mbschoen.org

Issued by R3

About this certificate

This digital certificate with serial number 03:8b:21:a7:b8:9a:cc:a0:b3:03:ae:3d:05:a1:c8:d2:e4:6a was issued on by Let's Encrypt.

With 13 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:
  • DV certificate contains a subject common name, this is not recommended. If certificate policy 2.23.140.1.2.1 (CA/B BR domain validated) is included, only country and/or common name is allowed in SubjectDN. (BRs: 7.1.2.7.2)
  • Subscriber certificates use of Subject Key Identifier is NOT RECOMMENDED (BRs v2: 7.1.2.7.6)
  • Subscriber Certificate: commonName is NOT RECOMMENDED. (BRs: 7.1.2.7.1)

Certificate Subject

CN=mbschoen.org

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 03:8b:21:a7:b8:9a:cc:a0:b3:03:ae:3d:05:a1:c8:d2:e4:6a
Serial Number (int): 308680842178955297215910813760294030074986
Serial Number lenght: 138 bits, 18 octets

SubjectKeyId: 15:a2:5d:a5:81:85:ca:ab:31:a0:9e:35:b2:91:a0:c2:18:27:ee:71
AuthorityKeyId: 14:2e:b3:17:b7:58:56:cb:ae:50:09:40:e6:1f:af:9d:8b:14:c2:c6

Fingerprint (sha1): b3:11:e9:83:df:a2:f2:fa:4e:c6:7e:d4:6e:6d:10:ba:95:ab:e6:a4
Fingerprint (sha256): 57:8b:19:c0:c4:82:fe:56:85:e6:5d:09:9a:6c:76:e1:8c:00:fe:50:1b:2c:6c:41:23:f7:5d:78:53:b9:50:f1

Issuing Certificate URL: http://r3.i.lencr.org/

Revocation information

OCSP Server: http://r3.o.lencr.org

Check the revocation status for certificate mbschoen.org

13

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for mbschoen.org

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

aibeatrix.com
big-joker.com
bitcoincoloringbook.com
bui.co.in
caribrealestate.com
ghostofchevalier.com
internet.photo
libertytownshipphotography.com
mbschoen.org
mc.thrive.fi
paranormalobsession.net
ptk.co.in
rxsugarauthorized.com

Other certificates including the domain name mbschoen.org

(limited to 100 certificates)
efiling.org
mbschoen.org
mbschoen.org
marsexpress.ca
sunsetlibrary.bible
mbschoen.org
mbschoen.org
marsexpress.ca
mbschoen.org
protec-security.asia
mbschoen.org
mbschoen.org
marsexpress.ca
sculpit.space
marsexpress.ca
mbschoen.org
crazyshrooms.ca
ryuk.org
shepper.ae
marsexpress.ca
marsexpress.ca
mbschoen.org
marsexpress.ca
mbschoen.org
sculpit.consulting
mbschoen.org
protec-security.asia
marsexpress.ca
contractworking.org
notdanimal.hacker.rehab
marsexpress.ca
yf.co.za

Certificate

The complete raw certificate details for mbschoen.org in PEM and ASN.1 format.

Certificate (PEM)

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

Public Key (PEM)

-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA8jLu4EzMss7rtbAvkOSQ
o4QOaA4PRxjFZ2vxfH3KDQP0O+YEvJvTQjNytpxLiaZtEwlHaA9oCxJ6BEbJnrac
xmqbanuTP6R4yJzdjrK9cI80EHZp5Wp0hniwzBozWepvsHfnzjkXf62TjwX6mp0g
q0GN3q3Ny87eyLyikQ3don37AQWd+wmiFJEuHSJgzhVrnxkr6hFFX4oXdJUYYu4x
pPDAXdDc5g4GEQ/40QuOLQfmp8wKv9CRXl1btogP6jAc2p3sd/UKaz3wekPlA6HB
FkYziexxNDrCH5l4Qom/ynm691bOeJEPcQWLwhy5McaQrT3gODZYMsZVgkkn+qPk
iwIDAQAB
-----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 308680842178955297215910813760294030074986
 . . . . . . . . [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 'R3'
 . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2024-02-19 06:06:44 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2024-05-19 06:06:43 +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 'mbschoen.org'
 . . . . . . . . [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 30574785854438149896119935922034967518339580882799003186252922789842744257762599333569439100979811179223088677310422116606371614294007026301243420102661706483644115819062423630406637245515694181009242217257803887253353625364673532225911319916554563828838431344806675150869369883456341856841911370004204294660454780870864556586918089193747139904601245526635256636579167816625180872704613531956971122048430066968000948103403765564870438402757511578182267460652300343424323950505098201407793546218494881215375538931134569051756363035866287976777838609351520442549374508673746996255772304583953773621064015433735373841547
 . . . . . . . . . . . . . . . . . . . . [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)
							15a25da58185caab31a09e35b291a0c21827ee71
 . . . . . . . . . . . . . . . . [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 142eb317b75856cbae500940e61faf9d8b14c2c6
 . . . . . . . . . . . . . . . . [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 (73 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://r3.o.lencr.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://r3.i.lencr.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 'aibeatrix.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'big-joker.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'bitcoincoloringbook.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'bui.co.in'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'caribrealestate.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'ghostofchevalier.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'internet.photo'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'libertytownshipphotography.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'mbschoen.org'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'mc.thrive.fi'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'paranormalobsession.net'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'ptk.co.in'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'rxsugarauthorized.com'
 . . . . . . . . . . . . . . . . [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 (12 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 1.3.6.1.4.1.11129.2.4.2
 . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (245 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (242 bytes)
							00f000760076ff883f0ab6fb9551c261ccf587ba34b4a4cdbb29dc68420a9fe6674c5a3a740000018dc030402b000004030047304502203321c0a6c91737e2364cdcbc1ed52e873c7dd6222a4bbc82b2c8eed146e18fde022100e46805056bbe5ad27bbae1288602ed6aaf6a034cb9767f6871c9b46f7d30d46600760048b0e36bdaa647340fe56a02fa9d30eb1c5201cb56dd2c81d9bbbfab39d884730000018dc03041ec0000040300473045022100dfe8745db23d91562c44a379f768207cb60c46be93e90384bdb7ec91ae6c24eb02207efc94ba05cfe83a9a197175fbb6081f593e54b0b13fc11043056a2bcd0c413d
 . . . . [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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