Always deduce N from P, Q in mbedtls_rsa_complete
Previously, a parameter set of (-, P, Q, -, E) was completed, but (-, P, Q, D,
E) wasn't - this is odd.
@@ -623,18 +623,35 @@ int mbedtls_rsa_complete( mbedtls_rsa_context *ctx,
* (2) D and potentially N missing.
*
*/
- const int complete = have_N && have_P && have_Q && have_D && have_E;
+
+ const int n_missing = have_P && have_Q && have_D && have_E;
const int pq_missing = have_N && !have_P && !have_Q && have_D && have_E;
const int d_missing = have_P && have_Q && !have_D && have_E;
const int is_pub = have_N && !have_P && !have_Q && !have_D && have_E;
- const int is_priv = complete || pq_missing || d_missing;
+ /* These three alternatives are mutually exclusive */
+ const int is_priv = n_missing || pq_missing || d_missing;
if( !is_priv && !is_pub )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
/*
- * Step 1: Deduce and verify all core parameters.
+ * Step 1: Deduce N if P, Q are provided.
+ */
+
+ if( !have_N && have_P && have_Q )
+ {
+ if( ( ret = mbedtls_mpi_mul_mpi( &ctx->N, &ctx->P,
+ &ctx->Q ) ) != 0 )
+ {
+ return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret );
+ }
+
+ ctx->len = mbedtls_mpi_size( &ctx->N );
+ }
+
+ /*
+ * Step 2: Deduce and verify all remaining core parameters.
*/
if( pq_missing )
@@ -660,13 +677,6 @@ int mbedtls_rsa_complete( mbedtls_rsa_context *ctx,
}
#endif /* MBEDTLS_GENPRIME */
- /* Compute N if missing. */
- if( !have_N &&
- ( ret = mbedtls_mpi_mul_mpi( &ctx->N, &ctx->P, &ctx->Q ) ) != 0 )
- {
- return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret );
- }
-
/* Deduce private exponent. This includes double-checking of the result,
* so together with the primality test above all core parameters are
* guaranteed to be sane if this call succeeds. */
@@ -680,7 +690,7 @@ int mbedtls_rsa_complete( mbedtls_rsa_context *ctx,
/* In the remaining case of a public key, there's nothing to check for. */
/*
- * Step 2: Deduce all additional parameters specific
+ * Step 3: Deduce all additional parameters specific
* to our current RSA implementaiton.
*/
