STM32CubeWL/Middlewares/Third_Party/LoRaWAN/Crypto/cmac.c

/**************************************************************************
Copyright (C) 2009 Lander Casado, Philippas Tsigas

All rights reserved.

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files
(the "Software"), to deal with the Software without restriction, including
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the following conditions:

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conditions and the following disclaimers in the documentation and/or
other materials provided with the distribution.

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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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*****************************************************************************/
#include "lorawan_aes.h"
#include "cmac.h"
#include "utilities.h"

#define LSHIFT( v, r )                                    \
    do                                                    \
    {                                                     \
        int32_t i;                                        \
        for( i = 0; i < 15; i++ )                         \
            ( r )[i] = ( v )[i] << 1 | ( v )[i + 1] >> 7; \
        ( r )[15] = ( v )[15] << 1;                       \
    } while( 0 )

#define XOR( v, r )                         \
    do                                      \
    {                                       \
        int32_t i;                          \
        for( i = 0; i < 16; i++ )           \
        {                                   \
            ( r )[i] = ( r )[i] ^ ( v )[i]; \
        }                                   \
    } while( 0 )

void AES_CMAC_Init( AES_CMAC_CTX* ctx )
{
    memset1( ctx->X, 0, sizeof ctx->X );
    ctx->M_n = 0;
    memset1( ctx->rijndael.ksch, '\0', 240 );
}

void AES_CMAC_SetKey( AES_CMAC_CTX* ctx, const uint8_t key[AES_CMAC_KEY_LENGTH] )
{
    lorawan_aes_set_key( key, AES_CMAC_KEY_LENGTH, &ctx->rijndael );
}

void AES_CMAC_Update( AES_CMAC_CTX* ctx, const uint8_t* data, uint32_t len )
{
    uint32_t mlen;
    uint8_t  in[16];

    if( ctx->M_n > 0 )
    {
        mlen = MIN( 16 - ctx->M_n, len );
        memcpy1( ctx->M_last + ctx->M_n, data, mlen );
        ctx->M_n += mlen;
        if( ctx->M_n < 16 || len == mlen )
            return;
        XOR( ctx->M_last, ctx->X );

        memcpy1( in, &ctx->X[0], 16 );  // Otherwise it does not look good
        lorawan_aes_encrypt( in, in, &ctx->rijndael );
        memcpy1( &ctx->X[0], in, 16 );

        data += mlen;
        len -= mlen;
    }
    while( len > 16 )
    { /* not last block */

        XOR( data, ctx->X );

        memcpy1( in, &ctx->X[0], 16 );  // Otherwise it does not look good
        lorawan_aes_encrypt( in, in, &ctx->rijndael );
        memcpy1( &ctx->X[0], in, 16 );

        data += 16;
        len -= 16;
    }
    /* potential last block, save it */
    memcpy1( ctx->M_last, data, len );
    ctx->M_n = len;
}

void AES_CMAC_Final( uint8_t digest[AES_CMAC_DIGEST_LENGTH], AES_CMAC_CTX* ctx )
{
    uint8_t K[16];
    uint8_t in[16];
    /* generate subkey K1 */
    memset1( K, '\0', 16 );

    lorawan_aes_encrypt( K, K, &ctx->rijndael );

    if( K[0] & 0x80 )
    {
        LSHIFT( K, K );
        K[15] ^= 0x87;
    }
    else
        LSHIFT( K, K );

    if( ctx->M_n == 16 )
    {
        /* last block was a complete block */
        XOR( K, ctx->M_last );
    }
    else
    {
        /* generate subkey K2 */
        if( K[0] & 0x80 )
        {
            LSHIFT( K, K );
            K[15] ^= 0x87;
        }
        else
            LSHIFT( K, K );

        /* padding(M_last) */
        ctx->M_last[ctx->M_n] = 0x80;
        while( ++ctx->M_n < 16 )
            ctx->M_last[ctx->M_n] = 0;

        XOR( K, ctx->M_last );
    }
    XOR( ctx->M_last, ctx->X );

    memcpy1( in, &ctx->X[0], 16 );  // Otherwise it does not look good
    lorawan_aes_encrypt( in, digest, &ctx->rijndael );
    memset1( K, 0, sizeof K );
}