55 lines
1.1 KiB
Python
55 lines
1.1 KiB
Python
from typing import List
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def mask_r(r: int) -> int:
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r_bytes = r.to_bytes(16, "little")
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r_masked = bytearray(r_bytes)
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r_masked[3] &= 15;
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r_masked[7] &= 15;
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r_masked[11] &= 15;
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r_masked[15] &= 15;
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r_masked[4] &= 252;
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r_masked[8] &= 252;
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r_masked[12] &= 252;
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r_masked = int.from_bytes(r_masked, "little")
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return r_masked
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def poly1305(message: bytes, r: int, s: int):
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r = mask_r(r)
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p = 2**130-5
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acc = 0
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blocks = [int.from_bytes(message[i:i+16], "little") for i in range(0, len(message), 16)]
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for block in blocks:
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byte_length = (block.bit_length() + 7) // 8
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block += 1 << (8*byte_length)
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acc = ((acc+block)*r) % p
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acc += s
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return acc & (2**128-1)
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def main():
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r = 0xa806d542fe52447f336d555778bed685
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s = 0x1bf54941aff6bf4afdb20dfb8a800301
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golden_result = 0xa927010caf8b2bc2c6365130c11d06a8
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msg = b"Cryptographic Forum Research Group"
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result = poly1305(msg, r, s)
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print(f"{golden_result:x}")
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print(f"{result:x}")
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if __name__ == "__main__":
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main()
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