Pico Keys SDK 8.5

Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>

config/rp2350/pt.json

@@ -10,7 +10,7 @@
   },
   "partitions": [
     {
-      "name": "Pico Keys Firmware",
+      "name": "PicoKeys Firmware",
       "id": 0,
       "start": 0,
       "size": "1024K",
@@ -22,10 +22,10 @@
       }
     },
     {
-      "name": "Pico Keys Data",
+      "name": "PicoKeys Data",
       "id": 1,
-      "start": "1024K",
+      "start": "1032K",
-      "size": "3072K",
+      "size": "3064K",
       "families": ["data"],
       "permissions": {
         "secure": "rw",
@@ -35,6 +35,21 @@
       "link": ["owner", 0],
       "ignored_during_arm_boot": true,
       "ignored_during_riscv_boot": true
+    },
+    {
+      "name": "PicoKeys Binding",
+      "id": 2,
+      "start": "1024K",
+      "size": "8K",
+      "families": ["data"],
+      "permissions": {
+        "secure": "r",
+        "nonsecure": "",
+        "bootloader": "w"
+      },
+      "link": ["owner", 0],
+      "ignored_during_arm_boot": true,
+      "ignored_during_riscv_boot": true
     }
   ]
 }

src/crypto_utils.c

@@ -278,3 +278,16 @@ mbedtls_ecp_group_id ec_get_curve_from_prime(const uint8_t *prime, size_t prime_
     }
     return MBEDTLS_ECP_DP_NONE;
 }
+
+#define POLY 0xedb88320
+
+uint32_t crc32c(const uint8_t *buf, size_t len) {
+    uint32_t crc = 0xffffffff;
+    while (len--) {
+        crc ^= *buf++;
+        for (int k = 0; k < 8; k++) {
+            crc = (crc >> 1) ^ (POLY & (0 - (crc & 1)));
+        }
+    }
+    return ~crc;
+}

src/crypto_utils.h

@@ -56,5 +56,6 @@ extern int aes_decrypt(const uint8_t *key, const uint8_t *iv, uint16_t key_size,
 extern int aes_encrypt_cfb_256(const uint8_t *key, const uint8_t *iv, uint8_t *data, uint16_t len);
 extern int aes_decrypt_cfb_256(const uint8_t *key, const uint8_t *iv, uint8_t *data, uint16_t len);
 extern mbedtls_ecp_group_id ec_get_curve_from_prime(const uint8_t *prime, size_t prime_len);
+extern uint32_t crc32c(const uint8_t *buf, size_t len);
 
 #endif

src/fs/low_flash.c

@@ -22,6 +22,7 @@
 
 #include "pico_keys.h"
 #include <string.h>
+#include "crypto_utils.h"
 #ifdef PICO_PLATFORM
  #include "pico/stdlib.h"
  #include "hardware/flash.h"
@@ -158,8 +159,14 @@ void do_flash() {
     sem_release(&sem_flash);
 }
 
+#ifdef PICO_RP2040
+void phymarker_write();
+#endif
 //this function has to be called from the core 0
 void low_flash_init() {
+#ifdef PICO_RP2040
+    phymarker_write();
+#endif
     memset(flash_pages, 0, sizeof(page_flash_t) * TOTAL_FLASH_PAGES);
     mutex_init(&mtx_flash);
     sem_init(&sem_flash, 0, 1);
@@ -371,3 +378,40 @@ bool flash_check_blank(const uint8_t *p_start, size_t size) {
     }
     return true;
 }
+
+#ifdef PICO_RP2040
+typedef struct {
+    uint64_t magic;
+    uint16_t version;
+    uint16_t flags;
+    uint8_t  uid[PICO_UNIQUE_BOARD_ID_SIZE_BYTES];
+    uint32_t crc32;
+} __attribute__ ((packed)) phymarker_t;
+
+uintptr_t __phymarker_start = (uintptr_t)0x10100000;
+
+const uint64_t PHYSICAL_MARKER_MAGIC = 0x5049434F4B455953ULL; // "PICOKEYS"
+
+void phymarker_write() {
+    const uint64_t magic = *(uint64_t *)__phymarker_start;
+    if (magic == PHYSICAL_MARKER_MAGIC) {
+        return;
+    }
+    phymarker_t pm = {
+        .magic = PHYSICAL_MARKER_MAGIC, // "PICOKEYS"
+        .version = 0x0001,
+        .flags = 0x0000,
+        .crc32 = 0x00000000
+    };
+    memcpy(pm.uid, pico_serial.id, PICO_UNIQUE_BOARD_ID_SIZE_BYTES);
+    pm.crc32 = crc32c((const uint8_t *)&pm, sizeof(phymarker_t) - sizeof(uint32_t));
+
+    uint32_t ints = save_and_disable_interrupts();
+
+    flash_range_erase((uint32_t)__phymarker_start - XIP_BASE, FLASH_SECTOR_SIZE);
+    flash_range_program((uint32_t)__phymarker_start - XIP_BASE, (const uint8_t *)&pm, sizeof(phymarker_t));
+
+    restore_interrupts(ints);
+}
+
+#endif

