1 use bitcoin::blockdata::script::{Script,Builder};
2 use bitcoin::blockdata::opcodes;
3 use bitcoin::util::hash::Hash160;
5 use secp256k1::key::{PublicKey,SecretKey};
6 use secp256k1::Secp256k1;
9 use crypto::digest::Digest;
10 use crypto::ripemd160::Ripemd160;
12 use util::sha2::Sha256;
14 // Various functions for key derivation and transaction creation for use within channels. Primarily
15 // used in Channel and ChannelMonitor.
17 pub fn build_commitment_secret(commitment_seed: [u8; 32], idx: u64) -> [u8; 32] {
18 let mut res: [u8; 32] = commitment_seed;
21 if idx & (1 << bitpos) == (1 << bitpos) {
22 res[bitpos / 8] ^= 1 << (bitpos & 7);
23 let mut sha = Sha256::new();
31 pub fn derive_private_key(secp_ctx: &Secp256k1, per_commitment_point: &PublicKey, base_secret: &SecretKey) -> Result<SecretKey, secp256k1::Error> {
32 let mut sha = Sha256::new();
33 sha.input(&per_commitment_point.serialize());
34 sha.input(&PublicKey::from_secret_key(&secp_ctx, &base_secret).unwrap().serialize());
35 let mut res = [0; 32];
38 let mut key = base_secret.clone();
39 key.add_assign(&secp_ctx, &SecretKey::from_slice(&secp_ctx, &res)?)?;
43 pub fn derive_public_key(secp_ctx: &Secp256k1, per_commitment_point: &PublicKey, base_point: &PublicKey) -> Result<PublicKey, secp256k1::Error> {
44 let mut sha = Sha256::new();
45 sha.input(&per_commitment_point.serialize());
46 sha.input(&base_point.serialize());
47 let mut res = [0; 32];
50 let hashkey = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&secp_ctx, &res)?).unwrap();
51 base_point.combine(&secp_ctx, &hashkey)
54 /// Derives a revocation key from its constituent parts
55 pub fn derive_private_revocation_key(secp_ctx: &Secp256k1, per_commitment_secret: &SecretKey, revocation_base_secret: &SecretKey) -> Result<SecretKey, secp256k1::Error> {
56 let revocation_base_point = PublicKey::from_secret_key(&secp_ctx, &revocation_base_secret).unwrap();
57 let per_commitment_point = PublicKey::from_secret_key(&secp_ctx, &per_commitment_secret).unwrap();
59 let rev_append_commit_hash_key = {
60 let mut sha = Sha256::new();
61 sha.input(&revocation_base_point.serialize());
62 sha.input(&per_commitment_point.serialize());
63 let mut res = [0; 32];
66 SecretKey::from_slice(&secp_ctx, &res)?
68 let commit_append_rev_hash_key = {
69 let mut sha = Sha256::new();
70 sha.input(&per_commitment_point.serialize());
71 sha.input(&revocation_base_point.serialize());
72 let mut res = [0; 32];
75 SecretKey::from_slice(&secp_ctx, &res)?
78 let mut part_a = revocation_base_secret.clone();
79 part_a.mul_assign(&secp_ctx, &rev_append_commit_hash_key)?;
80 let mut part_b = per_commitment_secret.clone();
81 part_b.mul_assign(&secp_ctx, &commit_append_rev_hash_key)?;
82 part_a.add_assign(&secp_ctx, &part_b)?;
86 pub fn derive_public_revocation_key(secp_ctx: &Secp256k1, per_commitment_point: &PublicKey, revocation_base_point: &PublicKey) -> Result<PublicKey, secp256k1::Error> {
87 let rev_append_commit_hash_key = {
88 let mut sha = Sha256::new();
89 sha.input(&revocation_base_point.serialize());
90 sha.input(&per_commitment_point.serialize());
91 let mut res = [0; 32];
94 SecretKey::from_slice(&secp_ctx, &res)?
96 let commit_append_rev_hash_key = {
97 let mut sha = Sha256::new();
98 sha.input(&per_commitment_point.serialize());
99 sha.input(&revocation_base_point.serialize());
100 let mut res = [0; 32];
101 sha.result(&mut res);
