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generator: allow own PRNG seed source

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This commit is contained in:
Mirek Kratochvil 2017-06-26 14:28:54 +02:00
parent d53586d582
commit dc3a874cd5
7 changed files with 54 additions and 22 deletions
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2
autogen.sh
View file

@ -1,4 +1,4 @@
#!/bin/sh
#!/bin/bash
# simple autogen script that generates basic layout for autotools.

20
man/ccr.1
View file

@ -237,9 +237,14 @@ private keyring.
Backups of user data (i.e. for each file the last state that was loaded
successfully) are, on each change, written to files "pubkeys~" and "secrets~".
When Codecrypt is running, it locks the .ccr directory using a lockfile "lock"
When Codecrypt is running, it locks the ".ccr" directory using a lockfile "lock"
and applying flock(2) to it.
For seeding the random number generator, Codecrypt uses data from "/dev/random"
for generating keys and "/dev/urandom" for everything else, e.g. nonces or
envelopes. Both cases can be overriden at once by specifying some other
filename in environment variable CCR_RANDOM_SEED.
.SH RETURN VALUE
\fBccr\fR returns exit status 0 if there was no error and all cryptography went
@ -353,6 +358,17 @@ import of keys can bring serious inconsistencies into your key naming scheme.
In a distant universe after much computation, KeyIDs can collide. If you find
someone who has a colliding KeyID, kiss him and generate another key.
.SS Own sources of random seed
Using CCR_RANDOM_SEED is slightly counterintuitive and dangerous, use it only
for debugging.
If your system does not have /dev/(u)random, make a port by choosing a safe
value in the source code instead of specifying the seed each time you invoke
Codecrypt.
If the seed source of your system can not be trusted, fix the system instead.
.SH Troubleshooting/FAQ
Q: I can't read/verify messages from versions 1.3.1 and older!
@ -443,5 +459,5 @@ it with caution.
.SH AUTHORS
Codecrypt was written by Mirek Kratochvil in 2013-2016.
Codecrypt was written by Mirek Kratochvil in 2013-2017.

22
src/actions.cpp
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@ -2,7 +2,7 @@
/*
* This file is part of Codecrypt.
*
* Copyright (C) 2013-2016 Mirek Kratochvil <exa.exa@gmail.com>
* Copyright (C) 2013-2017 Mirek Kratochvil <exa.exa@gmail.com>
*
* Codecrypt is free software: you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
@ -46,6 +46,8 @@
#define MSG_CLEARTEXT "MESSAGE-IN-CLEARTEXT"
#define MSG_DETACHED "MESSAGE-DETACHED"
#define SEED_FAILED { err("error: could not seed PRNG"); return 1; }
inline bool open_keyring (keyring&KR)
{
if (!KR.open()) {
@ -62,7 +64,7 @@ int action_gen_symkey (const std::string&algspec,
{
symkey sk;
ccr_rng r;
r.seed (256);
if (!r.seed (256)) SEED_FAILED;
if (!sk.create (algspec, r)) {
err ("error: symkey creation failed");
@ -219,7 +221,7 @@ int action_gen_key (const std::string& p_algspec, const std::string&name,
err ("If nothing happens, move mouse, type random stuff on keyboard,");
err ("or just wait longer.");
r.seed (512, false);
if (!r.seed (512, false)) SEED_FAILED;
err ("Seeding done, generating the key...");
@ -312,7 +314,7 @@ int action_sym_encrypt (const std::string&symmetric, bool armor)
sencode_destroy (SK);
ccr_rng r;
r.seed (256);
if (!r.seed (256)) SEED_FAILED;
if (!sk.encrypt (std::cin, std::cout, r)) {
err ("error: encryption failed");
@ -375,7 +377,7 @@ int action_encrypt (const std::string&recipient, bool armor,
//encryption part
encrypted_msg msg;
ccr_rng r;
r.seed (256);
if (!r.seed (256)) SEED_FAILED;
bvector plaintext;
plaintext.from_string (data);
@ -589,7 +591,7 @@ int action_hash_sign (bool armor, const std::string&symmetric)
parts.resize (1);
base64_encode (data, parts[0]);
ccr_rng r;
r.seed (128);
if (!r.seed (256)) SEED_FAILED;
data = envelope_format (ENVELOPE_HASHFILE, parts, r);
}
@ -679,7 +681,7 @@ int action_sign (const std::string&user, bool armor, const std::string&detach,
//signature production part
signed_msg msg;
ccr_rng r;
r.seed (256);
if (!r.seed (256)) SEED_FAILED;
bvector message;
message.from_string (data);
@ -1120,7 +1122,7 @@ int action_sign_encrypt (const std::string&user, const std::string&recipient,
//make a signature
signed_msg smsg;
ccr_rng r;
r.seed (256);
if (!r.seed (256)) SEED_FAILED;
bvector bv;
bv.from_string (data);
@ -1521,7 +1523,7 @@ int action_export (bool armor,
parts.resize (1);
base64_encode (data, parts[0]);
ccr_rng r;
r.seed (128);
if (!r.seed (256)) SEED_FAILED;
data = envelope_format (ENVELOPE_PUBKEYS, parts, r);
}
@ -1777,7 +1779,7 @@ int action_export_sec (bool armor, bool yes,
parts.resize (1);
base64_encode (data, parts[0]);
ccr_rng r;
r.seed (128);
if (!r.seed (256)) SEED_FAILED;
data = envelope_format (ENVELOPE_SECRETS, parts, r);
}

