www.71782.com

Issued by Let's Encrypt Authority X3

About this certificate

This digital certificate with serial number 03:13:25:e7:25:ae:3b:5b:94:ca:90:0f:9a:c6:bf:e5:84:58 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.71782.com

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 03:13:25:e7:25:ae:3b:5b:94:ca:90:0f:9a:c6:bf:e5:84:58
Serial Number (int): 267852604387450160121225154625759957320792
Serial Number lenght: 138 bits, 18 octets

SubjectKeyId: 53:5b:57:f8:02:78:f2:85:07:a1:2a:69:39:0c:14:b9:7c:c6:80:c5
AuthorityKeyId: a8:4a:6a:63:04:7d:dd:ba:e6:d1:39:b7:a6:45:65:ef:f3:a8:ec:a1

Fingerprint (sha1): af:02:8b:50:6a:7f:10:a7:c2:a9:d5:e0:7e:57:b9:d8:8b:f7:2b:68
Fingerprint (sha256): 6e:88:a7:d1:44:21:15:44:54:6f:e3:b3:6d:1d:b2:92:4e:53:8f:00:9a:72:a0:b6:e5:eb:5b:8b:98:1c:bc:a8

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.71782.com

1

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for www.71782.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.71782.com

Other certificates including the domain name 71782.com

(limited to 100 certificates)
www.71782.com
71782.com
83275.com
71782.com
71782.com
71897.com
www.71782.com
71782.com
71782.com
www.71782.com
71782.com
71782.com
www.71782.com
www.71782.com
www.83275.com
www.71782.com
71782.com

Certificate

The complete raw certificate details for www.71782.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 267852604387450160121225154625759957320792
 . . . . . . . . [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 2020-03-14 22:06:22 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2020-06-12 22:06:22 +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.71782.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 930274338598718482863882556730570583838343972586005881498229352753399671317320730950639084890132677140480564464989522210196473881263008475403241451241911738742432655939736835642335464839622050839014218856745045315496884725473669136687435446825436763338152596037051824149019553915755849960732501960902361183705498752189944878264290629813063259040580400384910263642093491096970877307523935411824675372224802239880108896525326542130780951143392735592218610405119940719428386204442118268532555754403752572455021400088563747967704969784584569965402946631140189228172883661396424183392283949940198321560703933188715461102728322462072810836305426926379438435058007320742859620593889856915052118129635184726917225585015625552255483381246757842296521742658062329720997569727559466177140910879069459981228834867539098512942934279191412558407214848835653927928309160292871001938528882638711386746142306002379136447809523467586077311116820496179041385722177955849152957503068131323780406720948000078018735501594467736578565078288931574178342646994043933466061853006818881395488924763735185770921199630011927339739397919365378855563564678671695551272007779174234040801898492246489749756694805751008059674117006420117305216320404426020437136900049
 . . . . . . . . . . . . . . . . . . . . [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)
							535b57f80278f28507a12a69390c14b97cc680c5
 . . . . . . . . . . . . . . . . [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.71782.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 (245 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (242 bytes)
							00f00076006f5376ac31f03119d89900a45115ff77151c11d902c10029068db2089a37d91300000170db4c67db000004030047304502204bc8f6665f90f6c423c3f89484a8b8988b264a537f61c90a38444f956513c9ae022100d9b4c33863f9a3647aac12280457ca5b2780a581205ed201b47e48f2004221b200760007b75c1be57d68fff1b0c61d2315c7bae6577c5794b76aeebc613a1a69d3a21c00000170db4c67dc000004030047304502210096dddd132f68736d4b71762bad953022ff03f814b6974e621e6c61a9eab79f9602207dacb7e050859267c4a3d66ca31128a23f6c0e95d263527872daf3bcf88a6abd
 . . . . [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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