*.kfb.or.kr
- korea federation of banks -
Issued by GeoTrust RSA CA 2018
About this certificate
This digital certificate with serial number 09:a4:58:48:c5:3c:80:c6:81:8c:e1:30:fc:80:f9:d7 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)
korea federation of banks
Organization:
korea federation of banks
State / Province:
Seoul
Locality: jung-gu
Country: KR
Locality: jung-gu
Country: KR
DigiCert Inc
Organization:
DigiCert Inc
Organization unit: www.digicert.com
Organization unit: www.digicert.com
Country:
US
This certificate has expire since
Certificate Details
Serial Number (hex): 09:a4:58:48:c5:3c:80:c6:81:8c:e1:30:fc:80:f9:d7Serial Number (int): 12816379264378467569924952960278788567
Serial Number lenght: 124 bits, 16 octets
SubjectKeyId: f1:32:0a:4c:4c:8c:59:a8:70:4a:41:2b:e9:9c:b7:05:24:c6:8f:c3
AuthorityKeyId: 90:58:ff:b0:9c:75:a8:51:54:77:b1:ed:f2:a3:43:16:38:9e:6c:c5
Fingerprint (sha1): e4:be:f8:94:79:cd:6d:6b:8f:63:32:0e:0d:69:e3:f2:35:0f:38:64
Fingerprint (sha256): ec:6c:0d:57:f6:03:e8:15:12:95:eb:15:19:9b:e1:5c:6d:2d:64:86:26:58:ec:7c:38:9d:7e:00:06:95:34:29
Issuing Certificate URL: http://cacerts.geotrust.com/GeoTrustRSACA2018.crt
Revocation information
OCSP Server: http://status.geotrust.comCRL Distribution Point: http://cdp.geotrust.com/GeoTrustRSACA2018.crl
Check the revocation status for certificate *.kfb.or.kr
2
DNS Names
0
Email Addresses
0
IP Addresses
Advanced Certificate Properties
Tehnical certificate details for *.kfb.or.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
10 extensions
No
unhandled critical extensions
CA Certificate
This is not a CA certificate
Subject Alternative Names
*.kfb.or.kr
kfb.or.kr
kfb.or.kr
Other certificates including the domain name kfb.or.kr
(limited to 100 certificates)
Certificate
The complete raw certificate details for *.kfb.or.kr in PEM and ASN.1 format.
Certificate (PEM)
-----BEGIN CERTIFICATE----- MIIFDjCCA/agAwIBAgIQCaRYSMU8gMaBjOEw/ID51zANBgkqhkiG9w0BAQsFADBe MQswCQYDVQQGEwJVUzEVMBMGA1UEChMMRGlnaUNlcnQgSW5jMRkwFwYDVQQLExB3 d3cuZGlnaWNlcnQuY29tMR0wGwYDVQQDExRHZW9UcnVzdCBSU0EgQ0EgMjAxODAe Fw0xOTA1MjMwMDAwMDBaFw0yMTA2MjExMjAwMDBaMGkxCzAJBgNVBAYTAktSMQ4w DAYDVQQIEwVTZW91bDEQMA4GA1UEBxMHanVuZy1ndTEiMCAGA1UEChMZa29yZWEg ZmVkZXJhdGlvbiBvZiBiYW5rczEUMBIGA1UEAwwLKi5rZmIub3Iua3IwggEiMA0G CSqGSIb3DQEBAQUAA4IBDwAwggEKAoIBAQDZHt7YQcz6FK/vhwWiAy6nrVvJaf87 74YogvxhrtcH3E/8XpVuLN0OdakZOM8Z91s47KZXVMxiUeD2NQP9zDD69YxrDdi9 I33Z8iJmj0w+COInczjwJl+QY7yj1QHksQeTCmGgYp1whvfCmd2Hc943aDpXCAL0 XgI/HyD/9Ov79t5YGDhQjcbs0cFSbkKzHlBrr4Yk6XvoSzz9pDG2VRJT2LFlKPDL 9wkEWcugMV2jAoBQb2xlgVJzC3rYXnO7Aev1koC3UnKRKKfJgdILBQEvG8Nj5Q4e vH7V8ocYIcOQ+GbJch0e7RItoH8wPZ8yZdKpLKhbplDgMFXMzKamHxR5AgMBAAGj ggG7MIIBtzAfBgNVHSMEGDAWgBSQWP+wnHWoUVR3se3yo0MWOJ5sxTAdBgNVHQ4E FgQU8TIKTEyMWahwSkEr6Zy3BSTGj8MwIQYDVR0RBBowGIILKi5rZmIub3Iua3KC CWtmYi5vci5rcjAOBgNVHQ8BAf8EBAMCBaAwHQYDVR0lBBYwFAYIKwYBBQUHAwEG CCsGAQUFBwMCMD4GA1UdHwQ3MDUwM6AxoC+GLWh0dHA6Ly9jZHAuZ2VvdHJ1c3Qu Y29tL0dlb1RydXN0UlNBQ0EyMDE4LmNybDBMBgNVHSAERTBDMDcGCWCGSAGG/WwB ATAqMCgGCCsGAQUFBwIBFhxodHRwczovL3d3dy5kaWdpY2VydC5jb20vQ1BTMAgG BmeBDAECAjB1BggrBgEFBQcBAQRpMGcwJgYIKwYBBQUHMAGGGmh0dHA6Ly9zdGF0 