*.hycu.ac.kr

- HanyangCyber University -

Issued by GeoTrust RSA CA 2018

About this certificate

This digital certificate with serial number 0c:ca:94:d1:bb:c5:44:43:9e:a7:fd:6e:c9:94:96:cb was issued on by DigiCert Inc.

With 2 subject alternative names this certificate can be used to secure multiple fqdn's. This certificate has already expired and will cause a warning or error message in the browser it's still listed on this site to allow you to look back on previously issued certificates. If we have found any compliance issues with this certificate they will be shown below. I hope this certificate review is providing you the detailed information in a simple form you where looking for.


We have idenified some issues with this certificate:
  • Subscriber Certificate: commonName is deprecated. (BRs: 7.1.4.2.2)

HanyangCyber University

Organization: HanyangCyber University
Locality: Seongdong-gu
Country: KR

DigiCert Inc

Organization: DigiCert Inc
Organization unit: www.digicert.com
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 0c:ca:94:d1:bb:c5:44:43:9e:a7:fd:6e:c9:94:96:cb
Serial Number (int): 17002598328262509175618828930481690315
Serial Number lenght: 124 bits, 16 octets

SubjectKeyId: 35:5b:f6:f7:dc:08:9c:a0:be:75:2b:33:2f:19:d8:e6:11:66:de:92
AuthorityKeyId: 90:58:ff:b0:9c:75:a8:51:54:77:b1:ed:f2:a3:43:16:38:9e:6c:c5

Fingerprint (sha1): 09:bb:b5:17:6f:15:02:7d:6e:12:3a:bc:45:43:1d:ee:d6:ea:0c:42
Fingerprint (sha256): 88:a5:76:5f:91:e3:95:f4:65:d7:4a:f9:87:ca:c5:21:e6:a5:9b:5b:10:02:98:ea:9b:90:e6:03:6d:1c:08:a1

Issuing Certificate URL: http://cacerts.geotrust.com/GeoTrustRSACA2018.crt

Revocation information

OCSP Server: http://status.geotrust.com
CRL Distribution Point: http://cdp.geotrust.com/GeoTrustRSACA2018.crl

Check the revocation status for certificate *.hycu.ac.kr

2

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for *.hycu.ac.kr

Public Key Algorithm

RSA

Key Size

2048

Signature Algorithm

SHA256 with RSA

Key Usage

Digital Signature
Key Encipherment

Extended Key Usages

Server Authentication
Client Authentication

Extensions

9 extensions
No unhandled critical extensions

CA Certificate

This is not a CA certificate

Subject Alternative Names

*.hycu.ac.kr
hycu.ac.kr

Other certificates including the domain name hycu.ac.kr

(limited to 100 certificates)
*.hycu.ac.kr
*.hycu.ac.kr
*.hycu.ac.kr
*.hycu.ac.kr
*.hycu.ac.kr
autodiscover.hycu.ac.kr
*.hycu.ac.kr
*.hycu.ac.kr
autodiscover.hycu.ac.kr
*.hycu.ac.kr
*.hycu.ac.kr
*.hycu.ac.kr
*.hycu.ac.kr
*.hycu.ac.kr

Certificate

The complete raw certificate details for *.hycu.ac.kr in PEM and ASN.1 format.

Certificate (PEM)

-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

Public Key (PEM)

-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAyoc1nxvuhWvYWapc/l8k
SsUOnceLgHJEfdBkHKRjk4csCKXKwz11nsp/d1bZ/ga0f8xWS8XNdnjAGWpMwF3L
/Zn3pun1kX3ZlXfU+2y2bZ14ylK0eVr/Oxd4hqE099Il/jE1DeJm4FDDxZ2FqQxG
zjEpSJehGRFkAfOjhZmgqFniJY0HNuMYO5cKUyUJH4FXO151SjswH2FNAJIz31DQ
OrVQl2wvYBapz7H6od3qf0g26r94ByZeLG35n3UupYn+tNotcjnQOAXfhTCNhdxt
GKByuKHpH8SpDtNkd7jF0TXdg5KzXzeWoPJQeVQa19ABws8zyQ6MQfrDyRSMITCv
7QIDAQAB
-----END PUBLIC KEY-----

