www.83192.com

Issued by Let's Encrypt Authority X3

About this certificate

This digital certificate with serial number 03:55:91:ca:af:01:c6:38:8e:45:01:55:3a:19:86:2b:e5:34 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.83192.com

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 03:55:91:ca:af:01:c6:38:8e:45:01:55:3a:19:86:2b:e5:34
Serial Number (int): 290454649436477001376206630549925183350068
Serial Number lenght: 138 bits, 18 octets

SubjectKeyId: 0b:07:40:24:59:61:b9:25:57:85:06:b9:08:7b:1b:f9:a5:f8:5e:24
AuthorityKeyId: a8:4a:6a:63:04:7d:dd:ba:e6:d1:39:b7:a6:45:65:ef:f3:a8:ec:a1

Fingerprint (sha1): b4:d9:2d:2a:5c:6b:0f:43:d4:11:03:47:4e:25:da:20:bb:d5:41:07
Fingerprint (sha256): 89:96:3d:c9:1d:e4:11:67:77:57:dd:c9:90:ef:f0:1a:66:c7:48:5a:4f:e3:b5:a5:a2:26:12:61:36:8b:ce:6f

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.83192.com

1

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for www.83192.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.83192.com

Other certificates including the domain name 83192.com

(limited to 100 certificates)
87189.com
www.31282.com
www.83192.com
83192.com
83192a.com
83192.com
83192.com
83192.com
83192a.com
83192.com
www.83192.com
www.83192.com
www.83192.com
www.83192.com
www.83192.com
83192.com
83192.com
87292.com

Certificate

The complete raw certificate details for www.83192.com in PEM and ASN.1 format.

Certificate (PEM)

-----BEGIN CERTIFICATE-----
MIIGUjCCBTqgAwIBAgISA1WRyq8BxjiORQFVOhmGK+U0MA0GCSqGSIb3DQEBCwUA
MEoxCzAJBgNVBAYTAlVTMRYwFAYDVQQKEw1MZXQncyBFbmNyeXB0MSMwIQYDVQQD
ExpMZXQncyBFbmNyeXB0IEF1dGhvcml0eSBYMzAeFw0yMDAxMTIyMDQyMzNaFw0y
MDA0MTEyMDQyMzNaMBgxFjAUBgNVBAMTDXd3dy44MzE5Mi5jb20wggIiMA0GCSqG
SIb3DQEBAQUAA4ICDwAwggIKAoICAQDP9inL5MBjYZDtG8mvKWtWo2pBtmn5CtIX
3HEmeO2H0tnJ3c6Btzva6J4F6gZiiKR/iIiADsvAxy/G9+Lk84owJ5a8p9MPmAIG
zYxJ4eFBsSfQOZeEL7FyDvqRLkSliWeTozZqE0D9NOrmDcIhgs7s2jjdMERAdXwI
M52MeMFFsvZJi9oAvxMmMp8ra99+wBr9b4M5UOgV/rNqFFL5P2iHy5DgYkEINFXy
E/lzRwoESFlOQ87r/uKFPqXIc7gMwNHe9p1xWcG8MQ/86eEJ2LgBZpFoOOxu0fAG
4oT5kq/xl23NsQvna4C+aHPIp9ICOgplFelJOEY7GOgs+/WKf1M/hZdNEcfSdPH0
OWcnQIkKd+C4BUT0QyH9OrzsDaoiem7pHy7wBOZO96oymShsIi84q5kQ80GSpUwW
wBPcmXGPZMnAT4N6OE4osjTRpkrKv/iojmwye2q1iMLQWBI0dS0q/zecKilvk6Y/
vVJbyiFsA+0SnbOw6vn523hXDoX2d1rCQy6Gscbs3A5SOQQcdq+InR00sbli59LH
uns+2JbgDwQlGrOmw8kOl7jDlvoFE80Ue+oNaIu9z9gwfOBrzj1yLNU16DVP5pS0
6KxBfSCKmHVnxH+JGsEWtDeUGfC9IhI/7mFj3ThrXJ07g6LCbm8zSHEAwJU7L6np
pojgnHVfBwIDAQABo4ICYjCCAl4wDgYDVR0PAQH/BAQDAgWgMB0GA1UdJQQWMBQG
CCsGAQUFBwMBBggrBgEFBQcDAjAMBgNVHRMBAf8EAjAAMB0GA1UdDgQWBBQLB0Ak
WWG5JVeFBrkIexv5pfheJDAfBgNVHSMEGDAWgBSoSmpjBH3duubRObemRWXv86js
oTBvBggrBgEFBQcBAQRjMGEwLgYIKwYBBQUHMAGGImh0dHA6Ly9vY3NwLmludC14
My5sZXRzZW5jcnlwdC5vcmcwLwYIKwYBBQUHMAKGI2h0dHA6Ly9jZXJ0LmludC14
My5sZXRzZW5jcnlwdC5vcmcvMBgGA1UdEQQRMA+CDXd3dy44MzE5Mi5jb20wTAYD
VR0gBEUwQzAIBgZngQwBAgEwNwYLKwYBBAGC3xMBAQEwKDAmBggrBgEFBQcCARYa
aHR0cDovL2Nwcy5sZXRzZW5jcnlwdC5vcmcwggEEBgorBgEEAdZ5AgQCBIH1BIHy
APAAdgDwlaRZ8gDRgkAQLS+TiI6tS/4dR+OZ4dA0prCoqo6ycwAAAW+btWUqAAAE
AwBHMEUCIQD54Yct1lJBqhZ41RFYmLohj8cmLBhDTMH8lh6JH/UabAIgc5vQlJxl
tXBnD989gb8DRlEzKkf+GKFpXpMH8xOtrpwAdgCyHgXMi6LNiiBOh2b5K7mKJSBn
a9r6cOeySVMt74uQXgAAAW+btWUYAAAEAwBHMEUCIFa6HIwHGuTnTvdip7DbYxVS
LK6sSKeGU8TE65GN5BIIAiEAyTqnekEP073JNA3LxXU0bxh1evVUdTEpkCGbWoOC
We0wDQYJKoZIhvcNAQELBQADggEBACYSoxeoR29qZCsmwaaFPphHQKBEn32bKFTX
L1Bt/wm1/Mg420Y85mUKiojACs4AuOWt26gFZTae//74hTE/ROu0CyjgUc4cwLkI
le7c6PqM+Kk1dkklPvQiMuUDa6ww+WRPEjnOlTtSpOToU7V+24tzkgoFEUZaPfat
MPwsEKdDXI0tFoSawqok6BY9ZV+krMnZrVPEYOuDjDBc25RFOxNGPhjUargFdrQB
Vpw+5rQsjYNku5Q3Cq5zAJwFVQthDIps77qSTbTBiX0efYw4wN1kzONau+bLAWNN
KHOpOiw5sb0w2TdD4bg18kie58foWYbEvDCN2UzhZa30Re5IL6M=
-----END CERTIFICATE-----

