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common/hash_u5: routines to hash 5 bit values.

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Needed for creating/verifying signatures on bolt11 invoices.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2017-10-26 13:30:19 +10:30
parent 20ce829f81
commit 753f15f503
3 changed files with 70 additions and 1 deletions
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3
common/Makefile
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@ -11,6 +11,7 @@ COMMON_SRC := \
common/derive_basepoints.c \
common/dev_disconnect.c \
common/funding_tx.c \
common/hash_u5.c \
common/htlc_state.c \
common/htlc_tx.c \
common/htlc_wire.c \
@ -54,7 +55,7 @@ common/gen_htlc_state_names.h: common/htlc_state.h ccan/ccan/cdump/tools/cdump-e
check-makefile: check-common-makefile
check-common-makefile:
@if [ x"`LC_ALL=C ls common/*.h | grep -v ^common/gen_`" != x"`echo $(COMMON_HEADERS_NOGEN) | tr ' ' '\n' | LC_ALL=C sort`" ]; then echo COMMON_HEADERS_NOGEN incorrect; exit 1; fi
if [ x"`LC_ALL=C ls common/*.h | grep -v ^common/gen_`" != x"`echo $(COMMON_HEADERS_NOGEN) | tr ' ' '\n' | LC_ALL=C sort`" ]; then echo COMMON_HEADERS_NOGEN incorrect; exit 1; fi
check-source-bolt: $(COMMON_SRC:%=bolt-check/%) $(COMMON_HEADERS:%=bolt-check/%)
check-whitespace: $(COMMON_SRC:%=check-whitespace/%) $(COMMON_HEADERS:%=check-whitespace/%)

47
common/hash_u5.c Normal file
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@ -0,0 +1,47 @@
#include <ccan/endian/endian.h>
#include <common/hash_u5.h>
#include <string.h>
void hash_u5_init(struct hash_u5 *hu5, const char *hrp)
{
hu5->buf = 0;
hu5->num_bits = 0;
sha256_init(&hu5->hash);
sha256_update(&hu5->hash, hrp, strlen(hrp));
}
void hash_u5(struct hash_u5 *hu5, const u8 *u5, size_t len)
{
size_t bits = len * 5;
while (bits) {
size_t n = 5;
if (bits < n)
n = bits;
hu5->buf <<= n;
hu5->buf |= (*u5 >> (5-n));
bits -= n;
hu5->num_bits += n;
if (n == 5)
u5++;
if (hu5->num_bits >= 32) {
be32 be32 = cpu_to_be32(hu5->buf >> (hu5->num_bits-32));
sha256_update(&hu5->hash, &be32, sizeof(be32));
hu5->num_bits -= 32;
}
}
}
void hash_u5_done(struct hash_u5 *hu5, struct sha256 *res)
{
if (hu5->num_bits) {
be32 be32 = cpu_to_be32(hu5->buf << (32 - hu5->num_bits));
sha256_update(&hu5->hash, &be32, (hu5->num_bits + 7) / 8);
}
sha256_done(&hu5->hash, res);
}

21
common/hash_u5.h Normal file
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@ -0,0 +1,21 @@
/* bech32 (thus bolt11) deal in 5-bit values */
#ifndef LIGHTNING_COMMON_HASH_U5_H
#define LIGHTNING_COMMON_HASH_U5_H
#include "config.h"
#include <ccan/crypto/sha256/sha256.h>
#include <ccan/short_types/short_types.h>
/* Type to annotate a 5 bit value. */
typedef unsigned char u5;
struct hash_u5 {
u64 buf;
unsigned int num_bits;
struct sha256_ctx hash;
};
void hash_u5_init(struct hash_u5 *hu5, const char *hrp);
void hash_u5(struct hash_u5 *hu5, const u5 *u5, size_t len);
void hash_u5_done(struct hash_u5 *hu5, struct sha256 *res);
#endif /* LIGHTNING_COMMON_HASH_U5_H */