ASN.1 decoded

 [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . [c:2|t:0|true] OtherName 
 . . . . . . . . . . . . [c:0|t:2|false] INTEGER 2
 . . . . . . . . [c:0|t:2|false] INTEGER 17002598328262509175618828930481690315
 . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 1.2.840.113549.1.1.11 (sha256WithRSAEncryption)
 . . . . . . . . . . . . [c:0|t:5|false] NULL 
 . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . [c:0|t:17|true] SET, SET OF 
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.5.4.6 (countryName)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:19|false] PrintableString 'US'
 . . . . . . . . . . . . [c:0|t:17|true] SET, SET OF 
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.5.4.10 (organizationName)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:19|false] PrintableString 'DigiCert Inc'
 . . . . . . . . . . . . [c:0|t:17|true] SET, SET OF 
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.5.4.11 (organizationalUnitName)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:19|false] PrintableString 'www.digicert.com'
 . . . . . . . . . . . . [c:0|t:17|true] SET, SET OF 
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.5.4.3 (commonName)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:19|false] PrintableString 'GeoTrust RSA CA 2018'
 . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2018-01-19 00:00:00 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2018-08-17 12:00:00 +0000 UTC
 . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . [c:0|t:17|true] SET, SET OF 
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.5.4.6 (countryName)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:19|false] PrintableString 'KR'
 . . . . . . . . . . . . [c:0|t:17|true] SET, SET OF 
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.5.4.7 (localityName)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:19|false] PrintableString 'Seongdong-gu'
 . . . . . . . . . . . . [c:0|t:17|true] SET, SET OF 
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.5.4.10 (organizationName)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:19|false] PrintableString 'HanyangCyber University'
 . . . . . . . . . . . . [c:0|t:17|true] SET, SET OF 
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.5.4.3 (commonName)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:12|false] UTF8String '*.hycu.ac.kr'
 . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 1.2.840.113549.1.1.1 (rsaEncryption)
 . . . . . . . . . . . . . . . . [c:0|t:5|false] NULL 
 . . . . . . . . . . . . [c:0|t:3|false] BIT STRING (2160 bits)
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:2|false] INTEGER 25566811872391518048829117873961223954341814699678298373331265007733353168168669196989482871973330571880547266275875403988691532044927508480555887193488856260808959450752730392631485035907859755477814208564487545865453722583929778198210769687596055536284918299376180569268221614084148006736198181032003979269071346114197519728669620826899362768717926489374797563736662517477011996418375857517607831494411979799175530736703349094643955275028333053656649536283485676601211844570507410239543346934085826758935799106204865347971693245966873015712787992370607827111703977598848621315051642081796975593747294258647037685741
 . . . . . . . . . . . . . . . . . . . . [c:0|t:2|false] INTEGER 65537

 . . . . . . . . [c:2|t:3|true] ORAddress 
 . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.5.29.35 (authorityKeyIdentifier)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (24 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:0|false] OtherName 9058ffb09c75a8515477b1edf2a34316389e6cc5
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.5.29.14 (subjectKeyIdentifier)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (22 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (20 bytes)
							355bf6f7dc089ca0be752b332f19d8e61166de92
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.5.29.17 (subjectAltName)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (28 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String '*.hycu.ac.kr'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'hycu.ac.kr'
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.5.29.15 (keyUsage)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:1|false] BOOLEAN true
 . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (4 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:3|false] BIT STRING (3 bits)
							05a0
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.5.29.37 (extKeyUsage)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (22 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 1.3.6.1.5.5.7.3.1 (serverAuth)
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 1.3.6.1.5.5.7.3.2 (clientAuth)
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.5.29.31 (cRLDistributionPoints)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (55 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:0|true] OtherName 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:0|true] OtherName 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:6|false] IA5String 'http://cdp.geotrust.com/GeoTrustRSACA2018.crl'
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.5.29.32 (certificatePolicies)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (69 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.16.840.1.114412.1.1 (digiCertOVCert)
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 1.3.6.1.5.5.7.2.1 (cps)
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:22|false] IA5String 'https://www.digicert.com/CPS'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.23.140.1.2.2 (Organization Validation Certificates Policy)
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 1.3.6.1.5.5.7.1.1 (authorityInfoAccess)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (105 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 1.3.6.1.5.5.7.48.1 (ocsp)
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:6|false] IA5String 'http://status.geotrust.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 1.3.6.1.5.5.7.48.2 (caIssuers)
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:6|false] IA5String 'http://cacerts.geotrust.com/GeoTrustRSACA2018.crt'
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.5.29.19 (basicConstraints)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (2 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 1.2.840.113549.1.1.11 (sha256WithRSAEncryption)
 . . . . . . . . [c:0|t:5|false] NULL 
 . . . . [c:0|t:3|false] BIT STRING (2048 bits)
		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