Asymmetric Cryptography

Generate RSA, ECDSA, and Ed25519 key pairs, compute and verify digital signatures, and perform RSA-OAEP asymmetric encryption locally in your browser.

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Asymmetric Cryptography Workbench

RSA (RS256 / PSS / OAEP) • ECDSA (P-256 / P-384 / P-521) • Ed25519

🔐 Client-Side Asymmetric Processing:

RSA, ECDSA, and Ed25519 key generation, digital signing, verification, and RSA-OAEP encryption execute 100% locally in browser memory using native Web Crypto APIs. Private keys are never stored or transmitted to any server.

Operational Distinction: ECDSA and Ed25519 are signature algorithms only. RSA supports RSASSA-PKCS1-v1_5 / RSA-PSS for digital signatures, and RSA-OAEP for asymmetric key encryption.

What Is Asymmetric Cryptography?

Asymmetric (public-key) cryptography uses a mathematically linked key pair instead of one shared secret: a public key that can be shared freely, and a private key that must stay secret. This tool supports signing, signature verification, encryption, and decryption using RSA, ECDSA, Ed25519, and related algorithms.

How to Use the Asymmetric Cryptography Tool

Choose an operation: sign, verify, encrypt, or decrypt.
Provide a key pair, or generate a new one for the algorithm you need.
Enter the message, signature, or ciphertext relevant to the chosen operation.
Review the result.

Technical Notes

Signing proves a message came from whoever holds a specific private key; it does not keep the message secret. Encryption keeps a message confidential to whoever holds the matching private key; it does not by itself prove who sent it.
RSA, ECDSA, and Ed25519 are different algorithm families with different key formats and performance characteristics — a key generated for one cannot be used with another.
Never share a private key. Anyone who has it can sign or decrypt as if they were you.

Frequently Asked Questions

What is the difference between signing and encrypting here?+

Signing uses a private key to prove a message came from you; anyone with the public key can verify it, but the message is not hidden. Encryption uses a public key so only the holder of the matching private key can read it; it does not by itself prove who sent it.

Can I encrypt with ECDSA or Ed25519 keys?+

No. ECDSA and Ed25519 are signature-only algorithms. In this tool, asymmetric encryption and decryption are available with RSA-OAEP only; RSA also offers RSASSA-PKCS1-v1_5 and RSA-PSS for signatures.

Why does RSA-OAEP reject a long message?+

RSA can only encrypt data smaller than its key size minus padding overhead — for a 2048-bit key with SHA-256 OAEP, about 190 bytes. Larger payloads are normally handled by encrypting them with a symmetric key and then encrypting only that key with RSA.