Add sharing of groups between databases

* Add source folder keeshare for sharing with corresponding define WITH_XC_KEESHARE
* Move common crypto parts to src/crypto/ssh
* Extended OpenSSHKey
* Move filewatching to own file (currently in two related classes DelayedFileWatcher and BulkFileWatcher)
* Small improvements for style and code in several classes
* Sharing is secured using RSA-Keys which are generated on demand
* Publisher signs the container using their private key
* Client can verify the signed container and choose to decline an import,
import only once or trust the publisher and automatically import all
data of this source henceforth
* Integration of settings into Group-Settings, Database-Settings and Application-Settings
* Introduced dependency QuaZip as dependency to allow combined export of
key container and the (custom format) certificate

src/crypto/ssh/bcrypt_pbkdf.cpp

@@ -0,0 +1,172 @@
+/* $OpenBSD: bcrypt_pbkdf.c,v 1.13 2015/01/12 03:20:04 tedu Exp $ */
+/*
+ * Copyright (c) 2013 Ted Unangst <tedu@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <QtCore>
+
+extern "C" {
+#include "blf.h"
+}
+
+#define	MINIMUM(a,b) (((a) < (b)) ? (a) : (b))
+
+/*
+ * pkcs #5 pbkdf2 implementation using the "bcrypt" hash
+ *
+ * The bcrypt hash function is derived from the bcrypt password hashing
+ * function with the following modifications:
+ * 1. The input password and salt are preprocessed with SHA512.
+ * 2. The output length is expanded to 256 bits.
+ * 3. Subsequently the magic string to be encrypted is lengthened and modifed
+ *    to "OxychromaticBlowfishSwatDynamite"
+ * 4. The hash function is defined to perform 64 rounds of initial state
+ *    expansion. (More rounds are performed by iterating the hash.)
+ *
+ * Note that this implementation pulls the SHA512 operations into the caller
+ * as a performance optimization.
+ *
+ * One modification from official pbkdf2. Instead of outputting key material
+ * linearly, we mix it. pbkdf2 has a known weakness where if one uses it to
+ * generate (e.g.) 512 bits of key material for use as two 256 bit keys, an
+ * attacker can merely run once through the outer loop, but the user
+ * always runs it twice. Shuffling output bytes requires computing the
+ * entirety of the key material to assemble any subkey. This is something a
+ * wise caller could do; we just do it for you.
+ */
+
+#define BCRYPT_WORDS 8
+#define BCRYPT_HASHSIZE (BCRYPT_WORDS * 4)
+#define SHA512_DIGEST_LENGTH 64
+
+// FIXME: explicit_bzero exists to ensure bzero is not optimized out
+#define explicit_bzero bzero
+
+static void
+bcrypt_hash(const quint8* sha2pass, const quint8* sha2salt, quint8* out)
+{
+    blf_ctx state;
+    quint8 ciphertext[BCRYPT_HASHSIZE] = // "OxychromaticBlowfishSwatDynamite"
+        { 0x4f, 0x78, 0x79, 0x63, 0x68, 0x72, 0x6f, 0x6d,
+          0x61, 0x74, 0x69, 0x63, 0x42, 0x6c, 0x6f, 0x77,
+          0x66, 0x69, 0x73, 0x68, 0x53, 0x77, 0x61, 0x74,
+          0x44, 0x79, 0x6e, 0x61, 0x6d, 0x69, 0x74, 0x65 };
+    quint32 cdata[BCRYPT_WORDS];
+    int i;
+    quint16 j;
+    size_t shalen = SHA512_DIGEST_LENGTH;
+
+    /* key expansion */
+    Blowfish_initstate(&state);
+    Blowfish_expandstate(&state, sha2salt, shalen, sha2pass, shalen);
