add mnemonic generation methods with indexes option

bip39.c

@@ -55,6 +55,16 @@ const char *mnemonic_generate(int strength)
 	return mnemonic_from_data(data, strength / 8);
 }
 
+const uint16_t *mnemonic_generate_indexes(int strength)
+{
+	if (strength % 32 || strength < 128 || strength > 256) {
+		return 0;
+	}
+	uint8_t data[32];
+	random_buffer(data, 32);
+	return mnemonic_from_data_indexes(data, strength / 8);
+}
+
 const char *mnemonic_from_data(const uint8_t *data, int len)
 {
 	if (len % 4 || len < 16 || len > 32) {
@@ -89,6 +99,36 @@ const char *mnemonic_from_data(const uint8_t *data, int len)
 	return mnemo;
 }
 
+const uint16_t *mnemonic_from_data_indexes(const uint8_t *data, int len)
+{
+	if (len % 4 || len < 16 || len > 32) {
+		return 0;
+	}
+
+	uint8_t bits[32 + 1];
+
+	sha256_Raw(data, len, bits);
+	// checksum
+	bits[len] = bits[0];
+	// data
+	memcpy(bits, data, len);
+
+	int mlen = len * 3 / 4;
+	static uint16_t mnemo[24];
+
+	int i, j, idx;
+	for (i = 0; i < mlen; i++) {
+		idx = 0;
+		for (j = 0; j < 11; j++) {
+			idx <<= 1;
+			idx += (bits[(i * 11 + j) / 8] & (1 << (7 - ((i * 11 + j) % 8)))) > 0;
+		}
+		mnemo[i] = idx;
+	}
+
+	return mnemo;
+}
+
 int mnemonic_check(const char *mnemonic)
 {
 	if (!mnemonic) {

bip39.h

@@ -29,8 +29,10 @@
 #define BIP39_PBKDF2_ROUNDS 2048
 
 const char *mnemonic_generate(int strength);	// strength in bits
+const uint16_t *mnemonic_generate_indexes(int strength);	// strength in bits
 
 const char *mnemonic_from_data(const uint8_t *data, int len);
+const uint16_t *mnemonic_from_data_indexes(const uint8_t *data, int len);
 
 int mnemonic_check(const char *mnemonic);