www.coastlinesolutions.com

Issued by SSL.com RSA SSL subCA

About this certificate

This digital certificate with serial number 3e:49:6f:eb:74:e0:51:06:5b:ea:bc:c0:8e:87:5d:72 was issued on by SSL Corporation.

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.coastlinesolutions.com

SSL Corporation

Organization: SSL Corporation
State / Province: Texas
Locality: Houston
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 3e:49:6f:eb:74:e0:51:06:5b:ea:bc:c0:8e:87:5d:72
Serial Number (int): 82793443411593465876313752125076626802
Serial Number lenght: 126 bits, 16 octets

SubjectKeyId: c4:c5:4a:6e:6d:b7:1c:05:99:7c:f5:0a:63:b4:d9:bf:63:d0:38:76
AuthorityKeyId: 26:14:7e:e0:dc:d7:a6:f7:e2:d4:04:27:df:61:f1:c2:ec:e7:32:ca

Fingerprint (sha1): 87:9d:77:f8:ef:8e:f9:9e:86:c8:11:0e:db:cd:e1:5d:a3:31:b0:0b
Fingerprint (sha256): c9:a8:9f:8f:db:03:76:b8:c8:cb:4d:54:7e:9b:10:be:c0:5c:86:94:45:05:9c:c7:01:77:9d:41:3f:e9:d4:e1

Issuing Certificate URL: http://www.ssl.com/repository/SSLcom-SubCA-SSL-RSA-4096-R1.crt

Revocation information

OCSP Server: http://ocsps.ssl.com
CRL Distribution Point: http://crls.ssl.com/SSLcomRSASSLsubCA.crl

Check the revocation status for certificate www.coastlinesolutions.com

1

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for www.coastlinesolutions.com

Public Key Algorithm

RSA

Key Size

2048

Signature Algorithm

SHA256 with RSA

Key Usage

Digital Signature
Key Encipherment

Extended Key Usages

Client Authentication
Server Authentication

Extensions

9 extensions
No unhandled critical extensions

CA Certificate

This is not a CA certificate

Subject Alternative Names

www.coastlinesolutions.com

Other certificates including the domain name coastlinesolutions.com

(limited to 100 certificates)

Certificate

The complete raw certificate details for www.coastlinesolutions.com in PEM and ASN.1 format.

Certificate (PEM)

-----BEGIN CERTIFICATE-----
MIIF1jCCA76gAwIBAgIQPklv63TgUQZb6rzAjoddcjANBgkqhkiG9w0BAQsFADBp
MQswCQYDVQQGEwJVUzEOMAwGA1UECAwFVGV4YXMxEDAOBgNVBAcMB0hvdXN0b24x
GDAWBgNVBAoMD1NTTCBDb3Jwb3JhdGlvbjEeMBwGA1UEAwwVU1NMLmNvbSBSU0Eg
U1NMIHN1YkNBMB4XDTE5MDQyMzE2MTExMloXDTIxMDcyMTE2MTExMlowJTEjMCEG
A1UEAwwad3d3LmNvYXN0bGluZXNvbHV0aW9ucy5jb20wggEiMA0GCSqGSIb3DQEB
AQUAA4IBDwAwggEKAoIBAQDZ0dVlv26CWlJsRajszp6ll6/Ck0M1kikp8r1+aLZA
mIATtO7rF1BsRgGdR+Y+hveKRlxFYJntYypp1hJU0lkUIC4xGYuE++afbLSZ1CHR
YOpeBjBLdziJQvge6PPjH+O7+z/K/K3AUgKUNyTh1hdNM0jLHTlrrWsbNnK8T8f1
rgXz+ePUshas/Crtr+QsUuTKVAktbUQ+6lned7CzqSfEijzc/xse0YQikbB85W4g
TpE0sDAnCVC9WdLOjjb3wVlL1dY11hBAMmm62Nhx2qryhdsuXDcjOTF0mkuzZMgo
uAslyU33Y/I6PY8Yu5vk1waJM1rjLp4bjhj5eM19x6cpAgMBAAGjggG8MIIBuDAf
BgNVHSMEGDAWgBQmFH7g3Nem9+LUBCffYfHC7OcyyjB8BggrBgEFBQcBAQRwMG4w
SgYIKwYBBQUHMAKGPmh0dHA6Ly93d3cuc3NsLmNvbS9yZXBvc2l0b3J5L1NTTGNv
bS1TdWJDQS1TU0wtUlNBLTQwOTYtUjEuY3J0MCAGCCsGAQUFBzABhhRodHRwOi8v
b2NzcHMuc3NsLmNvbTAlBgNVHREEHjAcghp3d3cuY29hc3RsaW5lc29sdXRpb25z
LmNvbTBRBgNVHSAESjBIMAgGBmeBDAECATA8BgwrBgEEAYKpMAEBAQUwLDAqBggr
BgEFBQcCARYeaHR0cHM6Ly93d3cuc3NsLmNvbS9yZXBvc2l0b3J5MB0GA1UdJQQW
MBQGCCsGAQUFBwMCBggrBgEFBQcDATA6BgNVHR8EMzAxMC+gLaArhilodHRwOi8v
Y3Jscy5zc2wuY29tL1NTTGNvbVJTQVNTTHN1YkNBLmNybDAdBgNVHQ4EFgQUxMVK
bm23HAWZfPUKY7TZv2PQOHYwDgYDVR0PAQH/BAQDAgWgMBMGCisGAQQB1nkCBAMB
Af8EAgUAMA0GCSqGSIb3DQEBCwUAA4ICAQBqY5Ib4UGiEL2u7cFa/mPzlvR/HkTO
btpJlpNakf7Xv+S7bIZpYVEhINsgG9I9vxPuLTkDOoiXQDA7J8znA59xUFqBpRg5
J4pCMy+O7I76bXICZbBsdmjSK3I0bCVA6kzlaf7VVUekhEZgITQwb9eXOtru8GeG
JYsnLu/FqhWGH7DtVl0yx8A4LJTGM3jkhaWue1ECAlVr9EmWIXqGNXiTCrD8tY2m
VHDRSCRLREe8qNQNyXWMx50dp69AcCQ/1Lrmo9ERYcBpl1mcW0H2AhGAKCwCK1/s
vX7vMc1mDJ1jHjIRBQsvffjMMqA6Xc2en4KgLpDrPg2hW+QEValS6EfGYTbRRff/
Kw6C1YHOp6aV3d6LllvjMjHcIWVracRCz/SYo3MAIPem8ZI0KbR70+aAb17DhXpc
f63zAvYeKeLa+Nb2DIQSrifb/t8AyDoah8Jz1d/IUYgVTaCPzEQjiJGErr4F9xL7
ICPe3Tmd9AfYuZCMJI++gdhZYamokeRcrlhc6eEXrEs0n+H2zlBDYIvYwtdTKEIY
Ob4flMvAMUCNxNHRQK9BHy+Y2gEawoG0pxKvA8NHB+cTokpJ3hW9/fsR6CeuM6oJ
3LsR/chPVpEkvCLK9y+VE6CgZiMeiQhSPUao0UxWggFZhU+F6/na0N+D6C1DF6HR
OU2LpEq8ohXnag==
-----END CERTIFICATE-----

