www.btcdistributed.com

Issued by Let's Encrypt Authority X3

About this certificate

This digital certificate with serial number 03:75:b2:cd:c7:e6:cc:6a:e5:1e:74:b4:6f:6e:20:50:19:e1 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.btcdistributed.com

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 03:75:b2:cd:c7:e6:cc:6a:e5:1e:74:b4:6f:6e:20:50:19:e1
Serial Number (int): 301387565783621507505214635910605774526945
Serial Number lenght: 138 bits, 18 octets

SubjectKeyId: fc:8e:86:81:fe:44:04:7e:23:86:d7:2d:89:86:90:77:83:5f:2c:10
AuthorityKeyId: a8:4a:6a:63:04:7d:dd:ba:e6:d1:39:b7:a6:45:65:ef:f3:a8:ec:a1

Fingerprint (sha1): 70:85:2b:f2:6d:e1:80:5f:88:ec:56:67:1b:80:a8:e0:20:5e:c0:6b
Fingerprint (sha256): 40:9e:d1:b1:83:9d:d4:bc:67:d1:74:5f:35:15:6e:31:37:d0:00:24:66:0a:d2:4d:97:41:4d:dd:c9:a4:ef:0f

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.btcdistributed.com

1

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for www.btcdistributed.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

www.btcdistributed.com

Other certificates including the domain name btcdistributed.com

(limited to 100 certificates)

Certificate

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

Certificate (PEM)

