Merge pull request #229 from solokeys/fix-hmac-secret

Fix hmac secret

Author: conorpp

fido2/crypto.h

@@ -38,6 +38,7 @@ void generate_private_key(uint8_t * data, int len, uint8_t * data2, int len2, ui
 void crypto_ecc256_make_key_pair(uint8_t * pubkey, uint8_t * privkey);
 void crypto_ecc256_shared_secret(const uint8_t * pubkey, const uint8_t * privkey, uint8_t * shared_secret);
 
+#define CRYPTO_TRANSPORT_KEY2            ((uint8_t*)2)
 #define CRYPTO_TRANSPORT_KEY            ((uint8_t*)1)
 #define CRYPTO_MASTER_KEY               ((uint8_t*)0)
 

fido2/ctap.c

@@ -355,9 +355,9 @@ static int ctap_make_extensions(CTAP_extensions * ext, uint8_t * ext_encoder_buf
         }
 
         // Generate credRandom
-        crypto_sha256_hmac_init(CRYPTO_TRANSPORT_KEY, 0, credRandom);
+        crypto_sha256_hmac_init(CRYPTO_TRANSPORT_KEY2, 0, credRandom);
         crypto_sha256_update((uint8_t*)&ext->hmac_secret.credential->id, sizeof(CredentialId));
-        crypto_sha256_hmac_final(CRYPTO_TRANSPORT_KEY, 0, credRandom);
+        crypto_sha256_hmac_final(CRYPTO_TRANSPORT_KEY2, 0, credRandom);
 
         // Decrypt saltEnc
         crypto_aes256_init(shared_secret, NULL);
@@ -605,7 +605,6 @@ int ctap_calculate_signature(uint8_t * data, int datalen, uint8_t * clientDataHa
     crypto_sha256_final(hashbuf);
 
     crypto_ecc256_sign(hashbuf, 32, sigbuf);
-
     return ctap_encode_der_sig(sigbuf,sigder);
 }
 
@@ -1056,7 +1055,7 @@ uint8_t ctap_end_get_assertion(CborEncoder * map, CTAP_credentialDescriptor * cr
     else
 #endif
     {
-        sigder_sz = ctap_calculate_signature(auth_data_buf, sizeof(CTAP_authDataHeader), clientDataHash, auth_data_buf, sigbuf, sigder);
+        sigder_sz = ctap_calculate_signature(auth_data_buf, auth_data_buf_sz, clientDataHash, auth_data_buf, sigbuf, sigder);
     }
 
     {

targets/stm32l432/src/crypto.c

@@ -157,6 +157,11 @@ void crypto_sha256_hmac_final(uint8_t * key, uint32_t klen, uint8_t * hmac)
         key = master_secret;
         klen = sizeof(master_secret)/2;
     }
+    else if (key == CRYPTO_TRANSPORT_KEY2)
+    {
+        key = transport_secret;
+        klen = 32;
+    }
 
 
     if(klen > 64)

tools/testing/tests/fido2.py

@@ -211,7 +211,7 @@ def test_extensions(self,):
             assert "hmac-secret" in reg.auth_data.extensions
             assert reg.auth_data.extensions["hmac-secret"] == True
 
-        reg = self.testMC(
+        self.testMC(
             "Send MC with fake extension set to true, expect SUCCESS",
             cdh,
             rp,
@@ -278,6 +278,10 @@ def get_salt_params(salts):
                     assert shannon_entropy(ext["hmac-secret"]) > 5.4
                     assert shannon_entropy(key) > 5.4
 
+            with Test("Check that the assertion is valid"):
+                credential_data = AttestedCredentialData(reg.auth_data.credential_data)
+                auth.verify(cdh, credential_data.public_key)
+
         salt_enc, salt_auth = get_salt_params((salt3,))
 
         auth = self.testGA(
@@ -743,6 +747,40 @@ def test_get_assertion(self,):
             expectedError=CtapError.ERR.SUCCESS,
         )
 
+        with Test("Check assertion is correct"):
+            credential_data = AttestedCredentialData(prev_reg.auth_data.credential_data)
+            prev_auth.verify(cdh, credential_data.public_key)
+            assert (
+                prev_auth.credential["id"]
+                == prev_reg.auth_data.credential_data.credential_id
+            )
+
+        self.reboot()
+
+        prev_auth = self.testGA(
+            "Send GA request after reboot, expect success",
+            rp["id"],
+            cdh,
+            allow_list,
+            expectedError=CtapError.ERR.SUCCESS,
+        )
+
+        with Test("Check assertion is correct"):
+            credential_data = AttestedCredentialData(prev_reg.auth_data.credential_data)
+            prev_auth.verify(cdh, credential_data.public_key)
+            assert (
+                prev_auth.credential["id"]
+                == prev_reg.auth_data.credential_data.credential_id
+            )
+
+        prev_auth = self.testGA(
+            "Send GA request, expect success",
+            rp["id"],
+            cdh,
+            allow_list,
+            expectedError=CtapError.ERR.SUCCESS,
+        )
+
         with Test("Test auth_data is 37 bytes"):
             assert len(prev_auth.auth_data) == 37
 

tools/testing/tests/tester.py

@@ -2,6 +2,7 @@
 
 from fido2.hid import CtapHidDevice
 from fido2.client import Fido2Client
+from fido2.attestation import Attestation
 from fido2.ctap1 import CTAP1
 from fido2.utils import Timeout
 
@@ -201,7 +202,18 @@ def testReset(self,):
             self.ctap.reset()
 
     def testMC(self, test, *args, **kwargs):
-        return self.testFunc(self.ctap.make_credential, test, *args, **kwargs)
+        attestation_object = self.testFunc(
+            self.ctap.make_credential, test, *args, **kwargs
+        )
+        if attestation_object:
+            verifier = Attestation.for_type(attestation_object.fmt)
+            client_data = args[0]
+            verifier().verify(
+                attestation_object.att_statement,
+                attestation_object.auth_data,
+                client_data,
+            )
+        return attestation_object
 
     def testGA(self, test, *args, **kwargs):
         return self.testFunc(self.ctap.get_assertion, test, *args, **kwargs)

tools/testing/tests/u2f.py

@@ -78,6 +78,16 @@ def test_u2f(self,):
                 auth = self.authenticate(chal, appid, regs[i].key_handle)
                 auth.verify(appid, chal, regs[i].public_key)
 
+        self.reboot()
+
+        for i in range(0, self.user_count):
+            with Test(
+                "Post reboot, Checking previous registration %d/%d"
+                % (i + 1, self.user_count)
+            ):
+                auth = self.authenticate(chal, appid, regs[i].key_handle)
+                auth.verify(appid, chal, regs[i].public_key)
+
         print("Check that all previous credentials are registered...")
         for i in range(0, self.user_count):
             with Test("Check that previous credential %d is registered" % i):