JITP cert not created with mbedTLS+ATECC608A (works with moquitto_pub) - amazon-web-services

Question

I have the following setup:
ATECC608A
mbedTLS (tested with 2.16.6 and 2.16.9)
coreMQTT
The certificate chain is the following: RootCA > SignerCA > DeviceCert. I've registered both RootCA and SignerCA as CAs in the AWS IoT Console
I setup the chain in mbedTLS with the following:
/* Extract the device certificate and convert to mbedtls cert */
if (0 != atca_mbedtls_cert_add(&device_cert_chain, &g_cert_def_2_device))
{
printf("Failed to parse device cert from device\n");
goto exit;
}
/* Extract the signer certificate, convert, then attach to the chain */
if (0 != atca_mbedtls_cert_add(&device_cert_chain, &g_cert_def_1_signer))
{
printf("Failed to parse signer cert from device\n");
goto exit;
}
When connecting to my ats-endpoint with that stack, the TLS handshake is successul: the device cert and signerCA are presented and AWS presents its cert chain as well. mbedTLS seems to be happy:
....[SNIP]
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_cli.c:2898: <= parse server hello done
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_cli.c:3522: client state: 7
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:2753: => flush output
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:2765: <= flush output
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5343: => write certificate
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: own certificate #1:
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: cert. version : 3
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: serial number : 40:F7:D9:46:59:6E:2F:58:E6:87:04:4F:D5:6E:86:03
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: issuer name : O=CompanyName, CN=signer.companyname.com FFFF
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: subject name : O=CompanyName, CN=pu0223528E47B3461DEE
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: issued on : 2021-01-14 21:00:00
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: expires on : 3000-12-31 23:59:59
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: signed using : ECDSA with SHA256
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: EC key size : 256 bits
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: basic constraints : CA=false
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: key usage : Digital Signature, Key Agreement
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: value of 'crt->eckey.Q(X)' (256 bits) is:
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: c7 1f a4 ea e7 ae 51 16 fb c3 0b ce 33 f1 7a af
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: f1 27 3a af a7 5d 76 76 74 58 e8 56 36 94 56 76
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: value of 'crt->eckey.Q(Y)' (255 bits) is:
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: 5f a6 2e 21 53 a5 91 7d 95 f8 9e 0e f8 ce bd d9
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: c1 50 83 c2 7d 74 98 4b 66 b2 eb 9a b7 49 48 4c
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: own certificate #2:
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: cert. version : 3
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: serial number : 4D:29:66:FF:B8:09:8D:39:0E:39:C8:3A:94:6E:EE:6A
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: issuer name : O=CompanyName, CN=root.companyname.com FFFF
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: subject name : O=CompanyName, CN=signer.companyname.com FFFF
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: issued on : 2020-11-09 17:55:11
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: expires on : 2070-10-28 17:44:12
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: signed using : ECDSA with SHA256
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: EC key size : 256 bits
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: basic constraints : CA=true
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: key usage : Digital Signature, Key Cert Sign, CRL Sign
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: value of 'crt->eckey.Q(X)' (256 bits) is:
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: cc 63 87 d3 bd 58 08 1e c7 55 02 be a8 e1 d7 a2
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: f9 7f 62 0a 39 c6 40 45 cf 1d 83 4a 53 5e 6a e3
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: value of 'crt->eckey.Q(Y)' (255 bits) is:
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: 5b be ad 83 96 10 3c 0e 5b 0b 60 32 65 5d d3 3b
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5395: 77 90 b2 a7 a8 cb 90 b7 49 3f 24 cd c6 6b 1f 38
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:3192: => write handshake message
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:3351: => write record
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:3428: output record: msgtype = 22, version = [3:3], msglen = 982
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:3433: dumping 'output record sent to network' (987 bytes)
....[SNIP]
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:4399: <= read record
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:6606: <= parse finished
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_cli.c:3522: client state: 14
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:2753: => flush output
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:2765: <= flush output
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_cli.c:3633: handshake: done
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_cli.c:3522: client state: 15
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:2753: => flush output
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:2765: <= flush output
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:6350: => handshake wrapup
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:6323: => handshake wrapup: final free
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:6343: <= handshake wrapup: final free
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:6405: <= handshake wrapup
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:8108: <= handshake
ok
TLS Session Established and a Socket is ready for an Application
I then use the created mbedtls_ssl_context to connect coreMQTT. From log, coreMQTT is able to write on the socket but AWS closes the connection.
