feat(core): Add BLF-CRYPT scheme.

Dovecot promotes the use of BLF-CRYPT as a hashing scheme [1].
However, as not all libc-crypt() implementations support this scheme,
use the implementation added in a previous commit.

Also, update the references to the dovecot implementation and a small
test case for testing the blowfish implementation.

[1] https://doc.dovecot.org/configuration_manual/authentication/password_schemes/

Fixes #4958

Documentation/SOGoInstallationGuide.asciidoc

@@ -1069,7 +1069,7 @@ Possible values are: `none`, `plain`, `crypt`, `md5`, `md5-crypt`,
 (plus setting of the encoding with `.b64` or `.hex`).
 
 For a more detailed description see
-http://wiki.dovecot.org/Authentication/PasswordSchemes.
+https://doc.dovecot.org/configuration_manual/authentication/password_schemes/.
 
 Note that `cram-md5` is not actually using cram-md5 (due to the lack of
 challenge-response mechanism), its just saving the intermediate MD5
@@ -1659,13 +1659,13 @@ they have the same name as popular LDAP attributes (such as `givenName`,
 |The default algorithm used for password encryption when changing
 passwords. Possible values are: `none`, `plain`, `crypt`, `md5`,
 `md5-crypt`, `smd5`, `cram-md5`, `ldap-md5`, and `sha`, `sha256`,
-`sha256-crypt`, `sha512`, `sha512-crypt` and its ssha (e.g. `ssha` or
-`ssha256`) variants and `sym-aes-128-cbc`. Passwords can have the
-scheme prepended in the form `{scheme}encryptedPass`.
+`sha256-crypt`, `sha512`, `sha512-crypt`, its ssha (e.g. `ssha` or
+`ssha256`) variants, `blf-crypt`, and `sym-aes-128-cbc`. Passwords
+can have the scheme prepended in the form `{scheme}encryptedPass`.
 
 If no scheme is given, _userPasswordAlgorithm_ is used instead. The
 schemes listed above follow the algorithms described in
-http://wiki.dovecot.org/Authentication/PasswordSchemes.
+https://doc.dovecot.org/configuration_manual/authentication/password_schemes/.
 
 Note that `cram-md5` is not actually using cram-md5 (due to the lack of
 challenge-response mechanism), its just saving the intermediate MD5

SoObjects/SOGo/NSData+Crypto.h

@@ -53,6 +53,7 @@
 
 - (NSData *) asCryptUsingSalt: (NSData *) theSalt;
 - (NSData *) asMD5CryptUsingSalt: (NSData *) theSalt;
+- (NSData *) asBlowfishCryptUsingSalt: (NSData *) theSalt;
 
 - (NSData *) extractSalt: (NSString *) theScheme;
 

SoObjects/SOGo/NSData+Crypto.m

@@ -1,6 +1,6 @@
 /* NSData+Crypto.m - this file is part of SOGo
  *
- * Copyright (C) 2012 Nicolas Höft
+ * Copyright (C) 2012, 2020 Nicolas Höft
  * Copyright (C) 2012-2020 Inverse inc.
  * Copyright (C) 2012 Jeroen Dekkers
  *
@@ -50,6 +50,7 @@
 #endif
 
 #include "aes.h"
+#include "crypt_blowfish.h"
 #include "lmhash.h"
 
 #import <Foundation/NSArray.h>
@@ -62,6 +63,12 @@
 static void _nettle_md5_compress(uint32_t *digest, const uint8_t *input);
 #endif
 
+#define BLF_CRYPT_DEFAULT_COMPLEXITY (5)
+#define BLF_CRYPT_SALT_LEN (16)
+#define BLF_CRYPT_BUFFER_LEN (128)
+#define BLF_CRYPT_PREFIX_LEN (7+22+1) /* $2.$nn$ + salt */
+#define BLF_CRYPT_PREFIX "$2y"
+
 
 @implementation NSData (SOGoCryptoExtension)
 
