Documentation
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Index ¶
- func AssertIsTrit(api frontend.API, v frontend.Variable)
- func FromBase(api frontend.API, base Base, digits []frontend.Variable, ...) frontend.Variable
- func FromBinary(api frontend.API, digits []frontend.Variable, opts ...BaseConversionOption) frontend.Variable
- func FromTernary(api frontend.API, digits []frontend.Variable, opts ...BaseConversionOption) frontend.Variable
- func GetHints() []solver.Hint
- func ToBase(api frontend.API, base Base, v frontend.Variable, opts ...BaseConversionOption) []frontend.Variable
- func ToBinary(api frontend.API, v frontend.Variable, opts ...BaseConversionOption) []frontend.Variable
- func ToTernary(api frontend.API, v frontend.Variable, opts ...BaseConversionOption) []frontend.Variable
- type Base
- type BaseConversionOption
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func AssertIsTrit ¶
AssertIsTrit constrains digit to be 0, 1 or 2.
func FromBase ¶
func FromBase(api frontend.API, base Base, digits []frontend.Variable, opts ...BaseConversionOption) frontend.Variable
FromBase compute from a set of digits its canonical representation in little-endian order. For example for base 2, it returns Σbi = Σ (2**i * digits[i])
func FromBinary ¶
func FromBinary(api frontend.API, digits []frontend.Variable, opts ...BaseConversionOption) frontend.Variable
FromBinary is an alias of FromBase(api, Binary, digits)
func FromTernary ¶
func FromTernary(api frontend.API, digits []frontend.Variable, opts ...BaseConversionOption) frontend.Variable
FromTernary is an alias of FromBase(api, Ternary, digits)
func ToBase ¶
func ToBase(api frontend.API, base Base, v frontend.Variable, opts ...BaseConversionOption) []frontend.Variable
ToBase decomposes scalar v into digits in given base using options opts. The decomposition is in little-endian order.
Types ¶
type BaseConversionOption ¶
type BaseConversionOption func(opt *baseConversionConfig) error
BaseConversionOption configures the behaviour of scalar decomposition.
func OmitModulusCheck ¶ added in v0.9.0
func OmitModulusCheck() BaseConversionOption
OmitModulusCheck omits the comparison against native field modulus in case the bitlength of the decomposed value (if WithNbDigits not set or set to bitlength of the native modulus) eqals bitlength of the modulus.
The check is otherwise required as there are possibly multiple correct binary decompositions. For example, when decomposing small a the decomposition could return the slices for both a or a+r, where r is the native modulus and the enforced constraints are correct due to implicit modular reduction by r.
This option can be used in case the decomposed output is manually checked to be unique or if uniqueness is not required.
func WithNbDigits ¶
func WithNbDigits(nbDigits int) BaseConversionOption
WithNbDigits sets the resulting number of digits (nbDigits) to be used in the base conversion.
nbDigits must be > 0. If nbDigits is lower than the length of full decomposition and WithUnconstrainedOutputs option is not used, then the conversion functions will generate an unsatisfiable constraint.
If nbDigits is larger than the bitlength of the modulus, then the returned slice has length nbDigits with excess bits being 0.
If WithNbDigits option is not set, then the full decomposition is returned.
func WithUnconstrainedInputs ¶
func WithUnconstrainedInputs() BaseConversionOption
WithUnconstrainedInputs indicates to the FromBase apis to constrain its inputs (digits) to ensure they are valid digits in base b. For example, FromBinary without this option will add 1 constraint per bit to ensure it is either 0 or 1.
func WithUnconstrainedOutputs ¶
func WithUnconstrainedOutputs() BaseConversionOption
WithUnconstrainedOutputs sets the bit conversion API to NOT constrain the output bits. This is UNSAFE but is useful when the outputs are already constrained by other circuit constraints. The sum of the digits will is constrained like so Σbi = Σ (base**i * digits[i]) But the individual digits are not constrained to be valid digits in base b.
func WithUpperBound ¶ added in v0.16.4
func WithUpperBound(bound *big.Int) BaseConversionOption
WithUpperBound sets the constant the decomposed value is checked against, instead of the default native field modulus minus one.
The default check exists because a decomposition is only unique below the modulus: for a small value a, both a and a+r decompose correctly, where r is the native modulus, as the constraints are satisfied under the implicit modular reduction. Checking against a smaller constant is a strictly stronger statement, so it keeps that uniqueness and additionally pins the value into the caller's own range.
bound must be positive and must not exceed the native modulus minus one; a larger bound would readmit the multiple-decomposition case the check exists to prevent.
Setting this option always enforces the comparison, including when WithNbDigits is lower than the bitlength of the modulus, since the caller is asking for a bound the digit count alone does not imply. It cannot be combined with OmitModulusCheck, and it only applies to binary conversion.
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