src/main.c

@@ -235,6 +235,11 @@ bool wait_button() {
     req_button_pending = false;
     return timeout || cancel_button;
 }
+
+__attribute__((weak)) int picokey_init() {
+    return 0;
+}
+
 #endif
 
 bool set_rtc = false;
@@ -393,6 +398,10 @@ int main(void) {
 #endif
 #endif
 
+#ifndef ENABLE_EMULATION
+    picokey_init();
+#endif
+
 #ifdef ESP_PLATFORM
     xTaskCreatePinnedToCore(core0_loop, "core0", 4096*ITF_TOTAL*2, NULL, CONFIG_TINYUSB_TASK_PRIORITY - 1, &hcore0, ESP32_CORE0);
 #else

src/pico_keys_version.h

@@ -18,7 +18,7 @@
 #ifndef __VERSION_H_
 #define __VERSION_H_
 
-#define PICO_KEYS_SDK_VERSION 0x0804
+#define PICO_KEYS_SDK_VERSION 0x0805
 
 #define PICO_KEYS_SDK_VERSION_MAJOR ((PICO_KEYS_SDK_VERSION >> 8) & 0xff)
 #define PICO_KEYS_SDK_VERSION_MINOR (PICO_KEYS_SDK_VERSION & 0xff)

src/rescue.c

@@ -22,6 +22,7 @@
 #include "mbedtls/ecdsa.h"
 #include "mbedtls/sha256.h"
 #include "random.h"
+#include "crypto_utils.h"
 
 #ifdef PICO_PLATFORM
 extern char __flash_binary_start;
@@ -46,6 +47,8 @@ const uint8_t rescue_aid[] = {
 #define PICO_MCU 0
 #endif
 
+#define EF_DEVCERT_KEY 0xE0C1
+
 extern uint8_t PICO_PRODUCT;
 extern uint8_t PICO_VERSION_MAJOR;
 extern uint8_t PICO_VERSION_MINOR;
@@ -75,30 +78,69 @@ int rescue_unload() {
     return PICOKEY_OK;
 }
 
+static int load_internal_keydev(mbedtls_ecp_keypair *ecp, mbedtls_ecp_group_id ec_id) {
+    file_t *ef_devcert_key = file_new(EF_DEVCERT_KEY);
+    if (!ef_devcert_key) {
+        return SW_FILE_NOT_FOUND();
+    }
+    uint8_t kbase[32] = {0};
+    derive_kbase(kbase);
+    if (file_has_data(ef_devcert_key)) {
+        uint8_t pkey[32] = {0};
+        memcpy(pkey, file_get_data(ef_devcert_key), 32);
+        aes_decrypt(kbase, pico_serial_hash, 32 * 8, PICO_KEYS_AES_MODE_CBC, pkey, 32);
+        int ret = mbedtls_ecp_read_key(ec_id, ecp, pkey, 32);
+        mbedtls_platform_zeroize(pkey, sizeof(pkey));
+        if (ret != 0) {
+            return SW_EXEC_ERROR();
+        }
+    }
+    else {
+        // Generate new key
+        uint8_t pkey[MBEDTLS_ECP_MAX_BYTES] = {0};
+        size_t olen = 0;
+        mbedtls_ecp_gen_key(ec_id, ecp, random_gen, NULL);
+        mbedtls_ecp_write_key_ext(ecp, &olen, pkey, sizeof(pkey));
+
+        aes_encrypt(kbase, pico_serial_hash, 32 * 8, PICO_KEYS_AES_MODE_CBC, pkey, 32);
+        file_put_data(ef_devcert_key, pkey, (uint16_t)olen);
+        mbedtls_platform_zeroize(pkey, sizeof(pkey));
+        low_flash_available();
+    }
+    return PICOKEY_OK;
+}
+
 int cmd_keydev_sign() {
     uint8_t p1 = P1(apdu);
     if (p1 == 0x01) {
         if (apdu.nc != 32) {
             return SW_WRONG_LENGTH();
         }
+        mbedtls_ecp_keypair ecp;
+        mbedtls_ecp_keypair_init(&ecp);
+        mbedtls_ecp_group_id ec_id = MBEDTLS_ECP_DP_SECP256K1;
         if (!otp_key_2) {
-            return SW_INS_NOT_SUPPORTED();
+            int ret = load_internal_keydev(&ecp, ec_id);
+            if (ret != PICOKEY_OK) {
+                mbedtls_ecp_keypair_free(&ecp);
+                return ret;
+            }
         }
-        mbedtls_ecdsa_context ecdsa;
+        else {
-        mbedtls_ecdsa_init(&ecdsa);
+            int ret = mbedtls_ecp_read_key(ec_id, &ecp, otp_key_2, 32);
-        int ret = mbedtls_ecp_read_key(MBEDTLS_ECP_DP_SECP256K1, &ecdsa, otp_key_2, 32);
+            if (ret != 0) {
-        if (ret != 0) {
+                mbedtls_ecp_keypair_free(&ecp);
-            mbedtls_ecdsa_free(&ecdsa);
+                return SW_EXEC_ERROR();
-            return SW_EXEC_ERROR();
+            }
         }
-        uint16_t key_size = 2 * (int)((mbedtls_ecp_curve_info_from_grp_id(MBEDTLS_ECP_DP_SECP256K1)->bit_size + 7) / 8);
+        uint16_t key_size = 2 * (int)((mbedtls_ecp_curve_info_from_grp_id(ec_id)->bit_size + 7) / 8);
         mbedtls_mpi r, s;
         mbedtls_mpi_init(&r);
         mbedtls_mpi_init(&s);
 
