pifaa.org

Issued by Let's Encrypt Authority X3

About this certificate

This digital certificate with serial number 03:0f:a3:82:03:32:8e:04:77:4b:36:ad:f0:01:d5:27:de:05 was issued on by Let's Encrypt.

With 2 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=pifaa.org

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 03:0f:a3:82:03:32:8e:04:77:4b:36:ad:f0:01:d5:27:de:05
Serial Number (int): 266658432525851956913812542080373251104261
Serial Number lenght: 138 bits, 18 octets

SubjectKeyId: 38:7c:09:62:6e:49:40:53:ea:c8:f1:9a:12:36:ca:24:fb:01:50:e2
AuthorityKeyId: a8:4a:6a:63:04:7d:dd:ba:e6:d1:39:b7:a6:45:65:ef:f3:a8:ec:a1

Fingerprint (sha1): 5e:9f:b0:02:6e:c7:4e:10:7e:b0:08:97:17:41:ed:85:1d:0c:f8:dc
Fingerprint (sha256): 84:36:6c:40:37:4b:31:b7:52:a7:53:d8:43:09:99:87:31:37:22:a0:ac:c8:3a:98:9a:ab:2f:4d:a4:d5:aa:60

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 pifaa.org

2

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for pifaa.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

pifaa.org
www.pifaa.org

Other certificates including the domain name pifaa.org

(limited to 100 certificates)

Certificate

The complete raw certificate details for pifaa.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 266658432525851956913812542080373251104261
 . . . . . . . . [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 2019-02-13 16:46:22 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2019-05-14 16:46:22 +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 'pifaa.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 717928409748772476536248331248100032110488284141193246361157657737861397430185735957516402701479776471956289828959675869300525306737570171399713374109136329873058843165711315362558863256123101581161417394942613482839725406147882047463247807398136583322268942183407077870571587079778824963936396944989022283032396635575708166677686203921802845350008972466164948128028744795380201240227688662359597092039503315084312452296508368943934494601040559905680655261758887446469698347613366221975299107584031006857155968121620407622195043395010107396117857022492056798057748228212897179239556073608375049518952576156157899642156767516553406115409344039494672797548738510354446625877835228089866384977582074487512560386252264252252676119944549245609991852927906137240205128881641421247062241123103089384038412410215942540794523278869413360719666581585499712126383887304063686993016323278352949166395114580343797201368722832446840949531684562737970793935728366685150595525225319586244508659400316430652589987130686354263008887915276310057079424614776176732245810110184691457212277509476255484720496744499574653246408206128698437082809895792790652182469682055868020566386589564142651626788782864178992244343519812051835978144997025372022064257189
 . . . . . . . . . . . . . . . . . . . . [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)
							387c09626e494053eac8f19a1236ca24fb0150e2
 . . . . . . . . . . . . . . . . [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 (28 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'pifaa.org'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.pifaa.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)
							00f1007600747eda8331ad331091219cce254f4270c2bffd5e422008c6373579e6107bcc5600000168e7f77d96000004030047304502200aed8a0acb2da326f976fd7b55f2b3963660a2db8f503757488072381ef6825402210086c1fd27efd44b14598360b9f2b1be4c3277754765ed85a9fce482255e74a378007700293c519654c83965baaa50fc5807d4b76fbf587a2972dca4c30cf4e54547f47800000168e7f77faf00000403004830460221009ffd25711815cfa2cd670d396c0552889be1c8f7d5be2b0f6006b5fb53fb6b720221008f3d29e8f3eba48b30d65a135207f87a463d2c1d823e59a7da92201aca7410c0
 . . . . [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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