Added time validity checking to Device Attestation Verifier (#12212)

vijs · pull[bot] · commit 3270557b43a1 · 2024-01-11T15:17:04.000Z
* Added time validity checking to Device Attestation Verifier

* Added new methods to validate a certificate and implemented review comments

* Renamed IsCertificateValid to IsCertificateValidAtCurrentTime

* Removed "invalid issuing timestamp" test

* Disabled cert validation test in certain platforms
diff --git a/src/credentials/BUILD.gn b/src/credentials/BUILD.gn
@@ -15,6 +15,7 @@
 import("//build_overrides/chip.gni")
 import("//build_overrides/nlassert.gni")
 import("${chip_root}/src/crypto/crypto.gni")
+import("${chip_root}/src/platform/device.gni")
 
 static_library("credentials") {
   output_name = "libCredentials"
@@ -48,6 +49,10 @@ static_library("credentials") {
     sources += [ "${chip_root}/examples/platform/nxp/se05x/DeviceAttestationSe05xCredsExample.cpp" ]
   }
 
+  if (chip_device_platform == "esp32" || chip_device_platform == "nrfconnect") {
+    defines = [ "CURRENT_TIME_NOT_IMPLEMENTED=1" ]
+  }
+
   cflags = [ "-Wconversion" ]
 
   public_deps = [
diff --git a/src/credentials/DeviceAttestationVerifier.cpp b/src/credentials/DeviceAttestationVerifier.cpp
@@ -33,14 +33,14 @@ class UnimplementedDACVerifier : public DeviceAttestationVerifier
     AttestationVerificationResult VerifyAttestationInformation(const ByteSpan & attestationInfoBuffer,
                                                                const ByteSpan & attestationChallengeBuffer,
                                                                const ByteSpan & attestationSignatureBuffer,
-                                                               const ByteSpan & paiCertDerBuffer, const ByteSpan & dacCertDerBuffer,
+                                                               const ByteSpan & paiDerBuffer, const ByteSpan & dacDerBuffer,
                                                                const ByteSpan & attestationNonce) override
     {
         (void) attestationInfoBuffer;
         (void) attestationChallengeBuffer;
         (void) attestationSignatureBuffer;
-        (void) paiCertDerBuffer;
-        (void) dacCertDerBuffer;
+        (void) paiDerBuffer;
+        (void) dacDerBuffer;
         (void) attestationNonce;
         return AttestationVerificationResult::kNotImplemented;
     }
diff --git a/src/credentials/DeviceAttestationVerifier.h b/src/credentials/DeviceAttestationVerifier.h
@@ -196,18 +196,19 @@ class DeviceAttestationVerifier
      * @param[in] attestationInfoBuffer Buffer containing attestation information portion of Attestation Response (raw TLV)
      * @param[in] attestationChallengeBuffer Buffer containing the attestation challenge from the secure session
      * @param[in] attestationSignatureBuffer Buffer the signature portion of Attestation Response
-     * @param[in] paiCertDerBuffer Buffer containing the PAI certificate from device in DER format.
+     * @param[in] paiDerBuffer Buffer containing the PAI certificate from device in DER format.
      *                                If length zero, there was no PAI certificate.
-     * @param[in] dacCertDerBuffer Buffer containing the DAC certificate from device in DER format.
+     * @param[in] dacDerBuffer Buffer containing the DAC certificate from device in DER format.
      * @param[in] attestationNonce Buffer containing attestation nonce.
      *
      * @returns AttestationVerificationResult::kSuccess on success or another specific
      *          value from AttestationVerificationResult enum on failure.
      */
-    virtual AttestationVerificationResult
-    VerifyAttestationInformation(const ByteSpan & attestationInfoBuffer, const ByteSpan & attestationChallengeBuffer,
-                                 const ByteSpan & attestationSignatureBuffer, const ByteSpan & paiCertDerBuffer,
-                                 const ByteSpan & dacCertDerBuffer, const ByteSpan & attestationNonce) = 0;
+    virtual AttestationVerificationResult VerifyAttestationInformation(const ByteSpan & attestationInfoBuffer,
+                                                                       const ByteSpan & attestationChallengeBuffer,
+                                                                       const ByteSpan & attestationSignatureBuffer,
+                                                                       const ByteSpan & paiDerBuffer, const ByteSpan & dacDerBuffer,
+                                                                       const ByteSpan & attestationNonce) = 0;
 
