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GLib Reference Manual | |
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#include <glib.h>
GHmac;
GHmac * g_hmac_new (GChecksumType digest_type,
const guchar *key,
gsize key_len);
GHmac * g_hmac_copy (const GHmac *hmac);
GHmac * g_hmac_ref (GHmac *hmac);
void g_hmac_unref (GHmac *hmac);
void g_hmac_update (GHmac *hmac,
const guchar *data,
gssize length);
const gchar * g_hmac_get_string (GHmac *hmac);
void g_hmac_get_digest (GHmac *hmac,
guint8 *buffer,
gsize *digest_len);
gchar * g_compute_hmac_for_data (GChecksumType digest_type,
const guchar *key,
gsize key_len,
const guchar *data,
gsize length);
gchar * g_compute_hmac_for_string (GChecksumType digest_type,
const guchar *key,
gsize key_len,
const gchar *str,
gssize length);
HMACs should be used when producing a cookie or hash based on data and a key. Simple mechanisms for using SHA1 and other algorithms to digest a key and data together are vulnerable to various security issues. HMAC uses algorithms like SHA1 in a secure way to produce a digest of a key and data.
Both the key and data are arbitrary byte arrays of bytes or characters.
Support for HMAC Digests has been added in GLib 2.30.
typedef struct _GHmac GHmac;
An opaque structure representing a HMAC operation.
To create a new GHmac, use g_hmac_new(). To free
a GHmac, use g_hmac_unref().
Since 2.30
GHmac * g_hmac_new (GChecksumType digest_type,const guchar *key,gsize key_len);
Creates a new GHmac, using the digest algorithm digest_type.
If the digest_type is not known, NULL is returned.
A GHmac can be used to compute the HMAC of a key and an
arbitrary binary blob, using different hashing algorithms.
A GHmac works by feeding a binary blob through g_hmac_update()
until the data is complete; the digest can then be extracted
using g_hmac_get_string(), which will return the checksum as a
hexadecimal string; or g_hmac_get_digest(), which will return a
array of raw bytes. Once either g_hmac_get_string() or
g_hmac_get_digest() have been called on a GHmac, the HMAC
will be closed and it won't be possible to call g_hmac_update()
on it anymore.
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the desired type of digest |
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the key for the HMAC. [array length=key_len] |
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the length of the keys |
Returns : |
the newly created GHmac, or NULL.
Use g_hmac_unref() to free the memory allocated by it. |
Since 2.30
GHmac * g_hmac_copy (const GHmac *hmac);
Copies a GHmac. If hmac has been closed, by calling
g_hmac_get_string() or g_hmac_get_digest(), the copied
HMAC will be closed as well.
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the GHmac to copy |
Returns : |
the copy of the passed GHmac. Use g_hmac_unref()
when finished using it. |
Since 2.30
GHmac * g_hmac_ref (GHmac *hmac);
Atomically increments the reference count of hmac by one.
This function is MT-safe and may be called from any thread.
Since 2.30
void g_hmac_unref (GHmac *hmac);
Atomically decrements the reference count of hmac by one.
If the reference count drops to 0, all keys and values will be
destroyed, and all memory allocated by the hash table is released.
This function is MT-safe and may be called from any thread.
Frees the memory allocated for hmac.
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a GHmac |
Since 2.30
void g_hmac_update (GHmac *hmac,const guchar *data,gssize length);
Feeds data into an existing GHmac.
The HMAC must still be open, that is g_hmac_get_string() or
g_hmac_get_digest() must not have been called on hmac.
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a GHmac |
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buffer used to compute the checksum. [array length=length] |
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size of the buffer, or -1 if it is a nul-terminated string |
Since 2.30
const gchar * g_hmac_get_string (GHmac *hmac);
Gets the HMAC as an hexadecimal string.
Once this function has been called the GHmac can no longer be
updated with g_hmac_update().
The hexadecimal characters will be lower case.
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a GHmac |
Returns : |
the hexadecimal representation of the HMAC. The returned string is owned by the HMAC and should not be modified or freed. |
Since 2.30
void g_hmac_get_digest (GHmac *hmac,guint8 *buffer,gsize *digest_len);
Gets the digest from checksum as a raw binary array and places it
into buffer. The size of the digest depends on the type of checksum.
Once this function has been called, the GHmac is closed and can
no longer be updated with g_checksum_update().
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a GHmac |
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output buffer |
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an inout parameter. The caller initializes it to the
size of buffer. After the call it contains the length of the digest |
Since 2.30
gchar * g_compute_hmac_for_data (GChecksumType digest_type,const guchar *key,gsize key_len,const guchar *data,gsize length);
Computes the HMAC for a binary data of length. This is a
convenience wrapper for g_hmac_new(), g_hmac_get_string()
and g_hmac_unref().
The hexadecimal string returned will be in lower case.
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a GChecksumType to use for the HMAC |
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the key to use in the HMAC. [array length=key_len] |
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the length of the key |
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binary blob to compute the HMAC of |
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length of data
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Returns : |
the HMAC of the binary data as a string in hexadecimal.
The returned string should be freed with g_free() when done using it. |
Since 2.30
gchar * g_compute_hmac_for_string (GChecksumType digest_type,const guchar *key,gsize key_len,const gchar *str,gssize length);
Computes the HMAC for a string.
The hexadecimal string returned will be in lower case.
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a GChecksumType to use for the HMAC |
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the key to use in the HMAC. [array length=key_len] |
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the length of the key |
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the string to compute the HMAC for |
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the length of the string, or -1 if the string is nul-terminated |
Returns : |
the HMAC as a hexadecimal string.
The returned string should be freed with g_free()
when done using it. |
Since 2.30