(mozilla-projects-nss-reference-fc-verifyrecover)=

# FC_VerifyRecover

## [Name](#name)

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FC_VerifyRecover - Verify data in a single recoverable operation.
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## [Syntax](#syntax)

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```{code}
CK_RV FC_VerifyRecover(
  CK_SESSION_HANDLE hSession,
  CK_BYTE_PTR pSignature,
  CK_ULONG usSignatureLen,
  CK_BYTE_PTR pData,
  CK_ULONG_PTR pusDataLen
);
```

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## [Parameters](#parameters)

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`hSession`

: [in] session handle.

`pSignature`

: [in] mechanism to be used for the signing operation.

`usSignatureLen`

: [in] handle of the key to be usedn.

`pData`

: [out] pointer to the buffer or NULL.

`pusDataLen`

: [in, out] pointer to the size of the output buffer, replaced by the length of the signature if
  the operation is successful.
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## [Description](#description)

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`FC_VerifyRecover` verifies data in a single operation where the (digest) data can be recovered
from the signature. If `pSignature` is NULL only the length of the signature is returned in
`*pusSignatureLen`.

A user must log into the token (to assume the NSS User role) before calling `FC_VerifyRecover`.
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## [Return value](#return_value)

## [Examples](#examples)

## [See also](#see_also)

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- [NSC_VerifyRecover](/en-US/NSC_VerifyRecover)
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