Make SCRAM salts and nonces longer.

The salt is stored base64-encoded. With the old 10 bytes raw length, it was
always padded to 16 bytes after encoding. We might as well use 12 raw bytes
for the salt, and it's still encoded into 16 bytes.

Similarly for the random nonces, use a raw length that's divisible by 3, so
that there's no padding after base64 encoding. Make the nonces longer while
we're at it. 10 bytes was probably enough to prevent replay attacks, but
there's no reason to be skimpy here.

Per suggestion from Álvaro Hernández Tortosa.

Discussion: https://www.postgresql.org/message-id/df8c6e27-4d8e-5281-96e5-131a4e638fc8@8kdata.com

diff --git a/src/include/common/scram-common.h b/src/include/common/scram-common.h
index 307f92b54a4578502d3c5a1620784f3df4b077cb..b5d107494c53ea945ed6521325e5b30b35292d9b 100644 (file)
--- a/src/include/common/scram-common.h
+++ b/src/include/common/scram-common.h
@@ -26,10 +26,10 @@
  * is in "raw" number of bytes, the actual nonces sent over the wire are
  * encoded using only ASCII-printable characters.
  */
-#define SCRAM_RAW_NONCE_LEN                    10
+#define SCRAM_RAW_NONCE_LEN                    18
 
 /* length of salt when generating new verifiers */
-#define SCRAM_DEFAULT_SALT_LEN         10
+#define SCRAM_DEFAULT_SALT_LEN         12
 
 /* default number of iterations when generating verifier */
 #define SCRAM_DEFAULT_ITERATIONS       4096

diff --git a/src/test/regress/expected/password.out b/src/test/regress/expected/password.out
index 9ec5a52bba4e04a3cb576f762e6b90b311c01f5d..5b0b955b29bbaeeee168fbcffdd9ff6f998255f2 100644 (file)
--- a/src/test/regress/expected/password.out
+++ b/src/test/regress/expected/password.out
@@ -27,7 +27,7 @@ CREATE ROLE regress_passwd5 PASSWORD NULL;
 --
 -- Since the salt is random, the exact value stored will be different on every test
 -- run. Use a regular expression to mask the changing parts.
-SELECT rolname, regexp_replace(rolpassword, '(SCRAM-SHA-256)\$(\d+):([a-zA-Z0-9+/]+==)\$([a-zA-Z0-9+/]+=):([a-zA-Z0-9+/]+=)', '\1$\2:<salt>$<storedkey>:<serverkey>') as rolpassword_masked
+SELECT rolname, regexp_replace(rolpassword, '(SCRAM-SHA-256)\$(\d+):([a-zA-Z0-9+/=]+)\$([a-zA-Z0-9+=/]+):([a-zA-Z0-9+/=]+)', '\1$\2:<salt>$<storedkey>:<serverkey>') as rolpassword_masked
     FROM pg_authid
     WHERE rolname LIKE 'regress_passwd%'
     ORDER BY rolname, rolpassword;
@@ -63,7 +63,7 @@ ALTER ROLE regress_passwd4 ENCRYPTED PASSWORD 'SCRAM-SHA-256$4096:VLK4RMaQLCvNtQ
 SET password_encryption = 'scram-sha-256';
 ALTER ROLE  regress_passwd5 ENCRYPTED PASSWORD 'foo'; -- create SCRAM verifier
 CREATE ROLE regress_passwd6 ENCRYPTED PASSWORD 'md53725413363ab045e20521bf36b8d8d7f'; -- encrypted with MD5, use as it is
-SELECT rolname, regexp_replace(rolpassword, '(SCRAM-SHA-256)\$(\d+):([a-zA-Z0-9+/]+==)\$([a-zA-Z0-9+/]+=):([a-zA-Z0-9+/]+=)', '\1$\2:<salt>$<storedkey>:<serverkey>') as rolpassword_masked
+SELECT rolname, regexp_replace(rolpassword, '(SCRAM-SHA-256)\$(\d+):([a-zA-Z0-9+/=]+)\$([a-zA-Z0-9+=/]+):([a-zA-Z0-9+/=]+)', '\1$\2:<salt>$<storedkey>:<serverkey>') as rolpassword_masked
     FROM pg_authid
     WHERE rolname LIKE 'regress_passwd%'
     ORDER BY rolname, rolpassword;

diff --git a/src/test/regress/sql/password.sql b/src/test/regress/sql/password.sql
index 1e022dbf2d6d217568fba521b42a2ca6f4c6ed9e..d2e9eea79d2a207094f8f01f8a6bb82b4d5ff101 100644 (file)
--- a/src/test/regress/sql/password.sql
+++ b/src/test/regress/sql/password.sql
@@ -28,7 +28,7 @@ CREATE ROLE regress_passwd5 PASSWORD NULL;
 --
 -- Since the salt is random, the exact value stored will be different on every test
 -- run. Use a regular expression to mask the changing parts.
-SELECT rolname, regexp_replace(rolpassword, '(SCRAM-SHA-256)\$(\d+):([a-zA-Z0-9+/]+==)\$([a-zA-Z0-9+/]+=):([a-zA-Z0-9+/]+=)', '\1$\2:<salt>$<storedkey>:<serverkey>') as rolpassword_masked
+SELECT rolname, regexp_replace(rolpassword, '(SCRAM-SHA-256)\$(\d+):([a-zA-Z0-9+/=]+)\$([a-zA-Z0-9+=/]+):([a-zA-Z0-9+/=]+)', '\1$\2:<salt>$<storedkey>:<serverkey>') as rolpassword_masked
     FROM pg_authid
     WHERE rolname LIKE 'regress_passwd%'
     ORDER BY rolname, rolpassword;
@@ -54,7 +54,7 @@ SET password_encryption = 'scram-sha-256';
 ALTER ROLE  regress_passwd5 ENCRYPTED PASSWORD 'foo'; -- create SCRAM verifier
 CREATE ROLE regress_passwd6 ENCRYPTED PASSWORD 'md53725413363ab045e20521bf36b8d8d7f'; -- encrypted with MD5, use as it is
 
-SELECT rolname, regexp_replace(rolpassword, '(SCRAM-SHA-256)\$(\d+):([a-zA-Z0-9+/]+==)\$([a-zA-Z0-9+/]+=):([a-zA-Z0-9+/]+=)', '\1$\2:<salt>$<storedkey>:<serverkey>') as rolpassword_masked
+SELECT rolname, regexp_replace(rolpassword, '(SCRAM-SHA-256)\$(\d+):([a-zA-Z0-9+/=]+)\$([a-zA-Z0-9+=/]+):([a-zA-Z0-9+/=]+)', '\1$\2:<salt>$<storedkey>:<serverkey>') as rolpassword_masked
     FROM pg_authid
     WHERE rolname LIKE 'regress_passwd%'
     ORDER BY rolname, rolpassword;