loredana.org

Issued by Let's Encrypt Authority X3

About this certificate

This digital certificate with serial number 03:8c:78:9f:5d:93:8a:ab:25:0b:b8:ef:a7:cf:e7:e2:c3:87 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=loredana.org

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 03:8c:78:9f:5d:93:8a:ab:25:0b:b8:ef:a7:cf:e7:e2:c3:87
Serial Number (int): 309136723996860370628902043623935229215623
Serial Number lenght: 138 bits, 18 octets

SubjectKeyId: e8:6b:9c:34:80:83:4d:33:34:a4:a9:8e:65:25:9d:0f:c8:9a:26:f8
AuthorityKeyId: a8:4a:6a:63:04:7d:dd:ba:e6:d1:39:b7:a6:45:65:ef:f3:a8:ec:a1

Fingerprint (sha1): f9:d0:09:8d:b2:68:b0:a6:93:30:a9:cb:10:d7:36:1b:80:ec:8d:0b
Fingerprint (sha256): 0a:d2:f2:f0:08:7e:fa:2d:ae:c5:f1:6c:df:29:08:60:68:a5:e2:34:0e:47:3a:0f:25:de:1d:32:1e:ba:bd:fb

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 loredana.org

1

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for loredana.org

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

loredana.org

Other certificates including the domain name loredana.org

(limited to 100 certificates)
loredana.org
www.loredana.org
loredana.org
www.loredana.org
www.loredana.org
loredana.org
loredana.org
loredana.org
loredana.org
www.loredana.org
www.settimomilanese.org
www.loredana.org
loredana.org
loredana.org
loredana.org

Certificate

The complete raw certificate details for loredana.org 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 309136723996860370628902043623935229215623
 . . . . . . . . [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 2020-02-25 15:15:20 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2020-05-25 15:15:20 +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 'loredana.org'
 . . . . . . . . [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 704579894852210023547242608444300915765486959219179962375706959466112792561555185968865669305220706206246026177114181130146494094114426036116829180503385773479106052337140633759544285560816055950314790670045129095157737243189346160029844273253185293996567848444661406656279922894980234928208909063038984097272655314799476615534939191005443641469783875247183142938508824495505780355648006552448482444589581052405611287433494788055413793922108318652765256545268467175344832635760200613620870406424410194907049611153881542497043933491532418210972318432569998921616727323386047415128586363322788003193233431786325172118643062484405800651362437626998534736787069769820132007304100688777130676656212665105181812281793063997346058993659095183933186024190863093368151731659123917313936872738055596125752747828891449128851441882641975131958656382643387357621044351780242335728008324480823508081320718608158025453141640761089725214415922013970658448890762144301703386138229111832913986803054066931190280653237697231073130770571986011467259339596913150564860412757806938710263952306061279077019498962632809104572752338366393229653779157027106468279135754714914626654419885635708355926981041731659237143308678925735996834746633975647607548928141
 . . . . . . . . . . . . . . . . . . . . [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)
							e86b9c3480834d3334a4a98e65259d0fc89a26f8
 . . . . . . . . . . . . . . . . [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 (16 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'loredana.org'
 . . . . . . . . . . . . . . . . [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 (244 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (241 bytes)
							00ef007500b21e05cc8ba2cd8a204e8766f92bb98a2520676bdafa70e7b249532def8b905e000001707d21a15c000004030046304402200e65ab614f0088580d2f84f3aad7f784d73ba5a1a09cdcb9e03f8112ea55a6a202206bf6787a540e4298763fc03b67ba3459e9c05f4dcf6427f0e1ca1ec4ea9125c90076006f5376ac31f03119d89900a45115ff77151c11d902c10029068db2089a37d913000001707d21a1920000040300473045022100a67e563b52d8e2c50abaa7d3715fc8698f455197d340e14889422841ae1c698a02205e29348a389c536c10ae0cbca1a0743f226ec60c4d3ddcbe389df0d63bf43dca
 . . . . [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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