From 999d7180b2dfccd1848b289b215d2e5847bf93d0 Mon Sep 17 00:00:00 2001
From: Pol Henarejos <pol.henarejos@cttc.es>
Date: Fri, 14 Aug 2026 19:50:21 +0200
Subject: [PATCH] Validate algorithm attributes before key creation

Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>
---
 src/openpgp/cmd_import_data.c |  3 +++
 src/openpgp/cmd_keypair_gen.c |  3 +++
 src/openpgp/openpgp.c         | 18 ++++++++++++++++++
 src/openpgp/openpgp.h         |  1 +
 4 files changed, 25 insertions(+)

diff --git a/src/openpgp/cmd_import_data.c b/src/openpgp/cmd_import_data.c
index 08a0442..e21bd44 100644
--- a/src/openpgp/cmd_import_data.c
+++ b/src/openpgp/cmd_import_data.c
@@ -141,6 +141,9 @@ int cmd_import_data(void) {
     if (algo_len == 0 || algo_len > OPENPGP_MAX_ALGORITHM_ATTR_SIZE) {
         return SW_WRONG_DATA();
     }
+    if (!openpgp_algorithm_attr_supported(algo, algo_len)) {
+        return SW_WRONG_DATA();
+    }
     int r = 0;
     if (algo[0] == ALGO_RSA) {
         if (algo_len < 3) {
diff --git a/src/openpgp/cmd_keypair_gen.c b/src/openpgp/cmd_keypair_gen.c
index d0457be..5518ab1 100644
--- a/src/openpgp/cmd_keypair_gen.c
+++ b/src/openpgp/cmd_keypair_gen.c
@@ -60,6 +60,9 @@ int cmd_keypair_gen(void) {
     if (algo_len == 0 || algo_len > OPENPGP_MAX_ALGORITHM_ATTR_SIZE) {
         return SW_WRONG_DATA();
     }
+    if (!openpgp_algorithm_attr_supported(algo, algo_len)) {
+        return SW_WRONG_DATA();
+    }
     if (P1(apdu) == 0x80) { //generate
         if (algo[0] == ALGO_RSA) {
             if (algo_len < 3) {
diff --git a/src/openpgp/openpgp.c b/src/openpgp/openpgp.c
index 03ef9ff..c0de7cf 100644
--- a/src/openpgp/openpgp.c
+++ b/src/openpgp/openpgp.c
@@ -1441,6 +1441,24 @@ mbedtls_ecp_group_id get_ec_group_id_from_attr(const uint8_t *algo, size_t algo_
     return MBEDTLS_ECP_DP_NONE;
 }
 
+bool openpgp_algorithm_attr_supported(const uint8_t *algo, size_t algo_len) {
+    if (!algo || algo_len < 2 || algo_len > OPENPGP_MAX_ALGORITHM_ATTR_SIZE) {
+        return false;
+    }
+    if (algo[0] == ALGO_RSA) {
+        uint16_t modulus_bits;
+        if (algo_len != 6 || algo[3] != 0 || algo[4] != 0x20 || algo[5] != 0) {
+            return false;
+        }
+        modulus_bits = ((uint16_t)algo[1] << 8) | algo[2];
+        return modulus_bits == 1024 || modulus_bits == 2048 || modulus_bits == 3072 || modulus_bits == 4096;
+    }
+    if (algo[0] == ALGO_ECDH || algo[0] == ALGO_ECDSA || algo[0] == ALGO_EDDSA) {
+        return get_ec_group_id_from_attr(algo + 1, algo_len - 1) != MBEDTLS_ECP_DP_NONE;
+    }
+    return false;
+}
+
 void make_rsa_response(mbedtls_rsa_context *rsa) {
     memcpy(res_APDU, "\x7f\x49\x82\x00\x00", 5);
     res_APDU_size = 5;
diff --git a/src/openpgp/openpgp.h b/src/openpgp/openpgp.h
index 83471da..02f19a4 100644
--- a/src/openpgp/openpgp.h
+++ b/src/openpgp/openpgp.h
@@ -76,6 +76,7 @@ extern int openpgp_adminless_disable(void);
 extern int openpgp_adminless_reset(void);
 #endif
 extern mbedtls_ecp_group_id get_ec_group_id_from_attr(const uint8_t *algo, size_t algo_len);
+extern bool openpgp_algorithm_attr_supported(const uint8_t *algo, size_t algo_len);
 extern int reset_sig_count(void);
 extern uint16_t algo_dec, algo_aut, pk_dec, pk_aut;
 extern bool wait_button_pressed_fid(uint16_t fid);