encrypt.py 文件源码

def EVP_BytesToKey(password, key_len, iv_len):
    # equivalent to OpenSSL's EVP_BytesToKey() with count 1
    # so that we make the same key and iv as nodejs version
    if hasattr(password, 'encode'):
        password = password.encode('utf-8')
    cached_key = '%s-%d-%d' % (password, key_len, iv_len)
    r = cached_keys.get(cached_key, None)
    if r:
        return r
    m = []
    i = 0
    while len(b''.join(m)) < (key_len + iv_len):
        md5 = hashlib.md5()
        data = password
        if i > 0:
            data = m[i - 1] + password
        md5.update(data)
        m.append(md5.digest())
        i += 1
    ms = b''.join(m)
    key = ms[:key_len]
    iv = ms[key_len:key_len + iv_len]
    cached_keys[cached_key] = (key, iv)
    return key, iv