p610/ucrypto

Micropython package for doing fast rsa and elliptic curve cryptography, specifically digital signatures

Description

Micropython package for doing fast rsa and elliptic curve cryptography, specifically digital signatures. ECDSA API design inspired from fastecdsa and implementation based on tomsfastmath.

Examples

• Signing and Verifying ufastrsa

  from ufastrsa.rsa import RSA, genrsa
  
  
  def main():
  
      bits = 1024
      print("RSA bits", bits)
      r = RSA(*genrsa(bits, e=65537))
      if r:
          print("RSA OK")
          data = b"a message to sign and encrypt via RSA"
          print("random data len:", len(data), data)
          assert r.pkcs_verify(r.pkcs_sign(data)) == data
          print("pkcs_verify OK")
          assert r.pkcs_decrypt(r.pkcs_encrypt(data)) == data
          print("pkcs_decrypt OK")
  
  
  if __name__ == "__main__":
      main()

• Signing and Verifying ufastecdsa

  try:
      from ufastecdsa import curve, ecdsa, keys, util
  
      get_bit_length = util.get_bit_length
  except ImportError:
      from fastecdsa import curve, ecdsa, keys, util
  
      get_bit_length = int.bit_length
  
  
  def main():
  
      # private_key = 82378264402520040413352233063555671940555718680152892238371187003380781159101
      # public_key = keys.get_public_key(private_key, curve.P256)
  
      private_key, public_key = keys.gen_keypair(curve.P256)
      print("private_key:", private_key)
      print("public_key:", public_key.x, public_key.y, public_key.curve.name)
  
      m = "a message to sign via ECDSA"
  
      r, s = ecdsa.sign(m, private_key)
  
      print("R:", r)
      print("S:", s)
  
      verified = ecdsa.verify((r, s), m, public_key)
      print(verified)
  
  
  if __name__ == "__main__":
      main()

• Arbitrary Elliptic Curve Arithmetic

  from _crypto import ECC
  
  P256 = ECC.Curve(
      0xffffffff00000001000000000000000000000000ffffffffffffffffffffffff,
      -0x3,
      0x5ac635d8aa3a93e7b3ebbd55769886bc651d06b0cc53b0f63bce3c3e27d2604b,
      0xffffffff00000000ffffffffffffffffbce6faada7179e84f3b9cac2fc632551,
      0x6b17d1f2e12c4247f8bce6e563a440f277037d812deb33a0f4a13945d898c296,
      0x4fe342e2fe1a7f9b8ee7eb4a7c0f9e162bce33576b315ececbb6406837bf51f5
  )
  
  S = ECC.Point(
      0xde2444bebc8d36e682edd27e0f271508617519b3221a8fa0b77cab3989da97c9,
      0xc093ae7ff36e5380fc01a5aad1e66659702de80f53cec576b6350b243042a256,
      P256
  )
  
  T = ECC.Point(
      0x55a8b00f8da1d44e62f6b3b25316212e39540dc861c89575bb8cf92e35e0986b,
      0x5421c3209c2d6c704835d82ac4c3dd90f61a8a52598b9e7ab656e9d8c8b24316,
      P256
  )
  
  print("S==S  = ", S == S)
  
  print("S==T  = ", S == T)
  
  R = S + T
  print("S+T   = ({:X}, {:X})".format(R.x, R.y))
  
  R = S - T
  print("S-T   = ({:X}, {:X})".format(R.x, R.y))
  
  R = 2 * S
  print("2S    = ({:X}, {:X})".format(R.x, R.y))
  
  d = 0xc51e4753afdec1e6b6c6a5b992f43f8dd0c7a8933072708b6522468b2ffb06fd
  e = 0xd37f628ece72a462f0145cbefe3f0b355ee8332d37acdd83a358016aea029db7
  R = (d * S) + (e * T)
  print("dS+eT = ({:X}, {:X})".format(R.x, R.y))
  
  R = S + S
  print("S+S   = ({:X}, {:X})".format(R.x, R.y))
  
  R = S - S
  print("S-S   = ({:X}, {:X})".format(R.x, R.y))

• for other examples: tests

Optimizations are disabled by default for easy build on different platforms

#define TFM_NO_ASM

// #define TFM_ECC192
// #define TFM_ECC224
// #define TFM_ECC256
// #define TFM_ECC384
// #define TFM_ECC512
// #define TFM_RSA512
// #define TFM_RSA1024
// #define TFM_RSA2048

Compiling the cmodule into MicroPython

To build such a module, compile MicroPython with an extra make flag named USER_C_MODULES set to the directory containing all modules you want included (not to the module itself).