...[SNIP]...
TLS Session Established and a Socket is ready for an Application
Initializing MQTT...ok
Connecting to the MQTT broker with params:
- identifier='testclient'
- username='?SDK=Fedora&Version=33&Platform=PC&MQTTLib=core-mqtt#v1.1.0'
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:8696: => write
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:3351: => write record
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1443: => encrypt buf
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1453: dumping 'before encrypt: output payload' (85 bytes)
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1453: 0000: 10 53 00 04 4d 51 54 54 04 82 00 3c 00 0a 74 65 .S..MQTT...<..te
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1453: 0010: 73 74 63 6c 69 65 6e 74 00 3b 3f 53 44 4b 3d 46 stclient.;?SDK=F
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1453: 0020: 65 64 6f 72 61 26 56 65 72 73 69 6f 6e 3d 33 33 edora&Version=33
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1453: 0030: 26 50 6c 61 74 66 6f 72 6d 3d 50 43 26 4d 51 54 &Platform=PC&MQT
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1453: 0040: 54 4c 69 62 3d 63 6f 72 65 2d 6d 71 74 74 40 76 TLib=core-mqtt#v
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1453: 0050: 31 2e 31 2e 30 1.1.0
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1572: dumping 'additional data for AEAD' (13 bytes)
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1572: 0000: 00 00 00 00 00 00 00 01 17 03 03 00 55 ............U
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1602: dumping 'IV used (internal)' (12 bytes)
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1602: 0000: 91 d1 a1 52 00 00 00 00 00 00 00 01 ...R........
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1604: dumping 'IV used (transmitted)' (8 bytes)
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1604: 0000: 00 00 00 00 00 00 00 01 ........
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1614: before encrypt: msglen = 93, including 0 bytes of padding
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1641: dumping 'after encrypt: tag' (16 bytes)
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1641: 0000: db 24 89 b1 5f 7f e6 ff 78 dd c3 8b 34 99 79 1f .$.._...x...4.y.
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1779: <= encrypt buf
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:3428: output record: msgtype = 23, version = [3:3], msglen = 109
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:3433: dumping 'output record sent to network' (114 bytes)
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:3433: 0000: 17 03 03 00 6d 00 00 00 00 00 00 00 01 ba 08 e9 ....m...........
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:3433: 0010: fb f4 64 84 4e 6d 31 6e 89 3f 7b 74 e1 9a 0a af ..d.Nm1n.?{t....
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:3433: 0020: 82 33 4e 7b 13 23 de ba 55 19 41 24 6e 95 14 3c .3N{.#..U.A$n..<
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:3433: 0030: 2a 6e 02 67 6d 76 4d f8 32 a0 45 ca 12 a2 1a 31 *n.gmvM.2.E....1
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:3433: 0040: 97 26 45 13 88 07 2c 18 13 ab 92 4b 2b 98 41 49 .&E...,....K+.AI
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:3433: 0050: 03 5a 4f a9 5d 95 33 2b 68 c9 16 ee 2a ad 59 0a .ZO.].3+h...*.Y.
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:3433: 0060: 7a 52 db 24 89 b1 5f 7f e6 ff 78 dd c3 8b 34 99 zR.$.._...x...4.
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:3433: 0070: 79 1f y.
