/*
* Generate an RSA keypair
*/
int rsa_gen_key( rsa_context *ctx, int nbits, int exponent,
ulong (*rng_fn)(void *), void *rng_st )
{
int ret;
mpi P1, Q1, H, G;
mpi_init( &P1, &Q1, &H, &G, NULL );
memset( ctx, 0, sizeof( rsa_context ) );
/*
* find primes P and Q with Q < P so that:
* GCD( E, (P-1)*(Q-1) ) == 1
*/
CHK( mpi_lset( &ctx->E, exponent ) );
nbits >>= 1;
do
{
CHK( mpi_gen_prime( &ctx->P, nbits, 0, rng_fn, rng_st ) );
CHK( mpi_gen_prime( &ctx->Q, nbits, 0, rng_fn, rng_st ) );
if( mpi_cmp_mpi( &ctx->P, &ctx->Q ) < 0 )
mpi_swap( &ctx->P, &ctx->Q );
CHK( mpi_mul_mpi( &ctx->N, &ctx->P, &ctx->Q ) );
CHK( mpi_sub_int( &P1, &ctx->P, 1 ) );
CHK( mpi_sub_int( &Q1, &ctx->Q, 1 ) );
CHK( mpi_mul_mpi( &H, &P1, &Q1 ) );
CHK( mpi_gcd( &G, &ctx->E, &H ) );
}
while( mpi_cmp_int( &G, 1 ) != 0 );
/*
* D = E^-1 mod ((P-1)*(Q-1))
* DP = D mod (P - 1)
* DQ = D mod (Q - 1)
* QP = Q^-1 mod P
*/
CHK( mpi_inv_mod( &ctx->D , &ctx->E, &H ) );
CHK( mpi_mod_mpi( &ctx->DP, &ctx->D, &P1 ) );
CHK( mpi_mod_mpi( &ctx->DQ, &ctx->D, &Q1 ) );
CHK( mpi_inv_mod( &ctx->QP, &ctx->Q, &ctx->P ) );
ctx->len = ( mpi_size( &ctx->N ) + 7 ) >> 3;
cleanup:
mpi_free( &P1, &Q1, &H, &G, NULL );
if( ret != 0 )
{
rsa_free( ctx );
return( ERR_RSA_KEYGEN_FAILED | ret );
}
return( 0 );
}
/*
Generate an RSA keypair
*/
int rsa_gen_key(rsa_context *ctx, int nbits, int exponent)
{
mpi P1, Q1, H, G;
int ret;
if (ctx->f_rng == NULL || nbits < 128 || exponent < 3) {
return EST_ERR_RSA_BAD_INPUT_DATA;
}
mpi_init(&P1, &Q1, &H, &G, NULL);
/*
find primes P and Q with Q < P so that: GCD( E, (P-1)*(Q-1) ) == 1
*/
MPI_CHK(mpi_lset(&ctx->E, exponent));
do {
MPI_CHK(mpi_gen_prime(&ctx->P, (nbits + 1) >> 1, 0, ctx->f_rng, ctx->p_rng));
MPI_CHK(mpi_gen_prime(&ctx->Q, (nbits + 1) >> 1, 0, ctx->f_rng, ctx->p_rng));
if (mpi_cmp_mpi(&ctx->P, &ctx->Q) < 0) {
mpi_swap(&ctx->P, &ctx->Q);
}
if (mpi_cmp_mpi(&ctx->P, &ctx->Q) == 0) {
continue;
}
MPI_CHK(mpi_mul_mpi(&ctx->N, &ctx->P, &ctx->Q));
if (mpi_msb(&ctx->N) != nbits) {
continue;
}
MPI_CHK(mpi_sub_int(&P1, &ctx->P, 1));
MPI_CHK(mpi_sub_int(&Q1, &ctx->Q, 1));
MPI_CHK(mpi_mul_mpi(&H, &P1, &Q1));
MPI_CHK(mpi_gcd(&G, &ctx->E, &H));
