diff --git a/src/fido/cbor_get_assertion.c b/src/fido/cbor_get_assertion.c index 18297f0..211d89b 100644 --- a/src/fido/cbor_get_assertion.c +++ b/src/fido/cbor_get_assertion.c @@ -42,7 +42,7 @@ uint8_t numberOfCredentialsx = 0; int cbor_get_assertion(const uint8_t *data, size_t len) { size_t resp_size = 0; - uint64_t pinUvAuthProtocol = 0; + uint64_t pinUvAuthProtocol = 0, hmacSecretPinUvAuthProtocol = 1; CredOptions options = {0}; CredExtensions extensions = {0}; CborParser parser; @@ -56,6 +56,8 @@ int cbor_get_assertion(const uint8_t *data, size_t len) { size_t allowList_len = 0, creds_len = 0; uint8_t *aut_data = NULL; bool asserted = false; + int64_t kty = 0, alg = 0, crv = 0; + CborByteString kax = {0}, kay = {0}, salt_enc = {0}, salt_auth = {0}; CBOR_CHECK(cbor_parser_init(data, len, 0, &parser, &map)); uint64_t val_c = 1; @@ -94,9 +96,52 @@ int cbor_get_assertion(const uint8_t *data, size_t len) { CBOR_PARSE_ARRAY_END(_f1, 2); } else if (val_u == 0x04) { // extensions + extensions.present = true; CBOR_PARSE_MAP_START(_f1, 2) { CBOR_FIELD_GET_KEY_TEXT(2); - CBOR_FIELD_KEY_TEXT_VAL_BOOL(2, "hmac-secret", extensions.hmac_secret); + if (strcmp(_fd2, "hmac-secret") == 0) { + extensions.hmac_secret = ptrue; + uint64_t ukey = 0; + CBOR_PARSE_MAP_START(_f2, 3) { + CBOR_FIELD_GET_UINT(ukey, 3); + if (ukey == 0x01) { + int64_t kkey = 0; + CBOR_PARSE_MAP_START(_f3, 4) { + CBOR_FIELD_GET_INT(kkey, 4); + if (kkey == 1) { + CBOR_FIELD_GET_INT(kty, 4); + } + else if (kkey == 3) { + CBOR_FIELD_GET_INT(alg, 4); + } + else if (kkey == -1) { + CBOR_FIELD_GET_INT(crv, 4); + } + else if (kkey == -2) { + CBOR_FIELD_GET_BYTES(kax, 4); + } + else if (kkey == -3) { + CBOR_FIELD_GET_BYTES(kay, 4); + } + else + CBOR_ADVANCE(4); + } + CBOR_PARSE_MAP_END(_f3, 4); + } + else if (ukey == 0x02) { + CBOR_FIELD_GET_BYTES(salt_enc, 3); + } + else if (ukey == 0x03) { + CBOR_FIELD_GET_BYTES(salt_auth, 3); + } + else if (ukey == 0x04) { + CBOR_FIELD_GET_UINT(hmacSecretPinUvAuthProtocol, 3); + } + else + CBOR_ADVANCE(3); + } + CBOR_PARSE_MAP_END(_f2, 3); + } CBOR_FIELD_KEY_TEXT_VAL_UINT(2, "credProtect", extensions.credProtect); CBOR_ADVANCE(2); } @@ -122,7 +167,7 @@ int cbor_get_assertion(const uint8_t *data, size_t len) { } CBOR_PARSE_MAP_END(map, 1); - uint8_t flags = FIDO2_AUT_FLAG_AT; + uint8_t flags = 0; uint8_t rp_id_hash[32]; mbedtls_sha256((uint8_t *)rpId.data, rpId.len, rp_id_hash, 0); @@ -262,9 +307,12 @@ int cbor_get_assertion(const uint8_t *data, size_t len) { size_t ext_len = 0; uint8_t ext [512]; + /* if (extensions.present == true) { cbor_encoder_init(&encoder, ext, sizeof(ext), 0); int l = 0; + if (options.up == pfalse) + extensions.hmac_secret = NULL; if (extensions.hmac_secret != NULL) l++; if (extensions.credProtect != 0) @@ -277,39 +325,65 @@ int cbor_get_assertion(const uint8_t *data, size_t len) { if (extensions.hmac_secret != NULL) { CBOR_CHECK(cbor_encode_text_stringz(&mapEncoder, "hmac-secret")); - CBOR_CHECK(cbor_encode_boolean(&mapEncoder, *extensions.hmac_secret)); + + uint8_t sharedSecret[64]; + mbedtls_ecp_point Qp; + mbedtls_ecp_point_init(&Qp); + mbedtls_mpi_lset(&Qp.Z, 1); + if (mbedtls_mpi_read_binary(&Qp.X, kax.data, kax.len) != 0) { + mbedtls_ecp_point_free(&Qp); + CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER); + } + if (mbedtls_mpi_read_binary(&Qp.Y, kay.data, kay.len) != 0) { + mbedtls_ecp_point_free(&Qp); + CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER); + } + int ret = ecdh(hmacSecretPinUvAuthProtocol, &Qp, sharedSecret); + mbedtls_ecp_point_free(&Qp); + if (ret != 0) { + mbedtls_platform_zeroize(sharedSecret, sizeof(sharedSecret)); + CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER); + } + if (verify(hmacSecretPinUvAuthProtocol, sharedSecret, salt_enc.data, salt_enc.len, salt_auth.data) != 0) { + mbedtls_platform_zeroize(sharedSecret, sizeof(sharedSecret)); + CBOR_ERROR(CTAP2_ERR_PIN_AUTH_INVALID); + } + if (salt_enc.len != 32 || salt_enc.len != 64) { + mbedtls_platform_zeroize(sharedSecret, sizeof(sharedSecret)); + CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER); + } + uint8_t salt_dec[64]; + ret = decrypt(hmacSecretPinUvAuthProtocol, sharedSecret, salt_enc.data, salt_enc.len, salt_dec); + if (ret != 0) { + mbedtls_platform_zeroize(sharedSecret, sizeof(sharedSecret)); + CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER); + } + uint8_t cred_random[64], *crd = NULL; + ret = credential_derive_hmac_key(cred_id, cred_id_len, cred_random); + if (ret != 0) { + mbedtls_platform_zeroize(sharedSecret, sizeof(sharedSecret)); + CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER); + } + if (flags & FIDO2_AUT_FLAG_UV) + crd = cred_random + 32; + else + crd = cred_random; + uint8_t out1[64], hmac_res[64]; + mbedtls_md_hmac(mbedtls_md_info_from_type(MBEDTLS_MD_SHA256), crd, 32, salt_dec, 32, out1); + if (salt_enc.len == 64) + mbedtls_md_hmac(mbedtls_md_info_from_type(MBEDTLS_MD_SHA256), crd, 32, salt_dec+32, 32, out1+32); + encrypt(hmacSecretPinUvAuthProtocol, sharedSecret, out1, salt_enc.len, hmac_res); + CBOR_CHECK(cbor_encode_byte_string(&mapEncoder, hmac_res, salt_enc.len)); } CBOR_CHECK(cbor_encoder_close_container(&encoder, &mapEncoder)); ext_len = cbor_encoder_get_buffer_size(&encoder, ext); flags |= FIDO2_AUT_FLAG_ED; } - uint8_t pkey[66]; - const mbedtls_ecp_curve_info *cinfo = mbedtls_ecp_curve_info_from_grp_id(ekey.grp.id); - if (cinfo == NULL) - CBOR_ERROR(CTAP1_ERR_OTHER); - size_t olen = 0, pkey_len = ceil((float)cinfo->bit_size/8); +*/ uint32_t ctr = *(uint32_t *)file_get_data(ef_counter); - uint8_t cbor_buf[1024]; - cbor_encoder_init(&encoder, cbor_buf, sizeof(cbor_buf), 0); - CBOR_CHECK(cbor_encoder_create_map(&encoder, &mapEncoder, 5)); - CBOR_CHECK(cbor_encode_uint(&mapEncoder, 1)); - CBOR_CHECK(cbor_encode_uint(&mapEncoder, 2)); - CBOR_CHECK(cbor_encode_uint(&mapEncoder, 3)); - CBOR_CHECK(cbor_encode_negative_int(&mapEncoder, -selcred->alg)); - CBOR_CHECK(cbor_encode_negative_int(&mapEncoder, 1)); - CBOR_CHECK(cbor_encode_uint(&mapEncoder, selcred->curve)); - CBOR_CHECK(cbor_encode_negative_int(&mapEncoder, 2)); - mbedtls_mpi_write_binary(&ekey.Q.X, pkey, pkey_len); - CBOR_CHECK(cbor_encode_byte_string(&mapEncoder, pkey, pkey_len)); - CBOR_CHECK(cbor_encode_negative_int(&mapEncoder, 3)); - mbedtls_mpi_write_binary(&ekey.Q.Y, pkey, pkey_len); - CBOR_CHECK(cbor_encode_byte_string(&mapEncoder, pkey, pkey_len)); - CBOR_CHECK(cbor_encoder_close_container(&encoder, &mapEncoder)); - size_t rs = cbor_encoder_get_buffer_size(&encoder, cbor_buf); - - size_t aut_data_len = 32 + 1 + 4 + (16 + 2 + cred_id_len + rs) + ext_len; + size_t aut_data_len = 32 + 1 + 4 + ext_len; aut_data = (uint8_t *)calloc(1, aut_data_len + clientDataHash.len); uint8_t *pa = aut_data; memcpy(pa, rp_id_hash, 32); pa += 32; @@ -318,11 +392,6 @@ int cbor_get_assertion(const uint8_t *data, size_t len) { *pa++ = ctr >> 16; *pa++ = ctr >> 8; *pa++ = ctr & 0xff; - memcpy(pa, aaguid, 16); pa += 16; - *pa++ = cred_id_len >> 8; - *pa++ = cred_id_len & 0xff; - memcpy(pa, cred_id, cred_id_len); pa += cred_id_len; - memcpy(pa, cbor_buf, rs); pa += rs; memcpy(pa, ext, ext_len); pa += ext_len; if (pa-aut_data != aut_data_len) CBOR_ERROR(CTAP1_ERR_OTHER); @@ -330,6 +399,7 @@ int cbor_get_assertion(const uint8_t *data, size_t len) { memcpy(pa, clientDataHash.data, clientDataHash.len); uint8_t hash[32], sig[MBEDTLS_ECDSA_MAX_LEN]; ret = mbedtls_md(mbedtls_md_info_from_type(MBEDTLS_MD_SHA256), aut_data, aut_data_len+clientDataHash.len, hash); + size_t olen = 0; ret = mbedtls_ecdsa_write_signature(&ekey, MBEDTLS_MD_SHA256, hash, 32, sig, sizeof(sig), &olen, random_gen, NULL); mbedtls_ecdsa_free(&ekey); @@ -343,10 +413,10 @@ int cbor_get_assertion(const uint8_t *data, size_t len) { CBOR_CHECK(cbor_encode_uint(&mapEncoder, 0x01)); CBOR_CHECK(cbor_encoder_create_map(&mapEncoder, &mapEncoder2, 2)); - CBOR_CHECK(cbor_encode_text_stringz(&mapEncoder2, "type")); - CBOR_CHECK(cbor_encode_text_stringz(&mapEncoder2, "public-key")); CBOR_CHECK(cbor_encode_text_stringz(&mapEncoder2, "id")); CBOR_CHECK(cbor_encode_byte_string(&mapEncoder2, cred_id, cred_id_len)); + CBOR_CHECK(cbor_encode_text_stringz(&mapEncoder2, "type")); + CBOR_CHECK(cbor_encode_text_stringz(&mapEncoder2, "public-key")); CBOR_CHECK(cbor_encoder_close_container(&mapEncoder, &mapEncoder2)); CBOR_CHECK(cbor_encode_uint(&mapEncoder, 