Hashing functions

Functions
wget_digest_algorithm_t	wget_hash_get_algorithm (const char *hashname)
int	wget_hash_fast (wget_digest_algorithm_t algorithm, const void *text, size_t textlen, void *digest)
int	wget_hash_get_len (wget_digest_algorithm_t algorithm)
int	wget_hash_init (wget_hash_hd_t *handle, wget_digest_algorithm_t algorithm)
int	wget_hash (wget_hash_hd_t *handle, const void *text, size_t textlen)
void	wget_hash_deinit (wget_hash_hd_t *handle, void *digest)
int	wget_hash_file_fd (const char *hashname, int fd, char *digest_hex, size_t digest_hex_size, off_t offset, off_t length)
int	wget_hash_file_offset (const char *hashname, const char *fname, char *digest_hex, size_t digest_hex_size, off_t offset, off_t length)
int	wget_hash_file (const char *hashname, const char *fname, char *digest_hex, size_t digest_hex_size)

Detailed Description

Function Documentation

wget_hash_get_algorithm()

wget_digest_algorithm_t wget_hash_get_algorithm

(

const char *

hashname

)

Parameters

[in]

hashname

Name of the hashing algorithm (see table below)

Returns

A constant to be used by libwget hashing functions

Get the hashing algorithms list item that corresponds to the named hashing algorithm.

This function returns a constant that uniquely identifies a known supported hashing algorithm within libwget. All the supported algorithms are listed in the ::wget_digest_algorithm_t enum.

Algorithm name	Constant
sha1 or sha-1	WGET_DIGTYPE_SHA1
sha256 or sha-256	WGET_DIGTYPE_SHA256
sha512 or sha-512	WGET_DIGTYPE_SHA512
sha224 or sha-224	WGET_DIGTYPE_SHA224
sha384 or sha-384	WGET_DIGTYPE_SHA384
md5	WGET_DIGTYPE_MD5
md2	WGET_DIGTYPE_MD2
rmd160	WGET_DIGTYPE_RMD160

wget_hash_fast()

int wget_hash_fast	(	wget_digest_algorithm_t	algorithm,
		const void *	text,
		size_t	textlen,
		void *	digest
	)

Parameters

[in]	algorithm	One of the hashing algorithms returned by wget_hash_get_algorithm()
[in]	text	Input data to hash
[in]	textlen	Length of the input data
[in]	digest	Caller-supplied buffer where the output hash will be placed

Returns

Zero on success or a negative value on error

Convenience function to hash the given data in a single call.

The caller must ensure that the provided output buffer digest is large enough to store the hash. A particular hash algorithm is guaranteed to always generate the same amount of data (e.g. 512 bits) but different hash algorithms will output different lengths of data. To get the output length of the chosen algorithm algorithm, call wget_hash_get_len().

Note

This function's behavior depends on the underlying cryptographic engine libwget was compiled with.

wget_hash_get_len()

int wget_hash_get_len

(

wget_digest_algorithm_t

algorithm

)

Parameters

[in]

algorithm

One of the hashing algorithms returned by wget_hash_get_algorithm()

Returns

The length of the output data generated by the algorithm

Determines the output length of the given hashing algorithm.

A particular hash algorithm is guaranteed to always generate the same amount of data (e.g. 512 bits) but different hash algorithms will output different lengths of data.

wget_hash_init()

int wget_hash_init	(	wget_hash_hd_t *	handle,
		wget_digest_algorithm_t	algorithm
	)

Parameters

[out]	handle	Caller-provided pointer to a ::wget_hash_hd_t structure where the handle to this hashing primitive will be stored, needed in subsequent calls to wget_hash()
[in]	algorithm	One of the hashing algorithms returned by wget_hash_get_algorithm()

Returns

Zero on success or a negative value on error

Initialize the cryptographic engine to compute hashes with the given hashing algorithm, as well as the hashing algorithm itself.

After this function returns, wget_hash() might be called as many times as desired.

wget_hash()

int wget_hash	(	wget_hash_hd_t *	handle,
		const void *	text,
		size_t	textlen
	)

Parameters

[in]	handle	Handle to the hashing primitive returned by a subsequent call to wget_hash_init()
[in]	text	Input data
[in]	textlen	Length of the input data

Returns

Zero on success or a negative value on error

Update the digest by adding additional input data to it. This method can be called as many times as desired. Once finished, call wget_hash_deinit() to complete the computation and get the resulting hash.

wget_hash_deinit()

void wget_hash_deinit	(	wget_hash_hd_t *	handle,
		void *	digest
	)

Parameters

[in]	handle	Handle to the hashing primitive returned by a subsequent call to wget_hash_init()
[out]	digest	Caller-supplied buffer where the output hash will be placed.

Complete the hash computation by performing final operations, such as padding, and obtain the final result. The result will be placed in the caller-supplied buffer digest. The caller must ensure that the provided output buffer digest is large enough to store the hash. To get the output length of the chosen algorithm algorithm, call wget_hash_get_len().

wget_hash_file_fd()

int wget_hash_file_fd	(	const char *	hashname,
		int	fd,
		char *	digest_hex,
		size_t	digest_hex_size,
		off_t	offset,
		off_t	length
	)

Parameters

[in]	hashname	Name of the hashing algorithm. See wget_hash_get_algorithm()
[in]	fd	File descriptor for the target file
[out]	digest_hex	caller-supplied buffer that will contain the resulting hex string
[in]	digest_hex_size	Length of digest_hex
[in]	offset	File offset to start hashing at
[in]	length	Number of bytes to hash, starting from offset. Zero will hash up to the end of the file

Returns

0 on success or -1 in case of failure

Compute the hash of the contents of the target file and return its hex representation.

This function will encode the resulting hash in a string of hex digits, and place that string in the user-supplied buffer digest_hex.

wget_hash_file_offset()

int wget_hash_file_offset	(	const char *	hashname,
		const char *	fname,
		char *	digest_hex,
		size_t	digest_hex_size,
		off_t	offset,
		off_t	length
	)

Parameters

[in]	hashname	Name of the hashing algorithm. See wget_hash_get_algorithm()
[in]	fname	Target file name
[out]	digest_hex	Caller-supplied buffer that will contain the resulting hex string
[in]	digest_hex_size	Length of digest_hex
[in]	offset	File offset to start hashing at
[in]	length	Number of bytes to hash, starting from offset. Zero will hash up to the end of the file

Returns

0 on success or -1 in case of failure

Compute the hash of the contents of the target file starting from offset and up to length bytes and return its hex representation.

This function will encode the resulting hash in a string of hex digits, and place that string in the user-supplied buffer digest_hex.

wget_hash_file()

int wget_hash_file	(	const char *	hashname,
		const char *	fname,
		char *	digest_hex,
		size_t	digest_hex_size
	)

Parameters

[in]	hashname	Name of the hashing algorithm. See wget_hash_get_algorithm()
[in]	fname	Target file name
[out]	digest_hex	Caller-supplied buffer that will contain the resulting hex string
[in]	digest_hex_size	Length of digest_hex

Returns

0 on success or -1 in case of failure

Compute the hash of the contents of the target file and return its hex representation.

This function will encode the resulting hash in a string of hex digits, and place that string in the user-supplied buffer digest_hex.