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

# FC_DecryptUpdate

## [Name](#name)

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FC_DecryptUpdate - decrypt a block of a multi-part encryption operation.
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## [Syntax](#syntax)

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```{code}
CK_RV FC_DecryptUpdate(
  CK_SESSION_HANDLE hSession,
  CK_BYTE_PTR pEncryptedPart,
  CK_ULONG usEncryptedPartLen,
  CK_BYTE_PTR pPart,
  CK_ULONG_PTR pusPartLen
);
```

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## [Parameters](#parameters)

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`hSession`

: [in] session handle.

`pEncryptedPart`

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

`usEncryptedPartLen`

: [in] length of data block in bytes.

`pPart`

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

`pusPartLen`

: [in,out] pointer the location where the number of bytes of recovered data is to be stored.
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## [Description](#description)

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`FC_DecryptUpdate` decrypts a block of data according to the attributes of the previous call to
`FC_DecryptInit`. The block may be part of a multi-part decryption operation.

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

## [Examples](#examples)

## [See also](#see_also)

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- {ref}`mozilla_projects_nss_reference_fc_decryptinit`,
  [NSC_DecryptUpdate](/en-US/NSC_DecryptUpdate)
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