     /**
      * @brief Verify a CMS Signed Data signature against the CSA certificate of Subject Key Identifier that matches
diff --git a/src/credentials/examples/DefaultDeviceAttestationVerifier.cpp b/src/credentials/examples/DefaultDeviceAttestationVerifier.cpp
@@ -180,7 +180,7 @@ class DefaultDACVerifier : public DeviceAttestationVerifier
     AttestationVerificationResult VerifyAttestationInformation(const ByteSpan & attestationInfoBuffer,
                                                                const ByteSpan & attestationChallengeBuffer,
                                                                const ByteSpan & attestationSignatureBuffer,
-                                                               const ByteSpan & paiCertDerBuffer, const ByteSpan & dacCertDerBuffer,
+                                                               const ByteSpan & paiDerBuffer, const ByteSpan & dacDerBuffer,
                                                                const ByteSpan & attestationNonce) override;
 
     AttestationVerificationResult ValidateCertificationDeclarationSignature(const ByteSpan & cmsEnvelopeBuffer,
@@ -199,12 +199,12 @@ class DefaultDACVerifier : public DeviceAttestationVerifier
 AttestationVerificationResult DefaultDACVerifier::VerifyAttestationInformation(const ByteSpan & attestationInfoBuffer,
                                                                                const ByteSpan & attestationChallengeBuffer,
                                                                                const ByteSpan & attestationSignatureBuffer,
-                                                                               const ByteSpan & paiCertDerBuffer,
-                                                                               const ByteSpan & dacCertDerBuffer,
+                                                                               const ByteSpan & paiDerBuffer,
+                                                                               const ByteSpan & dacDerBuffer,
                                                                                const ByteSpan & attestationNonce)
 {
     VerifyOrReturnError(!attestationInfoBuffer.empty() && !attestationChallengeBuffer.empty() &&
-                            !attestationSignatureBuffer.empty() && !paiCertDerBuffer.empty() && !dacCertDerBuffer.empty() &&
+                            !attestationSignatureBuffer.empty() && !paiDerBuffer.empty() && !dacDerBuffer.empty() &&
                             !attestationNonce.empty(),
                         AttestationVerificationResult::kInvalidArgument);
 
@@ -214,17 +214,17 @@ AttestationVerificationResult DefaultDACVerifier::VerifyAttestationInformation(c
         uint16_t paiVid = VendorId::NotSpecified;
         uint16_t dacVid = VendorId::NotSpecified;
 
-        VerifyOrReturnError(ExtractDNAttributeFromX509Cert(MatterOid::kVendorId, paiCertDerBuffer, paiVid) == CHIP_NO_ERROR,
+        VerifyOrReturnError(ExtractDNAttributeFromX509Cert(MatterOid::kVendorId, paiDerBuffer, paiVid) == CHIP_NO_ERROR,
                             AttestationVerificationResult::kPaiFormatInvalid);
-        VerifyOrReturnError(ExtractDNAttributeFromX509Cert(MatterOid::kVendorId, dacCertDerBuffer, dacVid) == CHIP_NO_ERROR,
+        VerifyOrReturnError(ExtractDNAttributeFromX509Cert(MatterOid::kVendorId, dacDerBuffer, dacVid) == CHIP_NO_ERROR,
                             AttestationVerificationResult::kDacFormatInvalid);
 
         VerifyOrReturnError(paiVid == dacVid, AttestationVerificationResult::kDacVendorIdMismatch);
         dacVendorId = static_cast<VendorId>(dacVid);
     }
 
     P256PublicKey remoteManufacturerPubkey;
-    VerifyOrReturnError(ExtractPubkeyFromX509Cert(dacCertDerBuffer, remoteManufacturerPubkey) == CHIP_NO_ERROR,
+    VerifyOrReturnError(ExtractPubkeyFromX509Cert(dacDerBuffer, remoteManufacturerPubkey) == CHIP_NO_ERROR,
                         AttestationVerificationResult::kDacFormatInvalid);
 
