commit a4bf680e92dc5be758a730daaad7bf6eac5d7353
author Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com> Thu Jul 10 10:48:23 2025 +0200
committer Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com> Thu Aug 14 09:40:05 2025 +0200
tree e6b64c75b545135610da784cfae6944bfab077b8
parent 630148e67f0cd3d337308321f72f444ca4ef1c35

RSA: refactor: avoid code duplication

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>

library/rsa_alt_helpers.c

diff --git a/library/rsa_alt_helpers.c b/library/rsa_alt_helpers.c
index d91949a..08adbe3 100644
--- a/library/rsa_alt_helpers.c
+++ b/library/rsa_alt_helpers.c
@@ -212,7 +212,10 @@
     MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&K, &K, &L));
     MBEDTLS_MPI_CHK(mbedtls_mpi_div_mpi(&K, NULL, &K, D));
 
-    /* Compute modular inverse of E in LCM(P-1, Q-1) */
+    /* Compute modular inverse of E mod LCM(P-1, Q-1)
+     * This is FIPS 186-4 §B.3.1 criterion 3(b).
+     * This will return MBEDTLS_ERR_MPI_NOT_ACCEPTABLE if E is not coprime to
+     * (P-1)(Q-1), also validating FIPS 186-4 §B.3.1 criterion 2(a). */
     MBEDTLS_MPI_CHK(mbedtls_mpi_inv_mod(D, E, &K));
 
 cleanup: