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hsmd_wire: add HSM wire protocol support for secret type detection
Public commit record
73/100 · Adequate
What the developer wrote
Authored by Sangbida Chaudhuri
hsmd_wire: add HSM wire protocol support for secret type detection
Add TLV field to hsmd_init_reply_v4 to communicate the HSM secret type
(mnemonic vs legacy) from HSM to lightningd. This allows lightningd to
automatically determine whether to use BIP86 or BIP32 derivation without
needing separate address types.
✓ Specific, descriptive subject✓ Names a concrete action or component✓ Provides detailed explanatory context
What changed, and why it matters
This commit adds a small metadata field to the internal HSM (Hardware Security Module) initialization message so that lightningd can tell whether the wallet seed was created from a mnemonic phrase or from an older legacy secret. It is a protocol plumbing change, not a fix for a known vulnerability, and does not by itself change how secrets are generated, stored, or protected.
Recommended action
No immediate security action required. Review as part of normal code review; ensure downstream consumers of hsm_secret_type handle unknown/legacy values safely and that TLV parsing rejects invalid lengths.
Security signals we found
01
Adds new wire-protocol TLV field for HSM secret type metadata
02
Touches HSM initialization reply path
03
Does not alter secret generation, storage, or access-control logic
04
No mention of vulnerability, CVE, or security fix in commit message
Evidence from the diff
The patch extends the hsmd_init_reply_v4 wire message with an optional TLV field hsm_secret_type (type 1, u8). The HSM now includes the secret type when replying to lightningd during initialization, and lightningd parses the new TLV. The change is backward-compatible because TLV fields are optional and ignored if not understood. Supporting test stubs and a new HSM version capability hash are updated accordingly. No cryptographic operations, access controls, or secret-handling paths are modified.
Changed components
hsmd/hsmd.chsmd/libhsmd.chsmd/libhsmd.hhsmd/hsmd_wire.csvlightningd/hsm_control.ccommon/hsm_version.hInspect captured patch +25 / −14
diff --git a/common/hsm_version.h b/common/hsm_version.h
index 5b7df62..5e78238 100644
--- a/common/hsm_version.h
+++ b/common/hsm_version.h
@@ -31,6 +31,7 @@
* v6 with bip137_sign_message: 4bfe28b02e92aae276b8eca2228e32f32d5dee8d5381639e7364939fa2fa1370
* v6 with hsm_passphrase changes: c646d557d7561dd885df3cad5b99c82895cda4b040699f3853980ec61b2873fa
* v6 with hsm_secret struct cleanup: 06c56396fe42f4f47911d7f865dd0004d264fc1348f89547743755b6b33fec90
+ * v6 with hsm_secret_type TLV: 7bb5deb2367482feb084d304ee14b2373d42910ad56484fbf47614dbb3d4cb74
*/
#define HSM_MIN_VERSION 5
#define HSM_MAX_VERSION 6
diff --git a/hsmd/hsmd.c b/hsmd/hsmd.c
index 1205d14..11bcfe2 100644
--- a/hsmd/hsmd.c
+++ b/hsmd/hsmd.c
@@ -554,7 +554,7 @@ static struct io_plan *init_hsm(struct io_conn *conn,
return req_reply(conn, c, hsmd_init(hsm_secret->secret_data,
tal_bytelen(hsm_secret->secret_data),
hsmd_mutual_version,
- bip32_key_version));
+ bip32_key_version, hsm_secret->type));
