Add function generating the payinfo

Cargo.lock

@@ -6442,8 +6442,14 @@ name = "nym-compact-ecash"
 version = "0.1.0"
 dependencies = [
  "bls12_381 0.6.0",
+<<<<<<< HEAD
  "bs58 0.4.0",
  "criterion 0.3.6",
+=======
+ "bs58",
+ "chrono",
+ "criterion",
+>>>>>>> 4a54fd93f (Add function generating the payinfo)
  "digest 0.9.0",
  "ff 0.11.1",
  "getset",

common/nym_offline_compact_ecash/Cargo.toml

@@ -7,6 +7,7 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+chrono = "0.4.19"
 #bls12_381 = { version = "0.5", default-features = false, features = ["pairings", "alloc", "experimental"] }
 bls12_381 = { path = "/Users/simon/Documents/Nym/github/andrew_bls12_381", default-features = false, features = ["alloc", "pairings", "experimental", "zeroize"] }
 itertools = "0.10"

common/nym_offline_compact_ecash/src/scheme/mod.rs

@@ -7,7 +7,7 @@ use getset::{CopyGetters, Getters};
 
 use crate::error::{CompactEcashError, Result};
 use crate::proofs::proof_spend::{SpendInstance, SpendProof, SpendWitness};
-use crate::scheme::keygen::{SecretKeyUser, VerificationKeyAuth};
+use crate::scheme::keygen::{SecretKeyUser, VerificationKeyAuth, PublicKeyUser};
 use crate::scheme::setup::{GroupParameters, Parameters};
 use crate::traits::Bytable;
 use crate::utils::{
@@ -15,6 +15,8 @@ use crate::utils::{
     try_deserialize_g2_projective, try_deserialize_scalar, Signature, SignerIndex,
 };
 use crate::{Attribute, Base58};
+use chrono::{Utc, Timelike};
+use rand::{Rng, thread_rng};
 
 pub mod aggregation;
 pub mod identify;
@@ -316,6 +318,24 @@ pub struct PayInfo {
     pub info: [u8; 32],
 }
 
+pub fn generate_payinfo(provider_pk: PublicKeyUser) -> Vec<u8>{
+    let mut rng = thread_rng();
+    let mut rbytes = [0u8; 32];
+    rng.fill(&mut rbytes);
+
+    let timestamp = Utc::now().timestamp();
+    let timestamp_bytes: [u8; 8] = timestamp.to_be_bytes();
+
+    let ppk_bytes = provider_pk.pk.to_affine().to_compressed();
+
+    let mut payinfo = Vec::with_capacity(32 + 8 +48);
+    payinfo.extend_from_slice(&rbytes);
+    payinfo.extend_from_slice(&timestamp_bytes);
+    payinfo.extend_from_slice(&ppk_bytes);
+    
+    payinfo
+}
+
 #[derive(Debug, Clone, PartialEq)]
 pub struct Payment {
     pub kappa: G2Projective,