booking.lat

Issued by Let's Encrypt Authority X3

About this certificate

This digital certificate with serial number 04:75:f2:92:ea:76:c0:3a:c6:fe:b1:01:34:28:3c:1b:a3:1c 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=booking.lat

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 04:75:f2:92:ea:76:c0:3a:c6:fe:b1:01:34:28:3c:1b:a3:1c
Serial Number (int): 388584616662604345148271011917960796939036
Serial Number lenght: 139 bits, 18 octets

SubjectKeyId: 5e:68:4f:4d:97:8d:45:37:9c:46:21:dd:f8:f2:c7:b0:71:1e:c2:76
AuthorityKeyId: a8:4a:6a:63:04:7d:dd:ba:e6:d1:39:b7:a6:45:65:ef:f3:a8:ec:a1

Fingerprint (sha1): 8f:76:05:33:da:34:5f:22:bf:2e:44:1f:1b:4c:5e:3a:8b:4f:75:9f
Fingerprint (sha256): 5c:f1:2a:dc:c1:29:5b:2c:56:c2:7d:06:fc:9c:32:ee:c4:a8:be:4c:21:1c:9d:85:a5:82:35:b6:93:67:91:11

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 booking.lat

1

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for booking.lat

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

booking.lat

Other certificates including the domain name booking.lat

(limited to 100 certificates)
booking.lat
booking.lat
booking.lat
booking.lat
booking.lat
audiolivros.pt
booking.lat
booking.lat
hispanobonos-com.radicalnames.com

Certificate

The complete raw certificate details for booking.lat 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 388584616662604345148271011917960796939036
 . . . . . . . . [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 2019-12-31 23:32:32 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2020-03-30 23:32:32 +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 'booking.lat'
 . . . . . . . . [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 805581489169123313934184029669019043294507545117350038551966472046835376021644791857260742642218316354176031663915630760292465500643175958626627176093581003381422711703528778265353908876314129582014688132296800511065399982578597539460550214722148701964959508507074770548727966389582502989953129488916087071711607364721208868933396273785697628704450621678441710455173545060681209009602676893050630824245315445903506304308707365227536611367721005064103959971032096274822032489533816418144748389611770256964129487073549712055373223716909940117107037271638653122266054124993122405010764313654281609160573785279941998358207686859486991822751378618248176021596041978221057807160064832423622286837696601317300426313035755563905054490452879756100061864046772101159780702190272577569370495615786603110649616978468067192048069178745932104953602184841485560888518144089350554639689748633138850863917511056948848014564797996814195192028389942947152348150963295875096065834156308153303448287989651521744726304217248262072683080967399872555853562352657084899033983761265600279689735822928928427515224418935708487998388397163334145044369906523357463470605559750343301888658500895588759745925644788616402499406482435324152718476377407867254203717549
 . . . . . . . . . . . . . . . . . . . . [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)
							5e684f4d978d45379c4621ddf8f2c7b0711ec276
 . . . . . . . . . . . . . . . . [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 (15 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'booking.lat'
 . . . . . . . . . . . . . . . . [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)
							00f0007600f095a459f200d18240102d2f93888ead4bfe1d47e399e1d034a6b0a8aa8eb2730000016f5e84b1ea0000040300473045022100c92b1faef6e32be9b697421bb165dbba33eef2ee53d9e8280dc6e7b81717a64a0220608a59dc98b695a17369c7cb214f93ed51bf4ea5ea8ebdf423ef59ff873fc1f4007600b21e05cc8ba2cd8a204e8766f92bb98a2520676bdafa70e7b249532def8b905e0000016f5e84b1dc0000040300473045022028ae90d84d6095414dbd0a8cfdade84ad6fee09990ed4e90a440ce90aed4d728022100f7fcea9097c3c1f81c7e0be8cc4821c9f9de9a07f1caa4c736dae3e0e6f6a51e
 . . . . [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)
		0099ebb36db45752d7d879e2cfe3add4acae07c9659c45b930849a9c6a378c36140f88074c90198aac496e63fbdae9b6b6d22ab2f91f8169d4bd252e4c7146da2a356bf3d6beeea782733da3762babe67db72b83e999e6c1d777c47d2b5eb8b7027d705625981eff516ce852d1d12f80747fd996cabb5efdedcb5cb75aadc63ac58144d6483f787702259ef4691993e5fbce3a78fbafd5d4ba7fbc553b2b9406777454b15332342431909401848bbce89eab848132decc5648b5569a546abeeea5d0fbf3c1d7d03c1b491e2d1cb650c245963a3a9ca9fdccaff8782b66aceb3e94984a5cee485c2b18853fc8306fde3f3f73db74269b9d379ea5374a04f58b317f