autonomistasmultimarcas.com.br
Issued by Let's Encrypt Authority X3
About this certificate
This digital certificate with serial number 04:b3:98:2e:aa:75:3f:9c:de:0e:b7:c8:59:fa:d4:32:bc:6c 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=autonomistasmultimarcas.com.br
Let's Encrypt
Organization:
Let's Encrypt
Country:
US
This certificate has expire since
Certificate Details
Serial Number (hex): 04:b3:98:2e:aa:75:3f:9c:de:0e:b7:c8:59:fa:d4:32:bc:6cSerial Number (int): 409561972364202786192828304555100481961068
Serial Number lenght: 139 bits, 18 octets
SubjectKeyId: 1b:47:f2:08:fd:fc:e7:06:30:6c:b7:7a:e0:b8:9f:25:36:b3:e7:85
AuthorityKeyId: a8:4a:6a:63:04:7d:dd:ba:e6:d1:39:b7:a6:45:65:ef:f3:a8:ec:a1
Fingerprint (sha1): 7c:eb:4d:8e:6d:1d:0c:9b:23:b0:cc:0c:e5:50:52:dd:5c:95:f1:f4
Fingerprint (sha256): b6:49:26:f3:59:15:70:63:7b:d8:5f:e9:91:7f:77:50:0c:5a:68:d2:6a:4d:7c:06:28:32:72:fb:31:94:33:5a
Issuing Certificate URL: http://cert.int-x3.letsencrypt.org/
Revocation information
OCSP Server: http://ocsp.int-x3.letsencrypt.orgCheck the revocation status for certificate autonomistasmultimarcas.com.br
1
DNS Names
0
Email Addresses
0
IP Addresses
Advanced Certificate Properties
Tehnical certificate details for autonomistasmultimarcas.com.br
Public Key Algorithm
RSA
Key Size
3072
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
autonomistasmultimarcas.com.br
Other certificates including the domain name autonomistasmultimarcas.com.br
(limited to 100 certificates)
autonomistasmultimarcas.com.br
autonomistasmultimarcas.com.br
www.autonomistasmultimarcas.com.br
autonomistasmultimarcas.com.br
www.freemanlam.io
autonomistasmultimarcas.com.br
www.calkicker.com
www.autonomistasmultimarcas.com.br
webmail.autonomistasmultimarcas.com.br
autonomistasmultimarcas.com.br
webmail.autonomistasmultimarcas.com.br
webmail.autonomistasmultimarcas.com.br
autonomistasmultimarcas.com.br
autonomistasmultimarcas.com.br
autonomistasmultimarcas.com.br
autonomistasmultimarcas.com.br
autonomistasmultimarcas.com.br
autonomistasmultimarcas.com.br
webmail.autonomistasmultimarcas.com.br
autonomistasmultimarcas.com.br
autonomistasmultimarcas.com.br
autonomistasmultimarcas.com.br
www.autonomistasmultimarcas.com.br
autonomistasmultimarcas.com.br
www.freemanlam.io
autonomistasmultimarcas.com.br
www.calkicker.com
www.autonomistasmultimarcas.com.br
webmail.autonomistasmultimarcas.com.br
autonomistasmultimarcas.com.br
webmail.autonomistasmultimarcas.com.br
webmail.autonomistasmultimarcas.com.br
autonomistasmultimarcas.com.br
autonomistasmultimarcas.com.br
autonomistasmultimarcas.com.br
autonomistasmultimarcas.com.br
autonomistasmultimarcas.com.br
autonomistasmultimarcas.com.br
webmail.autonomistasmultimarcas.com.br
autonomistasmultimarcas.com.br
autonomistasmultimarcas.com.br
Certificate
The complete raw certificate details for autonomistasmultimarcas.com.br in PEM and ASN.1 format.
