merge u2f endian fix

.clabot

@@ -0,0 +1,4 @@
+{
+  "contributors": "https://raw.githubusercontent.com/solokeys/contributors/master/contributors.json",
+  "message": "We require contributors to sign our Copyright License Agreement, and we don't have {{usersWithoutCLA}} on file. In order for us to review and merge your code, please visit https://solokeys.com/legal/contributors, or contact @nickray, @conorpp or @0x0ece for further information or help."
+}

.gitmodules

@@ -3,7 +3,7 @@
 	url = https://github.com/intel/tinycbor
 [submodule "python-fido2"]
 	path = python-fido2
-	url = https://github.com/SoloKeysSec/python-fido2
+	url = https://github.com/solokeys/python-fido2
 [submodule "crypto/micro-ecc"]
 	path = crypto/micro-ecc
 	url = https://github.com/kmackay/micro-ecc.git
@@ -12,4 +12,4 @@
     url = https://github.com/kokke/tiny-AES-c
 [submodule "targets/stm32l442/dfuse-tool"]
 	path = targets/stm32l442/dfuse-tool
-    url = https://github.com/SoloKeysSec/dfuse-tool
+    url = https://github.com/solokeys/dfuse-tool

.travis.yml

@@ -1,4 +1,4 @@
-dist: trusty
+dist: xenial
 language: c
 compiler: gcc
 addons:
@@ -7,6 +7,7 @@ addons:
       - ubuntu-toolchain-r-test
     packages:
       - gcc-7
+      - cppcheck
 script:
   - export CC=gcc-7
   - make test

99-solo.rules

@@ -1,6 +1,17 @@
+# Notify ModemManager this device should be ignored
+ACTION!="add|change|move", GOTO="mm_usb_device_blacklist_end"
+SUBSYSTEM!="usb", GOTO="mm_usb_device_blacklist_end"
+ENV{DEVTYPE}!="usb_device",  GOTO="mm_usb_device_blacklist_end"
+
+ATTRS{idVendor}=="0483", ATTRS{idProduct}=="a2ca", ENV{ID_MM_DEVICE_IGNORE}="1"
+
+LABEL="mm_usb_device_blacklist_end"
+
 # Solo
 ATTRS{idVendor}=="0483", ATTRS{idProduct}=="a2ca", ATTRS{product}=="Solo",                   TAG+="uaccess", GROUP="plugdev", SYMLINK+="solokey"
 ATTRS{idVendor}=="0483", ATTRS{idProduct}=="a2ca", ATTRS{product}=="Solo HACKER (Unlocked)", TAG+="uaccess", GROUP="plugdev", SYMLINK+="solohacker"
 
+SUBSYSTEM=="tty", ATTRS{idVendor}=="0483", ATTRS{idProduct}=="a2ca", TAG+="uaccess", GROUP="plugdev", SYMLINK+="solokey-serial"
+
 # U2F Zero
 KERNEL=="hidraw*", SUBSYSTEM=="hidraw", ATTRS{idVendor}=="10c4", ATTRS{idProduct}=="8acf", TAG+="uaccess", GROUP="plugdev", SYMLINK+="u2fzero"

Makefile

@@ -45,9 +45,6 @@ cbor: $(LIBCBOR)
 $(LIBCBOR): tinycbor/Makefile
 	cd tinycbor/ && $(MAKE) clean && $(MAKE) -j8
 
-test:
-	$(MAKE) -C . main
-
 .PHONY: efm8prog
 efm8prog:
 	cd './targets/efm8\Keil 8051 v9.53 - Debug' && $(MAKE) all
@@ -92,6 +89,16 @@ wink3: env3
 fido2-test: env3
 	env3/bin/python tools/ctap_test.py
 
+CPPCHECK_FLAGS=--quiet --error-exitcode=2
+
+cppcheck:
+	cppcheck $(CPPCHECK_FLAGS) crypto/aes-gcm
+	cppcheck $(CPPCHECK_FLAGS) crypto/sha256
+	cppcheck $(CPPCHECK_FLAGS) fido2
+	cppcheck $(CPPCHECK_FLAGS) pc
+
+test: main cppcheck
+
 clean:
 	rm -f *.o main.exe main $(obj)
 	rm -rf env2 env3

