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RSA: Use MBEDTLS_MPI_GEN_PRIME_FLAG_LOW_ERR

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This commit is contained in:
Janos Follath 2018-09-03 15:37:01 +01:00 committed by Darryl Green
parent a3cb7eb8ad
commit b8fc1b02ee
1 changed files with 13 additions and 4 deletions
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17
library/rsa.c
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@ -502,6 +502,7 @@ int mbedtls_rsa_gen_key( mbedtls_rsa_context *ctx,
{
int ret;
mbedtls_mpi H, G, L;
int prime_quality = 0;
if( f_rng == NULL || nbits < 128 || exponent < 3 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
@ -509,6 +510,14 @@ int mbedtls_rsa_gen_key( mbedtls_rsa_context *ctx,
if( nbits % 2 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
/*
* If the modulus is 1024 bit long or shorter, then the security strength of
* the RSA algorithm is less than or equal to 80 bits and therefore an error
* rate of 2^-80 is sufficient.
*/
if( nbits > 1024 )
prime_quality = MBEDTLS_MPI_GEN_PRIME_FLAG_LOW_ERR;
mbedtls_mpi_init( &H );
mbedtls_mpi_init( &G );
mbedtls_mpi_init( &L );
@ -523,11 +532,11 @@ int mbedtls_rsa_gen_key( mbedtls_rsa_context *ctx,
do
{
MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->P, nbits >> 1, 0,
f_rng, p_rng ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->P, nbits >> 1,
prime_quality, f_rng, p_rng ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->Q, nbits >> 1, 0,
f_rng, p_rng ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->Q, nbits >> 1,
prime_quality, f_rng, p_rng ) );
/* make sure the difference between p and q is not too small (FIPS 186-4 §B.3.3 step 5.4) */
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( &H, &ctx->P, &ctx->Q ) );