This library provides implements the Shamir Secret Sharing Algorithm. The maximum values of K and N are 4294967310.

The details algorithm used is the following:

The input string (which may be binary) is padded to a length of modulo 4 bytes, each four bytes of the input is shared in GF(4294967311). The resulting secret is than the share index encoded as a variable size integer (values lower than 253 take 1 byte, values lower than 65535 take 3 bytes, other values take 5 bytes) concatenated with the resulting points encoded using 4 or 5 bytes (5 bytes are used when the value is larger than 2**32-2).

Example usage:

Sharing a binary string

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Below is an example usage for k=2 and n=3:

>>> from shamir.shamir import ShamirStringSharer
>>> shamir = ShamirStringSharer()
>>> secrets = shamir.share("the quick brown fox jumps over the lazy dog", 2, 3)
>>> for secret in secrets:
>>>     print secret.encode("hex")
00993d36fd2bbf51db8db8fbff596815a680bf353bd7e69f87bf65359bf0927dda3ae752b7db5bfd677b52318f
01be1208dae6093a62b051958c4358bd2c9b0ef2564557d18f0ba9fbb17bb2db310d698502553d819f9234fc1d
02e2e6dab7a05322dad2ea2f192d4964b2b55eaf71b2c903a657eec1d606d33888dfebb75ccf1f05e6a917c6ab

Recombining the shares

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>>> from shamir.shamir import ShamirStringSharer
>>> shamir = ShamirStringSharer()
>>> secrets = ["00993d36fd2bbf51db8db8fbff596815a680bf353bd7e69f87bf65359bf0927dda3ae752b7db5bfd677b52318f",
               "01be1208dae6093a62b051958c4358bd2c9b0ef2564557d18f0ba9fbb17bb2db310d698502553d819f9234fc1d"]
>>> print shamir.recombine([secret.decode("hex") for secret in secrets])
"the quick brown fox jumps over the lazy dog"