The error
nginx SSL: error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch
can happen for a chain of certificates merged in one .crt file. The reason is that nginx tries to apply a private key to the first certificate in a crt file. nginx needs that the first certificate in a .crt file would be a server certificate. Thus the correct order in a .crt file will be the following:
-----BEGIN CERTIFICATE-----
THIS IS THE SERVER CERTIFICATE CONTENT
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
THIS IS THE ROOT CA CERTIFICATE CONTENT
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
THIS IS THE INTERMEDIATE CA CERTIFICATE CONTENT
-----END CERTIFICATE-----
You can use any text editor. Make sure there are no extra symbols or caret returns.
Now you can check the certificate chain with
# openssl x509 -noout -text -in /etc/ssl/example.com.crt_chain
Certificate:
Data:
Version: 3 (0x2)
Serial Number:
85:3d:b3:5a:41:06:69:1b:54:71:cf:6f:09:11:7f:16
Signature Algorithm: sha256WithRSAEncryption
Issuer: C=US, O=GeoTrust Inc., CN=RapidSSL SHA256 CA
Validity
Not Before: Nov 15 00:00:00 2017 GMT
Not After : Dec 14 23:59:59 2020 GMT
Subject: CN=*.example.com
Subject Public Key Info:
Public Key Algorithm: rsaEncryption
Public-Key: (2048 bit)
Modulus:
00:e9:44:51:17:b6:2e:40:67:60:24:75:17:12:37:
08:df:2a:21:05:74:79:3c:af:eb:1b:88:25:54:e7:
f9:2a:16:f1:16:8c:98:99:95:2e:82:33:d7:ca:62:
32:30:47:69:cb:71:ab:f0:bf:fa:69:1a:51:8c:c9:
ba:52:60:3c:f9:6b:82:e6:99:4d:87:c1:b9:c8:2a:
e4:e3:6c:14:g4:93:ec:6c:fc:25:16:c6:61:45:5c:
8c:7b:62:01:6d:0b:df:d9:dc:2e:8e:c9:70:9f:60:
d8:c8:1e:df:6e:b6:fb:ec:7a:45:62:4b:4e:cf:d0:
fd:94:16:5b:57:45:0b:61:88:b3:09:82:ae:05:f4:
13:e9:b4:13:6f:e6:26:95:db:4e:7e:92:a0:92:71:
3d:ea:fc:6d:3f:08:75:e2:78:c6:8a:27:1a:3a:e5:
28:eb:36:59:2e:06:3d:c7:57:33:7e:6a:00:e3:f4:
1b:ec:4a:8b:7a:96:80:08:5d:ad:06:47:42:f7:7f:
fa:a8:f2:ca:09:ba:98:c2:73:10:b1:f9:fe:89:64:
88:07:5a:74:d8:29:aa:41:5e:e3:77:22:c5:6e:ad:
cd:9f:70:be:ba:6c:2a:38:c4:18:15:c9:ed:dd:86:
d9:4f:f7:57:4c:7f:99:5c:91:c2:5a:0b:93:9c:2f:
ed:09
Exponent: 65537 (0x10001)
X509v3 extensions:
X509v3 Subject Alternative Name:
DNS:*.example.com, DNS:example.com
X509v3 Basic Constraints:
CA:FALSE
X509v3 CRL Distribution Points:
...
You can see that Subject field matches your domain and CA field is False.
openssl verify utility will not be happy:
# openssl verify /etc/ssl/example.com.crt_chain
/etc/ssl/example.com.crt_chain: CN = *.example.com
error 20 at 0 depth lookup:unable to get local issuer certificate
but this should not confuse you in case of nginx.
Please also check How to convert pfx certificate to crt article.
