---
title: "isValidSignature(_:for:)"
framework: cryptokit
role: symbol
role_heading: Instance Method
path: "cryptokit/p521/signing/publickey/isvalidsignature(_:for:)-5kwev"
---

# isValidSignature(_:for:)

Verifies an elliptic curve digital signature algorithm (ECDSA) signature on a block of data over the P-521 elliptic curve.

## Declaration

```swift
func isValidSignature<D>(_ signature: P521.Signing.ECDSASignature, for data: D) -> Bool where D : DataProtocol
```

## Parameters

- `signature`: The signature to verify.
- `data`: The signed data.

## Return Value

Return Value A Boolean value that’s true if the signature is valid for the given data; otherwise, false.

## See Also

### Verifying a signature

- [isValidSignature(_:for:)](cryptokit/p521/signing/publickey/isvalidsignature(_:for:)-dhjh.md)
- [P521.Signing.ECDSASignature](cryptokit/p521/signing/ecdsasignature.md)