0x02)); @@ -366,7 +436,7 @@ int cbor_get_assertion(const uint8_t *data, size_t len) { CBOR_CHECK(cbor_encode_uint(&mapEncoder, numberOfCredentials)); } CBOR_CHECK(cbor_encoder_close_container(&encoder, &mapEncoder)); - res_APDU_size = cbor_encoder_get_buffer_size(&encoder, ctap_resp->init.data + 1); + resp_size = cbor_encoder_get_buffer_size(&encoder, ctap_resp->init.data + 1); err: if (asserted == false) { CBOR_FREE_BYTE_STRING(clientDataHash); diff --git a/src/fido/credential.c b/src/fido/credential.c index 49615d1..8062651 100644 --- a/src/fido/credential.c +++ b/src/fido/credential.c @@ -214,3 +214,17 @@ int credential_store(const uint8_t *cred_id, size_t cred_id_len, const uint8_t * low_flash_available(); return 0; } + +int credential_derive_hmac_key(const uint8_t *cred_id, size_t cred_id_len, uint8_t *outk) { + memset(outk, 0, 64); + int r = 0; + if ((r = load_keydev(outk)) != 0) + return r; + const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type(MBEDTLS_MD_SHA512); + + mbedtls_md_hmac(md_info, outk, 32, (uint8_t *)"SLIP-0022", 9, outk); + mbedtls_md_hmac(md_info, outk, 32, (uint8_t *)"\xf1\xd0\x02\x00", 4, outk); + mbedtls_md_hmac(md_info, outk, 32, (uint8_t *)"hmac-secret", 11, outk); + mbedtls_md_hmac(md_info, outk, 32, cred_id, cred_id_len, outk); + return 0; +} diff --git a/src/fido/credential.h b/src/fido/credential.h index 1004e03..8a8d786 100644 --- a/src/fido/credential.h +++ b/src/fido/credential.h @@ -57,5 +57,6 @@ extern void credential_free(Credential *cred); extern int credential_store(const uint8_t *cred_id, size_t cred_id_len, const uint8_t *rp_id_hash); extern int credential_load(const uint8_t *cred_id, size_t cred_id_len, const uint8_t *rp_id_hash, Credential *cred); extern int credential_create_cred(Credential *cred, uint8_t *cred_id, size_t *cred_id_len); +extern int credential_derive_hmac_key(const uint8_t *cred_id, size_t cred_id_len, uint8_t *outk); #endif // _CREDENTIAL_H_ diff --git a/src/fido/fido.h b/src/fido/fido.h index 7328c1b..59c35f3 100644 --- a/src/fido/fido.h +++ b/src/fido/fido.h @@ -37,6 +37,10 @@ extern CTAPHID_FRAME *ctap_req, *ctap_resp; extern void init_fido(); extern mbedtls_ecp_group_id fido_curve_to_mbedtls(int curve); extern int fido_load_key(int curve, const uint8_t *cred_id, mbedtls_ecdsa_context *key); +extern int load_keydev(uint8_t *key); +extern int encrypt(uint8_t protocol, const uint8_t *key, const uint8_t *in, size_t in_len, uint8_t *out); +extern int decrypt(uint8_t protocol, const uint8_t *key, const uint8_t *in, size_t in_len, uint8_t *out); +extern int ecdh(uint8_t protocol, const mbedtls_ecp_point *Q, uint8_t *sharedSecret); #define FIDO2_ALG_ES256 -7 //ECDSA-SHA256 P256 #define FIDO2_ALG_EDDSA -8 //EdDSA