Fix CMAC-AES implementation in OpenSSL>3.0.0. Add unit test

src/core/system_parameters/gnss_crypto.cc

@@ -38,6 +38,7 @@
 #include <openssl/err.h>
 #include <openssl/evp.h>
 #include <openssl/param_build.h>
+#include <openssl/params.h>
 #define OPENSSL_ENGINE nullptr
 #else
 #include <openssl/sha.h>
@@ -416,35 +417,62 @@ std::vector<uint8_t> Gnss_Crypto::computeCMAC_AES(const std::vector<uint8_t>& ke
     std::vector<uint8_t> output(16);
 #if USE_OPENSSL_FALLBACK
 #if USE_OPENSSL_3
-    std::vector<uint8_t> mac(EVP_MAX_MD_SIZE);  // CMAC-AES output size
+    std::vector<uint8_t> aux(EVP_MAX_MD_SIZE);  // CMAC-AES output size
+    size_t output_length = 0;
 
-    EVP_CIPHER_CTX* ctx = EVP_CIPHER_CTX_new();
-    EVP_MAC* cmac = EVP_MAC_fetch(nullptr, "CMAC-AES", nullptr);
+    // Create the context for the CMAC operation
+    EVP_MAC* mac = EVP_MAC_fetch(nullptr, "CMAC", nullptr);
+    if (!mac)
+        {
+            LOG(INFO) << "OSNMA CMAC-AES: Failed to fetch CMAC";
+            return output;
+        }
 
-    EVP_MAC_CTX* cmacCtx = EVP_MAC_CTX_new(cmac);
+    EVP_MAC_CTX* ctx = EVP_MAC_CTX_new(mac);
+    if (!ctx)
+        {
+            LOG(INFO) << "OSNMA CMAC-AES: Failed to create CMAC context";
+            return output;
+        }
 
-    OSSL_PARAM params[4];
-    params[0] = OSSL_PARAM_construct_utf8_string("key", (char*)key.data(), key.size());
-    params[1] = OSSL_PARAM_construct_octet_string("iv", nullptr, 0);   // Set IV to nullptr
-    params[2] = OSSL_PARAM_construct_octet_string("aad", nullptr, 0);  // Set AAD to nullptr
-    params[3] = OSSL_PARAM_construct_end();
+    // Initialize the CMAC context with the key and the AES algorithm
+    OSSL_PARAM params[] = {
+        OSSL_PARAM_construct_utf8_string(OSSL_MAC_PARAM_CIPHER, const_cast<char*>("AES-128-CBC"), 0),
+        OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_KEY, const_cast<unsigned char*>(key.data()), key.size()),
+        OSSL_PARAM_construct_end()};
 
-    // Set AES-128 CMAC cipher and key
-    EVP_MAC_init(cmacCtx, nullptr, 0, params);
+    if (EVP_MAC_init(ctx, nullptr, 0, params) <= 0)
+        {
+            EVP_MAC_CTX_free(ctx);
+            EVP_MAC_free(mac);
+            LOG(INFO) << "OSNMA CMAC-AES: Failed to initialize CMAC context";
+            return output;
+        }
 
-    // Compute CMAC-AES
-    EVP_MAC_update(cmacCtx, input.data(), input.size());
-    size_t macLength = mac.size();
-    size_t outputLength = 16;
+    // Update the CMAC context with the input data
+    if (EVP_MAC_update(ctx, input.data(), input.size()) <= 0)
+        {
+            EVP_MAC_CTX_free(ctx);
+            EVP_MAC_free(mac);
+            LOG(INFO) << "OSNMA CMAC-AES: Failed to update CMAC context";
+            return output;
+        }
 
-    EVP_MAC_final(cmacCtx, mac.data(), &macLength, outputLength);
+    // Finalize the CMAC and retrieve the output
+    if (EVP_MAC_final(ctx, aux.data(), &output_length, aux.size()) <= 0)
+        {
+            EVP_MAC_CTX_free(ctx);
+            EVP_MAC_free(mac);
+            LOG(INFO) << "OSNMA CMAC-AES: Failed to finalize CMAC";
+            return output;
+        }
 
-    EVP_MAC_free(cmac);
-    EVP_MAC_CTX_free(cmacCtx);
-    EVP_CIPHER_CTX_free(ctx);
+    // Clean up the CMAC context
+    EVP_MAC_CTX_free(ctx);
+    EVP_MAC_free(mac);
 
-    mac.resize(macLength);
-    output = mac;
+    aux.resize(output_length);
+    output = aux;
 #else
     std::vector<uint8_t> mac(16);  // CMAC-AES output size
 

src/tests/unit-tests/signal-processing-blocks/osnma/gnss_crypto_test.cc

@@ -155,4 +155,25 @@ TEST(GnssCryptoTest, TestComputeHMACSHA256_adkd4)
     ASSERT_EQ(expected_output, output);
 }
 
-// TODO extend to HMAC-AES
+
+TEST(GnssCryptoTest, TestComputeCMAC_AES)
+{
+    // Tests vectors from https://datatracker.ietf.org/doc/html/rfc4493#appendix-A
+    std::unique_ptr<Gnss_Crypto> d_crypto = std::make_unique<Gnss_Crypto>();
+
+    std::vector<uint8_t> key = {
+        0x2B, 0x7E, 0x15, 0x16, 0x28, 0xAE, 0xD2, 0xA6,
+        0xAB, 0xF7, 0x15, 0x88, 0x09, 0xCF, 0x4F, 0x3C};
+
+    std::vector<uint8_t> message{
+        0x6B, 0xC1, 0xBE, 0xE2, 0x2E, 0x40, 0x9F, 0x96,
+        0xE9, 0x3D, 0x7E, 0x11, 0x73, 0x93, 0x17, 0x2A};
+
+    std::vector<uint8_t> expected_output = {
+        0x07, 0x0A, 0x16, 0xB4, 0x6B, 0x4D, 0x41, 0x44,
+        0xF7, 0x9B, 0xDD, 0x9D, 0xD0, 0x4A, 0x28, 0x7C};
+
+    std::vector<uint8_t> output = d_crypto->computeCMAC_AES(key, message);
+
+    ASSERT_EQ(expected_output, output);
+}