brandripplr.com

Issued by Let's Encrypt Authority X3

About this certificate

This digital certificate with serial number 03:9e:72:9f:e1:1e:b8:79:f1:b7:40:2c:bf:1f:11:a8:fe:54 was issued on by Let's Encrypt.

With 4 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=brandripplr.com

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 03:9e:72:9f:e1:1e:b8:79:f1:b7:40:2c:bf:1f:11:a8:fe:54
Serial Number (int): 315253833901485102974544634032449934392916
Serial Number lenght: 138 bits, 18 octets

SubjectKeyId: 7d:ef:6e:e7:84:0d:32:58:01:12:dc:44:9e:69:1c:bd:a8:31:ca:61
AuthorityKeyId: a8:4a:6a:63:04:7d:dd:ba:e6:d1:39:b7:a6:45:65:ef:f3:a8:ec:a1

Fingerprint (sha1): 48:a3:ec:79:ce:66:b0:d5:61:b8:25:46:9c:07:75:1e:92:fc:35:a6
Fingerprint (sha256): 33:17:7f:84:9e:17:32:ec:94:9a:d1:17:29:de:a0:31:8b:c2:e6:b9:53:a7:32:7b:5e:e5:5f:57:5e:c6:d4:a9

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 brandripplr.com

4

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for brandripplr.com

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

brandripplr.com
influencer.brandripplr.com
internal-influencer.brandripplr.com
www.brandripplr.com

Other certificates including the domain name brandripplr.com

(limited to 100 certificates)

Certificate

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

Certificate (PEM)

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

Public Key (PEM)

-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA5aE+RAGwSaVrBJaonejm
L0YZibeys9hm6jDUzbYJ/YeYauO9rEz568bHTnoZDsBQsZfaehvVO4AjEJvDI0st
/btIUmFYXuAZsFGO2vixvHisKCOFXtbzw7ijfeo3vHl+EyVmfzS8dIkkerHZb9oT
Lu3+XwSnp7M0CdGfeG1GDJp2EXlPYnQiIWRkb23T/OcLVWJn1iBvy1kqAC27AVcg
K/JxER+3ejO63e1+Zzg8NQhNd9gUjtgFYvO+lusROv+y21gbGHLL6i11OSFTP2N7
EjJLC9xgx9XAlGfADS65hGxHKsKHMHphQF+7eDi10XYaKkk78XRAmzQ1ELsqNZm6
QQIDAQAB
-----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 315253833901485102974544634032449934392916
 . . . . . . . . [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 2018-08-03 17:30:56 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2018-11-01 17:30:56 +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 'brandripplr.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 (2160 bits)
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:2|false] INTEGER 28988083835025450397085993096229467209879867862244468730475877405796562542723910808428140400664960991622307475717486366329152477505766676394365917620437960244348663342600061259924439052911304489480232308317186335944360626486616273623571730960742822502874170032438790169835613086762983980471669297189851508194283343432066138252021063083350473594934610015746828117876860868371115602979762387768279556728411726133531176260813215945332405577682386372282661572515274143294967973258012573922826660802746162952616521682242679531766583018164227852096709060360192367192231535132655424470616275593242465891608759725966640134721
 . . . . . . . . . . . . . . . . . . . . [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)
							7def6ee7840d32580112dc449e691cbda831ca61
 . . . . . . . . . . . . . . . . [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 (105 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'brandripplr.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'influencer.brandripplr.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'internal-influencer.brandripplr.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.brandripplr.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 (246 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 1.3.6.1.5.5.7.2.2 (unotice)
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:12|false] UTF8String 'This Certificate may only be relied upon by Relying Parties and only in accordance with the Certificate Policy found at https://letsencrypt.org/repository/'
 . . . . . . . . . . . . . . . . [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)
							00f10077005581d4c2169036014aea0b9b573c53f0c0e43878702508172fa3aa1d0713d30c00000165010e921c0000040300483046022100a56c2891fa8ab0d563db8a9f96365847d737e16ee355e9e69934c2f43f1208f0022100e9b7a7c88e185d8c4b5fe059ee555342714ade9953fc15bf224829a8eaa71281007600a4501269055a15545e6211ab37bc103f62ae5576a45e4b1714453e1b22106a2500000165010e91f8000004030047304502204b1f224d97b84ef2cb47ee957813a8f4aafcb4866346f98d9138556d2174ea17022100eb4653e21603ed10c95786c8d0991a09b25f2041b7473769b241022859311d45
 . . . . [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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