www.p8.org

Issued by Let's Encrypt Authority X3

About this certificate

This digital certificate with serial number 03:75:a7:8f:02:92:e8:dd:9c:41:c7:e3:00:6e:68:26:54:6f 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.p8.org

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 03:75:a7:8f:02:92:e8:dd:9c:41:c7:e3:00:6e:68:26:54:6f
Serial Number (int): 301372618350981590963385577291663670662255
Serial Number lenght: 138 bits, 18 octets

SubjectKeyId: 3b:c0:03:4a:43:7b:34:99:2b:85:0c:d0:f5:3a:7d:eb:d3:e9:de:93
AuthorityKeyId: a8:4a:6a:63:04:7d:dd:ba:e6:d1:39:b7:a6:45:65:ef:f3:a8:ec:a1

Fingerprint (sha1): ec:18:73:24:60:0f:a7:fd:43:57:d4:90:a2:8f:f5:24:bd:8d:24:3e
Fingerprint (sha256): 17:a8:92:bf:89:3d:87:b7:d5:92:c9:4b:20:ba:f2:e6:88:48:3d:57:cb:0e:49:14:34:2b:36:df:9e:20:e9:e3

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.p8.org

1

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for www.p8.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

www.p8.org

Other certificates including the domain name p8.org

(limited to 100 certificates)
www.p8.org
www.p8.org
p8.org
p8.org
p8.org
www.p8.org
www.p8.org
p8.org
p8.org
p8.org
www.p8.org
www.p8.org
p8.org
www.p8.org
giudizio.com
p8.org
p8.org

Certificate

The complete raw certificate details for www.p8.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 301372618350981590963385577291663670662255
 . . . . . . . . [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 2019-03-23 00:48:50 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2019-06-21 00:48:50 +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.p8.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 861855145242943576361367752665681854532509484335469782565637599712421363563943354136024350598858183588947519322492568825606005964851399358280627921916154674084936167651405615283091043753870695528947776784625020189190106337411107399341562018376737805921977657668874608982323264541050829510692758078175833222990036811290797061822516428534061576481315498813311120913741729011247485547395228363895993967853218444734551777212921282361547266154858758767096801040338319836472205412457887144763490724076084122939280468853873496650226953021692898529429988784692119691654931231781562316937166319012052790905990796546012588319629425551267922190097056347785428359091916184564103379525794130061337313667488115997179248317078357741331265923821732325641907736889152593404957911298975907770285263202355975807345363494695300741083018745051592255304655901789819313890838557101674291383028227537864761366033894307207338057810593197586476144507131394103465841192423730065855769059671289092485248577823514296830046161233509784848113782705794633937321230219991345010593682456425574488743246425966175115248636560765781300356509725334506681906436332535578417220730183300765721228177545019908943923986902318458447158623378069784910166215406934229117965224047
 . . . . . . . . . . . . . . . . . . . . [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)
							3bc0034a437b34992b850cd0f53a7debd3e9de93
 . . . . . . . . . . . . . . . . [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 (14 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.p8.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 (246 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (243 bytes)
							00f1007600747eda8331ad331091219cce254f4270c2bffd5e422008c6373579e6107bcc5600000169a83c7e50000004030047304502203e43113e751d05d12b0dfb58eecc300832484c76a8b99610cc264db82ba4a4ec022100a5557bae92a522aec81ed02b44b4627bc3430781701ffb7186c9c5e3d5b9319400770063f2dbcde83bcc2ccf0b728427576b33a48d61778fbd75a638b1c768544bd88d00000169a83c7e7d0000040300483046022100ef02dada37dc87bde12e4cc38b91137fa4b70ce5d8945b4b3782f6acd33e464a022100f70b71d157cb66dd8f493dc46a9742541dcc704921d172406585485b68242b49
 . . . . [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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