*/
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#define getSBoxValue(num) (sbox[(num)])
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/*
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static uint8_t getSBoxInvert(uint8_t num)
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{
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return rsbox[num];
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}
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*/
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#define getSBoxInvert(num) (rsbox[(num)])
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// This function produces Nb(Nr+1) round keys. The round keys are used in each
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// round to decrypt the states.
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static void KeyExpansion(struct AES_ctx* ctx, const uint8_t* Key)
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{
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uint8_t* RoundKey = (uint8_t *)GetRoundKey(ctx);
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unsigned i, j, k;
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uint8_t tempa[4]; // Used for the column/row operations
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// The first round key is the key itself.
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for (i = 0; i < ctx->Nk; ++i)
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{
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RoundKey[(i * 4) + 0] = Key[(i * 4) + 0];
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RoundKey[(i * 4) + 1] = Key[(i * 4) + 1];
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RoundKey[(i * 4) + 2] = Key[(i * 4) + 2];
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RoundKey[(i * 4) + 3] = Key[(i * 4) + 3];
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}
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// All other round keys are found from the previous round keys.
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for (i = ctx->Nk; i < Nb * (ctx->Nr + 1); ++i)
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{
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{
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k = (i - 1) * 4;
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tempa[0]=RoundKey[k + 0];
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tempa[1]=RoundKey[k + 1];
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tempa[2]=RoundKey[k + 2];
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tempa[3]=RoundKey[k + 3];
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}
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if (i % ctx->Nk == 0)
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{
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// This function shifts the 4 bytes in a word to the left once.
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// [a0,a1,a2,a3] becomes [a1,a2,a3,a0]
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// Function RotWord()
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{
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const uint8_t u8tmp = tempa[0];
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tempa[0] = tempa[1];
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tempa[1] = tempa[2];
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tempa[2] = tempa[3];
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tempa[3] = u8tmp;
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}
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// SubWord() is a function that takes a four-byte input word and applies
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// the S-box to each of the four bytes to produce an output word.
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// Function Subword()
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{
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tempa[0] = getSBoxValue(tempa[0]);
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tempa[1] = getSBoxValue(tempa[1]);
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tempa[2] = getSBoxValue(tempa[2]);
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tempa[3] = getSBoxValue(tempa[3]);
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}
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tempa[0] = tempa[0] ^ Rcon[i/ctx->Nk];
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}
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#if defined(AES256) && (AES256 == 1)
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if (ctx->KeyLength == 32) {
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if (i % ctx->Nk == 4)
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{
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// Function Subword()
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{
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tempa[0] = getSBoxValue(tempa[0]);
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tempa[1] = getSBoxValue(tempa[1]);
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tempa[2] = getSBoxValue(tempa[2]);
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tempa[3] = getSBoxValue(tempa[3]);
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}
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}
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}
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#endif
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j = i * 4; k=(i - ctx->Nk) * 4;
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RoundKey[j + 0] = RoundKey[k + 0] ^ tempa[0];
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RoundKey[j + 1] = RoundKey[k + 1] ^ tempa[1];
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RoundKey[j + 2] = RoundKey[k + 2] ^ tempa[2];
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RoundKey[j + 3] = RoundKey[k + 3] ^ tempa[3];
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}
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}
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void AES_init_ctx(struct AES_ctx* ctx, const uint8_t* key, uint32_t keylen)
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{
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ctx->KeyLength = keylen;
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switch (ctx->KeyLength) {
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#if defined(AES128) && (AES128 == 1)
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case 16: ctx->Nr = Nr128; ctx->Nk = Nk128; break;
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#endif
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#if defined(AES192) && (AES192 == 1)
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case 24: ctx->Nr = Nr192; ctx->Nk = Nk192; break;
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#endif
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#if defined(AES256) && (AES256 == 1)
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case 32: ctx->Nr = Nr256; ctx->Nk = Nk256; break;
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#endif
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default: ctx->Nr = 0; ctx->Nk = 0; break;
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}
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KeyExpansion(ctx, key);
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}
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#if (defined(CBC) && (CBC == 1)) || (defined(CTR) && (CTR == 1))
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void AES_init_ctx_iv(struct AES_ctx* ctx, const uint8_t* key, uint32_t keylen, const uint8_t* iv)
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{
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AES_init_ctx(ctx, key, keylen);
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memcpy (ctx->Iv, iv, AES_BLOCKLEN);
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}
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void AES_ctx_set_iv(struct AES_ctx* ctx, const uint8_t* iv)
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{
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memcpy (ctx->Iv, iv, AES_BLOCKLEN);
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}
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#endif
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// This function adds the round key to state. The round key is added to the
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// state by an XOR function.
