Custom Certificates

1. What's it?

Proxyman supports Custom Root Certificate, Server Certificates, and Client Certificates that allow you to add your certificate that Proxyman uses to establish the SSL-Connection between your clients, servers, and Proxyman app.

Custom Certificate Type

Purpose

How Proxyman uses

Server Certificate

For intercepting HTTPS Traffic from clients that use SSL-Pinning

Use this certificate for SSL-Handshake to your Clients

Client Certificate

For intercepting HTTPS Traffic from clients that use Mutual Authentication

Use this certificate for SSL-Handshake to specific Server

Root Certificate

For intercepting HTTPS Traffic from clients and servers without using local Proxyman certificates

SSL Handshake for both clients & servers

Even though the Proxyman Root Certificate is locally generated in your machine, you can manually generate and add to Proxyman. Read more

2. Certificate Formats

Proxyman accepts the following formats:

  • PKCS #12 (p12)

  • PEM or DER Private Key and Certificate file

  • Proxyman automatically determines the format of Private Key and Certificate file (Support PEM or DER)

  • Proxyman will prompt to enter the password if import an encrypted Private Key or PKCS #12 file

  • All passphrases are securely stored in Proxyman Keychain

If your certificates are in different formats that Proxyman supports, please convert them to p12 or PEM/DER format before importing

3. Certificate Requirement on macOS 10.15+ and iOS 13+

If you're using a custom Root Certificate or Server Certificate on macOS 10.15 or iOS 13, you might encounter the failed handshake on Safari or iOS devices if the following requirements don't meet:

  • RSA Key must have a key size is greater than 2048 bits

  • The hash algorithm is SHA-2 family

  • DNS Name of the server must present on Subject Alternative Name. Common Name is no longer trusted

  • Valid certificate (Current day is in Not Before and Not After)

  • TLS server certificates must contain an ExtendedKeyUsage (EKU) extension containing the id-kp-serverAuth OID.

Read more https://support.apple.com/en-us/HT210176

To facilitate it, you can use Proxyman to generate a Certificate for you in Certificate Menu -> Install Certificate on macOS

4. Common issues

Problem

Solution

Private Key and Certificate are not matched

Try different certificates and private key and make sure they are matched

Get SSL Handshake Error for custom certificates

  • Try to add the custom Certificate to System Keychain and Trust it

  • Certificate doesn't match the requirement from macOS => Read section 3

  • Check expires day of the Certificate

Couldn't import certificate due to invalid passphrase

Ask your leader to give the correct passphrase to open the encrypted Private Key or P12 file

5. How to use

  • Access from Certificate Menu -> Add Custom Certificate

6. How to generate self-signed certificates for Custom Root Certificate that comply with new Apple's Security Requirements

Due to Apple's requirements from iOS 13 and Catalina (10.15), It requires extra configuration to generate the self-signed certificate properly.

The following steps will guide you on how to do it properly:

  1. Prepare cert.config file on Desktop folder

[ ca ]
default_ca = CA_default
[ CA_default ]
default_md = sha256
[ v3_ca ]
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid:always,issuer
basicConstraints = critical,CA:true
keyUsage=critical,keyCertSign
extendedKeyUsage = serverAuth,clientAuth
[ req ]
prompt = no
distinguished_name = req_distinguished_name
[ req_distinguished_name ]
C=SG
L=SG
O=Proxyman
CN=proxyman.dev
OU=Proxyman
  • Please update values for C, L, O, CN, and OU param.

2. Generate RSA Key in the Terminal app. (Make sure you replace your_password to your real password)

cd ~/Desktop
openssl genrsa -aes256 -passout pass:your_password -out key.pem 2048

3. Generate the self-signed certificate and private key. (Make sure you replace your_password to your real password)

openssl req -x509 -new -nodes -passin pass:your_password -config cert.config -key key.pem -sha256 -extensions v3_ca -days 825 -out root-ca.pem

4. Convert to p12 format. (Make sure you replace your_password to your real password)

openssl pkcs12 -export -out root-ca.p12 -in root-ca.pem -inkey key.pem -passin pass:your_password -passout pass:your_password

5. Finally, you would have root-ca.p12 file and move to the next step

Use as a Custom Root Certificate

  1. Go to Certificate Menu -> Custom Certificate -> Select Root Certificate Tab

  2. Click Import button -> P12

  3. Select root-ca.p12 and enter the password

  4. Trust your custom certificate in Keychain App:

  • Open Keychain App

  • Search for the certificate you've added. The name might be the common name (CN) of the certificate

  • Double Click to open and select Always Trust

  • Click "X" and save the change

5. Please verify that you can see the Green Tick that shows the certificate is installed and trusted properly.

Custom Root Certificate is installed and trusted properly. Ready to go!

Use as a Server/Client Certificate

For custom Server/Client certificates, you should not generate a self-signed certificate. Please ask your workmate or team lead about the certificate that the company is using. It could be in DER/PEM or P12 format.

Then import the certificate as a Server / Client Certificate in Custom Certificate Window.

You don't need to trust on Keychain since it's not a Root Certificate