expressoft.eu

Issued by Let's Encrypt Authority X3

About this certificate

This digital certificate with serial number 03:a0:ae:36:07:d8:0e:45:c1:01:af:2f:ad:27:59:c2:d8:84 was issued on by Let's Encrypt.

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=expressoft.eu

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 03:a0:ae:36:07:d8:0e:45:c1:01:af:2f:ad:27:59:c2:d8:84
Serial Number (int): 316013602717022397782698482336763211864196
Serial Number lenght: 138 bits, 18 octets

SubjectKeyId: 44:23:81:5c:cc:bd:cf:9c:d9:b3:c9:f3:15:5e:f6:9a:a6:0b:4b:b1
AuthorityKeyId: a8:4a:6a:63:04:7d:dd:ba:e6:d1:39:b7:a6:45:65:ef:f3:a8:ec:a1

Fingerprint (sha1): 33:95:10:82:f3:bf:8f:2c:b4:2b:d7:81:10:0f:3c:69:f9:53:df:f8
Fingerprint (sha256): 48:cd:c1:d7:fa:a8:aa:f5:bd:09:ce:4e:d0:4a:a0:a2:01:e1:4d:72:a8:f1:5f:21:21:ea:63:d4:cf:fd:d4:40

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 expressoft.eu

2

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for expressoft.eu

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

expressoft.eu
www.expressoft.eu

Other certificates including the domain name expressoft.eu

(limited to 100 certificates)
*.expressoft.eu
expressoft.eu
expressoft.eu
mybusiness.expressoft.eu
expressoft.eu
*.expressoft.eu
*.expressoft.eu
mybusiness.expressoft.eu
mybusiness.expressoft.eu
www.expressoft.eu
expressoft.eu
www.expressoft.eu
*.expressoft.eu
testcrm.expressoft.eu
*.expressoft.eu
*.expressoft.eu
expressoft.eu
*.expressoft.eu
mybusiness.expressoft.eu
www.expressoft.eu

Certificate

The complete raw certificate details for expressoft.eu in PEM and ASN.1 format.

Certificate (PEM)

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

Public Key (PEM)

-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA2/BVqeBSV/+8X34WMrPd
q8dcTZiQnUnfqeVY8iuPbY3bbWtcGrMC6WW46YcQNDHrGlRPYY3LyoZwGnRMC/yC
u6NsN8qw0rtv/15dGCkM9IfLBkEtIcy3Wdf9hAHADkW4Wmnms7VRojg8PUdnLBbQ
yng8OmpmhcMU/Ujt1Ss2P2DcA/sfFa82xB+2TACuTI8nPjAu1/vUmoBn8xBzVBQA
Ke240BgeCa5KRoRFzfca6pE4EO/86LWJ7EihY3WOB5QrMTzJiFyQGNM3Zm8B8S3r
T9MU/RATTAWd4/y1ajwOOWENTlmFA4CtGkSQYQuKNOtY6Ofli0L63XIG/QEUrErh
7wIDAQAB
-----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 316013602717022397782698482336763211864196
 . . . . . . . . [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 2018-05-15 07:09:11 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2018-08-13 07:09:11 +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 'expressoft.eu'
 . . . . . . . . [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 27764702207399311075165591499385924211042605128617877960659802831402326165440781025152159298537939227786350304043945597168864084443451782773056056830402898566334766344621731251400738242194714288316485278241078559615990936370826385067275573078593201825217146832875084386419643620139133739161962254466141114753109507767567361302844095530020177780277475480043873198435497472518747110452130876974014622725909192122156602872077702980402763742016700090710355575940156940280172265686401785331724243083710168077512055989272119518503555463305268399276452070351129139386247119421200518973928601258374749437922810146543981224431
 . . . . . . . . . . . . . . . . . . . . [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)
							4423815cccbdcf9cd9b3c9f3155ef69aa60b4bb1
 . . . . . . . . . . . . . . . . [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 (36 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'expressoft.eu'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.expressoft.eu'
 . . . . . . . . . . . . . . . . [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 1.3.6.1.4.1.11129.2.4.2
 . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (245 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (242 bytes)
							00f0007700db74afeecb29ecb1feca3e716d2ce5b9aabb36f7847183c75d9d4f37b61fbf640000016362d896070000040300483046022100b65231985873f8fcb414a47496dbb3bbad2816d7524ea3eea414082c9efa9d61022100e7ba12b3919a5e60545ef2445be0c1def1bbade90ff4a780d20706b71267733f007500293c519654c83965baaa50fc5807d4b76fbf587a2972dca4c30cf4e54547f4780000016362d89619000004030046304402207dd7ef296f0667fd255b3263a872734f3e4c94fd66c4e6f32167f6b4507f305e022061bfe0129f109bdf6de2e8b0d3cd409c1f6005a1ff5f3101cc5a3cce59ac5bdb
 . . . . [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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