# SVC_CalcSHA1

## Syntax

      #include <twl/os/common/systemCall.h>

      void SVC_CalcSHA1( void* md,
                          const void* data,
                          unsigned int len );

## Arguments

md | Pointer to the memory location that holds the calculated SHA-1 value.
data | Pointer to the input data.
len | Size of the input data.

## Return Values

None.

## Description

Performs the SHA-1 calculations.

This is a utility function that successively calls the `SVC_SHA1Init()`, `SVC_SHA1Update()`, and `SVC_SHA1GetHash()` functions. Internally, the `SVCSHA1Context` structure is allocated to the stack, so make sure you have sufficient stack space when calling the function.

The length of the generated SHA-1 value is 160 bits, or `SVC_SHA1_DIGEST_SIZE` (= 20) bytes. Use the md argument to pass an area that can store a value of this size.

Specify the input data using data and len. Any size and alignment position can be used.

SHA-1 is an algorithm to find the message digest value. For details, see RFC (Request For Comments) 3174, which is published by IETF (the Internet Engineering Task Force).

## See Also

`SVC_SHA1Init``, SVC_SHA1Update, SVC_SHA1GetHash`

## Revision History

2007/10/19 Initial version.

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