RSA Key Checker

Validate a private key's format and strength before using it. Supports RSA and EC keys — all validation runs entirely in your browser.

Your private key never leaves your browser. All validation is performed locally using JavaScript — nothing is sent to our servers.

Check Private Key

Paste your private key below (RSA or EC, PEM format, including the header and footer lines).

Strength
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Key Details

Key Type
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Key Size / Curve
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Strength Rating
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Format
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Encrypted
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Public Exponent (RSA)
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Security Checks

  • Key size
  • Valid PEM format
  • Safe public exponent
  • Modern algorithm

Key Size Recommendations

Choosing the right key size balances security and performance. Browser vendors and CAs follow NIST guidance on minimum acceptable key sizes.

RSA 4096-bit

Excellent — future-proof and exceeds all current CA/Browser Forum requirements. Recommended for high-security environments.

RSA 2048-bit

Secure — the current industry standard. Let's Encrypt and most CAs issue against 2048-bit keys. Acceptable until at least 2030.

RSA 1024-bit

Weak — deprecated by NIST since 2013. CAs will refuse to sign 1024-bit CSRs. Upgrade to 2048-bit or higher immediately.

EC P-256 / P-384

Excellent — elliptic curve keys offer equivalent security to RSA with much smaller key sizes and faster TLS handshakes.

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