feat(crypto): update segwit_addr to support Bech32m

crypto/segwit_addr.c

@@ -1,4 +1,4 @@
-/* Copyright (c) 2017 Pieter Wuille
+/* Copyright (c) 2017, 2021 Pieter Wuille
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -24,7 +24,7 @@
 
 #include "segwit_addr.h"
 
-uint32_t bech32_polymod_step(uint32_t pre) {
+static uint32_t bech32_polymod_step(uint32_t pre) {
     uint8_t b = pre >> 25;
     return ((pre & 0x1FFFFFF) << 5) ^
         (-((b >> 0) & 1) & 0x3b6a57b2UL) ^
@@ -34,6 +34,12 @@ uint32_t bech32_polymod_step(uint32_t pre) {
         (-((b >> 4) & 1) & 0x2a1462b3UL);
 }
 
+static uint32_t bech32_final_constant(bech32_encoding enc) {
+    if (enc == BECH32_ENCODING_BECH32) return 1;
+    if (enc == BECH32_ENCODING_BECH32M) return 0x2bc830a3;
+    return 0;
+}
+
 static const char* charset = "qpzry9x8gf2tvdw0s3jn54khce6mua7l";
 
 static const int8_t charset_rev[128] = {
@@ -47,7 +53,7 @@ static const int8_t charset_rev[128] = {
      1,  0,  3, 16, 11, 28, 12, 14,  6,  4,  2, -1, -1, -1, -1, -1
 };
 
-int bech32_encode(char *output, const char *hrp, const uint8_t *data, size_t data_len) {
+int bech32_encode(char *output, const char *hrp, const uint8_t *data, size_t data_len, bech32_encoding enc) {
     uint32_t chk = 1;
     size_t i = 0;
     while (hrp[i] != 0) {
@@ -75,7 +81,7 @@ int bech32_encode(char *output, const char *hrp, const uint8_t *data, size_t dat
     for (i = 0; i < 6; ++i) {
         chk = bech32_polymod_step(chk);
     }
-    chk ^= 1;
+    chk ^= bech32_final_constant(enc);
     for (i = 0; i < 6; ++i) {
         *(output++) = charset[(chk >> ((5 - i) * 5)) & 0x1f];
     }
@@ -83,14 +89,14 @@ int bech32_encode(char *output, const char *hrp, const uint8_t *data, size_t dat
     return 1;
 }
 
-int bech32_decode(char* hrp, uint8_t *data, size_t *data_len, const char *input) {
+bech32_encoding bech32_decode(char* hrp, uint8_t *data, size_t *data_len, const char *input) {
     uint32_t chk = 1;
     size_t i = 0;
     size_t input_len = strlen(input);
     size_t hrp_len = 0;
     int have_lower = 0, have_upper = 0;
     if (input_len < 8 || input_len > 90) {
-        return 0;
+        return BECH32_ENCODING_NONE;
     }
     *data_len = 0;
     while (*data_len < input_len && input[(input_len - 1) - *data_len] != '1') {
@@ -98,13 +104,13 @@ int bech32_decode(char* hrp, uint8_t *data, size_t *data_len, const char *input)
     }
     hrp_len = input_len - (1 + *data_len);
     if (1 + *data_len >= input_len || *data_len < 6) {
-        return 0;
+        return BECH32_ENCODING_NONE;
     }
     *(data_len) -= 6;
     for (i = 0; i < hrp_len; ++i) {
         int ch = input[i];
         if (ch < 33 || ch > 126) {
-            return 0;
+            return BECH32_ENCODING_NONE;
         }
         if (ch >= 'a' && ch <= 'z') {
             have_lower = 1;
@@ -126,7 +132,7 @@ int bech32_decode(char* hrp, uint8_t *data, size_t *data_len, const char *input)
         if (input[i] >= 'a' && input[i] <= 'z') have_lower = 1;
         if (input[i] >= 'A' && input[i] <= 'Z') have_upper = 1;
         if (v == -1) {
-            return 0;
+            return BECH32_ENCODING_NONE;
         }
         chk = bech32_polymod_step(chk) ^ v;
         if (i + 6 < input_len) {
@@ -135,9 +141,15 @@ int bech32_decode(char* hrp, uint8_t *data, size_t *data_len, const char *input)
         ++i;
     }
     if (have_lower && have_upper) {
-        return 0;
+        return BECH32_ENCODING_NONE;
+    }
+    if (chk == bech32_final_constant(BECH32_ENCODING_BECH32)) {
+        return BECH32_ENCODING_BECH32;
+    } else if (chk == bech32_final_constant(BECH32_ENCODING_BECH32M)) {
+        return BECH32_ENCODING_BECH32M;
+    } else {
+        return BECH32_ENCODING_NONE;
     }
-    return chk == 1;
 }
 
