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

# FC_DigestUpdate

## [Name](#name)

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FC_DigestUpdate - process the next block of a multi-part digest operation.
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## [Syntax](#syntax)

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```{code}
CK_RV FC_DigestUpdate(
  CK_SESSION_HANDLE hSession,
  CK_BYTE_PTR pPart,
  CK_ULONG usPartLen
);
```

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## [Parameters](#parameters)

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`hSession`

: [in] session handle.

`pPart`

: [in] pointer to the next block of data to be digested.

`usPartLen`

: [in] length of data block in bytes.
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## [Description](#description)

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`FC_DigestUpdate` starts or continues a multi-part digest operation. One or more blocks may be
part of the message digest operation. The digest for the entire message is returned by a call to
{ref}`mozilla_projects_nss_reference_fc_digestfinal`.

A user may call `FC_DigestUpdate` 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`,
  {ref}`mozilla_projects_nss_reference_fc_digestfinal`,
  [NSC_DigestUpdate](/en-US/NSC_DigestUpdate)
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