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:2753: => flush output
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:2771: message length: 114, out_left: 114
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:2777: ssl->f_send() returned 114 (-0xffffff8e)
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:2805: <= flush output
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:3484: <= write record
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:8724: <= write
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:8284: => read
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:4325: => read record
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:2534: => fetch input
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:2694: in_left: 0, nb_want: 5
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:2718: in_left: 0, nb_want: 5
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:2720: ssl->f_recv(_timeout)() returned 5 (-0xfffffffb)
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:2740: <= fetch input
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:4061: dumping 'input record header' (5 bytes)
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:4061: 0000: 15 03 03 00 1a .....
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:4067: input record: msgtype = 21, version = [3:3], msglen = 26
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:2534: => fetch input
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:2694: in_left: 5, nb_want: 31
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:2718: in_left: 5, nb_want: 31
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:2720: ssl->f_recv(_timeout)() returned 26 (-0xffffffe6)
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:2740: <= fetch input
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:4246: dumping 'input record from network' (31 bytes)
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:4246: 0000: 15 03 03 00 1a 00 00 00 00 00 00 00 01 33 90 3f .............3.?
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:4246: 0010: df 0b 29 53 90 20 f1 90 14 82 84 99 e9 f6 db ..)S. .........
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1792: => decrypt buf
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1879: dumping 'additional data for AEAD' (13 bytes)
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1879: 0000: 00 00 00 00 00 00 00 01 15 03 03 00 02 .............
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1908: dumping 'IV used' (12 bytes)
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1908: 0000: 3a e9 5a f2 00 00 00 00 00 00 00 01 :.Z.........
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1909: dumping 'TAG used' (16 bytes)
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:1909: 0000: 3f df 0b 29 53 90 20 f1 90 14 82 84 99 e9 f6 db ?..)S. .........
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:2374: <= decrypt buf
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:4273: dumping 'input payload after decrypt' (2 bytes)
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:4273: 0000: 01 00 ..
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5183: got an alert message, type: [1:0]
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:5199: is a close notify message
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:4383: mbedtls_ssl_handle_message_type() returned -30848 (-0x7880)
mbedtls-examples/cryptoauthlib/third_party/mbedtls/library/ssl_tls.c:8349: mbedtls_ssl_read_record() returned -30848 (-0x7880)
I expect the first connection to fail. But in this case, the certificate does not appear in the AWS IoT console and subsequent connection attempts fail as well.
I double checked the signerCA stored and its policy. They seem fine. To ensure that this confg is correct, I manually created a certificate on my machine and signed it with my SignerCA.I then used that certificate with mosquitto_pub. The process works and my certificate appears in the AWS IoT console with the correct policy attached. Here's a log of what I'm doing:
$ openssl genpkey -out fakeDeviceCert.key -algorithm EC -pkeyopt ec_paramgen_curve:P-256
$ openssl req -new -key fakeDeviceCert.key -out fakeDeviceCert.csr
$ openssl x509 -req -in fakeDeviceCert.csr -CA ../certs/signer-FFFF.crt \
-CAkey ../certs/signer-FFFF.key \
-CAcreateserial \
-out fakeDeviceCert.pem \
-days 357335 \
-sha256
$ cat fakeDeviceCert.pem ../certs/signer-FFFF.crt > deviceCertAndCACert.crt
$ mosquitto_pub --cafile AmazonRootCA1.pem \
--cert deviceCertAndCACertcrt --key fakeDeviceCert.key \
-h <redacted>-ats.iot.eu-central-1.amazonaws.com -p 8883 -q 1 -t ji/tp \
-i deviceCert --tls-version tlsv1.2 -m '{"let-me": "in"}' -d
Doing this, I know that the policy attached to my signerCA is correct and running well.
Another verification I've done is to check that my coreMQTT connection is correct. To connect without the JITP provisioning, I extracted the device certificate from the ATECC, manually uploaded its PEM and attached a policy to the device in the AWS console.
That MQTT connection was successful (and I see the 'MQTT.Connect event in the AWS logs).