 static int convert_bits(uint8_t* out, size_t* outlen, int outbits, const uint8_t* in, size_t inlen, int inbits, int pad) {
@@ -165,23 +177,28 @@ static int convert_bits(uint8_t* out, size_t* outlen, int outbits, const uint8_t
 int segwit_addr_encode(char *output, const char *hrp, int witver, const uint8_t *witprog, size_t witprog_len) {
     uint8_t data[65] = {0};
     size_t datalen = 0;
+    bech32_encoding enc = BECH32_ENCODING_BECH32;
     if (witver > 16) return 0;
     if (witver == 0 && witprog_len != 20 && witprog_len != 32) return 0;
     if (witprog_len < 2 || witprog_len > 40) return 0;
+    if (witver > 0) enc = BECH32_ENCODING_BECH32M;
     data[0] = witver;
     convert_bits(data + 1, &datalen, 5, witprog, witprog_len, 8, 1);
     ++datalen;
-    return bech32_encode(output, hrp, data, datalen);
+    return bech32_encode(output, hrp, data, datalen, enc);
 }
 
 int segwit_addr_decode(int* witver, uint8_t* witdata, size_t* witdata_len, const char* hrp, const char* addr) {
     uint8_t data[84] = {0};
     char hrp_actual[84] = {0};
     size_t data_len = 0;
-    if (!bech32_decode(hrp_actual, data, &data_len, addr)) return 0;
+    bech32_encoding enc = bech32_decode(hrp_actual, data, &data_len, addr);
+    if (enc == BECH32_ENCODING_NONE) return 0;
     if (data_len == 0 || data_len > 65) return 0;
     if (strncmp(hrp, hrp_actual, 84) != 0) return 0;
     if (data[0] > 16) return 0;
+    if (data[0] == 0 && enc != BECH32_ENCODING_BECH32) return 0;
+    if (data[0] > 0 && enc != BECH32_ENCODING_BECH32M) return 0;
     *witdata_len = 0;
     if (!convert_bits(witdata, witdata_len, 8, data + 1, data_len - 1, 5, 0)) return 0;
     if (*witdata_len < 2 || *witdata_len > 40) return 0;

crypto/segwit_addr.h

@@ -1,4 +1,4 @@
-/* Copyright (c) 2017 Pieter Wuille
+/* Copyright (c) 2017, 2021 Pieter Wuille
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -24,6 +24,7 @@
 
 #include <stdint.h>
 
+
 /** Encode a SegWit address
  *
  *  Out: output:   Pointer to a buffer of size 73 + strlen(hrp) that will be
@@ -35,8 +36,13 @@
  *       prog_len: Number of data bytes in prog.
  *  Returns 1 if successful.
  */
-int segwit_addr_encode(char *output, const char *hrp, int ver,
-                       const uint8_t *prog, size_t prog_len);
+int segwit_addr_encode(
+    char *output,
+    const char *hrp,
+    int ver,
+    const uint8_t *prog,
+    size_t prog_len
+);
 