dXMuZ2VvdHJ1c3QuY29tMD0GCCsGAQUFBzAChjFodHRwOi8vY2FjZXJ0cy5nZW90 cnVzdC5jb20vR2VvVHJ1c3RSU0FDQTIwMTguY3J0MAkGA1UdEwQCMAAwEwYKKwYB BAHWeQIEAwEB/wQCBQAwDQYJKoZIhvcNAQELBQADggEBAIsacMKlfv6MadlGeAia 4TEuFIsbB0lHViqZn4g1T6lP1KghUx7QTElVgmmkwpJXU9XDZZbuPr1wc7ZsC0wN N95w26FCqqjniES2LTYM6V1iOzsoLUdaM8GnACC8USUuPb2TDikPBYarw1GDvc42 IPsqPuDgnUxV82vF3c1gz5kowZVhNoxn28GXFU/816cfh8ss08lK2NzzyODBbLSc xaQlFO5iAJ0XjTtMp6YB3ocV5WNAf0fXIlN/9i/pFTFPGmoyH/yqGWNqrVoIIZv4 U873MGAEhlhS1of0oyCpsfy5x5nJk8gUA8shFMFOOpeNolRx9HIGxVWlVqQhvAnD Kp8= -----END CERTIFICATE-----
Public Key (PEM)
-----BEGIN PUBLIC KEY----- MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA2R7e2EHM+hSv74cFogMu p61byWn/O++GKIL8Ya7XB9xP/F6VbizdDnWpGTjPGfdbOOymV1TMYlHg9jUD/cww +vWMaw3YvSN92fIiZo9MPgjiJ3M48CZfkGO8o9UB5LEHkwphoGKdcIb3wpndh3Pe N2g6VwgC9F4CPx8g//Tr+/beWBg4UI3G7NHBUm5Csx5Qa6+GJOl76Es8/aQxtlUS U9ixZSjwy/cJBFnLoDFdowKAUG9sZYFScwt62F5zuwHr9ZKAt1JykSinyYHSCwUB LxvDY+UOHrx+1fKHGCHDkPhmyXIdHu0SLaB/MD2fMmXSqSyoW6ZQ4DBVzMymph8U eQIDAQAB -----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 12816379264378467569924952960278788567 . . . . . . . . [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 2019-05-23 00:00:00 +0000 UTC . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2021-06-21 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 2.5.4.8 (stateOrProvinceName) . . . . . . . . . . . . . . . . . . . . [c:0|t:19|false] PrintableString 'Seoul' . . . . . . . . . . . . [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 'jung-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 'korea federation of banks' . . . . . . . . . . . . [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 '*.kfb.or.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 27408934982294141420116668743410927425041580599099505440977430224534887608782741533008497370459596148126388261080630623653351430048776285111290538038083794234312537847171323923195175568413522790184558583276896883113542419581195823365524036182010027060947024974121014181466611750837275968152795085884445950818968342517396651371933305326558908141165434339164137830947922749073397164221871492122536937334583181295171458530660616165189830246153769164798611700430671449306944749685689516315690689954625198852470997540750269568517985909045188075425369878573581911468929731925357175744047589516842980300463276933717212206201 . . . . . . . . . . . . . . . . . . . . [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) f1320a4c4c8c59a8704a412be99cb70524c68fc3 . . . . . . . . . . . . . . . . [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 (26 bytes) . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String '*.kfb.or.kr' . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'kfb.or.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 1.3.6.1.4.1.11129.2.4.3 (CT Precertificate Poison) . . . . . . . . . . . . . . . . . . . . [c:0|t:1|false] BOOLEAN true . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (2 bytes) . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:5|false] NULL . . . . [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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