} while (mpi_cmp_int(&G, 1) != 0);
/*
D = E^-1 mod ((P-1)*(Q-1))
DP = D mod (P - 1)
DQ = D mod (Q - 1)
QP = Q^-1 mod P
*/
MPI_CHK(mpi_inv_mod(&ctx->D, &ctx->E, &H));
MPI_CHK(mpi_mod_mpi(&ctx->DP, &ctx->D, &P1));
MPI_CHK(mpi_mod_mpi(&ctx->DQ, &ctx->D, &Q1));
MPI_CHK(mpi_inv_mod(&ctx->QP, &ctx->Q, &ctx->P));
ctx->len = (mpi_msb(&ctx->N) + 7) >> 3;
cleanup:
mpi_free(&G, &H, &Q1, &P1, NULL);
if (ret != 0) {
rsa_free(ctx);
return EST_ERR_RSA_KEY_GEN_FAILED | ret;
}
return 0;
}
void
mpr_inv(mpr *rop, mpr *op)
{
if (rop == op)
mpi_swap(mpr_num(op), mpr_den(op));
else {
mpi_set(mpr_num(rop), mpr_den(op));
mpi_set(mpr_den(rop), mpr_num(op));
}
}
/*
* Generate an RSA keypair
*/
int rsa_gen_key( rsa_context *ctx,
int (*f_rng)(void *),
void *p_rng,
int nbits, int exponent )
{
int ret;
mpi P1, Q1, H, G;
if( f_rng == NULL || nbits < 128 || exponent < 3 )
return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
mpi_init( &P1, &Q1, &H, &G, NULL );
/*
* find primes P and Q with Q < P so that:
* GCD( E, (P-1)*(Q-1) ) == 1
*/
MPI_CHK( mpi_lset( &ctx->E, exponent ) );
do
{
MPI_CHK( mpi_gen_prime( &ctx->P, ( nbits + 1 ) >> 1, 0,
f_rng, p_rng ) );
MPI_CHK( mpi_gen_prime( &ctx->Q, ( nbits + 1 ) >> 1, 0,
f_rng, p_rng ) );
if( mpi_cmp_mpi( &ctx->P, &ctx->Q ) < 0 )
mpi_swap( &ctx->P, &ctx->Q );
if( mpi_cmp_mpi( &ctx->P, &ctx->Q ) == 0 )
continue;
MPI_CHK( mpi_mul_mpi( &ctx->N, &ctx->P, &ctx->Q ) );
if( mpi_msb( &ctx->N ) != nbits )
continue;
MPI_CHK( mpi_sub_int( &P1, &ctx->P, 1 ) );
MPI_CHK( mpi_sub_int( &Q1, &ctx->Q, 1 ) );
MPI_CHK( mpi_mul_mpi( &H, &P1, &Q1 ) );
MPI_CHK( mpi_gcd( &G, &ctx->E, &H ) );
}
while( mpi_cmp_int( &G, 1 ) != 0 );
/*
* D = E^-1 mod ((P-1)*(Q-1))
* DP = D mod (P - 1)
* DQ = D mod (Q - 1)
* QP = Q^-1 mod P
*/
MPI_CHK( mpi_inv_mod( &ctx->D , &ctx->E, &H ) );
MPI_CHK( mpi_mod_mpi( &ctx->DP, &ctx->D, &P1 ) );
MPI_CHK( mpi_mod_mpi( &ctx->DQ, &ctx->D, &Q1 ) );
MPI_CHK( mpi_inv_mod( &ctx->QP, &ctx->Q, &ctx->P ) );
ctx->len = ( mpi_msb( &ctx->N ) + 7 ) >> 3;
cleanup:
mpi_free( &G, &H, &Q1, &P1, NULL );
if( ret != 0 )
{
rsa_free( ctx );
return( POLARSSL_ERR_RSA_KEY_GEN_FAILED | ret );
}
return( 0 );
}