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static void AddRoundKey(uint8_t round, state_t* state, const uint8_t* RoundKey)
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{
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uint8_t i,j;
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for (i = 0; i < 4; ++i)
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{
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for (j = 0; j < 4; ++j)
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{
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(*state)[i][j] ^= RoundKey[(round * Nb * 4) + (i * Nb) + j];
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}
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}
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}
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// The SubBytes Function Substitutes the values in the state matrix with values
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// in an S-box.
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static void SubBytes(state_t* state)
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{
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uint8_t i, j;
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for (i = 0; i < 4; ++i)
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{
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for (j = 0; j < 4; ++j)
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{
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(*state)[j][i] = getSBoxValue((*state)[j][i]);
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}
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}
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}
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// The ShiftRows() function shifts the rows in the state to the left. Each row
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// is shifted with different offset. Offset = Row number. So the first row is
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// not shifted.
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static void ShiftRows(state_t* state)
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{
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uint8_t temp;
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// Rotate first row 1 columns to left
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temp = (*state)[0][1];
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(*state)[0][1] = (*state)[1][1];
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(*state)[1][1] = (*state)[2][1];
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(*state)[2][1] = (*state)[3][1];
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(*state)[3][1] = temp;
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// Rotate second row 2 columns to left
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temp = (*state)[0][2];
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(*state)[0][2] = (*state)[2][2];
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(*state)[2][2] = temp;
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temp = (*state)[1][2];
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(*state)[1][2] = (*state)[3][2];
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(*state)[3][2] = temp;
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// Rotate third row 3 columns to left
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temp = (*state)[0][3];
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(*state)[0][3] = (*state)[3][3];
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(*state)[3][3] = (*state)[2][3];
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(*state)[2][3] = (*state)[1][3];
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(*state)[1][3] = temp;
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}
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static uint8_t xtime(uint8_t x)
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{
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return ((x<<1) ^ (((x>>7) & 1) * 0x1b));
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}
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// MixColumns function mixes the columns of the state matrix
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static void MixColumns(state_t* state)
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{
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uint8_t i;
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uint8_t Tmp, Tm, t;
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for (i = 0; i < 4; ++i)
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{
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t = (*state)[i][0];
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Tmp = (*state)[i][0] ^ (*state)[i][1] ^ (*state)[i][2] ^ (*state)[i][3] ;
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Tm = (*state)[i][0] ^ (*state)[i][1] ; Tm = xtime(Tm); (*state)[i][0] ^= Tm ^ Tmp ;
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Tm = (*state)[i][1] ^ (*state)[i][2] ; Tm = xtime(Tm); (*state)[i][1] ^= Tm ^ Tmp ;
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Tm = (*state)[i][2] ^ (*state)[i][3] ; Tm = xtime(Tm); (*state)[i][2] ^= Tm ^ Tmp ;
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Tm = (*state)[i][3] ^ t ; Tm = xtime(Tm); (*state)[i][3] ^= Tm ^ Tmp ;
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}
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}
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// Multiply is used to multiply numbers in the field GF(2^8)
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// Note: The last call to xtime() is unneeded, but often ends up generating a smaller binary
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// The compiler seems to be able to vectorize the operation better this way.
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// See https://github.com/kokke/tiny-AES-c/pull/34
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#if MULTIPLY_AS_A_FUNCTION
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static uint8_t Multiply(uint8_t x, uint8_t y)
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{
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return (((y & 1) * x) ^
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((y>>1 & 1) * xtime(x)) ^
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((y>>2 & 1) * xtime(xtime(x))) ^
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((y>>3 & 1) * xtime(xtime(xtime(x)))) ^
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((y>>4 & 1) * xtime(xtime(xtime(xtime(x)))))); /* this last call to xtime() can be omitted */
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}
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#else
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#define Multiply(x, y) \
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( ((y & 1) * x) ^ \
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((y>>1 & 1) * xtime(x)) ^ \
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((y>>2 & 1) * xtime(xtime(x))) ^ \
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((y>>3 & 1) * xtime(xtime(xtime(x)))) ^ \
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((y>>4 & 1) * xtime(xtime(xtime(xtime(x)))))) \
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#endif
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#if (defined(CBC) && CBC == 1) || (defined(ECB) && ECB == 1)
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// MixColumns function mixes the columns of the state matrix. The method used to
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// multiply may be difficult to understand for the inexperienced. Please use the
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// references to gain more information.
