hanil.co

Issued by Let's Encrypt Authority X3

About this certificate

This digital certificate with serial number 04:79:ee:95:8f:e1:e2:50:47:b8:b1:06:26:d6:be:7d:fa:c3 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=hanil.co

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 04:79:ee:95:8f:e1:e2:50:47:b8:b1:06:26:d6:be:7d:fa:c3
Serial Number (int): 389940442957984222885510199491550179621571
Serial Number lenght: 139 bits, 18 octets

SubjectKeyId: 90:4d:5e:76:48:33:f6:92:ef:38:44:1e:ff:a3:ef:5b:a2:d0:b2:cd
AuthorityKeyId: a8:4a:6a:63:04:7d:dd:ba:e6:d1:39:b7:a6:45:65:ef:f3:a8:ec:a1

Fingerprint (sha1): 4c:ab:72:6d:43:4e:90:ce:a7:1c:98:51:e7:71:e4:bb:9a:4a:b8:b5
Fingerprint (sha256): 98:bb:ef:9a:89:ae:1f:39:2b:c1:30:86:e2:42:6a:7d:41:a6:f9:9d:aa:dd:3f:b5:2b:f2:ce:cf:8c:e8:9c:e3

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 hanil.co

2

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for hanil.co

Public Key Algorithm

RSA

Key Size

4096

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

hanil.co
www.hanil.co

Other certificates including the domain name hanil.co

(limited to 100 certificates)

Certificate

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

Certificate (PEM)

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

Public Key (PEM)

-----BEGIN PUBLIC KEY-----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-----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 389940442957984222885510199491550179621571
 . . . . . . . . [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 2019-11-24 06:46:22 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2020-02-22 06:46:22 +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 'hanil.co'
 . . . . . . . . [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 (4208 bits)
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:2|false] INTEGER 708585666681429565592410568497302054310013092507644954385332470495029933167568329041638262213154257560685834182934592231587562011491719561187473982636111492735296455775453677679049162697849751575711215143024191773489942855431597439379338756478576162734087148305612052780971148962556331209695444055146219323999985164425916039294871945933229362906155933109338894289043200177491857716855030878961814257361723043531390163153956148130475780696178334053423725846511361382238190480327535398279722929704742766351009220911417968818569727892513093637004382321925662065694725585853987089826653978403671309073549130029921102190070227824912554353815622088410079466639598332439460202715609741023214800531056032613325346559874444490277413038270942465343382325968942722681031724858736317685823434476538977331943296698616283048935254560068920931444033224830635784112059872326826465461109865306865446738711912767880481513703505192208407019738476353136143163050087679933334611636042551792944499415555160328312573027916799548931167899426971037616566982718514441847547836815577471893799121126663017018149106348766159681624444173896184080665008684535590357903394581844136443614201714304463092714623749849342195886801487670049105827276570700930755428173251
 . . . . . . . . . . . . . . . . . . . . [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)
							904d5e764833f692ef38441effa3ef5ba2d0b2cd
 . . . . . . . . . . . . . . . . [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 (26 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'hanil.co'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.hanil.co'
 . . . . . . . . . . . . . . . . [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 2.23.140.1.2.1 (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 1.3.6.1.4.1.11129.2.4.2
 . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (245 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (242 bytes)
							00f00077006f5376ac31f03119d89900a45115ff77151c11d902c10029068db2089a37d9130000016e9c603bcd00000403004830460221009b7762aed4e7c9cc296bb21d1c7185e4a7a3f27476c78490623c83248f1d1812022100aa266a23879190a6d8f8bbf9577df4fac4b1c7e30320d50f2f85ad21a4705a82007500b21e05cc8ba2cd8a204e8766f92bb98a2520676bdafa70e7b249532def8b905e0000016e9c603b99000004030046304402200c7b646ebb37fecadc313de220127aa5784e0c773fa926abe68f8831709e8e880220390769622c2bc4db4dbf97003a11cd1f937b7e406001ab21c2b704a0fbb0d214
 . . . . [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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