Add ssh auth flow (WIP)

dependencies.lock

@@ -9,13 +9,22 @@ dependencies:
       path: .
       type: git
     version: d9792119ebaec0c54839e6605acd3f11dd937205
+  esp-idf-ssh-client:
+    component_hash: d6f7b468c951d78e17e7a9b6911768c807729776338aad447f5c5dcd23642ee4
+    dependencies: []
+    source:
+      git: https://gitlab.com/ch405labs/ch405labs_esp_libssh2.git
+      path: .
+      type: git
+    version: 8b136ec9ee4ff26f19fad36e23062a0a79a32619
   idf:
     source:
       type: idf
     version: 5.5.2
 direct_dependencies:
 - esp-cryptoauthlib
+- esp-idf-ssh-client
 - idf
-manifest_hash: c756397bc94626ff7204b9330f85430937d2c27c736bf3075be0f87eb8eb0efc
+manifest_hash: c0dd2805d23d2f57e818e665712d10a21c7d820835cc0b907c812de71ec4daa7
 target: esp32c6
 version: 2.0.0

main/idf_component.yml

@@ -4,3 +4,5 @@ dependencies:
     version: ">=4.1.0"
   esp-cryptoauthlib:
     git: https://github.com/espressif/esp-cryptoauthlib.git
+  esp-idf-ssh-client:
+    git: https://gitlab.com/ch405labs/ch405labs_esp_libssh2.git

main/zk_auth.h

@@ -3,10 +3,12 @@
 
 #include "cryptoauthlib.h"
 #include "host/atca_host.h"
+#include "libssh2_config.h"
 #include "mbedtls/sha256.h"
 #include <cJSON.h>
 #include <esp_mac.h>
 #include <esp_system.h>
+#include <libssh2.h>
 #include <mbedtls/aes.h>
 #include <mbedtls/base64.h>
 #include <mbedtls/ctr_drbg.h>
@@ -19,15 +21,11 @@
 #include <stdio.h>
 #include <string.h>
 
-// Zero-Knowledge Authentication Module
-// Implements Client-Side KDF + ECIES Tunnel for ESP32-C6
-// Format: SHA-256 compatible with ATECC608B
-//
-// Encryption: AES-256-CBC + HMAC-SHA256 (Encrypt-then-MAC)
-// - Provides confidentiality (CBC) + authenticity (HMAC)
-// - Blob format: IV (16 bytes) + Ciphertext (32 bytes) + HMAC (32 bytes) = 80
-// bytes
-// - HMAC verified BEFORE decryption (prevents padding oracle attacks)
+// Added network headers for ESP-IDF (lwIP) sockets
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+#include <unistd.h>
 
 class ZKAuth {
 private:
@@ -91,6 +89,25 @@ public:
     return true;
   }
 
+  // Marked as static so it can be passed as a C callback to libssh2
+  static int sign_callback(LIBSSH2_SESSION *session, unsigned char **sig,
+                           size_t *sig_len, const unsigned char *data,
+                           size_t data_len, void **abstract) {
+    ATCA_STATUS status;
+    uint8_t signature[64];
+
+    // sign the data hash with ATECC608B
+    status = atcab_sign(0x0, data, signature);
+    if (status != ATCA_SUCCESS) {
+      return -1;
+    }
+
+    // TODO: implement DER encoding and allocate output blob
+    // ...
+
+    return 0;
+  }
+
   // Helper function to write a 32-bit integer in big-endian format
   void write_uint32_be(uint8_t *buf, uint32_t val) {
     buf[0] = (val >> 24) & 0xFF;
@@ -100,7 +117,8 @@ public:
   }
 
   // Function to generate the authorized_keys string
-  void generate_ssh_authorized_key(const uint8_t *atec_pubkey) {
+  void generate_ssh_authorized_key(const uint8_t *atecc_pubkey,
+                                   uint8_t *out_blob) {
     uint8_t ssh_blob[104];
     uint32_t offset = 0;
 
@@ -122,7 +140,7 @@ public:
     write_uint32_be(&ssh_blob[offset], 65);
     offset += 4;
     ssh_blob[offset++] = 0x04;
-    memcpy(&ssh_blob[offset], atec_pubkey, 64);
+    memcpy(&ssh_blob[offset], atecc_pubkey, 64);
     offset += 64;
 
     // 4. Base64 Encode the blob
@@ -136,23 +154,34 @@ public:
 
     // 5. Print out the final authorized_keys line
     printf("ecdsa-sha2-nistp256 %s esp32-atecc608b\n", b64_out);
+
+    memcpy(out_blob, ssh_blob, 104);
   }
 
   // Get device identity (for /api/identity endpoint)
   char *get_identity_json() {
-    char pubkey_hex[131];    // 65 bytes * 2 + null
-    uint8_t atec_pubkey[64]; // 65 bytes * 2 + null
+    char pubkey_hex[131];     // 65 bytes * 2 + null
+    uint8_t atecc_pubkey[64]; // 65 bytes * 2 + null
     uint8_t standard_pubkey[65];
     standard_pubkey[0] = 0x04;
     // Get public key from ATECC608B and convert to hex
-    ATCA_STATUS status = atcab_get_pubkey(0, atec_pubkey);
+    ATCA_STATUS status = atcab_get_pubkey(0, atecc_pubkey);
     if (status != ATCA_SUCCESS) {
       printf("Failed to read public key from ATECC608B: 0x%02X\n", status);
     }
 
-    generate_ssh_authorized_key(atec_pubkey);
+    uint8_t pubkey_blob[256];
 
-    memcpy(&standard_pubkey[1], atec_pubkey, 64);
+    generate_ssh_authorized_key(atecc_pubkey, pubkey_blob);
+
+    // Print the authorized_keys line for debugging
+    printf("Generated authorized_keys line:\n");
+    for (int i = 0; i < 104; i++) {
+      printf("%02x", pubkey_blob[i]);
+    }
+    printf("\n");
+
+    memcpy(&standard_pubkey[1], atecc_pubkey, 64);
     bin_to_hex(standard_pubkey, 65, pubkey_hex);
 
     // Get MAC address to use as salt
@@ -167,6 +196,48 @@ public:
 
     char *json_str = cJSON_PrintUnformatted(root);
     cJSON_Delete(root);
+
+    int sock;
+    struct sockaddr_in sin;
+    const char *hostname = "192.168.4.1";
+    unsigned short port = 22;
+    const char *username = "key";
+
+    void *my_abstract = NULL;
+    LIBSSH2_SESSION *session;
+
+    // Initialize libssh2
+    libssh2_init(0);
+
+    // Set up and connect socket
+    sock = socket(AF_INET, SOCK_STREAM, 0);
+    sin.sin_family = AF_INET;
+    sin.sin_port = htons(port);
+    inet_pton(AF_INET, hostname, &sin.sin_addr);
+    connect(sock, (struct sockaddr *)(&sin), sizeof(struct sockaddr_in));
+
+    // Create SSH session
+    session = libssh2_session_init();
+    libssh2_session_handshake(session, sock);
+
+    // PUBLIC KEY AUTH: using custom callback
+    int rc = libssh2_userauth_publickey(session, username, pubkey_blob,
+                                        sizeof(pubkey_blob), sign_callback,
+                                        &my_abstract);
+
+    if (rc == 0) {
+      printf("SSH authentication successful!\n");
+      // ... Continue SSH communication ...
+    } else {
+      printf("Authentication failed\n");
+    }
+
+    // Cleanup
+    libssh2_session_disconnect(session, "Bye");
+    libssh2_session_free(session);
+    close(sock);
+    libssh2_exit();
+
     return json_str;
   }
 };