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Restore P>Q in RSA key generation (#558)

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The PKCS#1 standard says nothing about the relation between P and Q
but many libraries guarantee P>Q and mbed TLS did so too in earlier
versions.

This commit restores this behaviour.
This commit is contained in:
Janos Follath 2016-09-21 13:18:12 +01:00 • committed by Simon Butcher
parent 468a84c7df
commit e5dc202469
4 changed files with 11 additions and 11 deletions
Download patch file Download diff file Expand all files Collapse all files

18
library/rsa.c
View file

@ -102,7 +102,10 @@ int mbedtls_rsa_gen_key( mbedtls_rsa_context *ctx,
if( f_rng == NULL || nbits < 128 || exponent < 3 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
mbedtls_mpi_init( &P1 ); mbedtls_mpi_init( &Q1 );
if( nbits % 2 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
mbedtls_mpi_init( &P1 ); mbedtls_mpi_init( &Q1 );
mbedtls_mpi_init( &H ); mbedtls_mpi_init( &G );
/*
@ -116,16 +119,8 @@ int mbedtls_rsa_gen_key( mbedtls_rsa_context *ctx,
MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->P, nbits >> 1, 0,
f_rng, p_rng ) );
if( nbits % 2 )
{
MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->Q, ( nbits >> 1 ) + 1, 0,
MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->Q, nbits >> 1, 0,
f_rng, p_rng ) );
}
else
{
MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->Q, nbits >> 1, 0,
f_rng, p_rng ) );
}
if( mbedtls_mpi_cmp_mpi( &ctx->P, &ctx->Q ) == 0 )
continue;
@ -134,6 +129,9 @@ int mbedtls_rsa_gen_key( mbedtls_rsa_context *ctx,
if( mbedtls_mpi_bitlen( &ctx->N ) != nbits )
continue;
if( mbedtls_mpi_cmp_mpi( &ctx->P, &ctx->Q ) < 0 )
mbedtls_mpi_swap( &ctx->P, &ctx->Q );
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &P1, &ctx->P, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &Q1, &ctx->Q, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &H, &P1, &Q1 ) );