The cacert.pem file from curl.haxx.se is a Certificate Authority (CA) bundle containing root certificates from major certificate authorities. This file serves as:

• A collection of trusted root certificates for verifying server identities
• Not a server certificate for your domains
• Primarily used by client applications to validate server certificates

For local development with multiple domains/subdomains, you need:

1. A valid certificate for each domain (can be self-signed)
2. Proper certificate chain configuration
3. Browser trust for your certificates

Here's how to generate a wildcard certificate using OpenSSL:

# Generate private key
openssl genrsa -out localhost.key 2048

# Create CSR config file (localhost.cnf)
[req]
distinguished_name = req_distinguished_name
req_extensions = v3_req
prompt = no

[req_distinguished_name]
C = US
ST = California
L = San Francisco
O = Development
CN = *.localhost

[v3_req]
keyUsage = keyEncipherment, dataEncipherment
extendedKeyUsage = serverAuth
subjectAltName = @alt_names

[alt_names]
DNS.1 = *.localhost
DNS.2 = localhost

# Generate CSR
openssl req -new -key localhost.key -out localhost.csr -config localhost.cnf

# Generate self-signed certificate
openssl x509 -req -days 365 -in localhost.csr -signkey localhost.key -out localhost.crt -extfile localhost.cnf -extensions v3_req

Add this to your Apache configuration:

<VirtualHost *:443>
    ServerName localhost
    ServerAlias *.localhost
    SSLEngine on
    SSLCertificateFile "/path/to/localhost.crt"
    SSLCertificateKeyFile "/path/to/localhost.key"
    # Optional: Include intermediate certificates if needed
    # SSLCertificateChainFile "/path/to/intermediate.crt"
</VirtualHost>

1. Open Keychain Access
2. Drag your localhost.crt file into the System keychain
3. Double-click the certificate
4. Under Trust section, set "When using this certificate" to "Always Trust"

For easier local certificate management:

# Install mkcert
brew install mkcert

# Setup local CA
mkcert -install

# Generate wildcard certificate
mkcert "*.localhost"

• Don't use the curl CA bundle as your server certificate
• For production, obtain certificates from Let's Encrypt or commercial CAs
• Self-signed certificates are only suitable for development
• Clear browser cache if certificate warnings persist

The cacert.pem file from curl.haxx.se is a bundle of Certificate Authority (CA) root certificates. It contains trusted root certificates from major CAs worldwide, used to verify the authenticity of SSL/TLS certificates presented by servers during HTTPS connections.

# Typical usage in PHP for verifying peer certificates
$ch = curl_init();
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, true);
curl_setopt($ch, CURLOPT_CAINFO, '/path/to/cacert.pem');

For local development, you have several options:

1. Self-signed certificates: Create your own CA and issue certificates
2. Local CA certificates: Tools like mkcert generate locally-trusted certs
3. Wildcard certificates: For multiple subdomains

Here's how to create a wildcard certificate for *.localhost development:

# Generate root CA (one-time)
openssl genrsa -out rootCA.key 2048
openssl req -x509 -new -nodes -key rootCA.key -sha256 -days 1024 -out rootCA.pem

# Create wildcard certificate
openssl genrsa -out wildcard.localhost.key 2048
openssl req -new -key wildcard.localhost.key -out wildcard.localhost.csr
openssl x509 -req -in wildcard.localhost.csr -CA rootCA.pem -CAkey rootCA.key -CAcreateserial -out wildcard.localhost.crt -days 500 -sha256

Add this to your Apache configuration:

<VirtualHost *:443>
    ServerName test.localhost
    ServerAlias *.localhost
    
    SSLEngine on
    SSLCertificateFile "/path/to/wildcard.localhost.crt"
    SSLCertificateKeyFile "/path/to/wildcard.localhost.key"
    
    # Optional: Include intermediate certificates
    SSLCertificateChainFile "/path/to/rootCA.pem"
</VirtualHost>

To make browsers trust your local certificate:

# Import root CA into Mac OS keychain
sudo security add-trusted-cert -d -r trustRoot -k /Library/Keychains/System.keychain rootCA.pem

For simpler setup, consider using mkcert:

# Install mkcert
brew install mkcert

# Create and install local CA
mkcert -install

# Generate wildcard certificate
mkcert "*.localhost"