www.41021.com

Issued by Let's Encrypt Authority X3

About this certificate

This digital certificate with serial number 03:a7:14:70:cf:b9:45:9a:d6:9f:13:66:2a:2d:da:a5:39:3e was issued on by Let's Encrypt.

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.41021.com

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 03:a7:14:70:cf:b9:45:9a:d6:9f:13:66:2a:2d:da:a5:39:3e
Serial Number (int): 318191183381378857231217160672953988626750
Serial Number lenght: 138 bits, 18 octets

SubjectKeyId: ca:33:c3:70:78:57:44:c5:a3:77:a5:17:b5:55:91:d9:5a:7b:6a:98
AuthorityKeyId: a8:4a:6a:63:04:7d:dd:ba:e6:d1:39:b7:a6:45:65:ef:f3:a8:ec:a1

Fingerprint (sha1): e1:bd:77:c8:65:d8:36:de:93:54:5f:26:e7:2e:2c:20:a9:4a:46:77
Fingerprint (sha256): 31:e7:db:e8:76:ee:22:78:f6:e1:d7:9f:d5:c5:6c:4c:67:e9:52:20:da:9b:00:72:93:53:19:f2:22:8f:20:9f

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.41021.com

1

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for www.41021.com

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

www.41021.com

Other certificates including the domain name 41021.com

(limited to 100 certificates)
wise.bible
esports.melbourne
41021.com
41021.com
www.41021.com
familysuperstore.com
www.41021.com
42401.com
687.me
41021.com
www.41021.com
40562.com
41021.com
www.41021.com
www.41021.com
41021.com
40952.com
41021.com

Certificate

The complete raw certificate details for www.41021.com 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 318191183381378857231217160672953988626750
 . . . . . . . . [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 2019-07-27 18:44:25 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2019-10-25 18:44:25 +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 'www.41021.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 (4208 bits)
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:2|false] INTEGER 759781858851402268547535641657723073920629785759591058158685331118952802232603902468163142994528478453431127831290802671047166313549480763858100909923546504382979229114728487430020875131222251850647954165558608594659244001552706394637440655663643634480579232984436104984383231079495607407761667297505445969855182487579052886344191431507624814976590316007798897063546067889935968333383782830456673858285830880335435484638905733328192499694929447061595858357670626226512830018993258203086294557822794895442599041946192175103458660514631049303797670530057765071099340238296829258913719633953151869476190452920179939595250035361247406129252043428958332436699910971149748310673548449415425370268714119368448170853627378842209760102969797523388480370656424945094012845685417675549204899374392542975878152903905073443500629124695144275365988019666357896339627196595591047879499785460776813360645654814976465008792911531238202322549505141313023523672593213949109223455665961462613966211370848948366507332059019784654525672621299852125386015096553967328871969032928100123132501925479115651188391996012152492002707442217886558925717403760132129513971755229792149309381930300724955935539706319453781892102495754893666111885531014056312315378601
 . . . . . . . . . . . . . . . . . . . . [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)
							ca33c370785744c5a377a517b55591d95a7b6a98
 . . . . . . . . . . . . . . . . [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 (17 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.41021.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 (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 (247 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (244 bytes)
							00f20077006f5376ac31f03119d89900a45115ff77151c11d902c10029068db2089a37d9130000016c34f680240000040300483046022100b132fc2c12744e90647dc326d90dd449a1ea242777f1734224daa06a7dfa6506022100f21769d4c172f267b467a541780d0df7c5287f0b412d249383ee8f88eee1c934007700293c519654c83965baaa50fc5807d4b76fbf587a2972dca4c30cf4e54547f4780000016c34f67ff10000040300483046022100af984b68405ca194e8a57eaa0b13ac431fdde300e3dbb145a2124e02e6f03a70022100e0d42290951902443297e4a9fdcb3b5f8fe26014f21a1e6e5a7f46030bf9d9cc
 . . . . [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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