+    for (i = 0; i < 64; i++) {
+        Blowfish_expand0state(&state, sha2salt, shalen);
+        Blowfish_expand0state(&state, sha2pass, shalen);
+    }
+
+    /* encryption */
+    j = 0;
+    for (i = 0; i < BCRYPT_WORDS; i++)
+        cdata[i] = Blowfish_stream2word(ciphertext, sizeof(ciphertext),
+            &j);
+    for (i = 0; i < 64; i++)
+        blf_enc(&state, cdata, sizeof(cdata) / sizeof(uint64_t));
+
+    /* copy out */
+    for (i = 0; i < BCRYPT_WORDS; i++) {
+        out[4 * i + 3] = (cdata[i] >> 24) & 0xff;
+        out[4 * i + 2] = (cdata[i] >> 16) & 0xff;
+        out[4 * i + 1] = (cdata[i] >> 8) & 0xff;
+        out[4 * i + 0] = cdata[i] & 0xff;
+    }
+
+    /* zap */
+    explicit_bzero(ciphertext, sizeof(ciphertext));
+    explicit_bzero(cdata, sizeof(cdata));
+    explicit_bzero(&state, sizeof(state));
+}
+
+int bcrypt_pbkdf(const QByteArray& pass, const QByteArray& salt, QByteArray& key, quint32 rounds)
+{
+    QCryptographicHash ctx(QCryptographicHash::Sha512);
+    QByteArray sha2pass;
+    QByteArray sha2salt;
+    quint8 out[BCRYPT_HASHSIZE];
+    quint8 tmpout[BCRYPT_HASHSIZE];
+    quint8 countsalt[4];
+
+    /* nothing crazy */
+    if (rounds < 1) {
+        return -1;
+    }
+
+    if (pass.isEmpty() || salt.isEmpty() || key.isEmpty() ||
+        static_cast<quint32>(key.length()) > sizeof(out) * sizeof(out)) {
+        return -1;
+    }
+
+    quint32 stride = (key.length() + sizeof(out) - 1) / sizeof(out);
+    quint32 amt = (key.length() + stride - 1) / stride;
+
+    /* collapse password */
+    ctx.reset();
+    ctx.addData(pass);
+    sha2pass = ctx.result();
+
+    /* generate key, sizeof(out) at a time */
+    for (quint32 count = 1, keylen = key.length(); keylen > 0; count++) {
+        countsalt[0] = (count >> 24) & 0xff;
+        countsalt[1] = (count >> 16) & 0xff;
+        countsalt[2] = (count >> 8) & 0xff;
+        countsalt[3] = count & 0xff;
+
+        /* first round, salt is salt */
+        ctx.reset();
+        ctx.addData(salt);
+        ctx.addData(reinterpret_cast<char *>(countsalt), sizeof(countsalt));
+        sha2salt = ctx.result();
+
+        bcrypt_hash(reinterpret_cast<quint8 *>(sha2pass.data()), reinterpret_cast<quint8 *>(sha2salt.data()), tmpout);
+        memcpy(out, tmpout, sizeof(out));
+
+        for (quint32 i = 1; i < rounds; i++) {
+            /* subsequent rounds, salt is previous output */
+            ctx.reset();
+            ctx.addData(reinterpret_cast<char *>(tmpout), sizeof(tmpout));
+            sha2salt = ctx.result();
+            bcrypt_hash(reinterpret_cast<quint8 *>(sha2pass.data()), reinterpret_cast<quint8 *>(sha2salt.data()), tmpout);
+            for (quint32 j = 0; j < sizeof(out); j++)
+                out[j] ^= tmpout[j];
+        }
+
+        /*
+         * pbkdf2 deviation: output the key material non-linearly.
+         */
+        amt = MINIMUM(amt, keylen);
+        quint32 i;
+        for (i = 0; i < amt; i++) {
+            int dest = i * stride + (count - 1);
+            if (dest >= key.length())
+                break;
+            key.data()[dest] = out[i];
+        }
+        keylen -= i;
+    }
+
+    /* zap */
+    explicit_bzero(out, sizeof(out));
+
+    return 0;
+}