README.md

@@ -1,8 +1,8 @@
-![GitHub](https://img.shields.io/github/license/mashape/apistatus.svg)
+[![License](https://img.shields.io/github/license/solokeys/solo.svg)](https://github.com/solokeys/solo/blob/master/LICENSE)
-[![Kickstarter](https://img.shields.io/badge/kickstarter-back%20us-red.svg)](https://solokeys.com/kickstarter)
+[![Build Status](https://travis-ci.com/solokeys/solo.svg?branch=master)](https://travis-ci.com/solokeys/solo)
-[![Build Status](https://travis-ci.com/SoloKeysSec/solo.svg?branch=master)](https://travis-ci.com/SoloKeysSec/solo)
+[![Discourse Users](https://img.shields.io/discourse/https/discourse.solokeys.com/users.svg)](https://discourse.solokeys.com)
-[![Discourse Status](https://img.shields.io/discourse/https/meta.discourse.org/status.svg)](https://discourse.solokeys.com)
 [![Keybase Chat](https://img.shields.io/badge/chat-on%20keybase-brightgreen.svg)](https://keybase.io/team/solokeys.public)
+[![FOSSA Status](https://app.fossa.io/api/projects/git%2Bgithub.com%2Fsolokeys%2Fsolo.svg?type=shield)](https://app.fossa.io/projects/git%2Bgithub.com%2Fsolokeys%2Fsolo?ref=badge_shield)
 
 
 # Solo
@@ -35,20 +35,25 @@ Solo for Hacker is a special version of Solo that let you customize its firmware
 
 You can only buy Solo for Hacker at [solokeys.com](https://solokeys.com), as we don't sell it on Amazon and other places to avoid confusing customers. If you buy a Hacker, you can permanently lock it into a regular Solo, but viceversa you can NOT take a regular Solo and turn it a Hacker.
 
-If you have a Solo for Hacker, here's how you can load your own code on it. You can find more details, including how to permanently lock it, in our [documentation](https://solo.solokeys.io/building/).
+If you have a Solo for Hacker, here's how you can load your own code on it. You can find more details, including how to permanently lock it, in our [documentation](https://docs.solokeys.io/solo/building/).
 
 ```bash
-git clone --recurse-submodules https://github.com/SoloKeysSec/solo
+git clone --recurse-submodules https://github.com/solokeys/solo
 cd solo
 
 cd targets/stm32l432
 make cbor
 make all-hacker
-python ../../tools/solotool.py program solo.hex
+cd ../..
+
+make env3
+source env3/bin/activate
+python tools/solotool.py program targets/stm32l432/solo.hex
 ```
 
 If you forgot the `--recurse-submodules` when cloning, simply `git submodule update --init --recursive`.
-For example, if you want to turn off any blue light emission, you can edit [`led_rgb()`](https://github.com/SoloKeysSec/solo/blob/master/targets/stm32l432/src/led.c#L15) and force:
+
+For example, if you want to turn off any blue light emission, you can edit [`led_rgb()`](https://github.com/solokeys/solo/blob/master/targets/stm32l432/src/led.c#L15) and force:
 ```
 uint32_t b = 0;
 ```
@@ -65,7 +70,7 @@ A frequently asked question is whether Solo for Hacker is less secure than regul
 Clone Solo and build it
 
 ```bash
-git clone --recurse-submodules https://github.com/SoloKeysSec/solo
+git clone --recurse-submodules https://github.com/solokeys/solo
 cd solo
 make all
 ```
@@ -93,12 +98,12 @@ Or any client example such as:
 python python-fido2/examples/credential.py
 ```
 
-You can find more details in our [documentation](https://solo.solokeys.io), including how to build on the the NUCLEO-L432KC development board.
+You can find more details in our [documentation](https://docs.solokeys.io/solo/), including how to build on the the NUCLEO-L432KC development board.
 
 
 # Documentation
 
-Check out our [official documentation](https://solo.solokeys.io).
+Check out our [official documentation](https://docs.solokeys.io/solo/).
 
 
 # Contributors
@@ -117,6 +122,9 @@ All software is licensed under GPLv3, and hardware under CC BY-SA 4.0.
 Software and hardware are available under licenses for commercial use. Please contact SoloKeys for more information.
 
 
+
+[![FOSSA Status](https://app.fossa.io/api/projects/git%2Bgithub.com%2Fsolokeys%2Fsolo.svg?type=large)](https://app.fossa.io/projects/git%2Bgithub.com%2Fsolokeys%2Fsolo?ref=badge_large)
+
 # Where To Buy Solo
 
-You can buy Solo, Solo Tap, and Solo for Hackers at [solokeys.com](https://solokeys.com).
+You can buy Solo, Solo Tap, and Solo for Hackers at [solokeys.com](https://solokeys.com).

docs/index.md

@@ -1,4 +0,0 @@
-Welcome to the technical documentation for [solokeyssec/solo](https://github.com/solokeyssec/solo).
-
-For now, you can read the repository `README.md`, more documentation to come!
-

docs/repo-readme.md

@@ -1 +0,0 @@
-../README.md

docs/solo/building.md

@@ -68,6 +68,10 @@ reconnect each time you program Solo.
 python tools/solotool.py monitor <serial-port>
 ```
 
