TweetNaCl is a compact reimplementation of the NaCl library by Daniel J. Bernstein, Bernard van Gastel, Wesley Janssen, Tanja Lange, Peter Schwabe and Sjaak Smetsers. The library is less than 20 KB in size and provides 25 of the NaCl library functions.
The compact library uses curve25519, XSalsa20, Poly1305 and SHA-512 as default primitives, and includes both x25519 key exchange and ed25519 signatures. The complete list of functions can be found in TweetNaCl: A crypto library in 100 tweets (20140917), Table 1, page 5.
Crypto++ retained the function names and signatures but switched to data types provided by <stdint.h> to promote interoperability with Crypto++ and avoid size problems on platforms like Cygwin. For example, NaCl typdef'd u64 as an unsigned long long, but Cygwin, MinGW and MSYS are LP64 systems (not LLP64 systems). In addition, Crypto++ was missing NaCl's signed 64-bit integer i64.
Crypto++ enforces the 0-key restriction due to small points. The TweetNaCl library allowed the 0-keys to small points. Also see RFC 7748, Elliptic Curves for Security, Section 6.
TweetNaCl is well written but not well optimized. It runs 2x to 3x slower than optimized routines from libsodium. However, the library is still 2x to 4x faster than the algorithms NaCl was designed to replace.
The Crypto++ wrapper for TweetNaCl requires OS features. That is, NO_OS_DEPENDENCE cannot be defined. It is due to TweetNaCl's internal function randombytes. Crypto++ used DefaultAutoSeededRNG within randombytes, so OS integration must be enabled. You can use another generator like RDRAND to avoid the restriction.
* GNUmakefile-cross: Fix install target
The install target was not working: missing mkdir before copying files,
wrong dynamic library copied, missing ldconf.
The fix is mostly taken from the install target from GNUmakefile.
* Makefile: call 'ln -sf' instead of 'ln -sf -sf'
regtest.cpp is where ciphers register by name. The library has added a number of ciphers over the last couple of years and the source file has experienced bloat. Most of the ARM and MIPS test borads were suffering Out of Memory (OOM) kills as the compiler processed the source fille and the included header files.
This won't stop the OOM kills, but it will help the situation. An early BeagleBoard with 512 MB of RAM is still going to have trouble, but it can be worked around by building with 1 make job as opposed to 2 or 4.
and prevented updated object files from regenerating targets.
The 'public_service' phony target should be an 'order-only' prerequisite so
that it doesn't cause its target to be rebuilt when it is run.
However, object files were specified as order-only while the 'public_service'
target was not. This is reproducible by running 'make' twice. Another effect
is that when these object files change they will not cause the target to be
updated while they are order-only.
Jeffrey Walton
zorun
Todd Knarr
Grant Ayers