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

• 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

#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

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"

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 

>>>