+#### Linux Users:
+
+[See issue 62](https://github.com/solokeys/solo/issues/62).
+
 ### Building a Solo release
 
 If you want to build a release of Solo, we recommend trying a Hacker build first

docs/solo/contributing.md

@@ -1,15 +1,15 @@
 We are very open to contributions!
 
-[Currently](https://github.com/solokeyssec/solo/issues), most work will go towards
+[Currently](https://github.com/solokeys/solo/issues), most work will go towards
 
-* implementing STM32L432
+* ~~implementing STM32L432~~
 * implementing NFC
 * adding documentation and improving accessability of the code
 
 In the future, we would love to see creative plugins/extensions, putting the TRNG and other features of the STM32L432 to good use! 
 
-Feel free to send a [pull request](https://github.com/SoloKeysSec/solo/pulls) at any time, we don't currently have a formal contribution process.
+Feel free to send a [pull request](https://github.com/solokeys/solo/pulls) at any time, please note that we do require a lightweight copyright license agreement in order to accept contributions. Reason and procedure: <https://solokeys.com/legal/contributors/>.
 
 If you want to discuss your plans in quasi-realtime beforehand, you can also join our [solokeys.public](https://keybase.io/team/solokeys.public) Keybase team.
 
-But first: [join our mailing list!](https://solokeys.us19.list-manage.com/subscribe/post?u=cc0c298fb99cd136bdec8294b&id=b9cb3de62d)
+But first: [join our mailing list!](https://solokeys.us19.list-manage.com/subscribe/post?u=cc0c298fb99cd136bdec8294b&id=6550fc947a)

docs/solo/fido2-impl.md

@@ -15,6 +15,8 @@ A master secret, `M`, is generated at initialization.  This is only used for
 all key generation and derivation in FIDO2.  Solo uses a key wrapping method
 for FIDO2 operation.
 
+** NOTE: The masked implementation of AES is planned, but not yet implemented. Currently it is normal AES. **
+
 ## Key wrapping
 
 When you register a service with a FIDO2 or U2F authenticator, the
@@ -55,6 +57,8 @@ keys which are then used for FIDO2/U2F.  -->
 
 ## Key derivation
 
+** Planned, but not yet implemented. **
+
 Master secret `M` consists of 64 bytes, split into equal parts `M1` and `M2`.
 In theory, we should only need 32 bytes to achieve 256 security, but we also
 plan to have side channel security hence the added bytes.

docs/solo/index.md

@@ -0,0 +1,4 @@
+Welcome to the technical documentation for [solokeys/solo](https://github.com/solokeys/solo).
+
+For now, you can read the repository `README.md`, more documentation to come!
+

docs/solo/metadata-statements.md

@@ -0,0 +1,12 @@
+For information on what this is, see the [spec](https://fidoalliance.org/specs/fido-v2.0-rd-20180702/fido-metadata-statement-v2.0-rd-20180702.html#fido2-example).
+## CTAP2
+
+```
+{!metadata/solo-FIDO2-CTAP2-Authenticator.json!}
+```
+
+## U2F
+
+```
+{!metadata/solo-FIDO2-U2F-Authenticator.json!}
+```

docs/solo/repo-readme.md

@@ -0,0 +1 @@
+../../README.md

docs/solo/signed-updates.md

@@ -22,5 +22,5 @@ In order to boot the application, a valid signature must be provided to the boot
 signature using a public key stored in the bootloader section, and the data in the application section.  If the signature
 is valid, the boot flag in the data section will be changed to allow boot.
 
