RSA Sign Verify
Sign UTF-8 text with an RSA private key PEM and verify PKCS#1 v1.5 signatures with the matching public key.
RSA PKCS#1 v1.5 sign and verify
RSA digital signatures prove that a message was signed with a specific private key. This tool signs UTF-8 text with an RSA private key in PEM format and verifies a Base64 PKCS#1 v1.5 signature using the matching public key. Choose SHA-256, SHA-384, or SHA-512 as the message digest algorithm. Processing stays in your browser, keys and plaintext never leave your device.
Pair this page with the RSA Key Pair Generator to create keys, or compare with ECDSA Sign Verify for elliptic-curve workflows.
Typical workflow
- Generate or paste a PEM private key and the corresponding public key.
- Enter the message to sign; the Base64 signature appears automatically.
- Paste the public key and signature into the verify section to confirm integrity.
Frequently Asked Questions
Which RSA padding does this tool use?
Signatures use RSASSA-PKCS1-v1_5 with the selected hash (SHA-256, SHA-384, or SHA-512), matching common
OpenSSL dgst -sign behavior for PEM keys.
Can I verify signatures from other tools?
Yes, if they use PKCS#1 v1.5 with the same hash and the signature is Base64-encoded. PSS-only signatures require a PSS-aware verifier.
Are my private keys uploaded?
No. Signing and verification run with in-browser cryptography libraries only; keys are not transmitted.
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