-----BEGIN CERTIFICATE-----
MIIGZTCCBU2gAwIBAgISA3WyzcfmzGrlHnS0b24gUBnhMA0GCSqGSIb3DQEBCwUA
MEoxCzAJBgNVBAYTAlVTMRYwFAYDVQQKEw1MZXQncyBFbmNyeXB0MSMwIQYDVQQD
ExpMZXQncyBFbmNyeXB0IEF1dGhvcml0eSBYMzAeFw0xOTEyMDkxNDQ3MDFaFw0y
MDAzMDgxNDQ3MDFaMCExHzAdBgNVBAMTFnd3dy5idGNkaXN0cmlidXRlZC5jb20w
ggIiMA0GCSqGSIb3DQEBAQUAA4ICDwAwggIKAoICAQCrnCD04jgc88zlqKYbG+uL
kAGQWO8s2QOw/XfJb/b6p3EB25kwBgDZqD+oTurFyOejdR7o3wk8s1GmK65++EzS
gA6UJ1TFIH7aOWfooBSoT6TM5dghITurHGByLqSJ/r3ycXlim3zFVHStdI2NAMzQ
3gV4gneMMI/w3/EpGhcPsRt3fVFY8GSyEMKFaKEYvMt1hmaw4lNhck8qXqGiL2jM
kqjQIAhm+4vd8LrlkMwYNxLW7ufrNdZIkgSaAv3sy+rIU9HYzhrm0OiKNHf776rH
/Tj5ZdbD3BD4uMnaPc/v2BpGNjGBWnE2NGuf13oZj0NSQYOW5gwg2YRzjFOjbeX9
x1Aw49G9GFy86SDI2l9EqJ9hxu6Ygo7tzt8MatNYUWPBSArGs21q4wHHz7lke2yS
MlF2Uyh32LzQSflQ0OknW1WITKkPEaGOIvJe74IQ4REycp/wVrpZjHLnW1tAgOAc
vy8i+aliVdhMLCYnd8I1e1Q7uvgCkZMQFhcPoFOkml9kj3NGZJA+D7B7b0Bv9tuG
/dQkXkLRoVBOR4vKjedl+V2rv9ttnhc8sRJenoyhTl3HAEnsbyc/9sUpZevx6hJX
Bhe8cyNsPIMYHJxQ8uUrro6hGiblQfB+f++15GNGdnQOKBthsaTp90zFOHjANaaR
eDrJRD6dGiWr4LpHI5H/2wIDAQABo4ICbDCCAmgwDgYDVR0PAQH/BAQDAgWgMB0G
A1UdJQQWMBQGCCsGAQUFBwMBBggrBgEFBQcDAjAMBgNVHRMBAf8EAjAAMB0GA1Ud
DgQWBBT8joaB/kQEfiOG1y2JhpB3g18sEDAfBgNVHSMEGDAWgBSoSmpjBH3duubR
ObemRWXv86jsoTBvBggrBgEFBQcBAQRjMGEwLgYIKwYBBQUHMAGGImh0dHA6Ly9v
Y3NwLmludC14My5sZXRzZW5jcnlwdC5vcmcwLwYIKwYBBQUHMAKGI2h0dHA6Ly9j
ZXJ0LmludC14My5sZXRzZW5jcnlwdC5vcmcvMCEGA1UdEQQaMBiCFnd3dy5idGNk
aXN0cmlidXRlZC5jb20wTAYDVR0gBEUwQzAIBgZngQwBAgEwNwYLKwYBBAGC3xMB
AQEwKDAmBggrBgEFBQcCARYaaHR0cDovL2Nwcy5sZXRzZW5jcnlwdC5vcmcwggEF
BgorBgEEAdZ5AgQCBIH2BIHzAPEAdgDwlaRZ8gDRgkAQLS+TiI6tS/4dR+OZ4dA0
prCoqo6ycwAAAW7rV6z4AAAEAwBHMEUCIFHaMNVYBzVv+bU4JsnU5m+C+PqNX6VT
1MBzCdOyc3IlAiEAo3xUCXTyMWhbm7J159JYdybpOTk9Q6LvKZU1DqHb1dUAdwCy
HgXMi6LNiiBOh2b5K7mKJSBna9r6cOeySVMt74uQXgAAAW7rV6zuAAAEAwBIMEYC
IQDL6WDzfVCYKwiTUqyUKqdT+ZjA1wbWjYniHCVlMNky8QIhAJLsPOTb29uYwkaF
sTQRA7vX05mRpdkhpvQDEbyRzoapMA0GCSqGSIb3DQEBCwUAA4IBAQBU0yiyaDml
XHB1oYEMorJgf0bEG1/Fj2quTLOKA2ElEJ0htljDn5fTkL+UlQaL+dZT9LaIhln4
XMgDnacq1/HQkx9ulDmufBVsF/nSnaOkSRq3Jqiy571GUlPymGHzmAJKni2IJtpo
ORs8Mk7IwZTdeo+VUQlHpqBIZnP5XG74uaORHuebYTbNIa7HMMPBSImF2RkMjbO9
LzgxuZBrdDME5+cA8QpXmOkklT1tSo1KywtJ5vGipiO80FDHI/YXyW+4Lp9Um8DL
w6NdEjrZSHKWWlt2pAoUtsQOFBYFtQ76ydd5FRwFz8jaX2iKd3a7nOXtv9gDYPb2
a0zA89NX43nM
-----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 301387565783621507505214635910605774526945
 . . . . . . . . [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 2019-12-09 14:47:01 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2020-03-08 14:47:01 +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.btcdistributed.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 700107220296413978179207689072451801557202289416426420002101691975364591655030897488933685441157080550303740302237802049124139320270722159323509277036831599326460234480075922216751899153159863105352881661209232191067840849710531865688073966485216130224360687416607550477046874082939194741031880134293041224256511930555142108186154777658783074923142626158552086702973790176377463650861220995194831797308626739134301898420145770916627752186913332161145410504023584074649198217664933240679769902582586655138123120675399513218050624051157410718639107618791330235115256703035637049304512992824606304218281354167879639510977431536301684937119852073293638918884902076756271979717048805583778784411015675520145199669535924957978179124386286174012753492565246556830556364359057663021130460205464103873085835098655009644964640615700661653808857339307438071320400964835773130658745160036678712245052712665486855695202191566806104264865529648236227328789737231253807922919075449340751520484111574432195596883406225220240543022413472942689205638052547020423569555325459835499660209667803701353164873632309850515326379066701026667832763942106832022915347277616948313380281178013643688783459485949219522758577902666811287203494395380532782805680091
 . . . . . . . . . . . . . . . . . . . . [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)
							fc8e8681fe44047e2386d72d89869077835f2c10
 . . . . . . . . . . . . . . . . [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 'www.btcdistributed.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 (246 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (243 bytes)
							00f1007600f095a459f200d18240102d2f93888ead4bfe1d47e399e1d034a6b0a8aa8eb2730000016eeb57acf80000040300473045022051da30d55807356ff9b53826c9d4e66f82f8fa8d5fa553d4c07309d3b2737225022100a37c540974f231685b9bb275e7d2587726e939393d43a2ef2995350ea1dbd5d5007700b21e05cc8ba2cd8a204e8766f92bb98a2520676bdafa70e7b249532def8b905e0000016eeb57acee0000040300483046022100cbe960f37d50982b089352ac942aa753f998c0d706d68d89e21c256530d932f102210092ec3ce4dbdbdb98c24685b1341103bbd7d39991a5d921a6f40311bc91ce86a9
 . . . . [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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