Depend on bitcoin/rand for rand (#261)

Rand is already available in secp256k1/rand transiently through rust
bitcoin. rand-std is also an option to for std environments but having
wide support seems more important in the near term than adding all of
those feature flags.

This fixes #258 which
may have been triggering in an environment where bitcoin/rand was not
available.

payjoin/Cargo.toml

@@ -16,9 +16,9 @@ exclude = ["tests"]
 
 [features]
 send = []
-receive = ["rand"]
+receive = ["bitcoin/rand"]
 base64 = ["bitcoin/base64"]
-v2 = ["bitcoin/rand-std", "bitcoin/serde", "chacha20poly1305", "ohttp", "bhttp", "serde"]
+v2 = ["bitcoin/rand", "bitcoin/serde", "chacha20poly1305", "ohttp", "bhttp", "serde"]
 
 [dependencies]
 bitcoin = { version = "0.30.0", features = ["base64"] }
@@ -27,7 +27,6 @@ chacha20poly1305 = { version = "0.10.1", optional = true }
 log = { version = "0.4.14"}
 ohttp = { version = "0.5.1", optional = true }
 bhttp = { version = "0.5.1", optional = true }
-rand = { version = "0.8.4", optional = true }
 serde = { version = "1.0.186", default-features = false, optional = true }
 url = "2.2.2"
 serde_json = "1.0.108"

payjoin/src/receive/mod.rs

@@ -35,11 +35,11 @@ mod optional_parameters;
 #[cfg(feature = "v2")]
 pub mod v2;
 
+use bitcoin::secp256k1::rand::seq::SliceRandom;
+use bitcoin::secp256k1::rand::{self, Rng};
 pub use error::{Error, RequestError, SelectionError};
 use error::{InternalRequestError, InternalSelectionError};
 use optional_parameters::Params;
-use rand::seq::SliceRandom;
-use rand::Rng;
 
 use crate::input_type::InputType;
 use crate::psbt::PsbtExt;

payjoin/src/receive/v2.rs

@@ -1,6 +1,7 @@
 use std::collections::HashMap;
 
 use bitcoin::psbt::Psbt;
+use bitcoin::secp256k1::rand;
 use bitcoin::{base64, Amount, FeeRate, OutPoint, Script, TxOut};
 use serde::ser::SerializeStruct;
 use serde::{Deserialize, Serialize, Serializer};

payjoin/src/send/mod.rs

@@ -29,6 +29,8 @@ use std::str::FromStr;
 use bitcoin::address::NetworkChecked;
 use bitcoin::psbt::Psbt;
 #[cfg(feature = "v2")]
+use bitcoin::secp256k1::rand;
+#[cfg(feature = "v2")]
 use bitcoin::secp256k1::PublicKey;
 use bitcoin::{FeeRate, Script, ScriptBuf, Sequence, TxOut, Weight};
 pub use error::{CreateRequestError, ResponseError, ValidationError};