Documentation
¶
Overview ¶
Package witness provides serialization helpers to encode a witness into a []byte.
Binary protocol
Witness -> [uint32(nbPublic) | uint32(nbSecret) | fr.Vector(variables)] fr.Vector is a *field element* vector encoded a big-endian byte array like so: [uint32(len(vector)) | elements]
Ordering ¶
First, `publicVariables`, then `secretVariables`. Each subset is ordered from the order of definition in the circuit structure. For example, with this circuit on `ecc.BN254`
type Circuit struct {
X frontend.Variable
Y frontend.Variable `gnark:",public"`
Z frontend.Variable
}
A valid witness would be:
- `[uint32(1)|uint32(2)|uint32(3)|bytes(Y)|bytes(X)|bytes(Z)]`
- Hex representation with values `Y = 35`, `X = 3`, `Z = 2` `000000010000000200000003000000000000000000000000000000000000000000000000000000000000002300000000000000000000000000000000000000000000000000000000000000030000000000000000000000000000000000000000000000000000000000000002`
Index ¶
Constants ¶
This section is empty.
Variables ¶
View Source
var ErrInvalidWitness = errors.New("invalid witness")
Functions ¶
This section is empty.
Types ¶
type Witness ¶
type Witness interface {
io.WriterTo
io.ReaderFrom
encoding.BinaryMarshaler
encoding.BinaryUnmarshaler
// Public returns the Public an object containing the public part of the Witness only.
Public() (Witness, error)
// Vector returns the underlying fr.Vector slice
Vector() any
// Fill range over the provided chan to fill the underlying vector.
// Will allocate the underlying vector with nbPublic + nbSecret elements.
// This is typically call by internal APIs to fill the vector by walking a structure.
Fill(nbPublic, nbSecret int, values <-chan any) error
}
Witness represents a zkSNARK witness.
The underlying data structure is a vector of field elements, but a Witness also may have some additional meta information about the number of public elements and secret elements.
In most cases a Witness should be [de]serialized using a binary protocol. JSON conversions for pretty printing are slow and don't handle all complex circuit structures well.
Source Files
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