- Previously Sig was defined as a variable length byte array and was
  encoded/decoded using the Encode/DecodeSig methods.

- But, its length depends upon the wallet backend. So, redefine it as an
  interface that implements binary.(Un)marshaler interfaces.

- Now, the wallet backend should implement the logic for converting a
  Sig to/from its binary representation. The perunio serializer can then
  directly Encode/Decode this binary representation as a byte array.

Signed-off-by: Manoranjith <[email protected]>

- Use a struct for storing the r and s components of the ECDSA
  signature.

- This eliminates the need for serializing / deserializing the
  signature each time when it is generated / verified respectively.

- Also, replace the test TestSignatureSerialize with
  GenericMarshalerTest

Signed-off-by: Manoranjith <[email protected]>

- Unexport the SigLen field, as it is not needed outside of the wallet
  package.

- Remove the length check in signature tests. Because, VerifySignature
  function checks if the signature was generated by the corresponding
  wallet, before verifying it it.

- In transactor tests, use the sigLen variable defined within the
  package.

Signed-off-by: Manoranjith <[email protected]>

Signed-off-by: Manoranjith <[email protected]>

- (En|De)code signatures directly using perunio.(En|De)code.

- SignData method on dummy account returns a Sig instead of byte array.

Signed-off-by: Manoranjith <[email protected]>

- After the wallet.Sig interface was introduced, each wallet backend
  defines its own concrete type for implementing the Sig interface.

- These implementations also include an UnmarshalBinary function, which
  is used for unmarshalling signatures from their binary representation.

- Because of this, when binary representations of signatures have
  incorrect length (when they are tampered), the unmarshalling of these
  signatures themselves fail. Which removes the need for checking the
  response of VerifySignature function for signatures of incorrect
  length.

- Hence, the tests are updated accordingly.

Signed-off-by: Manoranjith <[email protected]>

Signed-off-by: Manoranjith <[email protected]>

- Previously, signatures used in tests were directly generated as byte
  arrays.

- After the changing type of wallet.Sig from byte array to interface,
  this does not work.

- Hence, use the wallet randomizer to generate signatures needed for
  tests.

Signed-off-by: Manoranjith <[email protected]>

- Previously, VerifySignature function is defined on the wallet backend.

- This looked fine, because until recently, wallet.Sig was defined
  as a byte array.

- But, now it has been redefined as an interface with each wallet
  implementation implementing the wallet.Sig interface.

- Hence, moved the VerifySignature method from wallet.Backend to
  wallet.Sig interface.

Signed-off-by: Manoranjith <[email protected]>

Signed-off-by: Manoranjith <[email protected]>

Signed-off-by: Manoranjith <[email protected]>

Signed-off-by: Manoranjith <[email protected]>