go-concepts.nl

Issued by Let's Encrypt Authority X3

About this certificate

This digital certificate with serial number 03:9e:0c:e8:e7:8d:4d:0e:05:07:71:80:c4:7b:46:af:17:68 was issued on by Let's Encrypt.

With 5 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=go-concepts.nl

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 03:9e:0c:e8:e7:8d:4d:0e:05:07:71:80:c4:7b:46:af:17:68
Serial Number (int): 315118631814041252890083547325115348752232
Serial Number lenght: 138 bits, 18 octets

SubjectKeyId: dc:ef:43:b3:b2:34:c2:9d:cc:a4:3b:c0:d8:a6:59:42:2d:cf:77:81
AuthorityKeyId: a8:4a:6a:63:04:7d:dd:ba:e6:d1:39:b7:a6:45:65:ef:f3:a8:ec:a1

Fingerprint (sha1): 47:93:fd:9a:fe:e2:c3:4e:c6:4a:d0:36:4c:92:18:71:ba:95:a9:4f
Fingerprint (sha256): 54:b9:ce:81:79:43:ff:18:9a:49:ac:57:ed:e1:2f:df:e3:47:56:67:d0:ec:63:5d:05:fe:ea:ce:2c:f4:6a:9e

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 go-concepts.nl

5

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for go-concepts.nl

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

8 extensions
No unhandled critical extensions

CA Certificate

This is not a CA certificate

Subject Alternative Names

go-concepts.nl
jere.nl
webmail.go-concepts.nl
www.go-concepts.nl
www.jere.nl

Other certificates including the domain name go-concepts.nl

(limited to 100 certificates)
voip.go-concepts.nl
mail.go-concepts.nl
project.go-concepts.nl
go-concepts.nl
go-concepts.nl
mail.go-concepts.nl
project.go-concepts.nl
go-concepts.nl
go-concepts.nl
go-concepts.nl
go-concepts.nl
go-concepts.nl
git.go-concepts.nl
go-concepts.nl
go-concepts.nl
go-concepts.nl
go-concepts.nl
plesk.go-concepts.nl
git.go-concepts.nl
webmail.go-concepts.nl
go-concepts.nl
project.go-concepts.nl
ticket.go-concepts.nl
go-concepts.nl
plesk.go-concepts.nl
go-concepts.nl
project.go-concepts.nl
git.go-concepts.nl
go-concepts.nl
go-concepts.nl
plesk.go-concepts.nl
mail.go-concepts.nl
mail.go-concepts.nl
voip.go-concepts.nl
git.go-concepts.nl
voip.go-concepts.nl
plesk.go-concepts.nl
go-concepts.nl
go-concepts.nl
plesk.go-concepts.nl
go-concepts.nl
voip.go-concepts.nl
go-concepts.nl
go-concepts.nl
go-concepts.nl
ticket.go-concepts.nl
project.go-concepts.nl
ticket.go-concepts.nl
plesk.go-concepts.nl
voip.go-concepts.nl
plesk.go-concepts.nl
project.go-concepts.nl
git.go-concepts.nl
mail.go-concepts.nl
mail.go-concepts.nl
go-concepts.nl
plesk.go-concepts.nl
project.go-concepts.nl
plesk.go-concepts.nl
git.go-concepts.nl
plesk.go-concepts.nl
plesk.go-concepts.nl
ticket.go-concepts.nl
go-concepts.nl
go-concepts.nl
git.go-concepts.nl
git.go-concepts.nl
plesk.go-concepts.nl
go-concepts.nl
go-concepts.nl
plesk.go-concepts.nl
go-concepts.nl
project.go-concepts.nl
go-concepts.nl
go-concepts.nl
git.go-concepts.nl

Certificate

The complete raw certificate details for go-concepts.nl in PEM and ASN.1 format.

Certificate (PEM)

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

Public Key (PEM)

-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAyzBV41D6XdmcQkFXHenq
88vR+cvaK9zj2RVsjZOzhS6ViJSVOXI/EOaEk8uVMohitu6BRVrNgWXB4JfUr/Hf
I5OyRSpY9eRfj+D/QXyVT1v0DsubSrNFoYv1GS92qi5zmBotDEY72FxHz7xR/O7N
7OqgAwG4+3/OD2OCrjMOxJ1OTZgujvKbmiUlT50dnv3sAViqZCbKRmceQWuM1NS5
MwhelnWzoUpmy5Qle+xge4STPLTwSDgH74m+utqIbEuGwkn/OzKqLJTLbA6aWKW+
lStZ++F4aPGMYrr0ilX/x04PpZj17yc6yP0agU2q6oogrG8nP5e+lLu7cbyBb19O
hQIDAQAB
-----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 315118631814041252890083547325115348752232
 . . . . . . . . [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 2017-07-30 10:43:00 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2017-10-28 10:43:00 +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 'go-concepts.nl'
 . . . . . . . . [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 25650211031419232200792779653784658713328965148613971910295894797448910622666879366126778909164423941722342966100940678404726614522656124762858154650159472353804617940918689462472923658580926617541214051366387469745941368331289161817773125157041936360250902143447814346265252487911157722748548220145521662089189229721620810806793105332274516091722024205266543238448891402057815675293708760206223281737348632404465453143270258992869671042606630209885140408815853618899619357591699316808436092702265312600925097807448458069307580922033445588896920314224572153958533819911633010036367281800498092149161836668457202962053
 . . . . . . . . . . . . . . . . . . . . [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)
							dcef43b3b234c29dcca43bc0d8a659422dcf7781
 . . . . . . . . . . . . . . . . [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 (84 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'go-concepts.nl'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'jere.nl'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'webmail.go-concepts.nl'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.go-concepts.nl'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.jere.nl'
 . . . . . . . . . . . . . . . . [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 1.2.840.113549.1.1.11 (sha256WithRSAEncryption)
 . . . . . . . . [c:0|t:5|false] NULL 
 . . . . [c:0|t:3|false] BIT STRING (2048 bits)
		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