www.backriverroad.life

Issued by Let's Encrypt Authority X3

About this certificate

This digital certificate with serial number 04:6e:7f:57:0b:d1:53:66:54:74:08:8e:6d:fc:53:56:85:8b 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.backriverroad.life

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 04:6e:7f:57:0b:d1:53:66:54:74:08:8e:6d:fc:53:56:85:8b
Serial Number (int): 386049468013326596984046887455541823964555
Serial Number lenght: 139 bits, 18 octets

SubjectKeyId: 3f:87:bc:fb:23:60:f4:20:06:4c:0e:86:92:92:dc:9f:87:eb:d6:c8
AuthorityKeyId: a8:4a:6a:63:04:7d:dd:ba:e6:d1:39:b7:a6:45:65:ef:f3:a8:ec:a1

Fingerprint (sha1): 6c:b7:ff:9d:5d:df:7c:4f:b0:5e:69:2f:55:21:67:c0:5b:8a:b5:f1
Fingerprint (sha256): 9a:72:77:a8:31:36:c7:c9:fc:67:57:99:7a:c5:8b:83:bf:3b:1e:1e:49:16:96:89:5e:ae:da:4b:bb:49:e8:26

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.backriverroad.life

1

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for www.backriverroad.life

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.backriverroad.life

Other certificates including the domain name backriverroad.life

(limited to 100 certificates)

Certificate

The complete raw certificate details for www.backriverroad.life 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 386049468013326596984046887455541823964555
 . . . . . . . . [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 2020-04-05 09:57:12 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2020-07-04 09:57:12 +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.backriverroad.life'
 . . . . . . . . [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 816850304019536587124457369153142605087194945562102897717441277983620434938264414008549390581486723588011742795410882735694459475982550988537324703412794577304537644197379864760020569342859466649714274446862710147415875268225718640852800741104107142908954979221957086530583415012285573342603660341939345604248315081496231271274321394547468130946525842614311773562134815980460949769067780796124347697151331108398228001568786379044757674784337236241772833306465130453109643788515005523476009175438900629856950135367442813818073973923715738011969912121194874353934726620927704922217146601866291895892854785666758844261406913623909850928382668289962105972052141046169684535731699308385771883176308054316871937262928578720767757374039200607648034205982363911408863056343056329531077250678323388927470368731739065671897148395568554434058706184606305971104767276801556380205262956481312858147896528221104523740935186367916959333992237343386572716158070135894185560952989070525154608589390715249904116819366494684664048514728295464203064021562270532906478442671754496524896886912271866740815843289001541410279138146079988565794208245177811851924333850941915730874900706808517597025111566322505507198538354724114903960695438118824079788500377
 . . . . . . . . . . . . . . . . . . . . [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)
							3f87bcfb2360f420064c0e869292dc9f87ebd6c8
 . . . . . . . . . . . . . . . . [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 (26 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.backriverroad.life'
 . . . . . . . . . . . . . . . . [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)
							00f0007500e712f2b0377e1a62fb8ec90c6184f1ea7b37cb561d11265bf3e0f34bf241546e0000017149fcbe7a0000040300463044022035a4503891869037b491deca00de9dbd78b263a64b8b34d78f918d7942de45ad02204e358429554692cf1a44fd3878ec79dde8adc624e2181502d871722d08aa48eb007700b21e05cc8ba2cd8a204e8766f92bb98a2520676bdafa70e7b249532def8b905e0000017149fcbe7a0000040300483046022100dac4581399fe1f4577523a97c0cfe2bfa622ccc78571c734b2e1c171e57c7bc8022100eafb8880bbd0d4d08efa8b48086a48beb950fe7a2aaf6123b4f52e6813f5a066
 . . . . [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)
		000aa1aca354a65e84d353aa766d7401caf6a65e742f8729e6a7586c4fc77be55e2a612f94040488340c4ec16cbe2f265012c35c39b9aaeba14a5c5118bfe592243afb4d2e6cd0065b525d89ab0df23a88064d30cc94a22f1c4c5cc820932486282842fe8f732e20151bdac81e14af651ebb44506a99cac7ff8750ed330ad7d38a7ccbaaaad2bad7a1c6c4c745750d02ec8ff21139c31cbc50c89da6dbb882bc04870ebc8aa0b4bab6d5049d09c6d1f75bfaffbba587da5a01793bf5040ce83a24df9e7357cefc9181138ce46979d52621d60ff37a983797518fdae51a42bea2ca351ee1e1d0e142a7754ce3f16c4478a2a9fa98627d75f1d98031db4c23f73cc0