/*
setup needed for both encrypt & decrypt
*/
static void setup(u64 mlen, u64 adlen, const byte *npub, const byte *k)
{
assert( k != NULL) ;
assert( npub != NULL) ;
/*
run ChaCha key schedule
and then ChaCha
*/
chacha_keysetup(chacha_ctx, (byte *) k, 256, 64) ;
chacha_ivsetup(chacha_ctx, npub) ;
chacha_round() ;
/*
set up H, I & finalblock for authentication
*/
chacha_copy( H, 1 ) ;
memcpy( I, H, AUTH_BYTES ) ;
store64((byte *) finalblock,8 * adlen);
store64(((byte *) finalblock) + 8,8 * mlen);
/*
random init for counter
*/
chacha_copy( counter, 1 ) ;
iter_count = 0 ;
/*
use ChaCha to generate aes round keys
*/
chacha_copy( aes_rk, AES_RKEYS ) ;
#ifdef TESTING
printf( "setup: called for %lld text and %lld ad\n", mlen, adlen ) ;
printf( "setup: round keys start with %08x %08x\n", aes_rk[0], aes_rk[1] ) ;
#endif
}
static inline void chacha_rounds(uint32_t x[16])
{
chacha_round(x, 0, 4, 8,12);
chacha_round(x, 1, 5, 9,13);
chacha_round(x, 2, 6,10,14);
chacha_round(x, 3, 7,11,15);
chacha_round(x, 0, 5,10,15);
chacha_round(x, 1, 6,11,12);
chacha_round(x, 2, 7, 8,13);
chacha_round(x, 3, 4, 9,14);
}
/*
use 128-bit chunks from ChaCha
*/
static void chacha_copy( u32 *dest, u32 blocks )
{
u32 i ;
assert( dest != NULL ) ;
assert( chacha_got <= 4 ) ;
for( i = blocks ; i > 0 ; i-- ) {
if( chacha_got == 0 ) {
chacha_round() ;
}
memcpy( dest, chacha_next, AES_BYTES ) ;
dest += AES_WORDS ;
chacha_next += AES_WORDS ;
chacha_got-- ;
}
}