Bonjour,
Having a critical extension adds 3 octets (the BOOLEAN tag, length=1, value=0xff). It may, as a side effect, enlarge the number of octets necessary to encode some structure size.
Remove the 2 Netscape extensions, they're way obsolete (don't know why OpenSSL keeps them by default).
If size is a hard constraint:
- you can probably remove the emailProtection EKU (it's an OID, you'll gain 10 octets). Depending on your use-case, you may need to tweak the EKU (or remove it completely).
- SKI and AKI extensions may not be necessary
- Key Usage may be marked as non critical (it's a SHOULD in PKIX)
A quick reading of RFC8002 tells me that you may need to include the IssuerAltName extension as well?
Cordialement,
Erwann Abalea
Le 16/08/2019 17:11, « openssl-users au nom de Robert Moskowitz » <openssl-users-bounces@xxxxxxxxxxx au nom de rgm@xxxxxxxxxxxxxxx> a écrit :
Viktor,
On 8/16/19 8:41 AM, Viktor Dukhovni wrote:
>> On Aug 16, 2019, at 6:13 AM, Salz, Rich via openssl-users <openssl-users@xxxxxxxxxxx> wrote:
>>
>> subjectAltName is rarely marked as critical; sec 4.2.1.6 of PKIX says "SHOULD mark subjectAltName as non-critical"
> This is wrong. When the subject DN is empty, the subjectAltName should be
> marked as critical. IIRC some Java implementations reject the certificate
> otherwise.
I have just created a client cert with empty subjectName and critical
subjectAltName. Interestingly, it is 4 bytes larger than the earlier
non-critical SAN cert. See below for the output of the cert.
>> I can believe that OpenSSL doesn't support empty subjectName's. An empty one, with no relative disintuished name components, is not the same as not present.
> OpenSSL supports empty (empty RDN sequence) subject DNs.
> The "-subj /" option is one way to make that happen.
>
> Empty is of course different from "absent", which is not
> possible, since the subject DN is a required component of
> an X.509 certificate.
I now have it clear that Empty SN is NOT a cert with NO SN. It is there
with null content.
Thank you all.
$ openssl x509 -noout -text -in $dir/certs/device2.cert.pem
Certificate:
Data:
Version: 3 (0x2)
Serial Number:
c9:8f:b2:7b:e1:95:74:d0
Signature Algorithm: ED25519
Issuer: CN = 2001:24:28:14::/64
Validity
Not Before: Aug 16 14:54:58 2019 GMT
Not After : Aug 25 14:54:58 2020 GMT
Subject:
Subject Public Key Info:
Public Key Algorithm: ED25519
ED25519 Public-Key:
pub:
69:4f:1c:77:56:69:3a:cd:86:c4:3a:b0:67:b9:50:
c3:12:9c:6f:85:65:a0:8f:fa:b5:74:b1:c4:56:f8:
4c:a5
X509v3 extensions:
X509v3 Basic Constraints:
CA:FALSE
Netscape Cert Type:
SSL Client, S/MIME
Netscape Comment:
OpenSSL Generated Client Certificate
X509v3 Subject Key Identifier:
8A:8D:18:B6:F7:70:7D:17:64:AA:2F:C7:FF:1F:C2:30:E2:D8:56:DD
X509v3 Authority Key Identifier:
keyid:B1:45:18:9B:33:82:6C:74:29:69:2A:15:93:3B:1C:31:D2:37:D6:CA
X509v3 Key Usage: critical
Digital Signature, Non Repudiation, Key Encipherment
X509v3 Extended Key Usage:
TLS Web Client Authentication, E-mail Protection
X509v3 Subject Alternative Name: critical
IP Address:2001:24:28:14:2B6E:2C43:A2D8:507C
Signature Algorithm: ED25519
01:54:3e:d2:21:36:27:57:f2:da:d7:ee:42:ec:8f:05:99:b1:
4b:de:2c:c4:3b:95:6f:ba:f6:25:a5:10:bb:2d:5c:9b:15:46:
dc:67:ea:b4:74:df:a6:52:60:6f:cd:06:af:f4:69:5f:37:1a:
ba:1a:b4:17:c0:bb:0f:da:be:02