}
/*~ Since we process requests then service them in strict order, and because
diff --git a/hsmd/hsmd_wire.csv b/hsmd/hsmd_wire.csv
index 95ef50d..6472147 100644
--- a/hsmd/hsmd_wire.csv
+++ b/hsmd/hsmd_wire.csv
@@ -46,6 +46,10 @@ msgdata,hsmd_init_reply_v4,hsm_capabilities,u32,num_hsm_capabilities
msgdata,hsmd_init_reply_v4,node_id,node_id,
msgdata,hsmd_init_reply_v4,bip32,ext_key,
msgdata,hsmd_init_reply_v4,bolt12,pubkey,
+msgdata,hsmd_init_reply_v4,tlvs,hsmd_init_reply_v4_tlvs,
+# TLV to indicate HSM secret type
+tlvtype,hsmd_init_reply_v4_tlvs,hsm_secret_type,1
+tlvdata,hsmd_init_reply_v4_tlvs,hsm_secret_type,hsm_type,u8,
# HSM initialization failure response
msgtype,hsmd_init_reply_failure,115
diff --git a/hsmd/libhsmd.c b/hsmd/libhsmd.c
index 1f1096b..bff142b 100644
--- a/hsmd/libhsmd.c
+++ b/hsmd/libhsmd.c
@@ -2450,7 +2450,7 @@ void bip86_key(struct privkey *privkey, struct pubkey *pubkey, u32 index)
}
u8 *hsmd_init(const u8 *secret_data, size_t secret_len, const u64 hsmd_version,
- struct bip32_key_version bip32_key_version)
+ struct bip32_key_version bip32_key_version, u8 hsm_secret_type)
{
u8 bip32_seed[BIP32_ENTROPY_LEN_256];
struct pubkey key, bolt12;
@@ -2608,8 +2608,13 @@ u8 *hsmd_init(const u8 *secret_data, size_t secret_len, const u64 hsmd_version,
* And version is 4: we offer limited compatibility (or at least,
* incompatibility detection) with alternate implementations.
*/
+ /* Create TLV with HSM secret type */
+ struct tlv_hsmd_init_reply_v4_tlvs *tlvs = tlv_hsmd_init_reply_v4_tlvs_new(tmpctx);
+ tlvs->hsm_secret_type = tal(tlvs, u8);
+ *tlvs->hsm_secret_type = hsm_secret_type;
+
return take(towire_hsmd_init_reply_v4(
- NULL, hsmd_version, caps,
- &node_id, &secretstuff.bip32,
- &bolt12));
+ NULL, hsmd_version, caps,
+ &node_id, &secretstuff.bip32,
+ &bolt12, tlvs));
}
diff --git a/hsmd/libhsmd.h b/hsmd/libhsmd.h
index fe6aa47..484089d 100644
--- a/hsmd/libhsmd.h
+++ b/hsmd/libhsmd.h
@@ -47,7 +47,7 @@ struct hsmd_client {
* `lightningd`.
*/
u8 *hsmd_init(const u8 *secret_data, size_t secret_len, const u64 hsmd_version,
- struct bip32_key_version bip32_key_version);
+ struct bip32_key_version bip32_key_version, u8 hsm_secret_type);
struct hsmd_client *hsmd_client_new_main(const tal_t *ctx, u64 capabilities,
void *extra);
diff --git a/lightningd/hsm_control.c b/lightningd/hsm_control.c
index ae13a08..f8be6cc 100644
--- a/lightningd/hsm_control.c
+++ b/lightningd/hsm_control.c
@@ -146,11 +146,12 @@ struct ext_key *hsm_init(struct lightningd *ld)
}
/* Check for successful init reply */
+ struct tlv_hsmd_init_reply_v4_tlvs *tlvs;
if (fromwire_hsmd_init_reply_v4(ld, msg,
&hsm_version,
&ld->hsm_capabilities,
&ld->our_nodeid, bip32_base,
- &unused)) {
+ &unused, &tlvs)) {
/* nothing to do. */
} else {
/* Unknown message type */
diff --git a/lightningd/test/run-find_my_abspath.c b/lightningd/test/run-find_my_abspath.c
index 9953225..14a3998 100644
--- a/lightningd/test/run-find_my_abspath.c
+++ b/lightningd/test/run-find_my_abspath.c
@@ -12,6 +12,9 @@ int unused_main(int argc, char *argv[]);
/* Generated stub for begin_topology */
void begin_topology(struct chain_topology *topo UNNEEDED)
