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

# FC_Digest

## [Name](#name)

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FC_Digest - digest a block of data.
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## [Syntax](#syntax)

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```{code}
CK_RV FC_Digest(
  CK_SESSION_HANDLE hSession,
  CK_BYTE_PTR pData,
  CK_ULONG usDataLen,
  CK_BYTE_PTR pDigest,
  CK_ULONG_PTR pusDigestLen
);
```

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## [Parameters](#parameters)

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`hSession`

: [in] session handle.

`pData`

: [in] pointer to data block.

`usDataLen`

: [in] length of the data in bytes.

`pDigest`

: [out] pointer to location where recovered data is to be stored.

`pusDigestLen`

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

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`FC_Digest` digests a message in a single operation according to the attributes of the previous
call to `FC_DigestInit`.

A user may call `FC_Digest` without logging into the token (to assume the NSS User role).
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## [Return value](#return_value)

## [Examples](#examples)

## [See also](#see_also)

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- {ref}`mozilla_projects_nss_reference_fc_digestinit`, [NSC_Digest](/en-US/NSC_Digest)
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