Merge pull request #8779 from gilles-peskine-arm/rsa-bitlen-fix

Fix mbedtls_pk_get_bitlen for a key size that is not a multiple of 8

library/pk_wrap.c

@@ -58,7 +58,7 @@ static int rsa_can_do(mbedtls_pk_type_t type)
 static size_t rsa_get_bitlen(mbedtls_pk_context *pk)
 {
     const mbedtls_rsa_context *rsa = (const mbedtls_rsa_context *) pk->pk_ctx;
-    return 8 * mbedtls_rsa_get_len(rsa);
+    return mbedtls_rsa_get_bitlen(rsa);
 }
 
 #if defined(MBEDTLS_USE_PSA_CRYPTO)

library/rsa.c

@@ -1014,6 +1014,14 @@ int mbedtls_rsa_get_md_alg(const mbedtls_rsa_context *ctx)
     return ctx->hash_id;
 }
 
+/*
+ * Get length in bits of RSA modulus
+ */
+size_t mbedtls_rsa_get_bitlen(const mbedtls_rsa_context *ctx)
+{
+    return mbedtls_mpi_bitlen(&ctx->N);
+}
+
 /*
  * Get length in bytes of RSA modulus
  */