flexhoofboots.com

Issued by Let's Encrypt Authority X3

About this certificate

This digital certificate with serial number 04:30:51:c7:a7:67:cf:6e:20:20:3b:ab:fa:83:54:91:00:05 was issued on by Let's Encrypt.

With 8 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=flexhoofboots.com

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 04:30:51:c7:a7:67:cf:6e:20:20:3b:ab:fa:83:54:91:00:05
Serial Number (int): 364891401469366560528522551785167558606853
Serial Number lenght: 139 bits, 18 octets

SubjectKeyId: b9:4b:f8:a6:86:23:3e:55:4c:40:f0:69:bc:c1:0b:13:7e:18:75:62
AuthorityKeyId: a8:4a:6a:63:04:7d:dd:ba:e6:d1:39:b7:a6:45:65:ef:f3:a8:ec:a1

Fingerprint (sha1): dd:47:c5:59:fc:1e:25:a7:49:8c:1c:b7:c8:fb:b6:38:f7:3d:d6:ca
Fingerprint (sha256): ce:16:3b:43:d0:9f:5c:08:0f:9b:d5:85:08:37:70:bc:ae:fe:0a:23:de:42:42:8c:47:c9:d5:50:20:1e:73:cc

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 flexhoofboots.com

8

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for flexhoofboots.com

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

cpanel.flexhoofboots.com
flexhoofboots.com
flexhoofboots.kokonaisvaltainenkavionhoito.fi
mail.flexhoofboots.com
webdisk.flexhoofboots.com
webmail.flexhoofboots.com
www.flexhoofboots.com
www.flexhoofboots.kokonaisvaltainenkavionhoito.fi

Other certificates including the domain name flexhoofboots.com

(limited to 100 certificates)

Certificate

The complete raw certificate details for flexhoofboots.com in PEM and ASN.1 format.

Certificate (PEM)

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

Public Key (PEM)

-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA7IFpTdqP7MrHjgu2yZfC
iMO0mfaQqzbOw3zrZHqxOcKMigYxdFjh0+Av/eWernHsuLEUhc9PyJryuRjXfxMx
icLy3dUOcae+B3sgHgCND/5i6M6YnJA7OJ6FwaVvZjnKiZuyQHji6sH3jv5DUJP7
H8rtjNbUKL1bjmKPfCPLq89OkPDfoV5aGNEnivqAwbchl+Wgdw3WKrBs+dTV9CL3
xq0l4TR6dDvmu/xgFHFifWKRsh7ls9VsYmS1/TcMnKFyuTByfZeZ2WKxoPkCpERa
6JBHQ54AXkLZxtWhhJwgm7IKbyRHHfXVuZv7KJuD+vdNbF4lQSfPS95UeFzwPsfa
9wIDAQAB
-----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 364891401469366560528522551785167558606853
 . . . . . . . . [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 2020-03-10 00:18:25 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2020-06-08 00:18:25 +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 'flexhoofboots.com'
 . . . . . . . . [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 29856055084238671961600463708588066763522712291998846355596417693266471484069703147010170626521769845198842809842597499634180823453798555020619249272814405220692452427599276291905995061580220327287403116122494847728606386761494209675158937673481475331853096588564368245023758532173731294862696209823031597762969408701822821582737434597668156710410093211600575020850284015908430417265313431524226897893172972121060443806864437820527040214462559494967292138004313495839650744573071379099450540027475993982193472688446370172672955359507534646076234941918389218896468686892334467312698966322198048571804478730338505841399
 . . . . . . . . . . . . . . . . . . . . [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)
							b94bf8a686233e554c40f069bcc10b137e187562
 . . . . . . . . . . . . . . . . [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 (247 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'cpanel.flexhoofboots.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'flexhoofboots.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'flexhoofboots.kokonaisvaltainenkavionhoito.fi'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'mail.flexhoofboots.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'webdisk.flexhoofboots.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'webmail.flexhoofboots.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.flexhoofboots.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.flexhoofboots.kokonaisvaltainenkavionhoito.fi'
 . . . . . . . . . . . . . . . . [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 (244 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (241 bytes)
							00ef007500f095a459f200d18240102d2f93888ead4bfe1d47e399e1d034a6b0a8aa8eb27300000170c20582fd000004030046304402201eb5fb5b99008b314231778d629a6b48b10138c6108e0a4c96e2d8c9942bee2b022072a3c5fd0264be48496e6a17e1fe9dde8120fd247dc80d33ca1246b7561cab8e00760007b75c1be57d68fff1b0c61d2315c7bae6577c5794b76aeebc613a1a69d3a21c00000170c20583340000040300473045022100f25dd4263c8c89f59cecd3fc9549c3e820629b2b93da3cb5f8dc458b88c9536d02201a77551e775c763056d29f67f6ac6b3b5b3d4ea97777047a4ff12d4f4f972128
 . . . . [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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