Here's the relevant certs description. I've redacted the Issuer/Subject from the output so the signatures are incorrect:
The device cert stored in ATECC (the one that does not trigger the provisioning process):
$ openssl x509 -text -noout -in extracted_device_cert.pm
Certificate:
Data:
Version: 3 (0x2)
Serial Number:
40:f7:d9:46:59:6e:2f:58:e6:87:04:4f:d5:6e:86:03
Signature Algorithm: ecdsa-with-SHA256
Issuer: O = CompanyName, CN = signer.companyname.com FFFF
Validity
Not Before: Jan 14 21:00:00 2021 GMT
Not After : Dec 31 23:59:59 3000 GMT
Subject: O = CompanyName, CN = pu0223528E47B3461DEE
Subject Public Key Info:
Public Key Algorithm: id-ecPublicKey
Public-Key: (256 bit)
pub:
04:c7:1f:a4:ea:e7:ae:51:16:fb:c3:0b:ce:33:f1:
7a:af:f1:27:3a:af:a7:5d:76:76:74:58:e8:56:36:
94:56:76:5f:a6:2e:21:53:a5:91:7d:95:f8:9e:0e:
f8:ce:bd:d9:c1:50:83:c2:7d:74:98:4b:66:b2:eb:
9a:b7:49:48:4c
ASN1 OID: prime256v1
NIST CURVE: P-256
X509v3 extensions:
X509v3 Basic Constraints: critical
CA:FALSE
X509v3 Key Usage: critical
Digital Signature, Key Agreement
X509v3 Subject Key Identifier:
4A:F0:38:0D:8E:57:76:71:A2:92:07:B7:60:1B:C7:0A:B4:7E:8B:D1
X509v3 Authority Key Identifier:
keyid:4C:E5:14:B2:9D:3E:8F:29:43:34:45:83:34:C2:F4:09:53:60:13:99
Signature Algorithm: ecdsa-with-SHA256
30:44:02:20:5c:86:11:4b:79:07:ce:34:32:61:6d:00:2a:7c:
43:75:16:e9:b6:ae:13:21:91:25:5f:1b:80:c3:b2:41:93:0d:
02:20:31:fc:4c:6d:5e:f0:54:46:da:ae:d7:aa:b7:f8:6a:c8:
21:ba:45:62:31:7b:55:f7:b3:38:af:7c:97:25:81:72
And the manually generated cert that correctly triggers the JITP:
$ openssl x509 -text -noout -in fakeDeviceCert.pem
Certificate:
Data:
Version: 1 (0x0)
Serial Number:
7a:50:78:20:5e:dc:de:56:74:55:fb:fa:6e:61:ed:13:ed:c9:0a:b7
Signature Algorithm: ecdsa-with-SHA256
Issuer: O = CompanyName, CN = signer.companyname.com FFFF
Validity
Not Before: Jan 15 08:22:44 2021 GMT
Not After : May 23 08:22:44 2999 GMT
Subject: O = CompanyName, CN = pu010203040506070811
Subject Public Key Info:
Public Key Algorithm: id-ecPublicKey
Public-Key: (256 bit)
pub:
04:62:1e:35:5a:97:ec:7f:f7:82:6e:67:7a:ac:a5:
1b:b0:a3:bc:42:08:cb:0e:fe:ad:07:46:0c:dd:8c:
ca:b3:60:8f:e3:0b:59:a4:b3:e5:6b:a5:22:8e:49:
d3:3a:1e:76:43:7b:7a:cd:dd:0d:dc:52:1f:8f:83:
ee:10:e0:fb:1a
ASN1 OID: prime256v1
NIST CURVE: P-256
Signature Algorithm: ecdsa-with-SHA256
30:46:02:21:00:8f:3a:b4:e4:25:98:3c:79:23:65:e4:1b:68:
75:19:11:27:91:df:66:22:ea:c1:13:06:72:6f:e0:5d:3d:13:
49:02:21:00:e2:7e:2b:92:55:68:98:09:b9:a4:e9:7b:2a:7c:
48:2a:bb:23:c7:45:d2:96:ec:df:9b:62:a8:9d:7a:98:06:fe
Here's the signerCA description from AWS (with some redacted fields between <>)
$ aws iot describe-ca-certificate --certificate-id <my-ca-cert-id>
{
"certificateDescription": {
"certificateArn": "arn:aws:iot:eu-central-1:<accountID>:cacert/<ca-id>",