{ fprintf(stderr, "begin_topology called!\n"); abort(); }
+/* Generated stub for bip86_pubkey */
+void bip86_pubkey(struct lightningd *ld UNNEEDED, struct pubkey *pubkey UNNEEDED, u32 index UNNEEDED)
+{ fprintf(stderr, "bip86_pubkey called!\n"); abort(); }
/* Generated stub for channel_gossip_notify_new_block */
void channel_gossip_notify_new_block(struct lightningd *ld UNNEEDED)
{ fprintf(stderr, "channel_gossip_notify_new_block called!\n"); abort(); }
@@ -209,6 +212,9 @@ u8 *towire_hsmd_ecdh_req(const tal_t *ctx UNNEEDED, const struct pubkey *point U
void txfilter_add_derkey(struct txfilter *filter UNNEEDED,
const u8 derkey[PUBKEY_CMPR_LEN])
{ fprintf(stderr, "txfilter_add_derkey called!\n"); abort(); }
+/* Generated stub for txfilter_add_scriptpubkey */
+void txfilter_add_scriptpubkey(struct txfilter *filter UNNEEDED, const u8 *script TAKES UNNEEDED)
+{ fprintf(stderr, "txfilter_add_scriptpubkey called!\n"); abort(); }
/* Generated stub for txfilter_new */
struct txfilter *txfilter_new(const tal_t *ctx UNNEEDED)
{ fprintf(stderr, "txfilter_new called!\n"); abort(); }
@@ -227,12 +233,6 @@ struct wallet *wallet_new(struct lightningd *ld UNNEEDED, struct timers *timers
/* Generated stub for wallet_sanity_check */
bool wallet_sanity_check(struct wallet *w UNNEEDED)
{ fprintf(stderr, "wallet_sanity_check called!\n"); abort(); }
-/* Generated stub for bip86_pubkey */
-void bip86_pubkey(struct lightningd *ld UNNEEDED, struct pubkey *pubkey UNNEEDED, u32 index UNNEEDED)
-{ fprintf(stderr, "bip86_pubkey called!\n"); abort(); }
-/* Generated stub for txfilter_add_scriptpubkey */
-void txfilter_add_scriptpubkey(struct txfilter *filter UNNEEDED, const u8 *script TAKES UNNEEDED)
-{ fprintf(stderr, "txfilter_add_scriptpubkey called!\n"); abort(); }
/* AUTOGENERATED MOCKS END */
struct logger *crashlog;
diff --git a/wallet/test/run-wallet.c b/wallet/test/run-wallet.c
index d3087cc..a91ec6d 100644
--- a/wallet/test/run-wallet.c
+++ b/wallet/test/run-wallet.c
@@ -343,7 +343,7 @@ bool fromwire_hsmd_get_output_scriptpubkey_reply(const tal_t *ctx UNNEEDED, cons
bool fromwire_hsmd_init_reply_failure(const tal_t *ctx UNNEEDED, const void *p UNNEEDED, u32 *error_code UNNEEDED, wirestring **error_message UNNEEDED)
{ fprintf(stderr, "fromwire_hsmd_init_reply_failure called!\n"); abort(); }
/* Generated stub for fromwire_hsmd_init_reply_v4 */
-bool fromwire_hsmd_init_reply_v4(const tal_t *ctx UNNEEDED, const void *p UNNEEDED, u32 *hsm_version UNNEEDED, u32 **hsm_capabilities UNNEEDED, struct node_id *node_id UNNEEDED, struct ext_key *bip32 UNNEEDED, struct pubkey *bolt12 UNNEEDED)
+bool fromwire_hsmd_init_reply_v4(const tal_t *ctx UNNEEDED, const void *p UNNEEDED, u32 *hsm_version UNNEEDED, u32 **hsm_capabilities UNNEEDED, struct node_id *node_id UNNEEDED, struct ext_key *bip32 UNNEEDED, struct pubkey *bolt12 UNNEEDED, struct tlv_hsmd_init_reply_v4_tlvs **tlvs UNNEEDED)
{ fprintf(stderr, "fromwire_hsmd_init_reply_v4 called!\n"); abort(); }
/* Generated stub for fromwire_hsmd_new_channel_reply */
bool fromwire_hsmd_new_channel_reply(const void *p UNNEEDED)
Risk score
Our methodology →Why this scored 19/100
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