tv4.co.za

Issued by R3

About this certificate

This digital certificate with serial number 04:b1:5d:f1:73:3e:f9:f5:b3:d6:5e:57:22:0a:eb:3c:cf:e7 was issued on by Let's Encrypt.

With 10 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=tv4.co.za

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 04:b1:5d:f1:73:3e:f9:f5:b3:d6:5e:57:22:0a:eb:3c:cf:e7
Serial Number (int): 408803994556664607988507243227802100355047
Serial Number lenght: 139 bits, 18 octets

SubjectKeyId: d0:6f:71:79:82:93:fd:53:50:4b:cd:0f:4b:b5:8f:7e:e1:61:a4:32
AuthorityKeyId: 14:2e:b3:17:b7:58:56:cb:ae:50:09:40:e6:1f:af:9d:8b:14:c2:c6

Fingerprint (sha1): d7:6f:f5:72:e6:d4:db:d9:05:8d:85:eb:d9:e7:e2:eb:e9:2c:95:2b
Fingerprint (sha256): ac:6a:29:77:6a:2c:2c:4a:83:8a:ee:8f:2a:1f:5f:2a:24:bf:67:09:32:3e:1b:3f:0a:e7:32:02:b6:d0:f4:8b

Issuing Certificate URL: http://r3.i.lencr.org/

Revocation information

OCSP Server: http://r3.o.lencr.org

Check the revocation status for certificate tv4.co.za

10

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for tv4.co.za

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

9 extensions
No unhandled critical extensions

CA Certificate

This is not a CA certificate

Subject Alternative Names

10xmetaversity.com
cosmoestetica.com.q8.co.za
cryptoautobot.com
homeschooldefenders.com
itsprettyugly.com
news.banyantelecom.com.biodefensevaccines.org
nextquoting.com.epper.com
stonewaretiles.com
swoopbug.com.w46.net
tv4.co.za

Other certificates including the domain name tv4.co.za

(limited to 100 certificates)
housedoody.com.tv4.co.za
tv4.co.za
tv4.co.za
tv4.co.za
tv4.co.za
tv4.co.za
tv4.co.za
tv4.co.za
tv4.co.za
tv4.co.za

Certificate

The complete raw certificate details for tv4.co.za in PEM and ASN.1 format.

Certificate (PEM)

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

Public Key (PEM)

-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAqvgV1Dr+kAij760PVJlh
POWytpA7nJdl6tloYdGfYreEuIbKlRzpQMwj9VKXSShsl6pYK7HkM9ZWYtkbdHGO
/viqtKqG0najJuKG4ofnahjNUrJZPdrD0jYQxYBVis8S3RGH5LfhgHH7eW+/z5zV
LI63yzqdvXciXi38uYJV+3CJZE2xStqEW2W4/SZmiUmGw86ONbj3tYFbdXVr645Y
RIkh30ExJcf8UDvU8tfcL87WJyAyJ3RUaalz4M0B6HP5wO1R1h0dd5i9lvpk9HWS
8fHN/ZyryDa5TRbluledgSF61VUs2jM84n+Fn92cZ7DJi81tEoB5q9vNJIkwKjQN
fQIDAQAB
-----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 408803994556664607988507243227802100355047
 . . . . . . . . [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 'R3'
 . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2023-04-28 18:48:00 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2023-07-27 18:47:59 +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 'tv4.co.za'
 . . . . . . . . [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 21582847250187352231238104498065909380307273524530549646659026086763618535799407662288533990264761885121330035981507659743480359553340578550377127894502066198362808980861084809307361881251887794669616087504293554790163016975900764819656087959946461450403836143859871183666392588513253310481477849143960949844772295400892750392710562322625030398204065759911508675404687684294212618554450373542114958944592517510188834893322084533203604318360828945731075137007084706571490382705126372947784318772196511259760200854227577043036330322475209742144381314533647462456859607037871404523582253803316853061105775830633993735549
 . . . . . . . . . . . . . . . . . . . . [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)
							d06f71798293fd53504bcd0f4bb58f7ee161a432
 . . . . . . . . . . . . . . . . [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 142eb317b75856cbae500940e61faf9d8b14c2c6
 . . . . . . . . . . . . . . . . [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 (73 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://r3.o.lencr.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://r3.i.lencr.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 (241 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String '10xmetaversity.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'cosmoestetica.com.q8.co.za'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'cryptoautobot.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'homeschooldefenders.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'itsprettyugly.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'news.banyantelecom.com.biodefensevaccines.org'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'nextquoting.com.epper.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'stonewaretiles.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'swoopbug.com.w46.net'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'tv4.co.za'
 . . . . . . . . . . . . . . . . [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 (246 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (243 bytes)
							00f1007700b73efb24df9c4dba75f239c5ba58f46c5dfc42cf7a9f35c49e1d098125edb49900000187c9687c5c0000040300483046022100e6a5b03ef062ccfc94b7d4eb0891831a8372e957b4d7c32326fb81dc26522c600221008445c359a855284fb9d8b57f28aa6b42e167c77b482f104327087615b35e1cd40076007a328c54d8b72db620ea38e0521ee98416703213854d3bd22bc13a57a352eb5200000187c9687c690000040300473045022079c62dd46b31e994381a505dca71bf2d2fa523531769b8748ee1ec966fde4c46022100b215e10457cbc0f4f9c241cda39195434565ba3b0af8e83e81c6d0a6c6167dca
 . . . . [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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