-        ret = mbedtls_ecdsa_sign(&ecdsa.MBEDTLS_PRIVATE(grp), &r, &s, &ecdsa.MBEDTLS_PRIVATE(d), apdu.data, apdu.nc, random_gen, NULL);
+        int ret = mbedtls_ecdsa_sign(&ecp.MBEDTLS_PRIVATE(grp), &r, &s, &ecp.MBEDTLS_PRIVATE(d), apdu.data, apdu.nc, random_gen, NULL);
         if (ret != 0) {
-            mbedtls_ecdsa_free(&ecdsa);
+            mbedtls_ecp_keypair_free(&ecp);
             mbedtls_mpi_free(&r);
             mbedtls_mpi_free(&s);
             return SW_EXEC_ERROR();
@@ -106,26 +148,33 @@ int cmd_keydev_sign() {
 
         mbedtls_mpi_write_binary(&r, res_APDU, key_size / 2); res_APDU_size = key_size / 2;
         mbedtls_mpi_write_binary(&s, res_APDU + res_APDU_size, key_size / 2); res_APDU_size += key_size / 2;
-        mbedtls_ecdsa_free(&ecdsa);
+        mbedtls_ecp_keypair_free(&ecp);
         mbedtls_mpi_free(&r);
         mbedtls_mpi_free(&s);
     }
     else if (p1 == 0x02) {
         // Return public key
-        if (!otp_key_2) {
-            return SW_INS_NOT_SUPPORTED();
-        }
         if (apdu.nc != 0) {
             return SW_WRONG_LENGTH();
         }
         mbedtls_ecp_keypair ecp;
         mbedtls_ecp_keypair_init(&ecp);
-        int ret = mbedtls_ecp_read_key(MBEDTLS_ECP_DP_SECP256K1, &ecp, otp_key_2, 32);
+        mbedtls_ecp_group_id ec_id = MBEDTLS_ECP_DP_SECP256K1;
-        if (ret != 0) {
+        if (!otp_key_2) {
-            mbedtls_ecp_keypair_free(&ecp);
+            int ret = load_internal_keydev(&ecp, ec_id);
-            return SW_EXEC_ERROR();
+            if (ret != PICOKEY_OK) {
+                mbedtls_ecp_keypair_free(&ecp);
+                return ret;
+            }
         }
-        ret = mbedtls_ecp_mul(&ecp.MBEDTLS_PRIVATE(grp), &ecp.MBEDTLS_PRIVATE(Q), &ecp.MBEDTLS_PRIVATE(d), &ecp.MBEDTLS_PRIVATE(grp).G, random_gen, NULL);
+        else {
+            int ret = mbedtls_ecp_read_key(ec_id, &ecp, otp_key_2, 32);
+            if (ret != 0) {
+                mbedtls_ecp_keypair_free(&ecp);
+                return SW_EXEC_ERROR();
+            }
+        }
+        int ret = mbedtls_ecp_mul(&ecp.MBEDTLS_PRIVATE(grp), &ecp.MBEDTLS_PRIVATE(Q), &ecp.MBEDTLS_PRIVATE(d), &ecp.MBEDTLS_PRIVATE(grp).G, random_gen, NULL);
         if (ret != 0) {
             mbedtls_ecp_keypair_free(&ecp);
             return SW_EXEC_ERROR();

src/usb/usb_descriptors.c

@@ -323,14 +323,10 @@ char const *string_desc_arr [] = {
     "Pico Key",                       // 2: Product
     "11223344",                      // 3: Serials, should use chip ID
     "Config"               // 4: Vendor Interface
-#ifdef USB_ITF_HID
     , "HID Interface"
     , "HID Keyboard Interface"
-#endif
-#ifdef USB_ITF_CCID
     , "CCID OTP FIDO Interface"
     , "WebCCID Interface"
-#endif
 };
 
 #ifdef ESP_PLATFORM