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Diffstat (limited to 'libhashsum_init_blake2s_hasher.3')
| -rw-r--r-- | libhashsum_init_blake2s_hasher.3 | 294 |
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diff --git a/libhashsum_init_blake2s_hasher.3 b/libhashsum_init_blake2s_hasher.3 new file mode 100644 index 0000000..5250708 --- /dev/null +++ b/libhashsum_init_blake2s_hasher.3 @@ -0,0 +1,294 @@ +.TH LIBHASHSUM_INIT_BLAKE2S_HASHER 3 libhashsum +.SH NAME +libhashsum_init_blake2s_hasher - initialise state for BLAKE2s hashing + +.SH SYNOPSIS +.nf +#include <libhashsum.h> + +\fBstruct libhashsum_hasher\fP { + enum libhashsum_algorithm \fIalgorithm\fP; + const char *\fIalgorithm_string\fP; + size_t \fIinput_block_size\fP; + size_t \fIhash_size\fP; + unsigned char *\fIhash_output\fP; + unsigned char \fIsupports_non_whole_bytes\fP; + size_t (*\fIprocess\fP)(struct libhashsum_hasher *\fPthis\fP, const void *\fPdata\fP, size_t \fPbytes\fP); + int (*\fIfinalise_const\fP)(struct libhashsum_hasher *\fPthis\fP, const void *\fPdata\fP, size_t \fPbytes\fP, unsigned \fPextra_bits\fP); + int (*\fIfinalise\fP)(struct libhashsum_hasher *\fPthis\fP, void *\fPdata\fP, size_t \fPbytes\fP, unsigned \fPextra_bits\fP, size_t \fPsize\fP); + void (*\fIstretch\fP)(struct libhashsum_hasher *\fPthis\fP, int \fPskip\fP, void *\fPbuffer\fP); + void (*\fIdestroy\fP)(struct libhashsum_hasher *\fPthis\fP); + union libhashsum_state { /* definition omitted */ } \fIstate\fP; +}; + +int \fBlibhashsum_init_blake2s_hasher\fP(struct libhashsum_hasher *\fIhasher\fP, size_t \fIhashbits\fP, const void *\fIsalt\fP, + const void *\fIpepper\fP, const void *\fIkey\fP, size_t \fIkeybits\fP); +.fi +.PP +Link with +.I -lhashsum +.IR "-lblake" . + +.SH DESCRIPTION +The +.B libhashsum_init_blake2s_hasher +function initialises +.I *hasher +for hashing using the cryptographic hash function BLAKE2s +(a version of BLAKE2), and stores hash function information +and hashing functions for BLAKE2s in +.IR *hasher . +.PP +.I hashbits +shall be the hash size, in bits, which must be a multiple of +8, and must not be greater than 256. If +.I hashbits +is 0, the maximum value (256) will be used. +.PP +.I salt +shall be +.I NULL +or a buffer of 8 bytes that shall be used as a per-hash salt +.RI ( NULL +is equivalent to all zeroes). +.PP +.I pepper +shall be +.I NULL +or a buffer of 8 bytes that shall be used as a (secret) +per-application salt (pepper, or \(dqpersonalisation\(dq). +.RI ( NULL +is equivalent to all zeroes). +.PP +.I key +shall be +.I NULL +or the key for hashing in keyed mode. +.PP +.I keybits +shall be the number of bits in +.I key +(or 0 if +.I key +is +.IR NULL ), +and must be a multiple of 8, no greater than 256. +.PP +.I hasher->algorithm +will be set to +.IR LIBHASHSUM_BLAKE2S . +.PP +.I hasher->algorithm_string +will be set to +.RB \(dq BLAKE2s \(dq, +or (if +.I salt +or +.I pepper +is neither +.I NULL +nor all zeroes or if +.I keybits +is non-zero or +.I hashbits +is non-zero but not 256) +.RB \(dq BLAKE2s[n= \fIhashbits\fP ,salt= \fIlowercase_hexadecimal(salt,8)\fP ,pepper= \fIlowercase_hexadecimal(pepper,8)\fP ,key= \fIlowercase_hexadecimal(key,keybits/8)\fP ] \(dq +(which will be stored in a buffer in +.IR hasher->state ), +where +.RB \(dq n= \fIhashbits\fP , \(dq +is omitted if +.I hashbits +is 0 or 256, +.RB \(dq salt= \fIlowercase_hexadecimal(salt,8)\fP , \(dq +is omitted if +.I salt +is +.I NULL +or all zeroes, +.RB \(dq pepper= \fIlowercase_hexadecimal(pepper,8)\fP , \(dq +is omitted if +.I pepper +is +.I NULL +or all zeroes, and +.RB \(dq key= \fIlowercase_hexadecimal(key,keybits/8)\fP \(dq +(with immediately proceeding comma +.RB (' , ') +if any) is ommited if +.I keybits +is 0. +.PP +.I