SHA_Init SHA_Update SHA_Final SHA_End SHA_File SHA_FileChunk SHA_Data SHA1_Init SHA1_Update SHA1_Final SHA1_End SHA1_File SHA1_FileChunk SHA1_Data - calculate the FIPS 160 and 160-1 ``SHA'' message digests
SHA (or SHA-0 is the original Secure Hash Algorithm specified in FIPS 160. It was quickly proven insecure, and has been superseded by SHA-1 SHA-0 is included for compatibility purposes only.
and SHA1_Final ();
functions are the core functions. Allocate an Vt SHA_CTX , initialize it with SHA1_Init (,);
run over the data with SHA1_Update (,);
and finally extract the result using SHA1_Final (.);
is a wrapper for SHA1_Final ();
which converts the return value to a 41-character (including the terminating '\0') ASCII string which represents the 160 bits in hexadecimal.
calculates the digest of a file, and uses SHA1_End ();
to return the result. If the file cannot be opened, a null pointer is returned. SHA1_FileChunk ();
is similar to SHA1_File (,);
but it only calculates the digest over a byte-range of the file specified, starting at Fa offset and spanning Fa length bytes. If the Fa length parameter is specified as 0, or more than the length of the remaining part of the file, SHA1_FileChunk ();
calculates the digest from Fa offset to the end of file. SHA1_Data ();
calculates the digest of a chunk of data in memory, and uses SHA1_End ();
to return the result.
or SHA1_Data (,);
the Fa buf argument can be a null pointer, in which case the returned string is allocated with malloc(3) and subsequently must be explicitly deallocated using free(3) after use. If the Fa buf argument is non-null it must point to at least 41 characters of buffer space.
The IA32 (Intel) implementation of SHA-1 makes heavy use of the `bswapl' instruction, which is not present on the original 80386. Attempts to use SHA-1 on those processors will cause an illegal instruction trap. (Arguably, the kernel should simply emulate this instruction.)
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Created 1996-2021 by Maxim Chirkov
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