Assuming the SSL certificate is stored in a file called
example.crt, you can use the following OpenSSL command to display the details of the SSL certificate.
$ openssl x509 -noout -text -in example.crt Certificate: Data: Version: 3 (0x2) Serial Number: .. Signature Algorithm: sha256WithRSAEncryption Issuer: C=GB, ST=Greater Manchester, L=Salford, O=COMODO CA Limited, CN=COMODO RSA Domain Validation Secure Server CA Validity Not Before: Sep 10 00:00:00 2014 GMT Not After : Sep 10 23:59:59 2015 GMT
Signature Algorithm represents the hash algorithm used to sign the SSL certificate.
$ openssl x509 -noout -text -in example.crt | grep 'Signature Algorithm' Signature Algorithm: sha256WithRSAEncryption
If the value is
sha256WithRSAEncryption, the certificate is using SHA-256 (also known as SHA-2). Another common value is
sha1WithRSAEncryption, that means the certificate is signed with SHA-1.
If you haven't received the SSL certificate yet, you can check if the CSR is hashed with SHA-2.