commit 4c32b69f3724b0bc5fc1dd1d7885a61d26022957
author Gilles Peskine <Gilles.Peskine@arm.com> Fri Feb 16 00:11:09 2024 +0100
committer Gilles Peskine <Gilles.Peskine@arm.com> Mon Feb 26 08:50:38 2024 +0100
tree 7518318bd90c47bc4f07fe00866a898c5d73f7ca
parent 6a2c400b8c690e0e9db0ac784dac2ae03a6aa45d

Ignore domain parameters in RSA key generation

Remove the ability to select a custom public exponent via domain parameters
in RSA key generation. The only way to select a custom public exponent is
now to pass custom production parameters to psa_generate_key_ext().

A subsequent commit will remove domain parameters altogether from the API,
thus this commit does not bother to update the documentation.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

library/psa_crypto.c

diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index e9061f5..159b3c5 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -7576,11 +7576,8 @@
          * that mbedtls_psa_rsa_generate_key() gets e via a new
          * parameter instead. */
         psa_key_attributes_t override_attributes = *attributes;
-        if (params_data_length != 0) {
-            override_attributes.domain_parameters_size = params_data_length;
-            override_attributes.domain_parameters = (uint8_t *) &params->data;
-        }
         return mbedtls_psa_rsa_generate_key(&override_attributes,
+                                            params, params_data_length,
                                             key_buffer,
                                             key_buffer_size,
                                             key_buffer_length);

library/psa_crypto_rsa.c

diff --git a/library/psa_crypto_rsa.c b/library/psa_crypto_rsa.c
index 4a574d1..472a0e8 100644
--- a/library/psa_crypto_rsa.c
+++ b/library/psa_crypto_rsa.c
@@ -223,11 +223,6 @@
     size_t i;
     uint32_t acc = 0;
 
-    if (domain_parameters_size == 0) {
-        *exponent = 65537;
-        return PSA_SUCCESS;
-    }
-
     /* Mbed TLS encodes the public exponent as an int. For simplicity, only
      * support values that fit in a 32-bit integer, which is larger than
      * int on just about every platform anyway. */
@@ -246,18 +241,20 @@
 
 psa_status_t mbedtls_psa_rsa_generate_key(
     const psa_key_attributes_t *attributes,
+    const psa_key_production_parameters_t *params, size_t params_data_length,
     uint8_t *key_buffer, size_t key_buffer_size, size_t *key_buffer_length)
 {
     psa_status_t status;
     mbedtls_rsa_context rsa;
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
-    int exponent;
+    int exponent = 65537;
 
-    status = psa_rsa_read_exponent(attributes->domain_parameters,
-                                   attributes->domain_parameters_size,
-                                   &exponent);
-    if (status != PSA_SUCCESS) {
-        return status;
+    if (params_data_length != 0) {
+        status = psa_rsa_read_exponent(params->data, params_data_length,
+                                       &exponent);
+        if (status != PSA_SUCCESS) {
+            return status;
+        }
     }
 
     mbedtls_rsa_init(&rsa);

library/psa_crypto_rsa.h

diff --git a/library/psa_crypto_rsa.h b/library/psa_crypto_rsa.h
index e4c5caf..ffeef26 100644
--- a/library/psa_crypto_rsa.h
+++ b/library/psa_crypto_rsa.h
@@ -109,6 +109,15 @@
  *       entry point.
  *
  * \param[in]  attributes         The attributes for the RSA key to generate.
+ * \param[in]  params             Production parameters for the key
+ *                                generation. This function only uses
+ *                                `params->data`,
+ *                                which contains the public exponent.
+ *                                This can be a null pointer if
+ *                                \c params_data_length is 0.
+ * \param params_data_length      Length of `params->data` in bytes.
+ *                                This can be 0, in which case the
+ *                                public exponent will be 65537.
  * \param[out] key_buffer         Buffer where the key data is to be written.
  * \param[in]  key_buffer_size    Size of \p key_buffer in bytes.
  * \param[out] key_buffer_length  On success, the number of bytes written in
@@ -123,6 +132,7 @@
  */
 psa_status_t mbedtls_psa_rsa_generate_key(
     const psa_key_attributes_t *attributes,
+    const psa_key_production_parameters_t *params, size_t params_data_length,
     uint8_t *key_buffer, size_t key_buffer_size, size_t *key_buffer_length);
 
 /** Sign an already-calculated hash with an RSA private key.