     // Validate overall attestation signature on attestation information
@@ -239,23 +239,33 @@ AttestationVerificationResult DefaultDACVerifier::VerifyAttestationInformation(c
 
     uint8_t akidBuf[Crypto::kAuthorityKeyIdentifierLength];
     MutableByteSpan akid(akidBuf);
-    ExtractAKIDFromX509Cert(paiCertDerBuffer, akid);
+    ExtractAKIDFromX509Cert(paiDerBuffer, akid);
 
     constexpr size_t paaCertAllocatedLen = kMaxDERCertLength;
     chip::Platform::ScopedMemoryBuffer<uint8_t> paaCert;
     VerifyOrReturnError(paaCert.Alloc(paaCertAllocatedLen), AttestationVerificationResult::kNoMemory);
-    MutableByteSpan paa(paaCert.Get(), paaCertAllocatedLen);
-    VerifyOrReturnError(mAttestationTrustStore->GetProductAttestationAuthorityCert(akid, paa) == CHIP_NO_ERROR,
+    MutableByteSpan paaDerBuffer(paaCert.Get(), paaCertAllocatedLen);
+    VerifyOrReturnError(mAttestationTrustStore->GetProductAttestationAuthorityCert(akid, paaDerBuffer) == CHIP_NO_ERROR,
                         AttestationVerificationResult::kPaaNotFound);
 
-    VerifyOrReturnError(ValidateCertificateChain(paa.data(), paa.size(), paiCertDerBuffer.data(), paiCertDerBuffer.size(),
-                                                 dacCertDerBuffer.data(), dacCertDerBuffer.size()) == CHIP_NO_ERROR,
+#if !defined(CURRENT_TIME_NOT_IMPLEMENTED)
+    VerifyOrReturnError(IsCertificateValidAtCurrentTime(dacDerBuffer) == CHIP_NO_ERROR, AttestationVerificationResult::kDacExpired);
+#endif
+
+    VerifyOrReturnError(IsCertificateValidAtIssuance(dacDerBuffer, paiDerBuffer) == CHIP_NO_ERROR,
+                        AttestationVerificationResult::kPaiExpired);
+
+    VerifyOrReturnError(IsCertificateValidAtIssuance(dacDerBuffer, paaDerBuffer) == CHIP_NO_ERROR,
+                        AttestationVerificationResult::kPaaExpired);
+
+    VerifyOrReturnError(ValidateCertificateChain(paaDerBuffer.data(), paaDerBuffer.size(), paiDerBuffer.data(), paiDerBuffer.size(),
+                                                 dacDerBuffer.data(), dacDerBuffer.size()) == CHIP_NO_ERROR,
                         AttestationVerificationResult::kDacSignatureInvalid);
 
     // if PAA contains VID, see if matches with DAC's VID.
     {
         uint16_t paaVid  = VendorId::NotSpecified;
-        CHIP_ERROR error = ExtractDNAttributeFromX509Cert(MatterOid::kVendorId, paa, paaVid);
+        CHIP_ERROR error = ExtractDNAttributeFromX509Cert(MatterOid::kVendorId, paaDerBuffer, paaVid);
         VerifyOrReturnError(error == CHIP_NO_ERROR || error == CHIP_ERROR_KEY_NOT_FOUND,
                             AttestationVerificationResult::kPaaFormatInvalid);
         if (error != CHIP_ERROR_KEY_NOT_FOUND)
@@ -289,12 +299,12 @@ AttestationVerificationResult DefaultDACVerifier::VerifyAttestationInformation(c
         .dacVendorId = dacVendorId,
         .paiVendorId = dacVendorId,
     };
-    VerifyOrReturnError(ExtractDNAttributeFromX509Cert(MatterOid::kProductId, dacCertDerBuffer, deviceInfo.dacProductId) ==
+    VerifyOrReturnError(ExtractDNAttributeFromX509Cert(MatterOid::kProductId, dacDerBuffer, deviceInfo.dacProductId) ==
                             CHIP_NO_ERROR,
                         AttestationVerificationResult::kDacFormatInvalid);
     // If PID is missing from PAI, the next method call will return CHIP_ERROR_KEY_NOT_FOUND.
     // Valid return values are then CHIP_NO_ERROR or CHIP_ERROR_KEY_NOT_FOUND.
-    CHIP_ERROR error = ExtractDNAttributeFromX509Cert(MatterOid::kProductId, paiCertDerBuffer, deviceInfo.paiProductId);
+    CHIP_ERROR error = ExtractDNAttributeFromX509Cert(MatterOid::kProductId, paiDerBuffer, deviceInfo.paiProductId);
     VerifyOrReturnError(error == CHIP_NO_ERROR || error == CHIP_ERROR_KEY_NOT_FOUND,
                         AttestationVerificationResult::kPaiFormatInvalid);
     return ValidateCertificateDeclarationPayload(certificationDeclarationPayload, firmwareInfoSpan, deviceInfo);
diff --git a/src/crypto/CHIPCryptoPAL.h b/src/crypto/CHIPCryptoPAL.h
@@ -1211,6 +1211,36 @@ CHIP_ERROR GetNumberOfCertsFromPKCS7(const char * pkcs7, uint32_t * n_certs);
 CHIP_ERROR ValidateCertificateChain(const uint8_t * rootCertificate, size_t rootCertificateLen, const uint8_t * caCertificate,
                                     size_t caCertificateLen, const uint8_t * leafCertificate, size_t leafCertificateLen);
 
