CREATE OR REPLACE FUNCTION cipher_exists(text) RETURNS boolean
    AS '$libdir/pgcrypto', 'pg_cipher_exists'
    LANGUAGE c;

CREATE OR REPLACE FUNCTION crypt(text, text) RETURNS text
    AS '$libdir/pgcrypto', 'pg_crypt'
    LANGUAGE c;

CREATE OR REPLACE FUNCTION decrypt(bytea, bytea, text) RETURNS bytea
    AS '$libdir/pgcrypto', 'pg_decrypt'
    LANGUAGE c;

CREATE OR REPLACE FUNCTION decrypt_iv(bytea, bytea, bytea, text) RETURNS bytea
    AS '$libdir/pgcrypto', 'pg_decrypt_iv'
    LANGUAGE c;

CREATE OR REPLACE FUNCTION digest(text, text) RETURNS bytea
    AS '$libdir/pgcrypto', 'pg_digest'
    LANGUAGE c;

CREATE OR REPLACE FUNCTION digest(bytea, text) RETURNS bytea
    AS '$libdir/pgcrypto', 'pg_digest'
    LANGUAGE c;

CREATE OR REPLACE FUNCTION digest_exists(text) RETURNS boolean
    AS '$libdir/pgcrypto', 'pg_digest_exists'
    LANGUAGE c;

CREATE OR REPLACE FUNCTION encrypt(bytea, bytea, text) RETURNS bytea
    AS '$libdir/pgcrypto', 'pg_encrypt'
    LANGUAGE c;

CREATE OR REPLACE FUNCTION encrypt_iv(bytea, bytea, bytea, text) RETURNS bytea
    AS '$libdir/pgcrypto', 'pg_encrypt_iv'
    LANGUAGE c;

CREATE OR REPLACE FUNCTION gen_salt(text) RETURNS text
    AS '$libdir/pgcrypto', 'pg_gen_salt'
    LANGUAGE c;

CREATE OR REPLACE FUNCTION gen_salt(text, integer) RETURNS text
    AS '$libdir/pgcrypto', 'pg_gen_salt_rounds'
    LANGUAGE c;

CREATE OR REPLACE FUNCTION hmac(text, text, text) RETURNS bytea
    AS '$libdir/pgcrypto', 'pg_hmac'
    LANGUAGE c;

CREATE OR REPLACE FUNCTION hmac(bytea, bytea, text) RETURNS bytea
    AS '$libdir/pgcrypto', 'pg_hmac'
    LANGUAGE c;

CREATE OR REPLACE FUNCTION hmac_exists(text) RETURNS boolean
    AS '$libdir/pgcrypto', 'pg_hmac_exists'
    LANGUAGE c;

CREATE OR REPLACE FUNCTION md5(bytea) RETURNS character(32)
    AS $_$
BEGIN
RETURN ENCODE(DIGEST($1, 'md5'), 'hex');
END;
$_$LANGUAGE plpgsql;

CREATE OR REPLACE FUNCTION sha1(bytea) RETURNS character(40)
    AS $_$
BEGIN
RETURN ENCODE(DIGEST($1, 'sha1'), 'hex');
END;
$_$LANGUAGE plpgsql;

CREATE OR REPLACE FUNCTION sha1_md5(bytea) RETURNS character(40)
    AS $_$
BEGIN
RETURN ENCODE(DIGEST(ENCODE(DIGEST($1, 'md5'), 'hex'), 'sha1'), 'hex');
END;
$_$LANGUAGE plpgsql;

CREATE OR REPLACE FUNCTION md5(text) RETURNS character(32)
    AS $_$
BEGIN
RETURN ENCODE(DIGEST($1, 'md5'), 'hex');
END;
$_$LANGUAGE plpgsql;

CREATE OR REPLACE FUNCTION sha1(text) RETURNS character(40)
    AS $_$
BEGIN
RETURN ENCODE(DIGEST($1, 'sha1'), 'hex');
END;
$_$LANGUAGE plpgsql;

CREATE OR REPLACE FUNCTION sha1_md5(text) RETURNS character(40)
    AS $_$
BEGIN
RETURN ENCODE(DIGEST(ENCODE(DIGEST($1, 'md5'), 'hex'), 'sha1'), 'hex');
END;
$_$LANGUAGE plpgsql;


CREATE OR REPLACE FUNCTION uuid() RETURNS character(36)
AS $_$
SELECT SUBSTRING(x.my_rand FROM 1 FOR 8)||'-'||SUBSTRING(x.my_rand FROM 9 FOR 4)||'-4'||SUBSTRING(x.my_rand FROM 13 FOR 3)||'-'||x.clock_1||SUBSTRING(x.my_rand FROM 16 FOR 3)||'-'||SUBSTRING(x.my_rand FROM 19 FOR 12)
FROM  
(SELECT sha1(''||now()||random()) as my_rand, to_hex(8+(3*random())::int) as clock_1) as x;$_$
LANGUAGE SQL;