www.witzebibliothek.de

Issued by Let's Encrypt Authority X3

About this certificate

This digital certificate with serial number 04:66:eb:b5:95:f3:de:b8:ae:a5:3a:17:59:90:f8:d3:52:8e 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=www.witzebibliothek.de

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 04:66:eb:b5:95:f3:de:b8:ae:a5:3a:17:59:90:f8:d3:52:8e
Serial Number (int): 383471256579117963268028908251907336917646
Serial Number lenght: 139 bits, 18 octets

SubjectKeyId: 88:9c:de:83:b5:9f:dc:5e:85:44:03:99:e3:45:8d:c7:5b:df:2b:74
AuthorityKeyId: a8:4a:6a:63:04:7d:dd:ba:e6:d1:39:b7:a6:45:65:ef:f3:a8:ec:a1

Fingerprint (sha1): 3a:d1:d3:66:7d:bf:f7:0c:6a:12:36:df:aa:f8:74:1b:83:4b:1e:31
Fingerprint (sha256): a9:d0:6b:4c:e2:c5:1e:d5:e7:54:64:0d:7e:49:1f:b7:14:c6:c5:cd:c4:bc:ec:9f:ae:ad:97:0f:2f:d9:50:30

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 www.witzebibliothek.de

2

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for www.witzebibliothek.de

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

witzebibliothek.de
www.witzebibliothek.de

Other certificates including the domain name witzebibliothek.de

(limited to 100 certificates)
www.witzebibliothek.de
www.lexsolar.lima-city.de
www.lisa2402.lima-city.de
www.witzebibliothek.de
smalad.lima-city.org
capqt.lima-city.de
www.witzebibliothek.de
*.goov.ug
*.witzebibliothek.de
balleticsbynina.com
monitor.lima-city.info
www.witzebibliothek.de
mailgw.noobi.eu.org
www.witzebibliothek.de
wokpfanne.shop

Certificate

The complete raw certificate details for www.witzebibliothek.de in PEM and ASN.1 format.

Certificate (PEM)

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

Public Key (PEM)

-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAzNU4EhrjwkNeYq1h6DlK
3oykZeEXslCInNkB1JhtGnY33FxSoAAGv2a3mKk9Qbh2rqp5BWwAcnWHjqpmJqqA
hmOUfkK1TM7IGZ90qfcpufsiWJFlGZlu9VbMnxzTf8eckTpCXbsNX0eFpTJMQh/I
8u9WKAOLHVi3W1723kbfZCy4tq9/rq1o/pnVOfzwtY1fPmG1ERIiCV8OuzH85ALE
eIdHHvnLjwfp4dHQnk16SQrZAcmgtOZU3Hu5IIBm+hv00uvdCCKjSjbkJ3iWsYZU
vk8faCtu8oGjRT37bSbvl28jCIUsFxCNeiOQvYqgQ6SvsD1z7R/wcJA8ZkB59fMQ
BwIDAQAB
-----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 383471256579117963268028908251907336917646
 . . . . . . . . [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 2018-05-11 08:07:57 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2018-08-09 08:07:57 +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 'www.witzebibliothek.de'
 . . . . . . . . [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 25857756433629459969610512865312499317912984014684759409119199150531967692722906007562839036469976017531750475012431074299909761365723312568740148767210200338501866849166520977703111929544633271504286205881445264266468972536701642521446120066057029934774268857022830228892650331722529646675755965886533479688103267076848448066212260069615743713271611270786440386575084678005444196239452244274699178331774355537839684691564335002543085689978872841498122110748295844481167492148527523165435351040383036080903982333789315659180582897536832681425887225802409068719175778576995156704837140342229098840790303913415953027079
 . . . . . . . . . . . . . . . . . . . . [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)
							889cde83b59fdc5e85440399e3458dc75bdf2b74
 . . . . . . . . . . . . . . . . [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 (46 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'witzebibliothek.de'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.witzebibliothek.de'
 . . . . . . . . . . . . . . . . [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 (245 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (242 bytes)
							00f0007700293c519654c83965baaa50fc5807d4b76fbf587a2972dca4c30cf4e54547f478000001634e74f37a0000040300483046022100df3885c4e2597acc459bdb31bc080cee4aeaa5dcdebec45de17bbb1301b2709b022100f6c05bcf14125df5dd15b943adcac4b9aa816f5dfb92c2b5b97cb9d9d3e733f3007500db74afeecb29ecb1feca3e716d2ce5b9aabb36f7847183c75d9d4f37b61fbf64000001634e74f3bb000004030046304402200c48572ba470e5b32a363bbdaac9c7b3a052081ac64698e359b49db9d48f766202201606c871c61d308e4f5aed6f25dd23d0a72babec74342cf5cce00431c8e50494
 . . . . [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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