Generate Ed25519 key pairs, sign messages, and verify signatures using the EdDSA algorithm with Curve25519.
Ed25519 Signature Tool creates signing key pairs, produces Ed25519 signatures from a private key and message, and checks signatures using the corresponding public key. A valid signature establishes that the corresponding private key was used for the exact message bytes, but not that its holder personally approved the message; it does not encrypt or conceal the message. The most common surprise is that visually insignificant changes, including spaces, line endings, or Unicode normalization, create a different message and invalidate the signature. Because the tool runs in the browser, entered private-key material is not uploaded.
Key generation produces private signing material and a related public verification key. Keep the private value secret and distribute only the public key. Ed25519 public keys are 32 octets. Private-key representations vary among tools: some expect a 32-octet seed, while others expose a longer combined representation, so copied values must match the receiving field's expected format.
Signing combines the private key with the exact message to produce a 64-octet Ed25519 signature. Verification evaluates the message, signature, and public key together and returns whether that combination is valid. Standard Ed25519 signing is deterministic, so an unchanged key and identical message bytes produce the same signature. Verification requires no private key.
No, not as a general substitution. Ed25519 is a signature scheme built on Edwards25519, while X25519 is used for key agreement and has different key semantics and encodings. Defined conversions exist in some protocols and libraries, but an X25519 key should not be pasted into an Ed25519 field with the expectation that it is interchangeable.
No. It proves that the signature matches the message and public key, which indicates access to the corresponding private key. Identity depends on how reliably the public key was associated with a person or system. The result also provides no timestamp or replay protection, so a valid signed message can still be old or reused.
The behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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