velasqueztaxservices.net

Issued by Sectigo RSA Domain Validation Secure Server CA

About this certificate

This digital certificate with serial number f2:a8:76:26:6c:0c:11:61:11:34:e8:a4:b3:11:42:b8 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=velasqueztaxservices.net

Sectigo Limited

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

This certificate has expire since

Certificate Details

Serial Number (hex): f2:a8:76:26:6c:0c:11:61:11:34:e8:a4:b3:11:42:b8
Serial Number (int): 322547877220625868964814184799152456376
Serial Number lenght: 128 bits, 16 octets

SubjectKeyId: dd:bf:12:df:d6:63:09:7a:26:0f:62:e6:44:87:e8:ba:33:a9:62:10
AuthorityKeyId: 8d:8c:5e:c4:54:ad:8a:e1:77:e9:9b:f9:9b:05:e1:b8:01:8d:61:e1

Fingerprint (sha1): b6:11:3c:0d:a5:40:34:b4:84:70:8f:b8:68:11:3f:fb:5a:12:4b:83
Fingerprint (sha256): 3e:fb:33:aa:52:9c:45:80:81:f3:ff:77:e3:1e:73:4c:96:0b:09:41:0d:f2:f5:1c:b8:40:ce:a0:e1:83:c2:2e

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

Revocation information

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

Check the revocation status for certificate velasqueztaxservices.net

2

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for velasqueztaxservices.net

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

velasqueztaxservices.net
www.velasqueztaxservices.net

Other certificates including the domain name velasqueztaxservices.net

(limited to 100 certificates)
www.velasqueztaxservices.net
www.velasqueztaxservices.net
www.velasqueztaxservices.net
www.velasqueztaxservices.net
www.velasqueztaxservices.net
www.velasqueztaxservices.net
www.velasqueztaxservices.net
velasqueztaxservices.net
velasqueztaxservices.net
www.velasqueztaxservices.net
www.velasqueztaxservices.net
velasqueztaxservices.net
www.velasqueztaxservices.net
velasqueztaxservices.net
velasqueztaxservices.net
www.velasqueztaxservices.net

Certificate

The complete raw certificate details for velasqueztaxservices.net in PEM and ASN.1 format.

Certificate (PEM)

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

Public Key (PEM)

-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAwAyX02KlxdwOtqllbr0y
tgX2tRzb31EfKuvcKje2nJ1vT4gcPXWdPnUvraPiHSMnV+Z8JzNlRnRLcuWT+pyk
wp0/uxcdH4DSwtm7UXofSIdvB7+gRChLGra6cQWRF8OKAUxTGA30xdgbbD1dknId
cJzEb09vIoSycS3freL5zUY7eGmvqLk80+d6MkUbwqZeg2X3ouu+xrWthtWL3mHk
xo8emboAxKesBDqpWhbyiB9Hp94G0hyh3fDuo+iQNEl+C5gBt55HioQdZVZ9k+3V
COzM0sgS5OQQ0/yXw5SJ8XUw8rHLt/wTpymSiiBCWv7YddC5Ed5urrUd/2zWr9Fv
DQIDAQAB
-----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 322547877220625868964814184799152456376
 . . . . . . . . [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 2019-06-20 00:00:00 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2019-09-18 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 'velasqueztaxservices.net'
 . . . . . . . . [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 24243964427367879915755923442914080110399143724150345383400326130471375946183143081771446990340595152579150884501571333457059175698234104401472046948567912126696612393662478287424871131750833832802364877958429723755485323037267602132290601831755799035917740615269244240118861097557981440276507486766368523663139400157556598716395198877134259673687676991277189338966856383004844223340265238963990472435551101083707987675364714958271816124309037138365374754658369432410955656013699399025312873724934272932602896190016876352363013983672997536546127937260706775481423162674935676876503107904566820061872109663218826309389
 . . . . . . . . . . . . . . . . . . . . [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)
							ddbf12dfd663097a260f62e64487e8ba33a96210
 . . . . . . . . . . . . . . . . [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 (58 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'velasqueztaxservices.net'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.velasqueztaxservices.net'
 . . . . . . . . . . . . . . . . [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 (244 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (241 bytes)
							00ef007600bbd9dfbc1f8a71b593942397aa927b473857950aab52e81a909664368e1ed1850000016b75df45e50000040300473045022100c7a5ae80e3f9fa62bd709eedf527ce33c5916eeceb901d9bdb2c0a638bb26d1e02205c59dff35ec3d64b5ca75f7f36bc985837f8cc33cb78d5880503f8ff572c8beb007500747eda8331ad331091219cce254f4270c2bffd5e422008c6373579e6107bcc560000016b75df46080000040300463044022046f31409e897665863f46319af85b7a9837f18f5c74addb0f1e1cd6cc3ff48450220248fc97259bf1205a7fbfe42ed08789e0aec1eb7907bc2e7fbd5ffcc4a865308
 . . . . [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)
		00777a9b5c27302ac11c4cac415363a4ae3838d564a36804bb5739e028b8992d470be65fc54935738254795141b3340feffa3cd7c8f263774855f33cd48f70c57ed6693faf240a37e221a7bed8228a4889e38b936b85293b940668170fceba9e9b71f2b5ac8fd843d5effdfabb69b12fbba9b3196b912115d31ad650c112150fdf3c29f6a33c86958a8cd09c6256d87ee7592de224d65fb24ce1e32b21e8ac9bea2c97363ef88023eea8e2a75258ad3f212a5490db0f659c6f464bd85fd8a30be6bf85079a9e31b7f2ccf5c586cf61ad943983cf7052a73cef20a635769e3a2d1a12d0bc000ddd3e71433e766ada8993c59423c025e2c188349ddb21f2e3ad24f0