NAME
    sha - old Secure Hash Algorithm (SHS FIPS Pub 180)

SYNOPSIS
    sha([arg1 [, val ...]])

TYPES
    arg1	any
    val		any

    return	HASH or number

DESCRIPTION
    The sha() builtin implements the old Secure Hash Algorithm
    (SHA).  The SHA is sometimes referenced as SHS.  The SHA
    is a 160 bit hash.

    With no args, sha() returns the default initial SHA-1 HASH state.

    If arg1 is a HASH state and no other val args are given, then the
    HASH state is finalized and the numeric value of the hash is given.

    If arg1 is a HASH state and one or more val args are given,
    then the val args are used to modify the arg1 HASH state.
    The new arg1 HASH state is returned.

    If arg1 is not a a HASH state, then the initial HASH is
    used and modifed by arg1 and any val args supplied.  The
    return value is the new HASH state.

    The following table gives a summary of actions and return values.
    Here, assume that 'h' is a HASH state:

	sha()			HASH	returns initial HASH state

	sha(h)			number	h is put into final form and the
					numeric value of the hash state

	sha(x)			HASH	modify the initial state by hashing 'x'

	sha(sha(), x)		HASH	the same as sha(x)

	sha(x, y)		HASH	the same as sha(sha(x), y)

	sha(h, x, y)		HASH	modify state 'h' by 'x' and then 'y'

	sha(sha(h,x,y))		number	numeric value of the above call

EXAMPLE
    > base(16)
	    0xa

    > sha()
	    sha hash state
    > sha(sha())
	    0xf96cea198ad1dd5617ac084a3d92c6107708c0ef

    > sha("x", "y", "z") == sha("xyz")
	    1
    > sha("x", "y", "z") == sha("xy")
	    0

    > sha(sha("this is", 7^19-8, "a composit", 3i+4.5, "hash"))
	    0x21e42319a26787046c2b28b7ae70f1b54bf0ba2a

    > x = sha(list(1,2,3), "curds and whey", 2^21701-1, pi())
    > x
	    sha hash state
    > sha(x)
	    0xc9e155522ea4a38d85340e6f1c2e36636950ea7e

    > y = sha()
    > y = sha(y, list(1,2,3), "curds and whey")
    > y = sha(y, 2^21701-1)
    > y = sha(y, pi())
    > y
	    sha hash state
    > sha(y)
	    0xc9e155522ea4a38d85340e6f1c2e36636950ea7e

LIMITS
    none

LIBRARY
    HASH* hash_init(int, HASH*);
    void hash_free(HASH*);
    HASH* hash_copy(HASH*);
    int hash_cmp(HASH*, HASH*);
    void hash_print(HASH*);
    ZVALUE hash_final(HASH*);
    HASH* hash_long(int, long, HASH*);
    HASH* hash_zvalue(int, ZVALUE, HASH*);
    HASH* hash_number(int, void*, HASH*);
    HASH* hash_complex(int, void*, HASH*);
    HASH* hash_str(int, char*, HASH*);
    HASH* hash_usb8(int, USB8*, int, HASH*);
    HASH* hash_value(int, void*, HASH*);

SEE ALSO
    ishash, sha1