oilfieldsuperstore.com

Issued by Let's Encrypt Authority X3

About this certificate

This digital certificate with serial number 03:3e:e0:2a:74:80:e6:67:fe:b5:36:85:b0:10:f3:a9:83:ef 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=oilfieldsuperstore.com

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 03:3e:e0:2a:74:80:e6:67:fe:b5:36:85:b0:10:f3:a9:83:ef
Serial Number (int): 282732332054874830392753585359250826822639
Serial Number lenght: 138 bits, 18 octets

SubjectKeyId: 24:40:57:58:29:33:50:6b:fb:43:77:98:83:e2:84:af:dd:1b:67:e5
AuthorityKeyId: a8:4a:6a:63:04:7d:dd:ba:e6:d1:39:b7:a6:45:65:ef:f3:a8:ec:a1

Fingerprint (sha1): c3:f0:17:ce:10:13:f1:d5:81:c9:66:24:fe:c1:33:a4:2d:50:b8:dd
Fingerprint (sha256): 35:83:f6:76:15:64:46:6e:8b:7a:f3:f3:28:b7:d1:66:e8:2f:da:cf:90:81:7d:cc:49:a4:ca:a0:54:ef:89:6e

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 oilfieldsuperstore.com

1

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for oilfieldsuperstore.com

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

oilfieldsuperstore.com

Other certificates including the domain name oilfieldsuperstore.com

(limited to 100 certificates)

Certificate

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

Certificate (PEM)

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

Public Key (PEM)

-----BEGIN PUBLIC KEY-----
MIICIjANBgkqhkiG9w0BAQEFAAOCAg8AMIICCgKCAgEAz63Bwze0iwrB3u7r2YKh
cUm1tU1qy2bd2uq7SeRGxlNy9ubDZYw/C3fEweeKLdR1wFVfPo4sRGUVbd4tlH9B
tGpZ+zhL3MNei/wGuMICrLkj2z1VYIlqRQMDjUC3euW+fsw5P3zbdDPTx+toHFp+
lqnRSlDjxtheSVG3NrmKGIdWENCBsrc9xSnv7R5y/BjQp4QSN33Vw39nShI1KRE5
oWMNolIJiMCH+ABiactQS3I2yz4HAPUgfI38vS9JCDrsuFGDE4j+cZmHOEUCZPFc
t8Gc+vCs8rfC9+U4Jo4diGoV/MVVGHDhjgfB06gugUi/dLW4b01gjVPoU/N2qA4Q
lIlPnhR+I8bs6iLuRM1z/H0AZv/QYpBJnJi91Udin3b9nYjLxvao87YkGwL0fJvR
2e9QNnNSn5VyeuAUN4MFc026F1oVWKU1/QZQtYzqHl8Z7f6p5LMjChB1FcDVcLxV
aQ9Sr21q8cTL30n8ZVg3H6AjgUzHyovLlMlWGOZa6ap3CwxcSeSOxaQQ2hohVNKw
dT88hi6cwHDoz1R6K6Nk7yAFS1FS1XbdOh4Ny0mqAxI4wvyiLmPFzSCTKg7F4vG7
itKhZUB1ZUlhZAJVVd0R219xr6dtQc/4XTEugCEXK72qGvtpzbp9Pnljq05qZoe7
aNSG/4YO4HxziKll/q9LVIECAwEAAQ==
-----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 282732332054874830392753585359250826822639
 . . . . . . . . [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 2019-10-11 15:50:57 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2020-01-09 15:50:57 +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 'oilfieldsuperstore.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 (4208 bits)
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:2|false] INTEGER 847255330850897770680187154991714051294462137835075287774604668858344468927341363408035604085578446475322491857466905770386030301268457337733525444794293833181619876143697796676754491628330773099737705693004655209726872936781089340264439455631659837506515425921602590047535687166866691547123317733197110670159029271154338707390197236194777463921883645806683003531833607898406560103239853128587627279599644252937343551756701892711748476230955237241730283875585996941282025106594830919103547936378085948466298523660074821466707861164096412169460773166407341324261977725517866145198251640681452588879970967647108702642299780664071752060623344406465326497093733664444901090602263347289929297445181259601049366314989313475587129583560724610221170666246205789594006705307945836172685050486212371212414178961627003030396740054791679947630175283175634694312586560351576183869147616313516397547613065342290107211630335072356816034445917646066335964204461622915186456866718934745121265797186973147995902211556943306698598577903769425918075493544382961463031984211506266200200380465551814754138387359178020754133074937290765902734233445003702249423206935471392867318817215582550340606043169180459854740557632756097229133589916424175849678001281
 . . . . . . . . . . . . . . . . . . . . [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)
							244057582933506bfb43779883e284afdd1b67e5
 . . . . . . . . . . . . . . . . [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 (26 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'oilfieldsuperstore.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 (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)
							00ef0076005ea773f9df56c0e7b536487dd049e0327a919a0c84a1121284187596817145580000016dbbbafea10000040300473045022100f0858721380cbf998e05df62731c278009bfeea71c226f328f291aaa58e76bf70220209b25686d4163f0447dea7f17c10f32180467c476cf09e51bf8fef6dd74425d007500293c519654c83965baaa50fc5807d4b76fbf587a2972dca4c30cf4e54547f4780000016dbbbafebc000004030046304402203dfc57b9aed904175b81ef287fd9a4be9e67a82914f2dfeff252bda9dc48db1a022057a320a2133c5829d69ee47a9005052e06187d7cbb996acf6aaadb83557ba7f9
 . . . . [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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