rsa command with the -in flag to specify the source file and the -out flag for the destination. This process removes the passphrase protection by prompting you for the current password and then writing the raw key material without encryption headers.
Understanding Key Encryption States
RSA private keys are often stored in encrypted formats to protect sensitive cryptographic material from unauthorized access. When a key is generated or converted with a passphrase, OpenSSL wraps the key data in a symmetric cipher, typically AES-128-CBC or AES-256-CBC, depending on the version and options used. An encrypted key begins with headers like -----BEGIN ENCRYPTED PRIVATE KEY----- or -----BEGIN RSA PRIVATE KEY----- followed by base64-encoded ciphertext.
An unencrypted key, conversely, contains the plaintext private exponent and other parameters directly readable by any application that can parse the PEM format. While this makes the key easier to use in automated scripts or legacy systems that do not support interactive passphrase entry, it significantly increases security risks if the file is compromised. You should only remove encryption when absolutely necessary and ensure the resulting file has strict file permissions, such as chmod 600.
Prerequisites and Environment Setup
Before attempting the conversion, ensure you have OpenSSL 3.3.0 installed on your Mac. Apple’s default command-line tools may include an older version of OpenSSL, so verify your installation by running openssl version in the terminal. If the version string does not indicate 3.3.0, you likely need to install it via Homebrew using brew install [email protected] or similar package management commands.
You also need the path to your existing encrypted private key file and the correct passphrase associated with it. Without the correct passphrase, the decryption step will fail, and you will be unable to extract the unencrypted key. Do not share your passphrase or key files over insecure channels, as this operation involves handling sensitive cryptographic material in plain text temporarily.
Executing the Conversion Command
The core mechanism for this task is the openssl rsa subcommand. This utility handles the parsing of PKCS#1 formatted RSA keys and performs the decryption logic internally. Open your terminal and navigate to the directory containing your key file, or provide the full absolute path in your command arguments.
Run the following command structure:
openssl rsa -in encrypted_key.pem -out unencrypted_key.pemWhen you execute this command, OpenSSL will prompt you for the input passphrase. Type the current passphrase for the encrypted key carefully; the characters will not echo on the screen for security reasons. Once verified, OpenSSL decrypts the key material and writes it to the output file specified by -out. The resulting unencrypted_key.pem file will contain the standard -----BEGIN RSA PRIVATE KEY----- header and the unencrypted base64 payload.
Verifying the Output
After the command completes successfully, verify that the new key is indeed unencrypted. You can attempt to read the key using the -check flag, which validates the mathematical consistency of the key components without requiring a passphrase for unencrypted files.
openssl rsa -in unencrypted_key.pem -check -nooutIf the key is valid, the terminal will return RSA key ok. If you try to pass an incorrect passphrase to an unencrypted key, OpenSSL will typically ignore it or complain that no passphrase was provided, confirming the removal of encryption. Additionally, you can inspect the first line of the file using head -n 1 unencrypted_key.pem to ensure it starts with -----BEGIN RSA PRIVATE KEY----- rather than ENCRYPTED.
Security Best Practices
Removing encryption from a private key exposes it to any user or process with read access to the file system. Immediately after conversion, restrict file permissions using chmod 600 unencrypted_key.pem. This ensures that only the owner can read or write the file, preventing other users on the multi-user macOS environment from accessing the sensitive material.
Avoid storing unencrypted keys in temporary directories or shared cloud storage locations unless they are encrypted at rest by the operating system. Consider using SSH agent forwarding or certificate-based authentication where possible to avoid needing direct access to the private key file during operations.
Frequently Asked Questions
Can I convert a PKCS#8 encrypted key instead?
Yes, but you must use the pkey command instead of rsa. Use openssl pkey -in pkcs8_encrypted.pem -out unencrypted.pem to handle modern PKCS#8 formatted keys, which are the default in newer OpenSSL versions.
Why does my key still look encrypted after conversion?
This usually happens if you accidentally specified the same file for both input and output, or if you did not enter the correct passphrase. Always check the header of the output file to confirm it lacks the ENCRYPTED tag before proceeding.
Is it safe to leave an unencrypted key on my Mac?
It is risky if the drive is not fully encrypted or if other users have account access. Always set strict permissions with chmod 600 and consider re-encrypting the key immediately after use in automated scripts.
How do I re-encrypt the key later?
To reverse the process, run openssl rsa -in unencrypted_key.pem -out encrypted_key.pem -aes256. This will prompt you to create a new passphrase and wrap the key in strong AES-256 encryption again.
Does this method work for ECDSA keys?
No, the rsa command is specific to RSA keys. For Elliptic Curve keys, use the ec command or the generic pkey command with appropriate flags to handle EC private key formats.