# Certificate signing request decoder

> Inspect a pasted CSR and display subject and public key fields.

[Open tool](https://www.toolcabana.com/ff/certificate-signing-request-decoder) · [Privacy and security education](https://www.toolcabana.com/ff/category/privacy-and-security-education)

Tool ID: certificate-signing-request-decoder. Requested language: ff. Description language: en. Complete guide translation: no; untranslated sections use English.

## Overview (en)

Certificate signing request decoder reads a PEM-encoded PKCS#10 CSR and lists its subject fields, such as CN and O, together with the RSA public key size in bits and whether the request's signature verifies. Paste text beginning with -----BEGIN CERTIFICATE REQUEST-----, under 100 KB. A valid signature does not establish identity or certificate trust.

## Supported tasks (en)

Inspect a pasted CSR and display subject and public key fields.

## Steps (en)

1. Paste the source into the input editor, or load the built-in example.
2. Check the source format before running the operation.
3. Run certificate signing request decoder, review the output, then use the available copy or download controls.

## Settings

No additional settings.

## Limitations (en)

CSV/XLSX inputs are capped at 10 MB each, 200 columns and 20,000 rows; joined output is capped at 20,000 rows. JSONPath script/filter evaluation is disabled. Other operations apply their visible controls and text limits.

## Example input

```text
-----BEGIN CERTIFICATE REQUEST-----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-----END CERTIFICATE REQUEST-----

```

## Privacy and connections (en)

This operation processes its source in your browser. Copy and download are explicit actions; source input is not saved in an account or history.

## Questions (en)

### Does the CSR decoder support ECDSA keys?

No. Only RSA requests are decoded; a CSR with an elliptic-curve or other key type returns an error asking for a supported RSA PEM certificate signing request. The key size shown is the RSA modulus length in bits.

### What does Signature valid mean in the CSR decoder?

It shows whether the CSR's self-signature verifies with the public key it contains, checked through the browser's Web Crypto API. True means the request is internally consistent; it does not prove who created it or that a certificate authority will trust it.

### Why is my CSR rejected even though it looks correct?

The text must start with the exact line -----BEGIN CERTIFICATE REQUEST-----. Requests using the older NEW CERTIFICATE REQUEST label, binary DER files and inputs over 100 KB are rejected; change both header lines to the standard label and try again.

### Where is my input processed?

This operation processes its source in your browser. Copy and download are explicit actions; source input is not saved in an account or history.

### What are the input limits?

CSV/XLSX inputs are capped at 10 MB each, 200 columns and 20,000 rows; joined output is capped at 20,000 rows. JSONPath script/filter evaluation is disabled. Other operations apply their visible controls and text limits.

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