• Example:

  ➜  ~ git clone https://github.com/micropython/micropython.git micropython
  ➜  ~ cd micropython
  ➜  micropython (master) ✗ git submodule update --init
  ➜  micropython (master) ✗ git clone https://github.com/dmazzella/ucrypto.git ports/stm32/boards/PYBD_SF6/cmodules/ucrypto
  ➜  micropython (master) ✗ make -j8 -C mpy-cross && make -j8 -C ports/stm32/ BOARD="PYBD_SF6" USER_C_MODULES="$(pwd)/ports/stm32/boards/PYBD_SF6/cmodules"

Build size:

The build size depends on the asm optimizations of the tomsfastmath library that are enabled into ucrypto/tomsfastmath/tfm_mpi.h

#define TFM_ECC192
#define TFM_ECC224
#define TFM_ECC256
#define TFM_ECC384
#define TFM_ECC512
#define TFM_RSA512
#define TFM_RSA1024
#define TFM_RSA2048

• PYBD_SF6 without ucrypto:

  LINK build-PYBD_SF6/firmware.elf
  text	   data	    bss	    dec	    hex	filename
  1012856	    328	 100576	1113760	 10fea0	build-PYBD_SF6/firmware.elf
  

• PYBD_SF6 with ucrypto and with tomsfastmath only ECC 256 asm optimizations:

  // #define TFM_ECC192
  // #define TFM_ECC224
  #define TFM_ECC256
  // #define TFM_ECC384
  // #define TFM_ECC512
  // #define TFM_RSA512
  // #define TFM_RSA1024
  // #define TFM_RSA2048

  LINK build-PYBD_SF6/firmware.elf
  text	   data	    bss	    dec	    hex	filename
  1034872	    452	 101600	1136924	 11591c	build-PYBD_SF6/firmware.elf
  

• PYBD_SF6 with ucrypto and without tomsfastmath RSA asm optimizations:

  #define TFM_ECC192
  #define TFM_ECC224
  #define TFM_ECC256
  #define TFM_ECC384
  #define TFM_ECC512
  // #define TFM_RSA512
  // #define TFM_RSA1024
  // #define TFM_RSA2048

  LINK build-PYBD_SF6/firmware.elf
  text	   data	    bss	    dec	    hex	filename
  1042552	    452	 101600	1144604	 11771c	build-PYBD_SF6/firmware.elf
  

• PYBD_SF6 with ucrypto and full tomsfastmath asm optimizations:

  LINK build-PYBD_SF6/firmware.elf
  text	   data	    bss	    dec	    hex	filename
  1209976	    452	 101600	1312028	 14051c	build-PYBD_SF6/firmware.elf
  

To see which optimizations are enabled in the build:

MicroPython v1.19.1-705-gac5934c96-dirty on 2022-11-22; PORTENTA with STM32H747
Type "help()" for more information.
>>> import _crypto
>>> print(_crypto.NUMBER.ident())
TomsFastMath v0.13.1-next

Sizeofs
        fp_digit = 4
        fp_word  = 8

FP_MAX_SIZE = 4352

Defines: 
 TFM_ARM  TFM_ECC192  TFM_ECC224  TFM_ECC256  TFM_ECC384  TFM_ECC512  TFM_RSA512  TFM_RSA1024  TFM_RSA2048  TFM_ASM  TFM_MUL6  TFM_SQR6  TFM_MUL7  TFM_SQR7  TFM_MUL8  TFM_SQR8  TFM_MUL12  TFM_SQR12  TFM_SMALL_SET  TFM_MUL17  TFM_SQR17  TFM_MUL32  TFM_SQR32  TFM_MUL64  TFM_SQR64 

>>>