+/**
+ * @brief Validate timestamp of a certificate (toBeEvaluatedCertificate) in comparison with other certificate's
+ *        (referenceCertificate) issuing timestamp.
+ *
+ * Errors are:
+ *   - CHIP_ERROR_CERT_EXPIRED if the certificate timestamp does not satisfy the reference certificate's issuing timestamp.
+ *   - CHIP_ERROR_INVALID_ARGUMENT when passing an invalid argument.
+ *   - CHIP_ERROR_INTERNAL on any unexpected crypto or data conversion errors.
+ *
+ *  @param referenceCertificate     A DER Certificate ByteSpan used as the issuing timestamp reference.
+ *  @param toBeEvaluatedCertificate A DER Certificate ByteSpan used to evaluate issuance against the referenceCertificate.
+ *
+ *  @returns a CHIP_ERROR (see above) on failure or CHIP_NO_ERROR otherwise.
+ **/
+CHIP_ERROR IsCertificateValidAtIssuance(const ByteSpan & referenceCertificate, const ByteSpan & toBeEvaluatedCertificate);
+
+/**
+ * @brief Validate a certificate's validity date against current time.
+ *
+ * Errors are:
+ *   - CHIP_ERROR_CERT_EXPIRED if the certificate has expired.
+ *   - CHIP_ERROR_INVALID_ARGUMENT when passing an invalid argument.
+ *   - CHIP_ERROR_INTERNAL on any unexpected crypto or data conversion errors.
+ *
+ *  @param certificate A DER Certificate ByteSpan used as the validity reference to be checked against current time.
+ *
+ *  @returns a CHIP_ERROR (see above) on failure or CHIP_NO_ERROR otherwise.
+ **/
+CHIP_ERROR IsCertificateValidAtCurrentTime(const ByteSpan & certificate);
+
 CHIP_ERROR ExtractPubkeyFromX509Cert(const ByteSpan & certificate, Crypto::P256PublicKey & pubkey);
 
 /**
diff --git a/src/crypto/CHIPCryptoPALOpenSSL.cpp b/src/crypto/CHIPCryptoPALOpenSSL.cpp
@@ -1703,6 +1703,80 @@ CHIP_ERROR ValidateCertificateChain(const uint8_t * rootCertificate, size_t root
     return err;
 }
 
