chimajarak.co.kr

Issued by Let's Encrypt Authority X3

About this certificate

This digital certificate with serial number 04:e4:ec:07:77:21:ac:27:02:56:24:d1:f8:4d:27:77:d7:27 was issued on by Let's Encrypt.

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)

Certificate Subject

CN=chimajarak.co.kr

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 04:e4:ec:07:77:21:ac:27:02:56:24:d1:f8:4d:27:77:d7:27
Serial Number (int): 426347259954372756924293252727686664017703
Serial Number lenght: 139 bits, 18 octets

SubjectKeyId: f5:16:6f:79:11:c1:49:a9:21:f9:e3:a2:7d:ff:84:b4:2c:27:28:99
AuthorityKeyId: a8:4a:6a:63:04:7d:dd:ba:e6:d1:39:b7:a6:45:65:ef:f3:a8:ec:a1

Fingerprint (sha1): 8d:1e:dd:4e:c2:0d:95:1c:2d:92:ed:29:db:54:95:49:fa:e9:d6:28
Fingerprint (sha256): ac:86:d8:92:8e:87:21:85:d4:9e:1e:64:3a:85:1b:7b:61:a7:27:f6:f3:eb:cc:d1:44:6e:46:29:43:ce:99:c5

Issuing Certificate URL: http://cert.int-x3.letsencrypt.org/

Revocation information

OCSP Server: http://ocsp.int-x3.letsencrypt.org

Check the revocation status for certificate chimajarak.co.kr

2

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for chimajarak.co.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

chimajarak.co.kr
www.chimajarak.co.kr

Other certificates including the domain name chimajarak.co.kr

(limited to 100 certificates)
chimajarak.co.kr
chimajarak.co.kr
chimajarak.co.kr
chimajarak.co.kr
chimajarak.co.kr
chimajarak.co.kr
chimajarak.co.kr
chimajarak.co.kr
chimajarak.co.kr
chimajarak.co.kr
chimajarak.co.kr
chimajarak.co.kr
chimajarak.co.kr
chimajarak.co.kr
chimajarak.co.kr
chimajarak.co.kr
chimajarak.co.kr

Certificate

The complete raw certificate details for chimajarak.co.kr in PEM and ASN.1 format.

Certificate (PEM)

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

Public Key (PEM)

-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAtPHRbBBpGDHrxvJd/tbU
KgFBdhhZKH0qO42sdpLT7o17d/5Qd/FMYd6zGOg4hyS43xvgPI/z5xOB4VVeIViE
OrSSCqvLdWbGMlOhZR8Wb+ZqORlA3lmdtFh88dKt2t9r23gMYqqrxXwQsCmLyzJa
u3I5OEs2mh97OLrNPldi1rZc+Ag0QrZat66mmvor9K/vi8uMYyY5PICT9ZwJMkgp
G+dv3Yb4SCcYKcRyoMnowNC8mRRKpk9FMEosCf4IPTNIQRlyyVFhSZdvfzuSCE7W
pdpKNf7lGeJbYfinsPOixyj1RSd5/dK+O1a1EM5JavVZim4ZBxGmqjwpI6wGbchm
xQIDAQAB
-----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 426347259954372756924293252727686664017703
 . . . . . . . . [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 'Let's Encrypt'
 . . . . . . . . . . . . [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 'Let's Encrypt Authority X3'
 . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2018-05-19 05:30:35 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2018-08-17 05:30:35 +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 2.5.4.3 (commonName)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:19|false] PrintableString 'chimajarak.co.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 22842139821217813929442809137360851504210021968133975897297083074003036799952277678540207402240913359196897202424191987415244376265821092550095964762216747479713432726734118768250730213686759595110563499500825309866657635442612116420610802277668911153090196560538932712331062691816348869638104856184421024131510112510706758368781019179239671991865113372253076222614056815330341486326926906121350299521336635146193253845959193734344817838458910070923611784789121776242154402437538847401115175697729855098180591256670370644638504782288145783870513708238787197761099232109100627377373479648228331519563068050772532422341
 . . . . . . . . . . . . . . . . . . . . [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 2.5.29.15 (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 2.5.29.19 (basicConstraints)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:1|false] BOOLEAN true
 . . . . . . . . . . . . . . . . . . . . [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 2.5.29.14 (subjectKeyIdentifier)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (22 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (20 bytes)
							f5166f7911c149a921f9e3a27dff84b42c272899
 . . . . . . . . . . . . . . . . [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 a84a6a63047dddbae6d139b7a64565eff3a8eca1
 . . . . . . . . . . . . . . . . [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 (99 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://ocsp.int-x3.letsencrypt.org'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [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://cert.int-x3.letsencrypt.org/'
 . . . . . . . . . . . . . . . . [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 (42 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'chimajarak.co.kr'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.chimajarak.co.kr'
 . . . . . . . . . . . . . . . . [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 (246 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.23.140.1.2.1 (Domain Validation Certificates Policy)
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 1.3.6.1.4.1.44947.1.1.1
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [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 'http://cps.letsencrypt.org'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 1.3.6.1.5.5.7.2.2 (unotice)
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:12|false] UTF8String 'This Certificate may only be relied upon by Relying Parties and only in accordance with the Certificate Policy found at https://letsencrypt.org/repository/'
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 1.3.6.1.4.1.11129.2.4.2
 . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (244 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (241 bytes)
							00ef0076005581d4c2169036014aea0b9b573c53f0c0e43878702508172fa3aa1d0713d30c000001637717c10400000403004730450221009e7006724d3b11c1aa23d6015a75aeaeabc2b30efe83fae8275b7823824c76fc02203f3319b83c1d4d9fdefa541ba2074d1930c269a8d58962541624a27a03f26919007500293c519654c83965baaa50fc5807d4b76fbf587a2972dca4c30cf4e54547f478000001637717c0f3000004030046304402200ec8fc940c4c11c1ba94912bd2d3591bc2c9b789dcd94e16e997a64fb5c741320220159e6736955658e9cf50e5018a08a4e3cf406db055dfa35236b1200891104d04
 . . . . [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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