www.nea.nu

Issued by Let's Encrypt Authority X3

About this certificate

This digital certificate with serial number 03:41:0c:65:33:c7:30:ee:11:46:f1:78:dc:4f:cd:5f:a4:a6 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.nea.nu

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 03:41:0c:65:33:c7:30:ee:11:46:f1:78:dc:4f:cd:5f:a4:a6
Serial Number (int): 283471687853258308286035565096322256053414
Serial Number lenght: 138 bits, 18 octets

SubjectKeyId: 1a:35:77:73:5b:4a:99:a7:11:65:79:19:4b:92:08:02:02:f9:4e:84
AuthorityKeyId: a8:4a:6a:63:04:7d:dd:ba:e6:d1:39:b7:a6:45:65:ef:f3:a8:ec:a1

Fingerprint (sha1): e9:1d:db:10:8a:ab:a3:f3:84:fd:7f:2c:8c:9e:7a:65:fe:38:05:5e
Fingerprint (sha256): 60:77:9b:f4:1f:af:07:0e:c0:3d:dc:90:87:f0:9e:87:dc:fb:99:69:d0:4c:fa:1b:ce:38:cc:99:d5:37:22:61

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.nea.nu

2

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for www.nea.nu

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

nea.nu
www.nea.nu

Other certificates including the domain name nea.nu

(limited to 100 certificates)

Certificate

The complete raw certificate details for www.nea.nu 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 283471687853258308286035565096322256053414
 . . . . . . . . [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 2020-02-19 03:47:33 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2020-05-19 03:47:33 +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.nea.nu'
 . . . . . . . . [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 673429328058269193471790183368231016431336464893396866748258524689522151902095935444886337034135336665804290664536004430317746142215360844230211949789951904763006291043484785030643932658256780371078641019539152537281033972729836562388646972941650221806204985154226322559149531033555819379578568247599061096506359035515249544520823732239462342170225117291171943599778040526777299980749813278838576481597205870400409995705263126870095780054146386951001729147533606432275375992650989569037947227539814795577794751488499839328167531727234263672559893873560430741127792680731708325777872511836058913661072347904886473388581423760261742855693279344150450745799779581314084244550220272727162822955201906073932489625792882510379631450666781855044630175738677942490254543087873825648994173517924341818911033714062722441812211425660416948213757169503200614447626703533414795051744726623260108766971283908773684350118109484497653557031287136489944883605847339471183080377580067154174441012640549845514742507441896345546639636991660594919182194818481180527328220050013911376892534371191310719811660218285545267407668606577269213358711308538800020401679745757975038984950231336023649050771811601733141832637189559648669832433707588224349965190361
 . . . . . . . . . . . . . . . . . . . . [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)
							1a3577735b4a99a7116579194b92080202f94e84
 . . . . . . . . . . . . . . . . [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 (22 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'nea.nu'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.nea.nu'
 . . . . . . . . . . . . . . . . [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 (243 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (240 bytes)
							00ee0075005ea773f9df56c0e7b536487dd049e0327a919a0c84a112128418759681714558000001705bc5c8f10000040300463044022075bee0ee1f666866fec33e644a7aa1914b56d27a8fccfe054d06e63da783f16202204a9fa1f98a1470a058f25e5167597d9b4a1923330c674e0ed365bb4249c80aa9007500b21e05cc8ba2cd8a204e8766f92bb98a2520676bdafa70e7b249532def8b905e000001705bc5c8e0000004030046304402202dc6c4c976ed1a2c6c3a6e22ae88ce9c17c24575b95209cb756f21837c3b727e02205038fd898d02325957c61f2a40c816f58312fa297cacf30eb9071d53a54dfa98
 . . . . [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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