Function Decode

src/bech32.cpp:159–190

Decode a Bech32 string. */

/** Decode a Bech32 string. */
std::pair<std::string, data> Decode(const std::string& str) {
    bool lower = false, upper = false;
    for (size_t i = 0; i < str.size(); ++i) {
        unsigned char c = str[i];
        if (c >= 'a' && c <= 'z') lower = true;
        else if (c >= 'A' && c <= 'Z') upper = true;
        else if (c < 33 || c > 126) return {};
    }
    if (lower && upper) return {};
    size_t pos = str.rfind('1');
    if (str.size() > 90 || pos == str.npos || pos == 0 || pos + 7 > str.size()) {
        return {};
    }
    data values(str.size() - 1 - pos);
    for (size_t i = 0; i < str.size() - 1 - pos; ++i) {
        unsigned char c = str[i + pos + 1];
        int8_t rev = CHARSET_REV[c];

        if (rev == -1) {
            return {};
        }
        values[i] = rev;
    }
    std::string hrp;
    for (size_t i = 0; i < pos; ++i) {
        hrp += LowerCase(str[i]);
    }
    if (!VerifyChecksum(hrp, values)) {
        return {};
    }
    return {hrp, data(values.begin(), values.end() - 6)};
}

} // namespace bech32