Extracts the public key embedded in a certificate signing request.
Before using it, identify which data, connection or runtime state the operation reads or changes. This avoids examples that appear to work but apply to a different context.
What Is openssl_csr_get_public_key() in PHP?
Extracts the public key embedded in a certificate signing request.
Syntax:
<?php
// Signature for reference only
openssl_csr_get_public_key(OpenSSLCertificateSigningRequest|string $csr, [optional] bool $short_names) : OpenSSLAsymmetricKey|false
Parameters and Return Value
$csr— Required OpenSSLCertificateSigningRequest|string argument supplied to this operation.$short_names— Optional bool argument supplied to this operation.
The declared return type is OpenSSLAsymmetricKey|false.
Example 1: Basic Usage
<?php
$privateKey = openssl_pkey_new(["private_key_bits"=>2048,"private_key_type"=>OPENSSL_KEYTYPE_RSA]);
$certificateRequest = openssl_csr_new(["commonName"=>"demo.local"], $privateKey);
$publicKey = openssl_csr_get_public_key($certificateRequest);
var_dump($publicKey instanceof OpenSSLAsymmetricKey);Extracts the public key embedded in a certificate signing request.
Example 2: Another Case
<?php
$privateKey = openssl_pkey_new(["private_key_bits"=>2048]);
$certificateRequest = openssl_csr_new(["commonName"=>"example.local"], $privateKey);
$publicKey = openssl_csr_get_public_key($certificateRequest);
$keyInformation = openssl_pkey_get_details($publicKey);
echo $keyInformation["bits"];The second sample illustrates a different way to inspect or handle this operation. Configure the underlying session, socket, key material or connection first.
Practical Example
<?php
$privateKey = openssl_pkey_new(["private_key_bits"=>2048]);
$certificateRequest = openssl_csr_new(["commonName"=>"app.local"], $privateKey);
$publicKey = openssl_csr_get_public_key($certificateRequest);
if ($publicKey === false) { throw new RuntimeException("CSR public key unavailable"); }
echo openssl_pkey_get_details($publicKey)["type"];The practical example is a teaching scenario. Change sample configuration and credentials before using a similar design in an application.
Important Behavior and Edge Cases
- Use trusted certificate and key material; never print private keys or disclose secrets in logs.
- Relevant PHP environment: openssl. Ensure the required extension and operating-system capabilities are present.
- Check results and release resources where necessary; successful syntax alone does not guarantee a successful operation.
Comparison With Related Functions
| Option | When to Use It |
|---|---|
openssl_csr_get_public_key | Extracts the public key embedded in a certificate signing request. |
openssl_pkey_get_details | Use this related operation for its different responsibilities; do not assume identical inputs or return values. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Confusing public and private keys | Use the appropriate key type for each operation and never disclose secret key data. |
| Assuming every algorithm is safe for every purpose | Choose modern algorithms and protocol combinations supported by your deployment. |
| Printing certificate and key material to visitors | Keep cryptographic diagnostics restricted and redact secrets. |
Key Takeaways
- Extracts the public key embedded in a certificate signing request.
- Use trusted certificate and key material; never print private keys or disclose secrets in logs.
- Validate inputs and handle failure conditions before integrating this operation into a production workflow.
Extracts the public key embedded in a certificate signing request. Use the appropriate runtime and treat any environment-dependent output as an example, not a guaranteed result.