Public Key (PEM)

-----BEGIN PUBLIC KEY-----
MIICIjANBgkqhkiG9w0BAQEFAAOCAg8AMIICCgKCAgEAz/Ypy+TAY2GQ7RvJrylr
VqNqQbZp+QrSF9xxJnjth9LZyd3Ogbc72uieBeoGYoikf4iIgA7LwMcvxvfi5POK
MCeWvKfTD5gCBs2MSeHhQbEn0DmXhC+xcg76kS5EpYlnk6M2ahNA/TTq5g3CIYLO
7No43TBEQHV8CDOdjHjBRbL2SYvaAL8TJjKfK2vffsAa/W+DOVDoFf6zahRS+T9o
h8uQ4GJBCDRV8hP5c0cKBEhZTkPO6/7ihT6lyHO4DMDR3vadcVnBvDEP/OnhCdi4
AWaRaDjsbtHwBuKE+ZKv8ZdtzbEL52uAvmhzyKfSAjoKZRXpSThGOxjoLPv1in9T
P4WXTRHH0nTx9DlnJ0CJCnfguAVE9EMh/Tq87A2qInpu6R8u8ATmTveqMpkobCIv
OKuZEPNBkqVMFsAT3Jlxj2TJwE+DejhOKLI00aZKyr/4qI5sMntqtYjC0FgSNHUt
Kv83nCopb5OmP71SW8ohbAPtEp2zsOr5+dt4Vw6F9ndawkMuhrHG7NwOUjkEHHav
iJ0dNLG5YufSx7p7PtiW4A8EJRqzpsPJDpe4w5b6BRPNFHvqDWiLvc/YMHzga849
cizVNeg1T+aUtOisQX0giph1Z8R/iRrBFrQ3lBnwvSISP+5hY904a1ydO4Oiwm5v
M0hxAMCVOy+p6aaI4Jx1XwcCAwEAAQ==
-----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 290454649436477001376206630549925183350068
 . . . . . . . . [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 2020-01-12 20:42:33 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2020-04-11 20:42:33 +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.83192.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 848409206899266645935385619293127289225825509388653778231836702180782989547358449878834988006309108058052114826506607047189048317674406288984132615481815456572792788905486733630771270131551910819275515590514377550439574698862208990882311824036245896698677170892210703851534497023442633563980484922117656906343786135913700651157379875294476090322857939972573743847856026953423363991857077433769593180941992166932618073478339008827571708624590748103951253341814344454414514625523675271749945484994987736167610261932685611476474660342233280592977234529550312313477295264363610787593555338869498020074872363025343097060943759653449006308837483565266123418273776396936458196661669779419340970745922970567127121296221494192815226018032719257938767120704341445091563288819289860885818980843393147447160713873642113949021632429447480191051844165735319627785248680550643933107873610637892748460624257791867270495054828672256539175130448475934330045276564713984802260502137266756632311074288223835620387840871118763788578376918005791752743332839569553069678087285445535781848882071511321595139225081805202030392663033770216871460774221722077680691760262889194362184697426519146114882610247559033233632507619115949550379360611906330879285616391
 . . . . . . . . . . . . . . . . . . . . [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)
							0b0740245961b925578506b9087b1bf9a5f85e24
 . . . . . . . . . . . . . . . . [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.83192.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)
							00f0007600f095a459f200d18240102d2f93888ead4bfe1d47e399e1d034a6b0a8aa8eb2730000016f9bb5652a0000040300473045022100f9e1872dd65241aa1678d5115898ba218fc7262c18434cc1fc961e891ff51a6c0220739bd0949c65b570670fdf3d81bf034651332a47fe18a1695e9307f313adae9c007600b21e05cc8ba2cd8a204e8766f92bb98a2520676bdafa70e7b249532def8b905e0000016f9bb565180000040300473045022056ba1c8c071ae4e74ef762a7b0db6315522caeac48a78653c4c4eb918de41208022100c93aa77a410fd3bdc9340dcbc575346f18757af55475312990219b5a838259ed
 . . . . [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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