-Signature checks and checks to the data section boot flag are made redundantly to make glitching attacks more difficult.  Random delays
+We are working to make the signature checking process redundantly to make glitching attacks more difficult.  Also random delays
-between redundant checks are also made.
+between redundant checks.

docs/solo/udev.md

@@ -1,6 +1,6 @@
 # tl;dr
 
-Create [`/etc/udev/99-solo.rules`](https://github.com/SoloKeysSec/solo/blob/master/99-solo.rules) and add the following (which assumes your user is in group `plugdev`):
+Create [`/etc/udev/rules.d/99-solo.rules`](https://github.com/solokeys/solo/blob/master/99-solo.rules) and add the following (which assumes your user is in group `plugdev`):
 
 ```
 # Solo
@@ -13,7 +13,7 @@ KERNEL=="hidraw*", SUBSYSTEM=="hidraw", ATTRS{idVendor}=="10c4", ATTRS{idProduct
 Then run
 
 ```
-udevadm trigger
+sudo udevadm control --reload-rules && sudo udevadm trigger
 ```
 
 # How do udev rules work and why are they needed
@@ -65,8 +65,8 @@ udevadm trigger
 ## What about vendor and product ID for Solo?
 | Key | Vendor ID | Product ID |
 | --- | --- | --- |
-| Solo | 10c4 | 8acf |
+| Solo | 0483 | a2ca |
-| U2F Zero | 0483 | a2ca |
+| U2F Zero | 10c4 | 8acf |
 
 ## You got this all wrong, I can't believe it!
-Are you suffering from [us being wrong](https://xkcd.com/386/)? Please, send us a [pull request](https://github.com/SoloKeysSec/solo/pulls) and prove us wrong :D
+Are you suffering from [us being wrong](https://xkcd.com/386/)? Please, send us a [pull request](https://github.com/solokeys/solo/pulls) and prove us wrong :D

fido2/u2f.c

@@ -1,21 +1,21 @@
 /*
  * Copyright (C) 2018 SoloKeys, Inc. <https://solokeys.com/>
- * 
+ *
  * This file is part of Solo.
- * 
+ *
  * Solo is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation, either version 3 of the License, or
  * (at your option) any later version.
- * 
+ *
  * Solo is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
- * 
+ *
  * You should have received a copy of the GNU General Public License
  * along with Solo.  If not, see <https://www.gnu.org/licenses/>
- * 
+ *
  * This code is available under licenses for commercial use.
  * Please contact SoloKeys for more information.
  */
@@ -125,17 +125,17 @@ void u2f_request_nfc(uint8_t * req, int len, CTAP_RESPONSE * resp)
 {
 	if (len < 5 || !req)
 		return;
-	
+
     uint32_t alen = req[4];
-	
+
-	u2f_request_ex((APDU_HEADER *)req, &req[5], alen, resp, true);	
+	u2f_request_ex((APDU_HEADER *)req, &req[5], alen, resp, true);
 }
 
 void u2f_request(struct u2f_request_apdu* req, CTAP_RESPONSE * resp)
 {
     uint32_t len = ((req->LC3) | ((uint32_t)req->LC2 << 8) | ((uint32_t)req->LC1 << 16));
-	
+
-	u2f_request_ex((APDU_HEADER *)req, req->payload, len, resp, false);	
+	u2f_request_ex((APDU_HEADER *)req, req->payload, len, resp, false);
 }
 
 int8_t u2f_response_writeback(const uint8_t * buf, uint16_t len)

mkdocs.yml

@@ -1,21 +1,27 @@
-site_name: Solo
+site_name: Solo Technical Documentation
 site_author: SoloKeys
 site_description: 'Documentation for the SoloKeys solo software'
-repo_url: 'https://github.com/solokeyssec/solo'
+site_url: 'https://docs.solokeys.io/solo/'
-repo_name: 'solokeyssec/solo'
+repo_url: 'https://github.com/solokeys/solo'
-copyright: 'Copyright © 2018 SoloKeys'
+repo_name: 'solokeys/solo'
+copyright: 'Copyright © 2018 - 2019 SoloKeys'
 
 nav:
-    - Home: index.md
+    - Home: solo/index.md
-    - README.md: repo-readme.md
+    - FIDO2 Implementation: solo/fido2-impl.md
