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micro-ecc

A small and fast ECDH and ECDSA implementation for 8-bit, 32-bit, and 64-bit processors.

The old version of micro-ecc can be found in the "old" branch.

Features

  • Resistant to known side-channel attacks.
  • Written in C, with optional GCC inline assembly for AVR, ARM and Thumb platforms.
  • Supports 8, 32, and 64-bit architectures.
  • Small code size.
  • No dynamic memory allocation.
  • Support for 4 standard curves: secp160r1, secp192r1, secp256r1, and secp256k1.
  • BSD 2-clause license.

Usage Notes

Point Representation

Compressed points are represented in the standard format as defined in http://www.secg.org/collateral/sec1_final.pdf; uncompressed points are represented in standard format, but without the 0x04 prefix. uECC_make_key(), uECC_shared_secret(), uECC_sign(), and uECC_verify() only handle uncompressed points; you can use uECC_compress() and uECC_decompress() to convert between compressed and uncompressed point representations.

Private keys are represented in the standard format.

Using the Code

I recommend just copying (or symlink) uECC.h, uECC.c, and the appropriate asm_<arch>_.inc (if any) into your project. Then just #include "uECC.h" to use the micro-ecc functions.

For use with Arduino, you can just create a symlink to the uECC directory in your Arduino libraries directory. You can then use uECC just like any other Arduino library (uECC should show up in the Sketch=>Import Library submenu).

See uECC.h for documentation for each function.

Compilation Notes

  • Should compile with any C/C++ compiler that supports stdint.h (this includes Visual Studio 2013).
  • If you want to change the defaults for uECC_CURVE and uECC_ASM, you must change them in your Makefile or similar so that uECC.c is compiled with the desired values (ie, compile uECC.c with -DuECC_CURVE=uECC_secp256r1 or whatever).
  • When compiling for a Thumb-1 platform with inline assembly enabled (ie, uECC_ASM is defined to uECC_asm_small or uECC_asm_fast), you must use the -fomit-frame-pointer GCC option (this is enabled by default when compiling with -O1 or higher).
  • When compiling for an ARM/Thumb-2 platform with fast inline assembly enabled (ie, uECC_ASM is defined to uECC_asm_fast), you must use the -fomit-frame-pointer GCC option (this is enabled by default when compiling with -O1 or higher).
  • When compiling for AVR with inline assembly enabled, you must have optimizations enabled (compile with -O1 or higher).
  • When building for Windows, you will need to link in the advapi32.lib system library.

ARM Performance

All tests were built using gcc 4.8.2 with -O3, and were run on a Raspberry Pi B+. uECC_ASM was defined to uECC_asm_fast and ECC_SQUARE_FUNC was defined to 1 in all cases. All times are in milliseconds.

secp160r1 secp192r1 secp256r1 secp256k1
ECDH: 2.3 2.7 7.9 6.5
ECDSA sign: 2.8 3.1 8.6 7.2
ECDSA verify: 2.7 3.2 9.2 7.0

AVR Performance

All tests were built using avr-gcc 4.8.1 with -Os, and were run on a 16 MHz ATmega256RFR2. Code size refers to the space used by micro-ecc code and data.

ECDH (fast)

In these tests, uECC_ASM was defined to uECC_asm_fast and ECC_SQUARE_FUNC was defined to 1 in all cases.

secp160r1 secp192r1 secp256r1 secp256k1
ECDH time (ms): 470 810 2220 1615
Code size (bytes): 10768 13112 20886 21126

ECDH (small)

In these tests, uECC_ASM was defined to uECC_asm_small and ECC_SQUARE_FUNC was defined to 0 in all cases.

secp160r1 secp192r1 secp256r1 secp256k1
ECDH time (ms): 1250 1810 4790 4700
Code size (bytes): 3244 3400 5274 3426

ECDSA (fast)

In these tests, uECC_ASM was defined to uECC_asm_fast and ECC_SQUARE_FUNC was defined to 1 in all cases.

secp160r1 secp192r1 secp256r1 secp256k1
ECDSA sign time (ms): 555 902 2386 1773
ECDSA verify time (ms): 590 990 2650 1800
Code size (bytes): 13246 14798 22594 22826

ECDSA (small)

In these tests, uECC_ASM was defined to uECC_asm_small and ECC_SQUARE_FUNC was defined to 0 in all cases.

secp160r1 secp192r1 secp256r1 secp256k1
ECDSA sign time (ms): 1359 1931 4998 4904
ECDSA verify time (ms): 1515 2160 5700 5220
Code size (bytes): 5690 5054 6980 5080