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SECURITY SCORE
Certificate Information
Subject
CN=*.twentythree.com
Issuer
C=US, O=Certainly, CN=Certainly Intermediate R1
Valid From
January 21, 2026
Valid Until
February 20, 2026
26 days
Public Key
RSA
2048 bit
Adequate
Signature Algorithm
SHA256-RSA
SHA-256 Fingerprint
84:7C:A9:B5:18:B7:C2:E5:7C:C2:A5:3D:91:32:FA:03:3A:06:21:C6:68:00:4C:8E:62:21:E1:8E:67:48:D1:DA
Alternative Names
Security Configuration
TLS Protocols
TLS 1.2
Forward Secrecy
Limited
(Check cipher configuration)
Warnings
- • TLS 1.3 is not supported (recommended)
HTTP Security Headers
Status
Strict-Transport-Security
Good
max-age=31536000; includeSubDomains
Content-Security-Policy
Missing
Not configured
X-Frame-Options
Missing
Not configured
X-Content-Type-Options
Missing
Not configured
Referrer-Policy
Missing
Not configured
Permissions-Policy
Missing
Not configured
Recommendations
- • Consider adding 'preload' to HSTS for maximum security
- • Add Content-Security-Policy header to prevent XSS attacks
- • Add X-Frame-Options: DENY or SAMEORIGIN to prevent clickjacking
- • Add X-Content-Type-Options: nosniff
- • Add Referrer-Policy header (recommended: strict-origin-when-cross-origin)
- • Consider adding Permissions-Policy to control browser features
CAA Records (Certificate Authority Authorization)
CAA Records
Not Configured
(Any CA can issue certificates)
CAA Issues
- • No CAA records configured - any CA can issue certificates
Recommendations
- • Implement CAA records to restrict which CAs can issue certificates for your domain
- • This adds an extra layer of security against unauthorized certificate issuance
- • Example: Add CAA record 'example.com. CAA 0 issue "letsencrypt.org"'
- • Consider adding 'iodef' record to receive security incident reports