www.elasticnetworks.org

Issued by Let's Encrypt Authority X3

About this certificate

This digital certificate with serial number 03:d4:a1:dd:ef:98:1c:51:bf:82:fd:db:26:91:1c:8d:fb:95 was issued on by Let's Encrypt.

With 9 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=www.elasticnetworks.org

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 03:d4:a1:dd:ef:98:1c:51:bf:82:fd:db:26:91:1c:8d:fb:95
Serial Number (int): 333691877646994142229122697758426587331477
Serial Number lenght: 138 bits, 18 octets

SubjectKeyId: fb:c8:1c:d8:23:e8:64:9b:87:d7:8f:b7:16:1b:58:9c:42:31:ee:fb
AuthorityKeyId: a8:4a:6a:63:04:7d:dd:ba:e6:d1:39:b7:a6:45:65:ef:f3:a8:ec:a1

Fingerprint (sha1): f7:f9:95:33:f9:31:48:d9:dd:a1:11:c1:43:c8:89:73:6c:de:c5:d6
Fingerprint (sha256): 8d:b0:d3:89:00:10:9b:bd:b4:2d:ca:52:04:d5:27:e1:67:0a:fa:17:ff:71:ec:29:5c:e5:86:ea:f1:84:88:03

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.elasticnetworks.org

9

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for www.elasticnetworks.org

Public Key Algorithm

RSA

Key Size

2048

Signature Algorithm

SHA256 with RSA

Key Usage

Digital Signature
Key Encipherment

Extended Key Usages

Server Authentication
Client Authentication

Extensions

8 extensions
No unhandled critical extensions

CA Certificate

This is not a CA certificate

Subject Alternative Names

elastic-networks.ccaba.upc.edu
elasticnetworks.org
icton2017.udg.edu
smart-2015.cba.upc.edu
tma-2015.cba.upc.edu
www.elasticnetworks.org
www.icton2017.udg.edu
www.smart-2015.cba.upc.edu
www.tma-2015.cba.upc.edu

Other certificates including the domain name elasticnetworks.org

(limited to 100 certificates)
elasticnetworks.org
www.elasticnetworks.org
www.elasticnetworks.org
www.elasticnetworks.org
elasticnetworks.org
www.elasticnetworks.org
www.elasticnetworks.org
www.elasticnetworks.org
www.elasticnetworks.org
www.elasticnetworks.org
elasticnetworks.org
www.elasticnetworks.org
www.elasticnetworks.org
elasticnetworks.org
elasticnetworks.org
www.elasticnetworks.org
www.elasticnetworks.org
www.elasticnetworks.org
www.elasticnetworks.org
elasticnetworks.org
elasticnetworks.org
elasticnetworks.org

Certificate

The complete raw certificate details for www.elasticnetworks.org in PEM and ASN.1 format.

Certificate (PEM)

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

Public Key (PEM)

-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAxx72NJB/kNB1No3+jn7p
FTvajcWiQruq44WecBEkGIwtIJ71xPreXaV9mcsQO9p0ijGUdaEp1F4E0NWMdx+4
YQ18nxHINx/Tv1tiD5nj5Z/K7tcBfCdR8IkQFdN6sijyXg19VOMdebNskw2vxqQc
VVEiLh6Jit5AlvLFP6rZf1ssa80Jx7FjkRpBkEyeOoafsvjEQrS3ZQTgKLCCwhMG
pzl/jtNHQRgWwvgh9EvV146EB4E172uWcmJvxonhYCY4FaTOSJWXDoDn01bUEOoF
T46z3jRsgr5dzYOjPiMC0qFtq8Uzuc4AWY7asIQ0tERXVPwGeAaWmPgykGxLzuFw
bwIDAQAB
-----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 333691877646994142229122697758426587331477
 . . . . . . . . [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 2017-03-11 22:02:00 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2017-06-09 22:02:00 +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.elasticnetworks.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 (2160 bits)
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:2|false] INTEGER 25136690491066338725364123991986725321082862019517691500248683308284378920532989589088289324444401784981252206322739145240326728701278335052334753471196166434598658719255171002778964819168913291420095695051742567474414217782400603966361770460218081860752714440801156544474040175580330932371620749947260072480482749719019344125185174663647225223821642111082233664519627726337568652210966008919149493865958164000670740765550121044638827344166914633456976628275813724970489158197392153827656619087137980801910286816736915744115595649389363809719426234534997015898168094992154134235215577019414460623147070809926122172527
 . . . . . . . . . . . . . . . . . . . . [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)
							fbc81cd823e8649b87d78fb7161b589c4231eefb
 . . . . . . . . . . . . . . . . [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 (100 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 (223 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'elastic-networks.ccaba.upc.edu'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'elasticnetworks.org'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'icton2017.udg.edu'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'smart-2015.cba.upc.edu'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'tma-2015.cba.upc.edu'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.elasticnetworks.org'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.icton2017.udg.edu'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.smart-2015.cba.upc.edu'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.tma-2015.cba.upc.edu'
 . . . . . . . . . . . . . . . . [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 (246 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 1.3.6.1.5.5.7.2.2 (unotice)
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:12|false] UTF8String 'This Certificate may only be relied upon by Relying Parties and only in accordance with the Certificate Policy found at https://letsencrypt.org/repository/'
 . . . . [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)
		004a1e6840d085365523a7d7df0bdbaff8de5dca124cd8369c155af99b882f99e8fe351e336744608b8bbf62059c0eff89ddea53fa85bdb679a560c8b50f07c418f2b8a83ac6f19c94e0e66092949fdc21b71291090530cd5d2a8d8926b3915801600a7550cd1043743bdcafaa514b09e59c2d3ae92af9aae92f202ba3de106a561f946e39071d01dc36a9dfc1791147bafb33fe15a65235cff38a025b50f9cd6631beb34bd826fd1f011f1a029ac8aed88c1eba83102dc41e9facf552c03a439a347f0d4b7256a264ce6925de5fae3bb8a8414d187ab68a4c549e5bf7044686964a70862856497d104fc703d264966902c8635500c3aaa17bb9690b25418fa6fb