hasher->input_block_size +will be set to the block size BLAKE2s uses, in bytes. +.PP +.I hasher->hash_size +will be set to the hash size, in bytes: +.I hashbits/8 +unless +.IR hashbits==0 , +.I LIBHASHSUM_BLAKE2S_HASH_SIZE +otherwise. +.PP +.I hasher->hash_output +will be set to +.IR NULL . +.PP +.I hasher->supports_non_whole_bytes +will be set to 0 +to indicate that the +.I *hasher->finalise +and +.I *hasher->finalise_const +functions will fail unless their +.I extra_bits +parameter is 0. +.PP +.I hasher->process +will be set to a pointer to the function to call +to feed, and process, data into the hash function. +Its parameter +.I this +shall be set to +.IR hasher . +Its parameter +.I data +parameter shall be set to the buffer of data to +process, and its parameter +.I bytes +shall set to the number of bytes to process from +.IR data . +.I *hasher->process +will return the number of bytes processed, which +will be a multiple of +.IR hasher->input_block_size +no greater than +.IR bytes . +.PP +.I hasher->finalise_const +will be set to a pointer to the function to call +once the entire text being hashed has been loaded, +and to get the hash of the text. Its parameter +.I this +shall be set to +.IR hasher . +Its parameter +.I data +shall be set to the beginning of any yet unprocessed +data, and its parameter +.I bytes +shall be set to the number of bytes to process from +.IR data . +Its parameter +.I extra_bits +shall be set to the number of bits to process from +the lower bits of the incomplete byte +.IR data[bytes] . +The +.I *hasher->finalise_const +function will return 0 upon successful completion, +and set +.I hasher->hash_output +to a pointer to a buffer in +.I hasher->state +containing the binary hash of the processed data. +Otherwise, the function will return -1, and set +.I errno +to indicate the error. However, if the user has +already set +.I hasher->hash_output +to a +.RI non- NULL +pointer, the function will output the binary hash +to that pointer instead without redirecting +.I hasher->hash_output +(the application must make sure this buffer is +sufficiently large). The function will failure if: +.RS +.TP +.B EINVAL +.I extra_bits +is not 0. +.RE +.PP +.I hasher->finalise +will be set to the pointer to a function that +is an alternative to +.I *hasher->finalise_const +that can support zero-copy provided that the +buffer input as the argument +.I data +is sufficiently large. The +.I *hasher->finalise +function may rewrite +.I data +and shall is does not safe to use for multiple +hashers (if the same text is hashed using multiple +hashers, +.I *hasher->finalise_const +must be used). The +function's parameter +.I size +shall be set to the size of the buffer +.IR data . +.I *hasher->finalise +is otherwise identical to +.IR *hasher->finalise_const . +.PP +.I hasher->stretch +will be set to +.IR NULL . +.PP +.I hasher->destroy +will be set to +.IR NULL . +.PP +.I hasher->state +will be initialised, it shall be treated as +internal to the library's implementation, and +may change between versions. +.PP +.I hasher +must not be +.IR NULL . + +.SH RETURN VALUE +Upon successful completion, the +.B libhashsum_init_blake2s_hasher +function returns 0. Otherwise, +the function returns -1 and sets +.I errno +to indicate the error. If -1 +is returned, the state of +.I *hasher +is undefined. + +.SH ERRORS +The +.B libhashsum_init_blake2s_hasher +function fails if: +.TP +.B ENOSYS +Support was excluded at compile time. +.TP +.B EINVAL +.I hashbits +is not divisible by 8. +.TP +.B EINVAL +.I hashbits +is greater than 256. +.TP +.B EINVAL +.I keybits +is not divisible by 8. +.TP +.B EINVAL +.I keybits +is greater than 256. + +.SH HISTORY +libhashsum 1.0. + +.SH SEE ALSO +.BR libhashsum (7) |