diff --git a/specs/bls_signature.md b/specs/bls_signature.md index beef19df5..18e2d8c9a 100644 --- a/specs/bls_signature.md +++ b/specs/bls_signature.md @@ -86,7 +86,7 @@ def hash_to_G2(message_hash: Bytes32, domain: uint64) -> [uint384]: ### `modular_squareroot` -`modular_squareroot(x)` returns a solution `y` to `y**2 % q == x`, and `None` if none exists. If there are two solutions the one with higher imaginary component is favored; if both solutions have equal imaginary component the one with higher real component is favored (note that this is equivalent to saying that the single solution with either imaginary component > p/2 or imaginary component zero and real component > p/2 is favored). +`modular_squareroot(x)` returns a solution `y` to `y**2 % q == x`, and `None` if none exists. If there are two solutions, the one with higher imaginary component is favored; if both solutions have equal imaginary component, the one with higher real component is favored (note that this is equivalent to saying that the single solution with either imaginary component > p/2 or imaginary component zero and real component > p/2 is favored). The following is a sample implementation; implementers are free to implement modular square roots as they wish. Note that `x2 = -x1` is an _additive modular inverse_ so real and imaginary coefficients remain in `[0 .. q-1]`. `coerce_to_int(element: Fq) -> int` is a function that takes Fq element `element` (i.e. integers `mod q`) and converts it to a regular integer.