RSA Signature Generator & Verifier
RSA Signature Generator & Verifier: Computes SHA-256 digest of data, applies RSA private key signing exponent, and verifies signature with public key.
About this rsa signature generator & verifier
Computes SHA-256 digest of data, applies RSA private key signing exponent, and verifies signature with public key Runs entirely in-memory using Web Crypto primitives to keep sensitive tokens, certificates, and cryptographic keys secure from third-party interception.
Encoding & cryptographic principles
Uses Web Crypto RSASSA-PKCS1-v1_5 with SHA-256 to sign supplied text with a private JWK or verify a supplied Base64 signature with a public JWK. It does not establish certificate trust or manage key storage.
Worked verification example
Scenario: Verify a fixed RSASSA-PKCS1-v1_5/SHA-256 signature over a test document with a supplied public JWK.
Sample input:
Processing: Checks the supplied signature over the exact message with the public JWK; this verify example does not use a private key or establish signer identity.
Illustrative output:
Security parameters & input constraints
Encryption RSA-OAEP JWKs are distinct and cannot serve as the signing pair. A valid signature only proves key/message correspondence, not signer identity, certificate trust or timestamp. The private JWK is visible in the input.
Cryptographic digests, encoded strings, and signatures generated by RSA Signature Generator & Verifier should be verified against target authentication systems before production use.
Client-side Web Crypto boundary
Key derivation, hashing, and encoding in RSA Signature Generator & Verifier execute in local memory using Web Crypto APIs without remote socket transmission.
Cryptographic specifications & RFC standards
Technical specifications and cryptographic RFC standards governing algorithms and key representations:
RSA Signature Generator & Verifier verification · Audit standards
How to use it
- Use signing JWKs from the RSA key generator; enter JSON with message, privateJwk and operation sign.
- Sign locally with Web Crypto RSASSA-PKCS1-v1_5-SHA-256 and read Base64 signature.
- For verify, supply the same message, signing publicJwk and signature; read valid.
Frequently asked questions
Which signing operation and fields are accepted?+
`operation` defaults to `sign` only when missing or `null`; empty and unknown values are rejected. Signing requires `privateJwk`; verification requires `publicJwk` and base64 `signature`. The message is formed as `String(message || "")`.
How do I sign and verify a message?+
Use `signingPrivateJwk` from RSA Key Generator in `{ "operation": "sign", "privateJwk": { ... }, "message": "abc" }`. Copy the returned `signature`, then use the matching `signingPublicJwk` in `{ "operation": "verify", "publicJwk": { ... }, "message": "abc", "signature": "..." }`; it returns `true`.
Can an RSA-OAEP encryption key sign?+
No. Signing imports the separate RSASSA-PKCS1-v1_5 SHA-256 pair. RSA-OAEP encryption JWKs carry different key operations.
When does verification return false?+
It returns `false` when a successfully imported key and decodable signature do not match the message. Invalid base64, an unsupported key, or a JWK import failure instead raises an error.