www.chinacache.net

- Beijing Blue-IT Technology Co.,Ltd. -

Issued by GeoTrust SSL CA - G2

About this certificate

This digital certificate with serial number 03:19:2e:ef:a2:85:27:e3:8a:aa:07:53:23:ea:6d:db was issued on by GeoTrust Inc..

With 5 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)
  • Sub certificates SHOULD include Subject Key Identifier in end entity certs (RFC 5280: 4.2 & 4.2.1.2)

Beijing Blue-IT Technology Co.,Ltd.

Organization: Beijing Blue-IT Technology Co.,Ltd.
Organization unit: SNP
State / Province: Beijing
Locality: Beijing
Country: CN

GeoTrust Inc.

Organization: GeoTrust Inc.
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 03:19:2e:ef:a2:85:27:e3:8a:aa:07:53:23:ea:6d:db
Serial Number (int): 4118443385488274290203060258457939419
Serial Number lenght: 122 bits, 16 octets

SubjectKeyId:
AuthorityKeyId: 11:4a:d0:73:39:d5:5b:69:08:5c:ba:3d:bf:64:9a:a8:8b:1c:55:bc

Fingerprint (sha1): aa:d5:e4:2e:01:a8:2d:95:87:60:b9:e5:d1:9f:a6:93:ba:de:a3:67
Fingerprint (sha256): 3f:a1:68:bb:05:87:4e:26:c1:97:99:42:3f:e8:66:82:b5:a6:dd:b8:bd:74:71:5d:d5:75:d6:27:2a:05:a4:74

Issuing Certificate URL: http://gtssl2-aia.geotrust.com/gtssl2.cer

Revocation information

OCSP Server: http://gtssl2-ocsp.geotrust.com
CRL Distribution Point: http://gtssl2-crl.geotrust.com/gtssl2.crl

Check the revocation status for certificate www.chinacache.net

5

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for www.chinacache.net

Public Key Algorithm

RSA

Key Size

2048

Signature Algorithm

SHA1 with RSA

Key Usage

Digital Signature
Key Encipherment

Extended Key Usages

Server Authentication
Client Authentication

Extensions

8 extensions
No unhandled critical extensions

CA Certificate

This is not a CA certificate

Subject Alternative Names

api.chinacache.com
sfapi.chinacache.net
bandwidth-api.chinacache.com
www.chinacache.net
chinacache.net

Other certificates including the domain name chinacache.net

(limited to 100 certificates)
*.apple.chinacache.net
www.chinacache.net
www.chinacache.net
gslbmng.chinacache.net

Certificate

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

Certificate (PEM)

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

Public Key (PEM)

-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAvwtwbFO7g5QsXQParCAL
tAtGmjmPjyv4KOcQ7AyKyQYbUZF3+L5+9u9YzA/5ZHD0ahf4x6O8llLGZYIR19wT
zXGn8AidDtwvz//kIIFwW0EXxG0ZqNGmWk+vhJ2JtARemE8F20peZVUwO94FKnOW
Ru7IUHzl9kXiqtW5qJjAajh6bTvG9PtE0Ys4oRoPvpfgSBkRWpia3qswwwGaP6CD
S3vDUyzv2mbwmf61y42RYMLrtL6WeTMlk508c1W5dqhRp3mjiPs/7rzb2UTNkBIR
E1GOoU3R9tvOI/hRiCX+LKPaPEFUSRCD3Np9MACCqfSE4izCgdrWu/wiWA5xh1mM
cQIDAQAB
-----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 4118443385488274290203060258457939419
 . . . . . . . . [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 'GeoTrust 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 'GeoTrust SSL CA - G2'
 . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2014-03-25 00:00:00 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2014-10-18 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 2.5.4.6 (countryName)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:19|false] PrintableString 'CN'
 . . . . . . . . . . . . [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 'Beijing'
 . . . . . . . . . . . . [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:20|false] TeletexString, T61String 'Beijing'
 . . . . . . . . . . . . [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:20|false] TeletexString, T61String 'Beijing Blue-IT Technology Co.,Ltd.'
 . . . . . . . . . . . . [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:20|false] TeletexString, T61String 'SNP'
 . . . . . . . . . . . . [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:20|false] TeletexString, T61String 'www.chinacache.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 24117157105069544872021234605068247615483214219154814236014997384617988740880493023670230547959101920720622599574465044154592179149006097542485540004896778045925774844927501112296533963777001574599779251896384780357134807962088348789371273297752300850779478388159580898762085188896636648973624270169850265233631034165025693775223408627860365359931628029796683486430590690772899484159036906449069572882302769982620870516732367023392183661791928479103211058006968801078699900654752338285936578604198551702874368042693747225766594659022412769291364420301013434531110805237604090570789191849860150721496943601537143901297
 . . . . . . . . . . . . . . . . . . . . [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 2.5.29.19 (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 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 2.5.29.31 (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://gtssl2-crl.geotrust.com/gtssl2.crl'
 . . . . . . . . . . . . . . . . [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 (69 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:6|false] OBJECT IDENTIFIER 2.16.840.1.113733.1.7.54
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [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.geotrust.com/resources/cps'
 . . . . . . . . . . . . . . . . [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 2.5.29.35 (authorityKeyIdentifier)
 . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (24 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:0|false] OtherName 114ad07339d55b69085cba3dbf649aa88b1c55bc
 . . . . . . . . . . . . . . . . [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 (102 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://gtssl2-ocsp.geotrust.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [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://gtssl2-aia.geotrust.com/gtssl2.cer'
 . . . . . . . . . . . . . . . . [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 (110 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'api.chinacache.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'sfapi.chinacache.net'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'bandwidth-api.chinacache.com'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.chinacache.net'
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'chinacache.net'
 . . . . [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)
		0031e513ba7fbcde3aa06c835878887b0658262c846be0d2112bfe85ee6ff3327ecb476e38a97f3af650ab2254de815700a536957b8162f1247b204fd7c546be4d02df228a381165443637353fdce283926e8c25080698630e0a781444329b81ea6e3f8bc9e707c2d52949928a1de1d533d19e1272e59cd5a77a44f2a8fbd307e1d08adce30798c49a7aceac683cfd4f53bc861db49a31f4925c527e8ea955c073f6d492ac7acd782a132eb26c11d92235368276c130d725b0e33a878175874d5d1009c4f6ade3feb4ed8aae9db45df112f6a769d4aa11524c17eea64a4165c581eacf1d688d8f9165eae4b9e5d8553ae5a2d86438c5c3271149ca4918327c4a19