+CHIP_ERROR IsCertificateValidAtIssuance(const ByteSpan & referenceCertificate, const ByteSpan & toBeEvaluatedCertificate)
+{
+    CHIP_ERROR error                                = CHIP_NO_ERROR;
+    X509 * x509ReferenceCertificate                 = nullptr;
+    X509 * x509toBeEvaluatedCertificate             = nullptr;
+    const unsigned char * pReferenceCertificate     = referenceCertificate.data();
+    const unsigned char * pToBeEvaluatedCertificate = toBeEvaluatedCertificate.data();
+    ASN1_TIME * refNotBeforeTime                    = nullptr;
+    ASN1_TIME * tbeNotBeforeTime                    = nullptr;
+    ASN1_TIME * tbeNotAfterTime                     = nullptr;
+    // int result                                      = 0;
+
+    VerifyOrReturnError(!referenceCertificate.empty() && !toBeEvaluatedCertificate.empty(), CHIP_ERROR_INVALID_ARGUMENT);
+
+    x509ReferenceCertificate = d2i_X509(NULL, &pReferenceCertificate, static_cast<long>(referenceCertificate.size()));
+    VerifyOrExit(x509ReferenceCertificate != nullptr, error = CHIP_ERROR_NO_MEMORY);
+
+    x509toBeEvaluatedCertificate = d2i_X509(NULL, &pToBeEvaluatedCertificate, static_cast<long>(toBeEvaluatedCertificate.size()));
+    VerifyOrExit(x509toBeEvaluatedCertificate != nullptr, error = CHIP_ERROR_NO_MEMORY);
+
+    refNotBeforeTime = X509_get_notBefore(x509ReferenceCertificate);
+    tbeNotBeforeTime = X509_get_notBefore(x509toBeEvaluatedCertificate);
+    tbeNotAfterTime  = X509_get_notAfter(x509toBeEvaluatedCertificate);
+    VerifyOrExit(refNotBeforeTime && tbeNotBeforeTime && tbeNotAfterTime, error = CHIP_ERROR_INTERNAL);
+
+    // TODO: Handle PAA/PAI re-issue and enable below time validations
+    // result = ASN1_TIME_compare(refNotBeforeTime, tbeNotBeforeTime);
+    // check if referenceCertificate is issued at or after tbeCertificate's notBefore timestamp
+    // VerifyOrExit(result >= 0, error = CHIP_ERROR_CERT_EXPIRED);
+
+    // result = ASN1_TIME_compare(refNotBeforeTime, tbeNotAfterTime);
+    // check if referenceCertificate is issued at or before tbeCertificate's notAfter timestamp
+    // VerifyOrExit(result <= 0, error = CHIP_ERROR_CERT_EXPIRED);
+
+exit:
+    X509_free(x509ReferenceCertificate);
+    X509_free(x509toBeEvaluatedCertificate);
+
+    return error;
+}
+
+CHIP_ERROR IsCertificateValidAtCurrentTime(const ByteSpan & certificate)
+{
+    CHIP_ERROR error                   = CHIP_NO_ERROR;
+    X509 * x509Certificate             = nullptr;
+    const unsigned char * pCertificate = certificate.data();
+    ASN1_TIME * time                   = nullptr;
+    int result                         = 0;
+
+    VerifyOrReturnError(!certificate.empty(), CHIP_ERROR_INVALID_ARGUMENT);
+
+    x509Certificate = d2i_X509(NULL, &pCertificate, static_cast<long>(certificate.size()));
+    VerifyOrExit(x509Certificate != nullptr, error = CHIP_ERROR_NO_MEMORY);
+
+    time = X509_get_notBefore(x509Certificate);
+    VerifyOrExit(time, error = CHIP_ERROR_INTERNAL);
+
+    result = X509_cmp_current_time(time);
+    // check if certificate's notBefore timestamp is earlier than or equal to current time.
+    VerifyOrExit(result == -1, error = CHIP_ERROR_CERT_EXPIRED);
+
+    time = X509_get_notAfter(x509Certificate);
+    VerifyOrExit(time, error = CHIP_ERROR_INTERNAL);
+
+    result = X509_cmp_current_time(time);
+    // check if certificate's notAfter timestamp is later than current time.
+    VerifyOrExit(result == 1, error = CHIP_ERROR_CERT_EXPIRED);
+
+exit:
+    X509_free(x509Certificate);
+
+    return error;
+}
+
 CHIP_ERROR ExtractPubkeyFromX509Cert(const ByteSpan & certificate, Crypto::P256PublicKey & pubkey)
 {
     CHIP_ERROR err                       = CHIP_NO_ERROR;
diff --git a/src/crypto/CHIPCryptoPALmbedTLS.cpp b/src/crypto/CHIPCryptoPALmbedTLS.cpp
diff --git a/src/crypto/tests/BUILD.gn b/src/crypto/tests/BUILD.gn
diff --git a/src/crypto/tests/CHIPCryptoPALTest.cpp b/src/crypto/tests/CHIPCryptoPALTest.cpp