@@ -245,6 +252,10 @@ - (NSData *) asCryptedPassUsingScheme: (NSString *) passwordScheme
     {
       return [self asSHA512CryptUsingSalt: theSalt];
     }
+  else if ([passwordScheme caseInsensitiveCompare: @"blf-crypt"] == NSOrderedSame)
+    {
+      return [self asBlowfishCryptUsingSalt: theSalt];
+    }
   else if ([[passwordScheme lowercaseString] hasPrefix: @"sym"])
     {
       // We first support one sym cipher, AES-128-CBC. If something else is provided
@@ -764,6 +775,52 @@ - (NSData *) asCryptUsingSalt: (NSData *) theSalt
   return [NSData dataWithBytes: buf length: strlen(buf)];
 }
 
+/**
+ * Hash the data using blowfish-crypt
+ * @param theSalt The salt to be used must not be nil, if empty, one will be generated
+ */
+- (NSData *) asBlowfishCryptUsingSalt: (NSData *) theSalt
+{
+  NSString *cleartext;
+  char hashed_password[BLF_CRYPT_BUFFER_LEN];
+  char magic_salt[BLF_CRYPT_PREFIX_LEN]; // contains $2.$nn$ + salt
+
+  if ([theSalt length] == 0)
+    {
+      // generate a salt with default complexity if none was provided
+      NSData* salt = [NSData generateSaltForLength: BLF_CRYPT_SALT_LEN];
+      if (_crypt_gensalt_blowfish_rn(BLF_CRYPT_PREFIX, BLF_CRYPT_DEFAULT_COMPLEXITY,
+        [salt bytes], BLF_CRYPT_SALT_LEN,
+        magic_salt, BLF_CRYPT_PREFIX_LEN) == NULL)
+          return nil;
+    }
+  else
+    {
+      const char* salt = [theSalt bytes];
+      if ([theSalt length] < BLF_CRYPT_PREFIX_LEN ||
+          salt[0] != '$' || salt[1] != '2' ||
+          salt[2] < 'a' || salt[2] > 'z' ||
+          salt[3] != '$')
+        {
+          return nil;
+        }
+      memcpy(magic_salt, salt, BLF_CRYPT_PREFIX_LEN);
+    }
+
+  cleartext = [[NSString alloc] initWithData: self encoding: NSUTF8StringEncoding];
+  const char* password = [cleartext UTF8String];
+
+  char* bf_res = _crypt_blowfish_rn(password, magic_salt,
+    hashed_password, BLF_CRYPT_BUFFER_LEN);
+  [cleartext autorelease];
+
+  if (bf_res == NULL)
+    return nil;
+
+  return [NSData dataWithBytes: hashed_password length: strlen(hashed_password)];
+}
+
+
 /**
  * Get the salt from a password encrypted with a specied scheme
  *

Tests/Unit/TestNSString+Crypto.m

@@ -60,4 +60,29 @@ - (void) test_dataCrypto
     }
 }
 
+- (void) test_blowfish
+{
+  NSString *error;
+  // well-known comparison
+  NSString *blf_key = @"123456";
+  NSString *blf_hash = @"{BLF-CRYPT}$2a$05$tLVuFQTgdwrZmixu.QMxoedUAUEeIFIBv89Ur5mQ6F1vBL8Vw1mXO";
+  error = [NSString stringWithFormat:
+                          @"string '%@' wrong BLF-CRYPT: '%@'",
+                        blf_key, blf_hash];
+  testWithMessage([blf_key isEqualToCrypted:blf_hash withDefaultScheme: @"CRYPT" keyPath: nil], error);
+
+  // generate a new blowfish-crypt key
+  NSString *blf_prefix = @"$2y$05$";
+
+  NSString *blf_result = [blf_key asCryptedPassUsingScheme: @"blf-crypt" keyPath: nil];
+
+  error = [NSString stringWithFormat:
+                          @"returned hash '%@' has incorrect BLF-CRYPT prefix: '%@'",
+                        blf_result, blf_prefix];
+
+  testWithMessage([blf_result hasPrefix: blf_prefix], error);
+
+  test([blf_key isEqualToCrypted:blf_result withDefaultScheme: @"BLF-CRYPT" keyPath: nil]);
+}
+
 @end