Certificate (PEM)
-----BEGIN CERTIFICATE----- MIIF9TCCBN2gAwIBAgISBLOYLqp1P5zeDrfIWfrUMrxsMA0GCSqGSIb3DQEBCwUA MEoxCzAJBgNVBAYTAlVTMRYwFAYDVQQKEw1MZXQncyBFbmNyeXB0MSMwIQYDVQQD ExpMZXQncyBFbmNyeXB0IEF1dGhvcml0eSBYMzAeFw0yMDAxMTcxNzMyMjRaFw0y MDA0MTYxNzMyMjRaMCkxJzAlBgNVBAMTHmF1dG9ub21pc3Rhc211bHRpbWFyY2Fz LmNvbS5icjCCAaIwDQYJKoZIhvcNAQEBBQADggGPADCCAYoCggGBAMe4TV9Wle9S OaQnj72TqLKqKIEaYi/c25h8KAXO4dbMAu2DKCj9HPOca9S5PNmbXezDjfGnvXtz 5lfVV9MlASyQjRIzn0G0226Ryj7/ivxni2VDJ2eK5vhL6yjaRvcr41llpm7Jj9OA VBOvFbJG+mMpaqnBw7KR+q1ukD5Wr1smAkybrAMWFOUP6dryo9sAS8zcsW0hshhR eUHipQnHkzgRpg+gF0OAgxAPNVuyw6djMu6oQYLjrGu9R0u3TaF2fw1dIPIRLi5k pGpN6A7/9/ITBIelfbJGQTBHMYo3do0UtoLFjPzVyZGlYITs1WJUoebKynSDQyu8 8sdGzAl/O3CduIMZk9Z3dfH7jE+nWVHZh41BKrLr8iq4ZijygFu8MYKxv/Q6WXS/ JzoXBE+IZeYJQZvwcLrT22cFeOl/C9ctJxEM6sCb5kNj/PsUlAasZ/t5+jvY0Ffx cA2vNJ3+tIY8c1PF7BnM8wOYC+gky59iNiKIarErPPMOoood9ZUESwIDAQABo4IC dDCCAnAwDgYDVR0PAQH/BAQDAgWgMB0GA1UdJQQWMBQGCCsGAQUFBwMBBggrBgEF BQcDAjAMBgNVHRMBAf8EAjAAMB0GA1UdDgQWBBQbR/II/fznBjBst3rguJ8lNrPn hTAfBgNVHSMEGDAWgBSoSmpjBH3duubRObemRWXv86jsoTBvBggrBgEFBQcBAQRj MGEwLgYIKwYBBQUHMAGGImh0dHA6Ly9vY3NwLmludC14My5sZXRzZW5jcnlwdC5v cmcwLwYIKwYBBQUHMAKGI2h0dHA6Ly9jZXJ0LmludC14My5sZXRzZW5jcnlwdC5v cmcvMCkGA1UdEQQiMCCCHmF1dG9ub21pc3Rhc211bHRpbWFyY2FzLmNvbS5icjBM BgNVHSAERTBDMAgGBmeBDAECATA3BgsrBgEEAYLfEwEBATAoMCYGCCsGAQUFBwIB FhpodHRwOi8vY3BzLmxldHNlbmNyeXB0Lm9yZzCCAQUGCisGAQQB1nkCBAIEgfYE gfMA8QB3AG9Tdqwx8DEZ2JkApFEV/3cVHBHZAsEAKQaNsgiaN9kTAAABb7THGnoA AAQDAEgwRgIhAJcU/fb+wg95QMXakr9L8XgucO7iVHldJ0KINisPjQZjAiEA+L2S YlT1NyEjU7f7YG8bqipbnwMxTLQ5jC9FLOcIWckAdgCyHgXMi6LNiiBOh2b5K7mK JSBna9r6cOeySVMt74uQXgAAAW+0xxw7AAAEAwBHMEUCIQCGpd7S1aQUt8oys1hW +MLBkZBOLutKZfsXvsA/vnW+AwIgGMDTtRezX7mWUufLFqV0VULvs0n3UOh/O7yt WwG3BlkwDQYJKoZIhvcNAQELBQADggEBAHPesa1JphV4S3DTxjoSk4jLpPHUEXxO xwQasKJRcO2ZUMZA5s5uTf//HRxiqG7x0IyK3cPvQkuL5lsLD0Uuvqa5IyVSKxxt al0FTubUjBye4nRRIlO571CVh/elPmWElZwD+8+nMdVgd83eHbQwz3u4VciWlsjq p5qDB+Tvfru4clj5ICUG70V026U7ZHaBdnpGCf5T/5+lvDEghMQblX9Yqvzgl3PD folpP7TYivPMDRu4NmNQl1gzc7+GoTiWvTHYnS1kIkvkSreZ9kAzGyFnzsemg/Do jKFzW2CnkxoQKsYlEiBpDkrHBpVzP+e/8T8RifimZK4Vzwkd7s2dmao= -----END CERTIFICATE-----
Public Key (PEM)
-----BEGIN PUBLIC KEY----- MIIBojANBgkqhkiG9w0BAQEFAAOCAY8AMIIBigKCAYEAx7hNX1aV71I5pCePvZOo sqoogRpiL9zbmHwoBc7h1swC7YMoKP0c85xr1Lk82Ztd7MON8ae9e3PmV9VX0yUB LJCNEjOfQbTbbpHKPv+K/GeLZUMnZ4rm+EvrKNpG9yvjWWWmbsmP04BUE68Vskb6 YylqqcHDspH6rW6QPlavWyYCTJusAxYU5Q/p2vKj2wBLzNyxbSGyGFF5QeKlCceT OBGmD6AXQ4CDEA81W7LDp2My7qhBguOsa71HS7dNoXZ/DV0g8hEuLmSkak3oDv/3 8hMEh6V9skZBMEcxijd2jRS2gsWM/NXJkaVghOzVYlSh5srKdINDK7zyx0bMCX87 cJ24gxmT1nd18fuMT6dZUdmHjUEqsuvyKrhmKPKAW7wxgrG/9DpZdL8nOhcET4hl 5glBm/BwutPbZwV46X8L1y0nEQzqwJvmQ2P8+xSUBqxn+3n6O9jQV/FwDa80nf60 