 /** Decode a SegWit address
  *
@@ -44,27 +50,47 @@ int segwit_addr_encode(char *output, const char *hrp, int ver,
  *                 program version (between 0 and 16 inclusive).
  *       prog:     Pointer to a buffer of size 40 that will be updated to
  *                 contain the witness program bytes.
- *       prog_len: Pointer to a size_t that will be updated to contain the
- * length of bytes in prog. hrp:      Pointer to the null-terminated human
- * readable part that is expected (chain/network specific). addr:     Pointer to
- * the null-terminated address. Returns 1 if successful.
+ *       prog_len: Pointer to a size_t that will be updated to contain the length
+ *                 of bytes in prog.
+ *       hrp:      Pointer to the null-terminated human readable part that is
+ *                 expected (chain/network specific).
+ *       addr:     Pointer to the null-terminated address.
+ *  Returns 1 if successful.
  */
-int segwit_addr_decode(int *ver, uint8_t *prog, size_t *prog_len,
-                       const char *hrp, const char *addr);
+int segwit_addr_decode(
+    int* ver,
+    uint8_t* prog,
+    size_t* prog_len,
+    const char* hrp,
+    const char* addr
+);
 
-/** Encode a Bech32 string
+/** Supported encodings. */
+typedef enum {
+    BECH32_ENCODING_NONE,
+    BECH32_ENCODING_BECH32,
+    BECH32_ENCODING_BECH32M
+} bech32_encoding;
+
+/** Encode a Bech32 or Bech32m string
  *
  *  Out: output:  Pointer to a buffer of size strlen(hrp) + data_len + 8 that
  *                will be updated to contain the null-terminated Bech32 string.
  *  In: hrp :     Pointer to the null-terminated human readable part.
  *      data :    Pointer to an array of 5-bit values.
  *      data_len: Length of the data array.
+ *      enc:      Which encoding to use (BECH32_ENCODING_BECH32{,M}).
  *  Returns 1 if successful.
  */
-int bech32_encode(char *output, const char *hrp, const uint8_t *data,
-                  size_t data_len);
+int bech32_encode(
+    char *output,
+    const char *hrp,
+    const uint8_t *data,
+    size_t data_len,
+    bech32_encoding enc
+);
 
-/** Decode a Bech32 string
+/** Decode a Bech32 or Bech32m string
  *
  *  Out: hrp:      Pointer to a buffer of size strlen(input) - 6. Will be
  *                 updated to contain the null-terminated human readable part.
@@ -73,9 +99,15 @@ int bech32_encode(char *output, const char *hrp, const uint8_t *data,
  *       data_len: Pointer to a size_t that will be updated to be the number
  *                 of entries in data.
  *  In: input:     Pointer to a null-terminated Bech32 string.
- *  Returns 1 if succesful.
+ *  Returns BECH32_ENCODING_BECH32{,M} to indicate decoding was successful
+ *  with the specified encoding standard. BECH32_ENCODING_NONE is returned if
+ *  decoding failed.
  */
-int bech32_decode(char *hrp, uint8_t *data, size_t *data_len,
-                  const char *input);
+bech32_encoding bech32_decode(
+    char *hrp,
+    uint8_t *data,
+    size_t *data_len,
+    const char *input
+);
 
 #endif

crypto/tests/test_check_segwit.h

@@ -106,7 +106,7 @@ START_TEST(test_segwit) {
     size_t data_len;
     int res = bech32_decode(hrp, data, &data_len, valid_checksum[i]);
     ck_assert_int_eq(res, 1);
-    res = bech32_encode(rebuild, hrp, data, data_len);
+    res = bech32_encode(rebuild, hrp, data, data_len, BECH32_ENCODING_BECH32);
     ck_assert_int_eq(res, 1);
     ck_assert_int_eq(my_strncasecmp(rebuild, valid_checksum[i], 92), 0);
   }

legacy/firmware/.changelog.d/1656.added

@@ -0,0 +1 @@
+Support sending to Taproot addresses.