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Improve Password Generation Security #66

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8 changes: 4 additions & 4 deletions misc/generate_password.sql
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Original file line number Diff line number Diff line change
@@ -1,6 +1,5 @@
-- WARNING: random() that is used here is not cryptographically strong –
-- if an attacker knows one value, it's easy to guess the "next" value
-- TODO: rework to use pgcrypto instead
-- This script uses pgcrypto extension to generate cryptographically secure random passwords
-- You need to enable the pgcrypto extension first with: CREATE EXTENSION IF NOT EXISTS pgcrypto;

with init(len, arr) as (
-- edit password length and possible characters here
Expand All @@ -9,7 +8,8 @@ with init(len, arr) as (
select count(*)
from (select unnest(arr) from init) _
), indexes(i) as (
select 1 + int4(random() * (l - 1))
-- Using gen_random_bytes from pgcrypto for cryptographically secure randomness
select 1 + (get_byte(gen_random_bytes(1), 0)::int % (l - 1))
from arrlen, (select generate_series(1, len) from init) _
), res as (
select array_to_string(array_agg(arr[i]), '') as password
Expand Down
9 changes: 6 additions & 3 deletions roles/alter_user_with_random_password.psql
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Original file line number Diff line number Diff line change
Expand Up @@ -4,9 +4,11 @@
-- This interactive script solves this problem.

-- Usage (run in psql):
-- 1) Set messages level to DEBUG (and keep logging level higher, to avoid having password in logs):
-- 1) Make sure the pgcrypto extension is installed:
-- CREATE EXTENSION IF NOT EXISTS pgcrypto;
-- 2) Set messages level to DEBUG (and keep logging level higher, to avoid having password in logs):
-- set client_min_messages to DEBUG;
-- 2) Run interactive script in psql:
-- 3) Run interactive script in psql:
-- \i /path/to/PostgresDBA/roles/alter_user_with_random_password.psql

\prompt "Username?" postgres_dba_username
Expand Down Expand Up @@ -40,7 +42,8 @@ begin
allowed_len := length(allowed);
pwd := '';
while length(pwd) < 16 loop
j := int4(random() * allowed_len);
-- Using gen_random_bytes from pgcrypto for cryptographically secure randomness
j := get_byte(gen_random_bytes(1), 0) % allowed_len;
pwd := pwd || substr(allowed, j+1, 1);
end loop;
sql := 'alter role ' || current_setting('postgres_dba.username')::text || ' password ''' || pwd || ''';';
Expand Down
9 changes: 6 additions & 3 deletions roles/create_user_with_random_password.psql
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Original file line number Diff line number Diff line change
Expand Up @@ -4,9 +4,11 @@
-- This interactive script solves this problem.

-- Usage (run in psql):
-- 1) Set messages level to DEBUG (and keep logging level higher, to avoid having password in logs):
-- 1) Make sure the pgcrypto extension is installed:
-- CREATE EXTENSION IF NOT EXISTS pgcrypto;
-- 2) Set messages level to DEBUG (and keep logging level higher, to avoid having password in logs):
-- set client_min_messages to DEBUG;
-- 2) Run interactive script in psql:
-- 3) Run interactive script in psql:
-- \i /path/to/PostgresDBA/roles/create_user_with_random_password.psql

\prompt "Username?" postgres_dba_username
Expand Down Expand Up @@ -40,7 +42,8 @@ begin
allowed_len := length(allowed);
pwd := '';
while length(pwd) < 16 loop
j := int4(random() * allowed_len);
-- Using gen_random_bytes from pgcrypto for cryptographically secure randomness
j := get_byte(gen_random_bytes(1), 0) % allowed_len;
pwd := pwd || substr(allowed, j+1, 1);
end loop;
sql := 'create role ' || current_setting('postgres_dba.username')::text
Expand Down