-    - FIDO2 Implementation: fido2-impl.md
+    - Metadata Statements: solo/metadata-statements.md
-    - Signed update process: signed-updates.md
+    - Build instructions: solo/building.md
-    - Building: building.md
+    - Signed update process: solo/signed-updates.md
-    - Code documentation: code-overview.md
+    - Code documentation: solo/code-overview.md
-    - Contributing Code: contributing.md
+    - Contributing Code: solo/contributing.md
-    - Contributing Docs: documenting.md
+    - Contributing Docs: solo/documenting.md
-    - What the udev?!: udev.md
+    - udev Rules: solo/udev.md
+    - About: solo/repo-readme.md
 
 theme:
   name: material
-  logo: 'images/logo.svg'
+  logo: 'solo/images/logo.svg'
+  favicon: 'solo/images/favicon.ico'
+
+markdown_extensions:
+  - markdown_include.include

pc/device.c

@@ -54,7 +54,11 @@ void device_set_status(int status)
 
 int udp_server()
 {
-    int fd;
+    static bool run_already = false;
+    static int fd = -1;
+    if (run_already && fd >= 0) return fd;
+    run_already = true;
+
     if ( (fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0 ) {
         perror( "socket failed" );
         return 1;

targets/stm32l432/README.md

@@ -1,4 +1,4 @@
-# STM32L4xx Solo
+# STM32L432 Solo
 
-Check out our [official documentation](https://solo.solokeys.io/building/)
+Check out our [official documentation](https://docs.solokeys.io/solo/building/)
 for instructions on building and programming!

targets/stm32l432/lib/usbd/usbd_desc.c

@@ -56,12 +56,14 @@
 #ifndef SOLO_HACKER
 #define USBD_MANUFACTURER_STRING        "Solo Keys"
 #define USBD_PRODUCT_FS_STRING          "Solo"
-#define USBD_SERIAL_NUM                 "solocafebabe"
+#ifndef USBD_SERIAL_NUM
+#define USBD_SERIAL_NUM                 "0123456789ABCDEF"
+#endif
 #else
 #define USBD_MANUFACTURER_STRING        "Solo Keys"
 #define USBD_PRODUCT_FS_STRING          "Solo HACKER (Unlocked)"
 #ifndef USBD_SERIAL_NUM
-#define USBD_SERIAL_NUM                 "Solo-Keys-Solo"
+#define USBD_SERIAL_NUM                 "0123456789ABCDEF"
 #endif
 #endif
 

targets/stm32l432/lib/usbd/usbd_hid.c

@@ -114,15 +114,10 @@ USBD_ClassTypeDef  USBD_HID =
   NULL,
 
 
-
+  USBD_HID_GetFSCfgDesc,
-  NULL,
+  USBD_HID_GetFSCfgDesc,
-  NULL,
+  USBD_HID_GetFSCfgDesc,
-  NULL,
+  USBD_HID_GetDeviceQualifierDesc,
-  NULL,
-  // USBD_HID_GetFSCfgDesc,
-  // USBD_HID_GetFSCfgDesc,
-  // USBD_HID_GetFSCfgDesc,
-  // USBD_HID_GetDeviceQualifierDesc,
 };
 
 #define USBD_HID_CfgHSDesc USBD_HID_OtherSpeedCfgDesc

targets/stm32l432/src/init.c

@@ -276,7 +276,7 @@ void init_usb()
     // Enable USB Clock
     SET_BIT(RCC->APB1ENR1, RCC_APB1ENR1_USBFSEN);
 
-
+#if DEBUG_LEVEL > 0
     USBD_Composite_Set_Classes(&USBD_HID, &USBD_CDC);
     in_endpoint_to_class[HID_EPIN_ADDR & 0x7F] = 0;
     out_endpoint_to_class[HID_EPOUT_ADDR & 0x7F] = 0;
@@ -290,6 +290,10 @@ void init_usb()
     //
     // USBD_RegisterClass(&Solo_USBD_Device, &USBD_CDC);
     USBD_CDC_RegisterInterface(&Solo_USBD_Device, &USBD_Interface_fops_FS);
+#else
+    USBD_Init(&Solo_USBD_Device, &Solo_Desc, 0);
+    USBD_RegisterClass(&Solo_USBD_Device, &USBD_HID);
+#endif
 
     USBD_Start(&Solo_USBD_Device);
 }

tools/solotool.py

@@ -31,11 +31,17 @@ import tempfile
 from binascii import hexlify, unhexlify
 from hashlib import sha256
 
+from cryptography import x509
+from cryptography.hazmat.primitives import hashes
+from cryptography.hazmat.backends import default_backend
+