Public Key (PEM)

-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA2dHVZb9uglpSbEWo7M6e
pZevwpNDNZIpKfK9fmi2QJiAE7Tu6xdQbEYBnUfmPob3ikZcRWCZ7WMqadYSVNJZ
FCAuMRmLhPvmn2y0mdQh0WDqXgYwS3c4iUL4Hujz4x/ju/s/yvytwFIClDck4dYX
TTNIyx05a61rGzZyvE/H9a4F8/nj1LIWrPwq7a/kLFLkylQJLW1EPupZ3news6kn
xIo83P8bHtGEIpGwfOVuIE6RNLAwJwlQvVnSzo4298FZS9XWNdYQQDJputjYcdqq
8oXbLlw3IzkxdJpLs2TIKLgLJclN92PyOj2PGLub5NcGiTNa4y6eG44Y+XjNfcen
KQIDAQAB
-----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 82793443411593465876313752125076626802
 . . . . . . . . [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 2.5.4.8 (stateOrProvinceName)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:12|false] UTF8String 'Texas'
 . . . . . . . . . . . . [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:12|false] UTF8String 'Houston'
 . . . . . . . . . . . . [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:12|false] UTF8String 'SSL Corporation'
 . . . . . . . . . . . . [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:12|false] UTF8String 'SSL.com RSA SSL subCA'
 . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2019-04-23 16:11:12 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2021-07-21 16:11:12 +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:12|false] UTF8String 'www.coastlinesolutions.com'
 . . . . . . . . [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 27497184974289415883025860096952936635361491230142061021232577465694686596954635753278296371279625327598826653527901872452383030103707899522049544066098798856947709158900357058411351884597281022438136731405022394840537850193094961137410559317418066676424207654796153192091299088356035919481837883138461491503157996956795614137032072656400389641308022519098984262583423196914580255104435761130157835929133323571851806109278821283506576392729498368059411122259143283496199774754444852306902219657486366049003928505291764483523462534526283899867992994830407095536224483114840857224782504091696177707968205121929622300457
 . . . . . . . . . . . . . . . . . . . . [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 26147ee0dcd7a6f7e2d40427df61f1c2ece732ca
 . . . . . . . . . . . . . . . . [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 (112 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://www.ssl.com/repository/SSLcom-SubCA-SSL-RSA-4096-R1.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://ocsps.ssl.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 (30 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.coastlinesolutions.com'
 . . . . . . . . . . . . . . . . [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 (74 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 1.3.6.1.4.1.38064.1.1.1.5
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [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://www.ssl.com/repository'
 . . . . . . . . . . . . . . . . [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 1.3.6.1.5.5.7.3.2 (clientAuth)
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [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 (51 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://crls.ssl.com/SSLcomRSASSLsubCA.crl'
 . . . . . . . . . . . . . . . . [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)
							c4c54a6e6db71c05997cf50a63b4d9bf63d03876
 . . . . . . . . . . . . . . . . [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 1.3.6.1.4.1.11129.2.4.3 (CT Precertificate Poison)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:1|false] BOOLEAN true
 . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (2 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:5|false] NULL 
 . . . . [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 (4096 bits)
		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