www.monicacristian.com

Issued by Let's Encrypt Authority X3

About this certificate

This digital certificate with serial number 03:6f:36:16:11:69:86:7d:fb:a9:44:0c:0b:e1:b7:14:4c:75 was issued on by Let's Encrypt.

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.monicacristian.com

Let's Encrypt

Organization: Let's Encrypt
Country: US

This certificate has expire since

Certificate Details

Serial Number (hex): 03:6f:36:16:11:69:86:7d:fb:a9:44:0c:0b:e1:b7:14:4c:75
Serial Number (int): 299180093418969726229206968162876214496373
Serial Number lenght: 138 bits, 18 octets

SubjectKeyId: 4b:b9:f7:4d:b9:88:64:5e:3f:92:17:ec:51:ee:b8:8e:89:b9:06:11
AuthorityKeyId: a8:4a:6a:63:04:7d:dd:ba:e6:d1:39:b7:a6:45:65:ef:f3:a8:ec:a1

Fingerprint (sha1): 4a:26:8e:84:9f:18:4b:b0:f3:3f:aa:f9:59:f0:65:0f:3e:46:7a:68
Fingerprint (sha256): 4a:f3:c3:e9:45:f4:08:75:69:61:f8:56:83:6a:3d:b7:1a:e2:fe:f6:3e:e3:20:be:78:ad:d8:bf:b2:09:23:e2

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 www.monicacristian.com

1

DNS Names

0

Email Addresses

0

IP Addresses

Advanced Certificate Properties

Tehnical certificate details for www.monicacristian.com

Public Key Algorithm

RSA

Key Size

4096

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

www.monicacristian.com

Other certificates including the domain name monicacristian.com

(limited to 100 certificates)

Certificate

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

Certificate (PEM)

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

Public Key (PEM)

-----BEGIN PUBLIC KEY-----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-----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 299180093418969726229206968162876214496373
 . . . . . . . . [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 2020-01-11 16:39:25 +0000 UTC
 . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2020-04-10 16:39:25 +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 'www.monicacristian.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 (4208 bits)
 . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . [c:0|t:2|false] INTEGER 670517982099223616346788768254716446828022639684183543439909509687986434718827077116420071164009302230314630651127280880878952512491214519460249623890110211139701572695814663454692644629240028747619564360298552182320779673944285593053928425901077158175112669684204256139836907088443500964865469079030641022098919551606795165080842599503442343478630869063103904142666032834180144714681143718992282322618901188214824265817415623163397144548285210688825023640352987117638114813843023807085246032951810604307577399378551551879933638384498791416156849530217632105791289815671464549724647940503625674061626604250994597647859603023770611936815753714500931751420586367266670923149875416813454450456336773727557870797894969133893905474528200129452500712825066690461341236641584064086441927458769671095479803799696988981047816731368089396287930429363149768292367359621159686259596455978499620233795543779903576635627407588486196187012167988080990670972216009269306125664703993516260246221466771588809206139119183388368814476871508422659793659087308956682953061733858740963666852584528000334693378367710795106102582297059182448767590350583262934247080960677919149193658138418212622913138757709955366162393077473253086003784281606702501734818243
 . . . . . . . . . . . . . . . . . . . . [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)
							4bb9f74db988645e3f9217ec51eeb88e89b90611
 . . . . . . . . . . . . . . . . [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 (26 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF 
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'www.monicacristian.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 (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 2.23.140.1.2.1 (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 1.3.6.1.4.1.11129.2.4.2
 . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (247 bytes)
 . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (244 bytes)
							00f20077006f5376ac31f03119d89900a45115ff77151c11d902c10029068db2089a37d9130000016f95b070270000040300483046022100cb0b960d26ca93eaeb3b5313d7cb3abbeccea6fd33089f416d34fdf25f6a02bb022100a1ddd841ba38ed7791e4d9a786f47b50c7e5c5317a5f60d4135402ebfbddf0cb00770007b75c1be57d68fff1b0c61d2315c7bae6577c5794b76aeebc613a1a69d3a21c0000016f95b0705300000403004830460221009815ff4fb4384e26cccb92bf7cd3cc381aa0d765aa2f55f4e94d9cf0dbd6dbc7022100815632e2198537a52d6f34f8246c4bc691eded8b7a99f860b1e28a8e71dab4c5
 . . . . [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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