hjxzU8XsGczzA5gL6CTLn2I2IohqsSs88w6iih31lQRLAgMBAAE= -----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 409561972364202786192828304555100481961068 . . . . . . . . [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 2020-01-17 17:32:24 +0000 UTC . . . . . . . . . . . . [c:0|t:23|false] UTCTime 2020-04-16 17:32:24 +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 'autonomistasmultimarcas.com.br' . . . . . . . . [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 (3184 bits) . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF . . . . . . . . . . . . . . . . . . . . [c:0|t:2|false] INTEGER 4532398852589856532708257490132716502422862400817383598491770100868311775031099169883667534024917598733316191457151909486687519622792627520510527372231994257933821560784679760018116719655204760463628919212713183042652687720172919573393524590197243753268967659450578271467310228790046275622717030995261799946902303925799284928582100849112189783580714976356606924710644818235462292534930747886743052896360819357884276494315410754364060419265448276247291957713520525677290970950214514654565808998041163182159838787389441336545307481665409489729877920332596388752077459431967141555117240488017982050050247836975619324164877172458861577757562628955065022820411989491662599013319901781737161052115379387552476041865757774657765998711769403172937436576271871334229501578574054969592396229844161497718045213941756920955883430975918238982300250356113330828523660636329770716142755691270728885852785882258768187354120392355658633380939 . . . . . . . . . . . . . . . . . . . . [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) 1b47f208fdfce706306cb77ae0b89f2536b3e785 . . . . . . . . . . . . . . . . [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 (34 bytes) . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:16|true] SEQUENCE, SEQUENCE OF . . . . . . . . . . . . . . . . . . . . . . . . . . . . [c:2|t:2|false] IA5String 'autonomistasmultimarcas.com.br' . . . . . . . . . . . . . . . . [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 (246 bytes) . . . . . . . . . . . . . . . . . . . . . . . . [c:0|t:4|false] OCTET STRING (243 bytes) 00f10077006f5376ac31f03119d89900a45115ff77151c11d902c10029068db2089a37d9130000016fb4c71a7a00000403004830460221009714fdf6fec20f7940c5da92bf4bf1782e70eee254795d274288362b0f8d0663022100f8bd926254f537212353b7fb606f1baa2a5b9f03314cb4398c2f452ce70859c9007600b21e05cc8ba2cd8a204e8766f92bb98a2520676bdafa70e7b249532def8b905e0000016fb4c71c3b000004030047304502210086a5ded2d5a414b7ca32b35856f8c2c191904e2eeb4a65fb17bec03fbe75be03022018c0d3b517b35fb99652e7cb16a5745542efb349f750e87f3bbcad5b01b70659 . . . . [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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