2 .\" ----------------------------------------------------------------------------
3 .\" "THE BEER-WARE LICENSE" (Revision 42):
4 .\" <phk@FreeBSD.org> wrote this file. As long as you retain this notice you
5 .\" can do whatever you want with this stuff. If we meet some day, and you think
6 .\" this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp
7 .\" ----------------------------------------------------------------------------
9 .\" From: Id: mdX.3,v 1.14 1999/02/11 20:31:49 wollman Exp
30 .Nd calculate the FIPS 160 and 160-1 ``SHA'' message digests
37 .Fn SHA_Init "SHA_CTX *context"
39 .Fn SHA_Update "SHA_CTX *context" "const unsigned char *data" "size_t len"
41 .Fn SHA_Final "unsigned char digest[20]" "SHA_CTX *context"
43 .Fn SHA_End "SHA_CTX *context" "char *buf"
45 .Fn SHA_File "const char *filename" "char *buf"
47 .Fn SHA_FileChunk "const char *filename" "char *buf" "off_t offset" "off_t length"
49 .Fn SHA_Data "const unsigned char *data" "unsigned int len" "char *buf"
51 .Fn SHA1_Init "SHA_CTX *context"
53 .Fn SHA1_Update "SHA_CTX *context" "const unsigned char *data" "size_t len"
55 .Fn SHA1_Final "unsigned char digest[20]" "SHA_CTX *context"
57 .Fn SHA1_End "SHA_CTX *context" "char *buf"
59 .Fn SHA1_File "const char *filename" "char *buf"
61 .Fn SHA1_FileChunk "const char *filename" "char *buf" "off_t offset" "off_t length"
63 .Fn SHA1_Data "const unsigned char *data" "unsigned int len" "char *buf"
69 functions calculate a 160-bit cryptographic checksum (digest)
70 for any number of input bytes.
71 A cryptographic checksum is a one-way
72 hash function; that is, it is computationally impractical to find
73 the input corresponding to a particular output.
77 of the input-data, which does not disclose the actual input.
79 SHA (or SHA-0) is the original Secure Hash Algorithm specified in FIPS 160.
80 It was quickly proven insecure, and has been superseded by SHA-1.
81 SHA-0 is included for compatibility purposes only.
88 functions are the core functions.
93 run over the data with
95 and finally extract the result using
97 which will also erase the
103 which converts the return value to a 41-character
104 (including the terminating '\e0')
105 ASCII string which represents the 160 bits in hexadecimal.
108 calculates the digest of a file, and uses
110 to return the result.
111 If the file cannot be opened, a null pointer is returned.
115 but it only calculates the digest over a byte-range of the file specified,
123 parameter is specified as 0, or more than the length of the remaining part
126 calculates the digest from
130 calculates the digest of a chunk of data in memory, and uses
132 to return the result.
141 argument can be a null pointer, in which case the returned string
144 and subsequently must be explicitly deallocated using
149 argument is non-null it must point to at least 41 characters of buffer space.
153 function called with a null buf argument may fail and return NULL if:
156 Insufficient storage space is available.
163 may return NULL when underlying
178 These functions appeared in
181 The core hash routines were implemented by Eric Young based on the
185 The SHA1 algorithm has been proven to be vulnerable to practical collision
186 attacks and should not be relied upon to produce unique outputs,
187 .Em nor should it be used as part of a new cryptographic signature scheme.