Diacritical letters (ÖÄÜÕ) in HTTPS certificate name and oracle wallet (orapki)

I had to use oracle UTL_HTTP to access HTTPS site.

The site uses diacritical letters (öäüõ) in certificate organization name.
This site was https://ariregister.rik.ee/ where subject was

CN = *.rik.ee
O = Registrite ja infosüsteemide Keskus
L = Tallinn
C = EE

Typically I have added all certificates in path as trusted root certs into oracle wallet.
In this case, there were three certificates on path:

So I exported those as:

• *.rik.ee to arireg1.cer
• DigiCert SHA2 High Assurance Server CA to arireg2.cer
• DigiCert High Assurance EV Root CA to arireg3.cer

And imported them to oracle wallet:

orapki wallet add -wallet /u01/app/oracle/admin/MYSID/xdb_wallet/ -trusted_cert -cert "/tmp/arireg1.cer" -pwd XXXXXX
orapki wallet add -wallet /u01/app/oracle/admin/MYSID/xdb_wallet/ -trusted_cert -cert "/tmp/arireg2.cer" -pwd XXXXXX
orapki wallet add -wallet /u01/app/oracle/admin/MYSID/xdb_wallet/ -trusted_cert -cert "/tmp/arireg3.cer" -pwd XXXXXX

Using it this way, it has worked for me before. But, not this time!
With UTL_HTTP I got certificate validation error:

ORA-29024: Certificate validation failure

orapki displays:

orapki wallet display -wallet /u01/app/oracle/admin/MYSID/xdb_wallet/ -detailed

Requested Certificates:
User Certificates:
Trusted Certificates:
Subject:        CN=DigiCert SHA2 High Assurance Server CA,OU=www.digicert.com,O=DigiCert Inc,C=US
Issuer:         CN=DigiCert High Assurance EV Root CA,OU=www.digicert.com,O=DigiCert Inc,C=US
Serial Number:  04:E1:E7:A4:DC:5C:F2:F3:6D:C0:2B:42:B8:5D:15:9F
Key Length      2048
MD5 digest:     AA:EE:5C:F8:B0:D8:59:6D:2E:0C:BE:67:42:1C:F7:DB
SHA digest:     A0:31:C4:67:82:E6:E6:C6:62:C2:C8:7C:76:DA:9A:A6:2C:CA:BD:8E

Subject:        CN=DigiCert High Assurance EV Root CA,OU=www.digicert.com,O=DigiCert Inc,C=US
Issuer:         CN=DigiCert High Assurance EV Root CA,OU=www.digicert.com,O=DigiCert Inc,C=US
Serial Number:  02:AC:5C:26:6A:0B:40:9B:8F:0B:79:F2:AE:46:25:77
Key Length      2048
MD5 digest:     D4:74:DE:57:5C:39:B2:D3:9C:85:83:C5:C0:65:49:8A
SHA digest:     5F:B7:EE:06:33:E2:59:DB:AD:0C:4C:9A:E6:D3:8F:1A:61:C7:DC:25

Subject:        CN=*.rik.ee,O=Registrite ja infosĆ¼steemide Keskus,L=Tallinn,C=EE
Issuer:         CN=DigiCert SHA2 High Assurance Server CA,OU=www.digicert.com,O=DigiCert Inc,C=US
Serial Number:  09:2B:5F:E2:CC:EB:C5:26:81:99:91:3F:9B:55:1F:8F
Key Length      2048
MD5 digest:     5B:2E:D6:67:DD:C8:46:20:F6:6E:6C:3E:52:0F:F6:1D
SHA digest:     E8:DA:53:57:C5:6F:3D:5D:EB:4E:EA:49:71:C3:72:A5:94:97:D6:67

Struggled a whole day. 

With no solution. The bad thing is that Oracle does not give any additional trace information, what is wrong with the cert. As other sites were working OK this way, the diacritical letters became suspects.
Also tested with

openssl s_client -connect ariregister.rik.ee:443 -tls1 -showcerts

Finally I learned

Because site certificate don't have to be in wallet (only root certificates must be). I decided to remove the site certificate (with diacritical letters) from wallet.
Cleared the wallet:

orapki wallet remove -wallet /u01/app/oracle/admin/MYSID/xdb_wallet/ -trusted_cert_all  -pwd XXXXX

Added only 2 upper level certificates (and not leaf cert "arireg1.cer"):

orapki wallet add -wallet /u01/app/oracle/admin/MYSID/xdb_wallet/ -trusted_cert -cert "/tmp/arireg2.cer" -pwd XXXXXX
orapki wallet add -wallet /u01/app/oracle/admin/MYSID/xdb_wallet/ -trusted_cert -cert "/tmp/arireg3.cer" -pwd XXXXXX

After that, it started working!

Conclusions

• I am not entirely sure that the diacritical letters were the reason. But other sites (without diacritical letters on O name) were working OK.
• I wonder what would happen if some trusted root certificate issuer had diagritical letters in its name?
• Got problem solved as site certificate itself does not have to be in wallet.