burpcustomcert

Generate a custom OpenSSL CA certificate for use with Burp Suite, mitmproxy, or any HTTPS interception proxy. Useful when an Android app blacklists the default Burp/PortSwigger CA.

Output files

File	Format	Use
<name>.crt	PEM	CA certificate
<name>.key	PEM	CA private key
<name>.der	DER	CA certificate (binary)
<name>_key.der	DER	Private key (binary)
<name>_key.pkcs8.der	PKCS#8 DER	Burp Suite import format

Requirements

• Python 3.6+
• OpenSSL in PATH

openssl version   # verify it is available

Usage

git clone https://github.com/im-whoami/burpcustomcert
cd burpcustomcert
python3 burpcustomcert.py

You will be prompted for certificate details (name, country, org, validity period). All files are saved to the current directory.

Burp Suite setup

1. Go to Proxy > Options > Import/export CA certificate
2. Import certificate: <name>.der
3. Import key: <name>_key.pkcs8.der

Android device trust

1. Transfer <name>.crt to the device
2. Go to Settings > Security > Encryption & credentials > Install a certificate > CA
3. Select and install the file

Android 7+ restricts user-installed CAs to user-space trust by default. For apps that enforce system-level trust, use a rooted device or configure network_security_config.xml in the target app.

Troubleshooting

openssl: command not found — install OpenSSL and add it to PATH

Android does not trust the cert — the app may be pinning the system CA store; try a rooted device or patch the app's network_security_config.xml

License

MIT

Disclaimer

For authorized security testing only. Delete generated certificates and keys after use in lab environments.