"certificateId": "<ca-id>",
"status": "ACTIVE",
"certificatePem": "-----BEGIN CERTIFICATE-----\n<pem-content>-----END CERTIFICATE-----\n",
"ownedBy": "<owner-account-id>",
"creationDate": "2021-01-11T10:40:58.736000+01:00",
"autoRegistrationStatus": "ENABLE",
"lastModifiedDate": "2021-01-14T23:38:52.132000+01:00",
"customerVersion": 2,
"generationId": "09eb8608-630c-4632-a1ef-0879f6f2dd6f",
"validity": {
"notBefore": "2020-11-09T18:55:11+01:00",
"notAfter": "2070-10-28T18:44:12+01:00"
}
},
"registrationConfig": {
"templateBody": "{\"Parameters\": {\"AWS::IoT::Certificate::CommonName\": {\"Type\": \"String\"}, \"AWS::IoT::Certificate::Id\": {\"Type\": \"String\"}}, \"Resources\": {\"thing\": {\"Type\": \"AWS::IoT::Thing\", \"Properties\": {\"ThingName\": {\"Ref\": \"AWS::IoT::Certificate::CommonName\"}, \"AttributePayload\": {\"version\": \"v1\"}}}, \"certificate\": {\"Type\": \"AWS::IoT::Certificate\", \"Properties\": {\"CertificateId\": {\"Ref\": \"AWS::IoT::Certificate::Id\"}, \"Status\": \"ACTIVE\"}}, \"policy\": {\"Type\": \"AWS::IoT::Policy\", \"Properties\": {\"PolicyDocument\": \"{\\\"Version\\\": \\\"2012-10-17\\\", \\\"Statement\\\": [{\\\"Effect\\\": \\\"Allow\\\", \\\"Action\\\": [\\\"iot:Connect\\\", \\\"iot:Publish\\\", \\\"iot:Subscribe\\\", \\\"iot:Receive\\\", \\\"iot:GetThingShadow\\\", \\\"iot:DeleteThingShadow\\\", \\\"iot:UpdateThingShadow\\\"], \\\"Resource\\\": [\\\"*\\\"]}]}\"}}}}",
"roleArn": "arn:aws:iam::<account-id>:role/JITP-Role"
}
}
I'm a bit lost and have a few questions:
mbedTLS seems to present the two concatened certificates. Would the handshake be successful if one them was not correct or if mbedTLS was misconfigured?
Could the X509v3 extensions be responsible for the JITP failure? The device cert has them, while the manually-generated one has not.
Is there a way to log mutual authentication failures in Cloudwatch?
Is there anything that I missed?
(EDIT: If I don't include the signerCA in the cert chain when connecting, the TLS handshake is still successful. Of course, in that case I expect the JITP process to fail because AWS cannot find the associated CA).
EDIT2:
I've tried to connect with mosquitto and a certificate that is much closer to the one used by the ATECC (same algos and same X509v3 extensions). The outcome is the same: the manually generated one with mosquitto can trigger the JITP while the one from ATECC cannot.

Answer 1

Got it. I was retrieving the public key of my root certificate in the wrong slot in the ATECC (ouch). This was resulting in a slightly different signerCA to be generated by the atcacert_def_t and the template at runtime.
I missed it because all my tooling in Python was fetching the right slot while the C version was not kept perfectly in sync.