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static void InvMixColumns(state_t* state)
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{
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int i;
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uint8_t a, b, c, d;
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for (i = 0; i < 4; ++i)
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{
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a = (*state)[i][0];
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b = (*state)[i][1];
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c = (*state)[i][2];
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d = (*state)[i][3];
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(*state)[i][0] = Multiply(a, 0x0e) ^ Multiply(b, 0x0b) ^ Multiply(c, 0x0d) ^ Multiply(d, 0x09);
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(*state)[i][1] = Multiply(a, 0x09) ^ Multiply(b, 0x0e) ^ Multiply(c, 0x0b) ^ Multiply(d, 0x0d);
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(*state)[i][2] = Multiply(a, 0x0d) ^ Multiply(b, 0x09) ^ Multiply(c, 0x0e) ^ Multiply(d, 0x0b);
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(*state)[i][3] = Multiply(a, 0x0b) ^ Multiply(b, 0x0d) ^ Multiply(c, 0x09) ^ Multiply(d, 0x0e);
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}
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}
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// The SubBytes Function Substitutes the values in the state matrix with values
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// in an S-box.
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static void InvSubBytes(state_t* state)
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{
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uint8_t i, j;
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for (i = 0; i < 4; ++i)
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{
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for (j = 0; j < 4; ++j)
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{
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(*state)[j][i] = getSBoxInvert((*state)[j][i]);
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}
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}
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}
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static void InvShiftRows(state_t* state)
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{
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uint8_t temp;
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// Rotate first row 1 columns to right
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temp = (*state)[3][1];
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(*state)[3][1] = (*state)[2][1];
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(*state)[2][1] = (*state)[1][1];
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(*state)[1][1] = (*state)[0][1];
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(*state)[0][1] = temp;
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// Rotate second row 2 columns to right
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temp = (*state)[0][2];
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(*state)[0][2] = (*state)[2][2];
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(*state)[2][2] = temp;
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temp = (*state)[1][2];
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(*state)[1][2] = (*state)[3][2];
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(*state)[3][2] = temp;
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// Rotate third row 3 columns to right
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temp = (*state)[0][3];
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(*state)[0][3] = (*state)[1][3];
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(*state)[1][3] = (*state)[2][3];
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(*state)[2][3] = (*state)[3][3];
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(*state)[3][3] = temp;
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}
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#endif // #if (defined(CBC) && CBC == 1) || (defined(ECB) && ECB == 1)
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// Cipher is the main function that encrypts the PlainText.
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static void Cipher(state_t* state, const struct AES_ctx* ctx)
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{
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const uint8_t* RoundKey = GetRoundKey(ctx);
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uint8_t round = 0;
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// Add the First round key to the state before starting the rounds.
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AddRoundKey(0, state, RoundKey);
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// There will be Nr rounds. The first Nr-1 rounds are identical. These Nr
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// rounds are executed in the loop below. Last one without MixColumns()
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for (round = 1; ; ++round)
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{
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SubBytes(state);
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ShiftRows(state);
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if (round == ctx->Nr) {
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break;
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}
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MixColumns(state);
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AddRoundKey(round, state, RoundKey);
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}
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// Add round key to last round
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AddRoundKey(ctx->Nr, state, RoundKey);
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}
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#if (defined(CBC) && CBC == 1) || (defined(ECB) && ECB == 1)
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static void InvCipher(state_t* state, const struct AES_ctx* ctx)
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{
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const uint8_t* RoundKey = GetRoundKey(ctx);
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uint8_t round = 0;
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// Add the First round key to the state before starting the rounds.
