dedhamexchange.org

Issued by Sectigo RSA Domain Validation Secure Server CA

About this certificate

This digital certificate with serial number d8:45:08:2c:0f:41:e8:c7:d0:8a:79:31:ed:25:54:28 was issued on by Sectigo Limited.

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=dedhamexchange.org

Sectigo Limited

Organization: Sectigo Limited
State / Province: Greater Manchester
Locality: Salford
Country: GB

This certificate has expire since

Certificate Details

Serial Number (hex): d8:45:08:2c:0f:41:e8:c7:d0:8a:79:31:ed:25:54:28
Serial Number (int): 287471681322818666095133354676346770472
Serial Number lenght: 128 bits, 16 octets

SubjectKeyId: 0a:ee:e0:9e:45:58:10:35:01:1d:d0:38:b9:02:30:69:7b:17:13:72
AuthorityKeyId: 8d:8c:5e:c4:54:ad:8a:e1:77:e9:9b:f9:9b:05:e1:b8:01:8d:61:e1

Fingerprint (sha1): 11:6c:27:54:52:0b:d1:62:e5:5a:10:6e:3c:5e:e5:68:5c:a2:c4:b3
Fingerprint (sha256): f4:fd:39:b1:0e:51:18:c0:0f:43:67:97:8d:f8:d9:43:d1:9f:50:82:cc:11:43:11:c3:67:13:15:62:97:9d:07

Issuing Certificate URL: http://crt.sectigo.com/SectigoRSADomainValidationSecureServerCA.crt

Revocation information

OCSP Server: http://ocsp.sectigo.com

Check the revocation status for certificate dedhamexchange.org

2

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for dedhamexchange.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

9 extensions
No unhandled critical extensions

CA Certificate

This is not a CA certificate

Subject Alternative Names

dedhamexchange.org
www.dedhamexchange.org

Other certificates including the domain name dedhamexchange.org

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

Certificate

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

Certificate (PEM)

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

Public Key (PEM)

-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAgLVvUZCykNyIxmh7MHZL
bAG9sX99fU/yWTkTm3/1s2PARg1lxx3Fzd37PLXKBab7qFlCow3ZEs0kguP6uPAc
jasa0tO6CJJ0zcw0xB3mhToc3O++54/TKqgDc7Xp688duwGH8M7x82HHDC+iw4P6
K2TP6s2B9YNjrf8nxCWk4ML3qS2bTBrTQaoh71ew8VSq/cNM61J7v7oEjd1Uw9MZ
LcsjVxNmnPNHBRxsmOHS1dBevDSsb6EcNc0n4gdheacJ7YYKWDLniO+kgLCbSjL2
0mHpNEbyRUEFCbjaEcthO7qTH53B1H0a1zYvZlq4o2amllSnuOYWlwPZ/tKpmJqP
xQIDAQAB
-----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 287471681322818666095133354676346770472
 . . . . . . . . [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 'GB'
 . . . . . . . . . . . . [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 'Greater Manchester'
 . . . . . . . . . . . . [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 'Salford'
 . . . . . . . . . . . . [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 'Sectigo Limited'
 . . . . . . . . . . . . [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 'Sectigo RSA Domain Validation Secure Server CA'
 . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2019-01-27 00:00:00 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2019-04-27 23:59:59 +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 'dedhamexchange.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 16247971888989089658729275468639758626747210435733867901458278985623530204225562965331272621125705761808588403354563701316913786122996517429521936505565019105092215540842205887634871123426717621863926824594627812229102462025083583885433436786312792963250154644934605067938356077076506178979498636629948262613925225098339172730003108757200263050950531422572940969085646608488284030717264772159880558413294298178569003074918545828457401895111623339109702483069828090888777037735969824265015730365891314502862234598589883792232576710974784967578691360621668904694457716832804622943170689468736925896839705940702195781573
 . . . . . . . . . . . . . . . . . . . . [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 2.5.29.35 (authorityKeyIdentifier)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (24 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:0|false] OtherName 8d8c5ec454ad8ae177e99bf99b05e1b8018d61e1
 . . . . . . . . . . . . . . . . [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)
							0aeee09e45581035011dd038b90230697b171372
 . . . . . . . . . . . . . . . . [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 2.5.29.19 (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 2.5.29.37 (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 2.5.29.32 (certificatePolicies)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (66 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 1.3.6.1.4.1.6449.1.2.2.7
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [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 'https://sectigo.com/CPS'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [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 1.3.6.1.5.5.7.1.1 (authorityInfoAccess)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (120 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 1.3.6.1.5.5.7.48.2 (caIssuers)
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:6|false] IA5String 'http://crt.sectigo.com/SectigoRSADomainValidationSecureServerCA.crt'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [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.sectigo.com'
 . . . . . . . . . . . . . . . . [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 (46 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'dedhamexchange.org'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.dedhamexchange.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)
							00f1007700bbd9dfbc1f8a71b593942397aa927b473857950aab52e81a909664368e1ed185000001688cf1e53a00000403004830460221009d188bac43c10278f1c3620e81859c119d90672226c5088d17e46c5c9d787c6e022100f957438b706f62fe7461346c93322a365b60a5fda62b9d1434f7d26c9ec04a13007600747eda8331ad331091219cce254f4270c2bffd5e422008c6373579e6107bcc56000001688cf1e57a000004030047304502207438a6efd90d3596acba60294f096a129e26db65cc7c7f6969b3d93c2ee4c11b022100f672f795fa20d52cb5cabeb81d144073ef5906042d4b5a44862034de109fcfcd
 . . . . [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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