39 lines
1.4 KiB
Python
39 lines
1.4 KiB
Python
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import binascii, ctypes, math, struct
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class sha2_ctx(ctypes.Structure):
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_fields_ = [("state", ctypes.c_uint32 * 8),
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("count", ctypes.c_uint64),
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("buf", ctypes.c_byte * 64)]
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sodium = ctypes.CDLL("libsodium.so")
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sodium.crypto_hash_sha256_init.argtypes = [ctypes.POINTER(sha2_ctx)]
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sodium.crypto_hash_sha256_init.restype = ctypes.c_int
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sodium.crypto_hash_sha256_update.argtypes = [ctypes.POINTER(sha2_ctx), ctypes.c_char_p,
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ctypes.c_size_t]
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sodium.crypto_hash_sha256_update.restype = ctypes.c_int
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sodium.crypto_hash_sha256_final.argtypes = [ctypes.POINTER(sha2_ctx), ctypes.c_char_p]
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sodium.crypto_hash_sha256_final.restype = ctypes.c_int
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def hash_extend(orig_data_len, orig_hash, extend_data):
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if isinstance(orig_hash, str):
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orig_hash = binascii.unhexlify(orig_hash)
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total_len = math.ceil((orig_data_len + 1 + 8) / 64) * 64
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padding_len = total_len - orig_data_len - 1 - 8
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padding = b"\x80" + (b"\x00" * padding_len) + struct.pack(">Q", orig_data_len*8)
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ctx = sha2_ctx()
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sodium.crypto_hash_sha256_init(ctx)
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for i in range(8):
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ctx.state[i] = struct.unpack(">I", orig_hash[i*4:(i+1)*4])[0]
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ctx.count = total_len * 8
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out_hash = ctypes.create_string_buffer(32)
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sodium.crypto_hash_sha256_update(ctx, extend_data, len(extend_data))
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sodium.crypto_hash_sha256_final(ctx, out_hash)
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return padding + extend_data, bytes(out_hash)
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