dars.uanet.edu

- The University of Akron -

Issued by Entrust Certification Authority - L1C

About this certificate

This digital certificate with serial number 4c:1f:63:8e was issued on by Entrust, Inc..

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)
  • The keyUsage extension SHOULD be critical (RFC 5280: 4.2.1.3)

The University of Akron

Organization: The University of Akron
State / Province: Ohio
Locality: Akron
Country: US

Entrust, Inc.

Organization: Entrust, Inc.
Organization unit: www.entrust.net/rpa is incorporated by reference
Organization unit: (c) 2009 Entrust, Inc.
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 4c:1f:63:8e
Serial Number (int): 1277125518
Serial Number lenght: 31 bits, 4 octets

SubjectKeyId: 42:ff:93:5b:d0:c3:63:c1:be:eb:d7:1e:e2:47:73:a4:77:0a:fb:57
AuthorityKeyId: 1e:f1:ab:89:06:f8:49:0f:01:33:77:ee:14:7a:ee:19:7c:93:28:4d

Fingerprint (sha1): bd:63:f2:4c:13:63:c3:8c:8d:34:a0:9b:51:ea:67:e8:9c:b7:f9:23
Fingerprint (sha256): 01:db:a7:d6:95:4d:93:a5:a8:4b:3c:7e:e6:fe:fe:d9:c0:b3:95:ea:54:a9:09:da:00:6c:5c:e1:f0:bc:65:62

Issuing Certificate URL: http://aia.entrust.net/2048-l1c.cer

Revocation information

OCSP Server: http://ocsp.entrust.net
CRL Distribution Point: http://crl.entrust.net/level1c.crl

Check the revocation status for certificate dars.uanet.edu

1

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for dars.uanet.edu

Public Key Algorithm

RSA

Key Size

2048

Signature Algorithm

SHA1 with RSA

Key Usage

Digital Signature
Key Encipherment

Extended Key Usages

Server Authentication

Extensions

9 extensions
No unhandled critical extensions

CA Certificate

This is not a CA certificate

Subject Alternative Names

dars.uanet.edu

Other certificates including the domain name uanet.edu

(limited to 100 certificates)

Certificate

The complete raw certificate details for dars.uanet.edu in PEM and ASN.1 format.

Certificate (PEM)

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

Public Key (PEM)

-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAmFEE8W2AUWmXJIqPkIEe
lTTPh0qlVZ2gN6/Eo5Q1NRDI0iamRDwAEEXj/HyOleUKCxiBHbVL7/ZEkHhcByz6
BKH4BBkrd6QOHKGEipiv/cCwWdmbb6tISGNJ3dr+RattUap9vmdJ2LB5kMKMuOr6
Fpw1iJcaUvVlLHcSIUQxiWW4C4GVxvgn6mWSqX2gc8hFZML81cTH3DlQ9VTQT2Sf
flQ/6vWON4l1CLlymEtz52uyn1IpTR5KGQvR3c+Bk6hV1favF29sTkDFNrPsbJIy
TugCjx9TX0RHCxg1mm7d3kJ9jM3E/ILQO5HjiVTU13OfxhKhVhUgb0jYhz2rF0nZ
dwIDAQAB
-----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 1277125518
 . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 1.2.840.113549.1.1.5 (sha1WithRSAEncryption)
 . . . . . . . . . . . . [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 'Entrust, Inc.'
 . . . . . . . . . . . . [c:0|t:17|true] SET, SET OF 
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.5.4.11 (organizationalUnitName)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:19|false] PrintableString 'www.entrust.net/rpa is incorporated by reference'
 . . . . . . . . . . . . [c:0|t:17|true] SET, SET OF 
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.5.4.11 (organizationalUnitName)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:19|false] PrintableString '(c) 2009 Entrust, Inc.'
 . . . . . . . . . . . . [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 'Entrust Certification Authority - L1C'
 . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2013-03-31 22:00:22 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2016-02-10 23:00:07 +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 2.5.4.6 (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 2.5.4.8 (stateOrProvinceName)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:19|false] PrintableString 'Ohio'
 . . . . . . . . . . . . [c:0|t:17|true] SET, SET OF 
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.5.4.7 (localityName)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:19|false] PrintableString 'Akron'
 . . . . . . . . . . . . [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 'The University of Akron'
 . . . . . . . . . . . . [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 'dars.uanet.edu'
 . . . . . . . . [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 19228174465092549603235236262404747140553856817664968234826078508781961325565442148847414796646543844194472136824275887887106614747375057018157770592090808649002065836482489989495673489077191989368146048799046377337513507040646289749316197979075806216710465737512637436342584114842864364932572448127724538081153821793051427740177377365219227891654265289397929186526964957986771608759195768946843806004104305138683909343988127000474867883731458151366796977470998555811175191468887713313281118275391719868877090605970897901515727434229783096392579499915245944447497261993600876903709942308253054051540428744150003341687
 . . . . . . . . . . . . . . . . . . . . [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: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 (12 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:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.5.29.31 (cRLDistributionPoints)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (44 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:0|true] OtherName 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:0|true] OtherName 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:6|false] IA5String 'http://crl.entrust.net/level1c.crl'
 . . . . . . . . . . . . . . . . [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 (88 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.entrust.net'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [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://aia.entrust.net/2048-l1c.cer'
 . . . . . . . . . . . . . . . . [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 (67 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 1.2.840.113533.7.75.2
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [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://www.entrust.net/rpa'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.23.140.1.2.2 (Organization Validation Certificates Policy)
 . . . . . . . . . . . . . . . . [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 (18 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'dars.uanet.edu'
 . . . . . . . . . . . . . . . . [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 1ef1ab8906f8490f013377ee147aee197c93284d
 . . . . . . . . . . . . . . . . [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)
							42ff935bd0c363c1beebd71ee24773a4770afb57
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.5.29.19 (basicConstraints)
 . . . . . . . . . . . . . . . . . . . . [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 1.2.840.113549.1.1.5 (sha1WithRSAEncryption)
 . . . . . . . . [c:0|t:5|false] NULL 
 . . . . [c:0|t:3|false] BIT STRING (2048 bits)
		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