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AddRoundKey(ctx->Nr, state, RoundKey);
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|
// There will be Nr rounds. The first Nr-1 rounds are identical. These Nr
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// rounds are executed in the loop below. Last one without InvMixColumn()
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for (round = (ctx->Nr - 1); ; --round)
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|
{
|
|
InvShiftRows(state);
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|
InvSubBytes(state);
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|
AddRoundKey(round, state, RoundKey);
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if (round == 0) {
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break;
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|
}
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InvMixColumns(state);
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|
}
|
|
|
|
}
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|
#endif // #if (defined(CBC) && CBC == 1) || (defined(ECB) && ECB == 1)
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|
|
|
/*****************************************************************************/
|
|
/* Public functions: */
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|
/*****************************************************************************/
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|
#if defined(ECB) && (ECB == 1)
|
|
|
|
|
|
void AES_ECB_encrypt(const struct AES_ctx* ctx, uint8_t* buf)
|
|
{
|
|
// The next function call encrypts the PlainText with the Key using AES
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// algorithm.
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|
Cipher((state_t*)buf, ctx);
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}
|
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|
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void AES_ECB_decrypt(const struct AES_ctx* ctx, uint8_t* buf)
|
|
{
|
|
// The next function call decrypts the PlainText with the Key using AES
|
|
// algorithm.
|
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InvCipher((state_t*)buf, ctx);
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}
|
|
|
|
|
|
#endif // #if defined(ECB) && (ECB == 1)
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|
|
|
|
|
|
|
|
|
|
|
#if defined(CBC) && (CBC == 1)
|
|
|
|
|
|
static void XorWithIv(uint8_t* buf, const uint8_t* Iv)
|
|
{
|
|
uint8_t i;
|
|
for (i = 0; i < AES_BLOCKLEN; ++i) // The block in AES is always 128bit no matter the key size
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|
{
|
|
buf[i] ^= Iv[i];
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|
}
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|
}
|
|
|
|
void AES_CBC_encrypt_buffer(struct AES_ctx *ctx, uint8_t* buf, uint32_t length)
|
|
{
|
|
uintptr_t i;
|
|
uint8_t *Iv = ctx->Iv;
|
|
for (i = 0; i < length; i += AES_BLOCKLEN)
|
|
{
|
|
XorWithIv(buf, Iv);
|
|
Cipher((state_t*)buf, ctx);
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|
Iv = buf;
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|
buf += AES_BLOCKLEN;
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|
}
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|
/* store Iv in ctx for next call */
|
|
memcpy(ctx->Iv, Iv, AES_BLOCKLEN);
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|
}
|
|
|
|
void AES_CBC_decrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, uint32_t length)
|
|
{
|
|
uintptr_t i;
|
|
uint8_t storeNextIv[AES_BLOCKLEN];
|
|
for (i = 0; i < length; i += AES_BLOCKLEN)
|
|
{
|
|
memcpy(storeNextIv, buf, AES_BLOCKLEN);
|
|
InvCipher((state_t*)buf, ctx);
|
|
XorWithIv(buf, ctx->Iv);
|
|
memcpy(ctx->Iv, storeNextIv, AES_BLOCKLEN);
|
|
buf += AES_BLOCKLEN;
|
|
}
|
|
|
|
}
|
|
|
|
#endif // #if defined(CBC) && (CBC == 1)
|
|
|
|
|
|
|
|
#if defined(CTR) && (CTR == 1)
|
|
|
|
/* Symmetrical operation: same function for encrypting as for decrypting. Note
|
|
any IV/nonce should never be reused with the same key */
|
|
void AES_CTR_xcrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, uint32_t length)
|
|
{
|
|
uint8_t buffer[AES_BLOCKLEN];
|
|
|
|
unsigned i;
|
|
int bi;
|
|
for (i = 0, bi = AES_BLOCKLEN; i < length; ++i, ++bi)
|
|
{
|
|
if (bi == AES_BLOCKLEN) /* we need to regen xor compliment in buffer */
|
|
{
|
|
memcpy(buffer, ctx->Iv, AES_BLOCKLEN);
|
|
Cipher((state_t*)buffer, ctx);
|
|
|
|
/* Increment Iv and handle overflow */
|
|
for (bi = (AES_BLOCKLEN - 1); bi >= 0; --bi)
|
|
{
|
|
/* inc will overflow */
|
|
if (ctx->Iv[bi] == 255)
|
|
{
|
|
ctx->Iv[bi] = 0;
|
|
continue;
|
|
}
|
|
ctx->Iv[bi] += 1;
|
|
break;
|
|
}
|
|
bi = 0;
|
|
}
|
|
|
|
buf[i] = (buf[i] ^ buffer[bi]);
|
|
}
|
|
}
|
|
|
|
#endif // #if defined(CTR) && (CTR == 1)
|
|
|