George Blakley

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George Blakley is an American cryptographer, best known for inventing a secret sharing scheme in 1979.

In order to split a secret into several shares, Blakley's scheme specifies the secret as a point in n-dimensional space, and gives out shares that coorrespond to hyperplanes that intersect the secret point. Any n such hyperplanes will specify the point, while fewer than n hyperplanes will leave at least one degree of freedom, and thus leave the point unspecified.

In contrast, Shamir's secret sharing scheme represents the secret as the y-intercept of an n-degree polynomial, and shares correspond to points on the polynomial. Blakley and Shamir independently invented secret sharing in 1979, however, Shamir's scheme is more popular.

Blakley's scheme is less space-efficient than Shamir's; while Shamir's shares are each only as large as the original secret, Blakley's shares are t times larger, where t is the threshold number of players. In addition, in Shamir's scheme, fewer than enough shares leave the secret totally unknown and random, whereas in Blakley's scheme, the secret is restricted to lie in a lower-dimensional subspace. Blakley's scheme can be tightened by adding restrictions on which planes are usable as shares. The resulting scheme is identical to Shamir's polynomial system.