cyclefriendlyhotels.com

Issued by Let's Encrypt Authority X3

About this certificate

This digital certificate with serial number 03:f4:3f:89:07:dd:ac:d9:df:4a:14:8d:c5:27:c7:42:a6:1a was issued on by Let's Encrypt.

With 3 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=cyclefriendlyhotels.com

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 03:f4:3f:89:07:dd:ac:d9:df:4a:14:8d:c5:27:c7:42:a6:1a
Serial Number (int): 344450208191933579950573656343912242128410
Serial Number lenght: 138 bits, 18 octets

SubjectKeyId: 5f:7c:5c:0c:0c:f8:b1:63:80:19:be:1a:55:3b:8b:5f:0b:21:ea:82
AuthorityKeyId: a8:4a:6a:63:04:7d:dd:ba:e6:d1:39:b7:a6:45:65:ef:f3:a8:ec:a1

Fingerprint (sha1): 08:c8:3c:2c:13:54:fa:65:a3:e6:04:1e:27:b4:bb:54:8b:6d:a0:c4
Fingerprint (sha256): 4c:ae:65:5c:7d:64:b3:e0:5b:1b:82:29:59:10:59:19:a9:2e:24:8f:fa:05:83:5a:f9:5c:9f:cc:3b:5d:52:74

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 cyclefriendlyhotels.com

3

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for cyclefriendlyhotels.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

cyclefriendlyhotels.com
mail.cyclefriendlyhotels.com
www.cyclefriendlyhotels.com

Other certificates including the domain name cyclefriendlyhotels.com

(limited to 100 certificates)

Certificate

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

Certificate (PEM)

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

Public Key (PEM)

-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAzjpvx7h/mx47LTebVb6I
Ro8uEkxL13h7BKKDVQD2h2rS2XcwBq8vWtWvWiEdiYIAJmjqQn+jRFyU4QdtgAcO
biZ+slnSAeBPS9csqz7WJGP/e8vf67xkIjUDTUWTfanHupkpr2FdjxQ0FQ6sx6E5
NoyxjOyd/v94wZ8HLZiIfGupprD12VeB3VVflhOSkbHwjT9nipMjZZYOrFE4XiAg
3lV7paejMsJuH5bV4P0pegDDANGARnVl2fvjj2sdOdjvEB1iCPAYRIXGeF3RPEpe
BWMlJw5kw/QZDBMt+IuBcYHbbIs6/cTqCYub9xrYh3uYXY2TJ5YfS2173CoBsv5A
NQIDAQAB
-----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 344450208191933579950573656343912242128410
 . . . . . . . . [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 2018-08-25 14:04:35 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2018-11-23 14:04:35 +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 'cyclefriendlyhotels.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 26033907004800276479217020924929385047115594636854369689001586907435262579389892041039673497027705912403688284657423195638748799427066633801260087359819377423190493792235672733135567765019904649292799720751401245348670489991677510534748171940357425646850030809356919419423906992642446670182059576967165693007964723411971479328983735584567668476285061119123280442422807070608633520787570808588078103512067928620825667592271540628663343393827433194427874945246591145308678522454233880353273430873051000943730792170734317696555468704223469465798299245884043928127554493033817423609290264267162572818585117662551209820213
 . . . . . . . . . . . . . . . . . . . . [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)
							5f7c5c0c0cf8b1638019be1a553b8b5f0b21ea82
 . . . . . . . . . . . . . . . . [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 (86 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'cyclefriendlyhotels.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'mail.cyclefriendlyhotels.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.cyclefriendlyhotels.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 (244 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (241 bytes)
							00ef007600293c519654c83965baaa50fc5807d4b76fbf587a2972dca4c30cf4e54547f47800000165719d8e060000040300473045022013dd31098b0aa2ed10279a53b9ae275df7560f155817fa896f4f6c214f967f6e022100f292a0159ed3bc3a718e147134b9a65fd3fd9630a0c40c81340f1dd5c71ac95f007500c1164ae0a772d2d4392dc80ac10770d4f0c49bde991a4840c1fa075164f6336000000165719d8fe700000403004630440220628757d2b87b7a61970f4d8fe69de1694bccd03ddd27f4ea94ba5034581534af022048eee84e9a176ed2bd59332da50d0a9a4b51094f8a2f105dccfa1d22410c8784
 . . . . [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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