103 SecretKey::from_slice(&secp_ctx, &res)?
106 let mut part_a = revocation_base_point.clone();
107 part_a.mul_assign(&secp_ctx, &rev_append_commit_hash_key)?;
108 let mut part_b = per_commitment_point.clone();
109 part_b.mul_assign(&secp_ctx, &commit_append_rev_hash_key)?;
110 part_a.combine(&secp_ctx, &part_b)
113 pub struct TxCreationKeys {
114 pub per_commitment_point: PublicKey,
115 pub revocation_key: PublicKey,
116 pub a_htlc_key: PublicKey,
117 pub b_htlc_key: PublicKey,
118 pub a_delayed_payment_key: PublicKey,
119 pub b_payment_key: PublicKey,
122 impl TxCreationKeys {
123 pub fn new(secp_ctx: &Secp256k1, per_commitment_point: &PublicKey, a_delayed_payment_base: &PublicKey, a_htlc_base: &PublicKey, b_revocation_base: &PublicKey, b_payment_base: &PublicKey, b_htlc_base: &PublicKey) -> Result<TxCreationKeys, secp256k1::Error> {
125 per_commitment_point: per_commitment_point.clone(),
126 revocation_key: derive_public_revocation_key(&secp_ctx, &per_commitment_point, &b_revocation_base)?,
127 a_htlc_key: derive_public_key(&secp_ctx, &per_commitment_point, &a_htlc_base)?,
128 b_htlc_key: derive_public_key(&secp_ctx, &per_commitment_point, &b_htlc_base)?,
129 a_delayed_payment_key: derive_public_key(&secp_ctx, &per_commitment_point, &a_delayed_payment_base)?,
130 b_payment_key: derive_public_key(&secp_ctx, &per_commitment_point, &b_payment_base)?,
135 /// Gets the "to_local" output redeemscript, ie the script which is time-locked or spendable by
136 /// the revocation key
137 pub fn get_revokeable_redeemscript(revocation_key: &PublicKey, to_self_delay: u16, delayed_payment_key: &PublicKey) -> Script {
138 Builder::new().push_opcode(opcodes::All::OP_IF)
139 .push_slice(&revocation_key.serialize())
140 .push_opcode(opcodes::All::OP_ELSE)
141 .push_int(to_self_delay as i64)
142 .push_opcode(opcodes::OP_CSV)
143 .push_opcode(opcodes::All::OP_DROP)
144 .push_slice(&delayed_payment_key.serialize())
145 .push_opcode(opcodes::All::OP_ENDIF)
146 .push_opcode(opcodes::All::OP_CHECKSIG)
151 pub struct HTLCOutputInCommitment {
153 pub amount_msat: u64,
154 pub cltv_expiry: u32,
155 pub payment_hash: [u8; 32],
156 pub transaction_output_index: u32,
160 pub fn get_htlc_redeemscript_with_explicit_keys(htlc: &HTLCOutputInCommitment, a_htlc_key: &PublicKey, b_htlc_key: &PublicKey, revocation_key: &PublicKey) -> Script {
161 let payment_hash160 = {
162 let mut ripemd = Ripemd160::new();
163 ripemd.input(&htlc.payment_hash);
164 let mut res = [0; 20];
165 ripemd.result(&mut res);
169 Builder::new().push_opcode(opcodes::All::OP_DUP)
170 .push_opcode(opcodes::All::OP_HASH160)
171 .push_slice(&Hash160::from_data(&revocation_key.serialize())[..])
172 .push_opcode(opcodes::All::OP_EQUAL)
173 .push_opcode(opcodes::All::OP_IF)
174 .push_opcode(opcodes::All::OP_CHECKSIG)
175 .push_opcode(opcodes::All::OP_ELSE)
176 .push_slice(&b_htlc_key.serialize()[..])
177 .push_opcode(opcodes::All::OP_SWAP)
178 .push_opcode(opcodes::All::OP_SIZE)
180 .push_opcode(opcodes::All::OP_EQUAL)
181 .push_opcode(opcodes::All::OP_NOTIF)
182 .push_opcode(opcodes::All::OP_DROP)
184 .push_opcode(opcodes::All::OP_SWAP)
185 .push_slice(&a_htlc_key.serialize()[..])
187 .push_opcode(opcodes::All::OP_CHECKMULTISIG)
188 .push_opcode(opcodes::All::OP_ELSE)
189 .push_opcode(opcodes::All::OP_HASH160)
190 .push_slice(&payment_hash160)
191 .push_opcode(opcodes::All::OP_EQUALVERIFY)
192 .push_opcode(opcodes::All::OP_CHECKSIG)
193 .push_opcode(opcodes::All::OP_ENDIF)
194 .push_opcode(opcodes::All::OP_ENDIF)
197 Builder::new().push_opcode(opcodes::All::OP_DUP)
198 .push_opcode(opcodes::All::OP_HASH160)
199 .push_slice(&Hash160::from_data(&revocation_key.serialize())[..])
200 .push_opcode(opcodes::All::OP_EQUAL)
201 .push_opcode(opcodes::All::OP_IF)
202 .push_opcode(opcodes::All::OP_CHECKSIG)
203 .push_opcode(opcodes::All::OP_ELSE)
204 .push_slice(&b_htlc_key.serialize()[..])
205 .push_opcode(opcodes::All::OP_SWAP)
206 .push_opcode(opcodes::All::OP_SIZE)
208 .push_opcode(opcodes::All::OP_EQUAL)
209 .push_opcode(opcodes::All::OP_IF)
210 .push_opcode(opcodes::All::OP_HASH160)
211 .push_slice(&payment_hash160)
212 .push_opcode(opcodes::All::OP_EQUALVERIFY)
214 .push_opcode(opcodes::All::OP_SWAP)
215 .push_slice(&a_htlc_key.serialize()[..])
217 .push_opcode(opcodes::All::OP_CHECKMULTISIG)
218 .push_opcode(opcodes::All::OP_ELSE)
219 .push_opcode(opcodes::All::OP_DROP)
220 .push_int(htlc.cltv_expiry as i64)
221 .push_opcode(opcodes::OP_CLTV)
222 .push_opcode(opcodes::All::OP_DROP)
223 .push_opcode(opcodes::All::OP_CHECKSIG)
224 .push_opcode(opcodes::All::OP_ENDIF)
225 .push_opcode(opcodes::All::OP_ENDIF)
230 /// note here that 'a_revocation_key' is generated using b_revocation_basepoint and a's
231 /// commitment secret. 'htlc' does *not* need to have its previous_output_index filled.
233 pub fn get_htlc_redeemscript(htlc: &HTLCOutputInCommitment, keys: &TxCreationKeys) -> Script {
234 get_htlc_redeemscript_with_explicit_keys(htlc, &keys.a_htlc_key, &keys.b_htlc_key, &keys.revocation_key)