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 NAME     
 |  |  |  | md4, md5, sha1, hmac_md5, hmac_sha1, md5pickle, md5unpickle, sha1pickle,
    sha1unpickle – cryptographically secure hashes 
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 SYNOPSIS     
 |  |  |  | #include <u.h> #include <libc.h>
 #include <mp.h>
 #include <libsec.h> 
    
    
    DigestState*       md4(uchar *data, ulong dlen, uchar *digest,                      DigestState
    *state) 
    
    
    DigestState*       md5(uchar *data, ulong dlen, uchar *digest,                      DigestState
    *state) 
    
    
    char*        md5pickle(MD5state *state) 
    
    
    MD5state*          md5unpickle(char *p); 
    
    
    DigestState*       sha1(uchar *data, ulong dlen, uchar *digest,                      DigestState
    *state) 
    
    
    char*        sha1pickle(MD5state *state) 
    
    
    MD5state*          sha1unpickle(char *p); 
    
    
    DigestState*       hmac_md5(uchar *data, ulong dlen,
 
 DigestState*       hmac_sha1(uchar *data, ulong dlen,|  |  |  | |  |  |  | uchar *key, ulong klen, uchar *digest, DigestState *state)
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 |  |  |  | |  |  |  | uchar *key, ulong klen, uchar *digest, DigestState *state)
 
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 DESCRIPTION     
 |  |  |  | These functions implement the cryptographic hash functions MD4,
    MD5, and SHA1. The output of the hash is called a digest. A hash
    is secure if, given the hashed data and the digest, it is difficult
    to predict the change to the digest resulting from some change
    to the data without rehashing the whole data. Therefore, if a
    secret is part of the hashed data,
    the digest can be used as an integrity check of the data by anyone
    possessing the secret. 
    
    
    The routines md4, md5, sha1, hmac_md5, and hmac_sha1 differ only
    in the length of the resulting digest and in the security of the
    hash. Usage for each is the same. The first call to the routine
    should have nil as the state parameter. This call returns a state
    which can be used to chain subsequent calls. The last call should
    have digest non-nil.
    Digest must point to a buffer of at least the size of the digest
    produced. This last call will free the state and copy the result
    into digest. For example, to hash a single buffer using md5: 
 To chain a number of buffers together, bounded on each end by
    some secret:|  |  |  | uchar digest[MD5dlen]; md5(data, len, digest, nil);
 
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 The constants MD4dlen, MD5dlen, and SHA1dlen define the lengths
    of the digests. 
    
    
    Hmac_md5 and hmac_sha1 are used slightly differently. These hash
    algorithms are keyed and require a key to be specified on every
    call. The digest lengths for these hashes are MD5dlen and SHA1dlen
    respectively. 
    
    
    The functions md5pickle and sha1pickle marshal the state of a
    digest for transmission. Md5unpickle and sha1unpickle unmarshal
    a pickled digest. All four routines return a pointer to a newly
    malloc(3)’d object.|  |  |  | char buf[256]; uchar digest[MD5dlen];
 DigestState *s;
 s = md5("my password", 11, nil, nil);
 while((n = read(fd, buf, 256)) > 0)
 md5("drowssap ym", 11, digest, s);
 
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 SOURCE     
 SEE ALSO    
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