 from fido2.hid import CtapHidDevice, CTAPHID
 from fido2.client import Fido2Client, ClientError
 from fido2.ctap import CtapError
 from fido2.ctap1 import CTAP1, ApduError
+from fido2.ctap2 import CTAP2
 from fido2.utils import Timeout
+from fido2.attestation import Attestation
 
 import usb.core
 import usb.util
@@ -119,6 +125,7 @@ class SoloBootloader:
 class SoloClient:
     def __init__(self,):
         self.origin = 'https://example.org'
+        self.host = 'example.org'
         self.exchange = self.exchange_hid
         self.do_reboot = True
 
@@ -145,6 +152,8 @@ class SoloClient:
             raise RuntimeError('No FIDO device found')
         self.dev = dev
         self.ctap1 = CTAP1(dev)
+        self.ctap2 = CTAP2(dev)
+        self.client = Fido2Client(dev, self.origin)
 
         if self.exchange == self.exchange_hid:
             self.send_data_hid(CTAPHID.INIT, '\x11\x11\x11\x11\x11\x11\x11\x11')
@@ -222,6 +231,32 @@ class SoloClient:
     def wink(self,):
         self.send_data_hid(CTAPHID.WINK, b'')
 
+    def reset(self,):
+        self.ctap2.reset()
+
+    def make_credential(self,):
+        rp = {'id': self.host, 'name': 'example site'}
+        user = {'id': b'abcdef', 'name': 'example user'}
+        challenge = 'Y2hhbGxlbmdl'
+        attest, data = self.client.make_credential(
+            rp, user, challenge, exclude_list=[]
+        )
+        try:
+            attest.verify(data.hash)
+        except AttributeError:
+            verifier = Attestation.for_type(attest.fmt)
+            verifier().verify(
+                attest.att_statement,
+                attest.auth_data,
+                data.hash
+            )
+        print('Register valid')
+        x5c = attest.att_statement['x5c'][0]
+        cert = x509.load_der_x509_certificate(x5c, default_backend())
+
+        return cert
+
+
     def enter_solo_bootloader(self,):
         """
         If solo is configured as solo hacker or something similar,
@@ -560,11 +595,16 @@ def solo_main():
         help='Continuously dump random numbers generated from Solo.',
     )
     parser.add_argument("--wink", action="store_true", help='HID Wink command.')
+    parser.add_argument("--reset", action="store_true", help='Issue a FIDO2 reset command.  Warning: your credentials will be lost.')
+    parser.add_argument("--verify-solo", action="store_true", help='Verify that the Solo firmware is from SoloKeys.')
     args = parser.parse_args()
 
     p = SoloClient()
     p.find_device()
 
+    if args.reset:
+        p.reset()
+
     if args.rng:
         while True:
             r = p.get_rng(255)
@@ -575,6 +615,15 @@ def solo_main():
         p.wink()
         sys.exit(0)
 
+    if args.verify_solo:
+        cert = p.make_credential()
+        solo_fingerprint = b'r\xd5\x831&\xac\xfc\xe9\xa8\xe8&`\x18\xe6AI4\xc8\xbeJ\xb8h_\x91\xb0\x99!\x13\xbb\xd42\x95'
+
+        if (cert.fingerprint(hashes.SHA256()) == solo_fingerprint):
+            print('Valid firmware from SoloKeys')
+        else:
+            print('This is either a Solo Hacker or a invalid Solo.')
+
 
 def asked_for_help():
     for i, v in enumerate(sys.argv):
@@ -954,6 +1003,10 @@ def main_mergehex():
 
 if __name__ == '__main__':
 
+    if sys.version_info[0] < 3:
+        print('Sorry, python3 is required.')
+        sys.exit(1)
+
     if len(sys.argv) < 2 or (len(sys.argv) == 2 and asked_for_help()):
         print('Diverse command line tool for working with Solo')
         print('usage: %s <command> [options] [-h]' % sys.argv[0])