22
src/generator.cpp
View file

@ -2,7 +2,7 @@
/*
* This file is part of Codecrypt.
*
* Copyright (C) 2013-2016 Mirek Kratochvil <exa.exa@gmail.com>
* Copyright (C) 2013-2017 Mirek Kratochvil <exa.exa@gmail.com>
*
* Codecrypt is free software: you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
@ -19,16 +19,20 @@
*/
#include "generator.h"
#include "iohelpers.h"
#include <fstream>
#include <vector>
#include <string.h> //for strerror
#include <stdlib.h> //for getenv
static inline uint bytes (uint bits)
{
return (bits >> 3) + ( (bits & 7) ? 1 : 0);
}
void ccr_rng::seed (uint bits, bool quick)
bool ccr_rng::seed (uint bits, bool quick)
{
std::vector<byte> s;
std::ifstream f;
@ -36,12 +40,22 @@ void ccr_rng::seed (uint bits, bool quick)
uint b = bytes (bits);
if (b > 256) b = 256;
f.open (quick ? "/dev/urandom" : "/dev/random",
std::ios::in | std::ios::binary);
char*user_source = getenv ("CCR_RANDOM_SEED");
std::string seed_source = user_source ? user_source :
quick ? "/dev/urandom" :
"/dev/random";
f.open (seed_source, std::ios::in | std::ios::binary);
if (!f.good()) {
err ("opening " << seed_source << " failed: "
<< strerror (errno));
return false;
}
s.resize (b);
for (uint i = 0; i < b; ++i) f >> s[i];
f.close();
r.load_key_vector (s);
return true;
}

4
src/generator.h
View file

@ -2,7 +2,7 @@
/*
* This file is part of Codecrypt.
*
* Copyright (C) 2013-2016 Mirek Kratochvil <exa.exa@gmail.com>
* Copyright (C) 2013-2017 Mirek Kratochvil <exa.exa@gmail.com>
*
* Codecrypt is free software: you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
@ -40,7 +40,7 @@ public:
r.clear();
}
void seed (uint bits, bool quick = true);
bool seed (uint bits, bool quick = true);
uint random (uint n) {
randmax_type i;

4
src/main.cpp
View file

@ -2,7 +2,7 @@
/*
* This file is part of Codecrypt.
*
* Copyright (C) 2013-2016 Mirek Kratochvil <exa.exa@gmail.com>
* Copyright (C) 2013-2017 Mirek Kratochvil <exa.exa@gmail.com>
*
* Codecrypt is free software: you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
@ -23,7 +23,7 @@
void print_version()
{
out ("codecrypt " PACKAGE_VERSION);
out ("Copyright (C) 2013-2016 Mirek Kratochvil <exa.exa@gmail.com>");
out ("Copyright (C) 2013-2017 Mirek Kratochvil <exa.exa@gmail.com>");
out ("This is free software; see the source "
"for copying conditions. There is NO");
out ("warranty; not even for MERCHANTABILITY "

2
src/xsynd.h
View file

@ -26,7 +26,7 @@
#include <stdint.h>
/*
* XSYND is a stream cipher based on XSYND, the stream cipher with
* This is a stream cipher based on XSYND, the stream cipher with
* mathematicaly provable (AND also proven) security.
*
* Parameters chosen for this implementation were chosen to have better attack