Replace SHA-1 with SHA-256 for X.509 SubjectKeyId computation in certificate_generator.go

[nikhilsagotiya]

Summary

certificate_generator.go uses crypto/sha1 to compute the X.509 SubjectKeyId extension
value from the RSA public key modulus. SHA-1 is deprecated for all uses by NIST (SP 800-131A Rev 2),
disallowed under FIPS 140-2/3 general-purpose hashing requirements.

Affected code

File: types/certificate_generator.go

import "crypto/sha1"   // line 13
func (cfg CertificateGenerator) bigIntHash(n *big.Int) []byte {
    h := sha1.New()    // line 64  ← SHA-1 here
    h.Write(n.Bytes())
    return h.Sum(nil)
}
certTemplate.SubjectKeyId = cfg.bigIntHash(privateKey.N)  // line 97