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diff --git a/doc/manual/tss.rst b/doc/manual/tss.rst new file mode 100644 index 000000000..947b835d0 --- /dev/null +++ b/doc/manual/tss.rst @@ -0,0 +1,45 @@ +Threshold Secret Sharing +======================================== + +.. versionadded:: 1.9.1 + +Threshold secret sharing allows splitting a secret into ``N`` shares such that +``M`` (for specified ``M`` <= ``N``) is sufficient to recover the secret, but an +attacker with ``M - 1`` shares cannot derive any information about the secret. + +The implementation in Botan follows an expired Internet draft +"draft-mcgrew-tss-03". Several other implementations of this TSS format exist. + +.. cpp:class:: RTSS_Share + + .. cpp:function:: static std::vector<RTSS_Share> split(uint8_t M, uint8_t N, \ + const uint8_t secret[], uint16_t secret_len, \ + const std::vector<uint8_t>& identifier, \ + const std::string& hash_fn, \ + RandomNumberGenerator& rng) + + Split a secret. The identifier is an optional key identifier which may be + up to 16 bytes long. Shorter identifiers are padded with zeros. + + The hash function must be either "SHA-1", "SHA-256", or "None" to disable + the checksum. + + This will return a vector of length ``N``, any ``M`` of these shares is + sufficient to reconstruct the data. + + .. cpp:function:: static secure_vector<uint8_t> reconstruct(const std::vector<RTSS_Share>& shares) + + Given a sufficient number of shares, reconstruct a secret. + + .. cpp:function:: RTSS_Share(const uint8_t data[], size_t len) + + Read a TSS share as a sequence of bytes. + + .. cpp:function:: const secure_vector<uint8>& data() const + + Return the data of this share. + + .. cpp:function:: uint8_t share_id() const + + Return the share ID which will be in the range 1...255 + |