Simple Python and Javascript-based programs for generating valid BIP39 mnemonics, including reversible 'palindromic' mnemonics (i.e. reversible recovery phrases) that are BIP-39 compliant in terms of security, wordlist, and checksum, and that can be used offline as standalone applications (internet-less) without the need of an internet connection or third-party libraries, as all code is contained inline within the singular file (either python file or html file).

This repository currently contains three separate tools, which consist of two Python (.py) files and one Javascript-based app that is wrapped in an .html file, each of which works on a standalone basis independently either from the command-line or within an application (browser or compiler):

[bip39appv1_8.py] https://github.com/hatgit/BIP39-Mnemonic-Tools/blob/master/bip39appv1_8.py

[Palindromic_Mnemonic_Tool.py] https://github.com/hatgit/BIP39-Mnemonic-Tools/blob/master/Palindromic_Mnemonic_Tool.py

 [Palindromic-Mnemonic-Tool.html] https://github.com/hatgit/BIP39-Mnemonic-Tools/blob/master/Palindromic-Mnemonic-Tool.html

Description:

Simplified Python and Javascript programs for generating valid bip39 mnemonics, using an initial random entropy via the secrets module in Python for cryptographically secure entropy (for the Python-related .py files), and the Web3 Cryptography API (for the Javascript-based .html files) then revealing the entropy in its various formats including hex, as a binary string, and as a bytearray before hashing with the SHA256 algorithm to obtain the leading required number of bits from the hash digest in order to compute the checksum and complete the final groups of words shown as 11 bit strings that correspond to an index value for a word as per the BIP39 specification.

The resulting words can be used as valid BIP39 mnemonic recovery phrases for related compatible crypto wallets, and because these apps are early stage and under experimental development, they should be checked against more established tools, in order to confirm that a given entropy maps correctly to its resulting mnemonic words.

The general formula followed in the creation of BIP39-compliant mnemonics is as follows:

• Initial Entropy in bits /32 = checksum length in bits (this is equal to wordcount/3 == checksum length)

  Initial entropy mod 11 = remaining bits + checksum = last word

  Initial entropy + checksum = total bits /11 = total words. (total words can be either 12 or 24, depending on initial entropy length)

Example usage: For a 12-word mnemonic, 128 bits of entropy is needed, and then a 4 bit checksum is calculated from those 128 bits, resulting in a total of 132 bits, which become broken into groups of 11 bits each, where each group corresponds to an index value that represents a word on a list of 2048 words (2^11). A user can choose that the tool generates the entropy for them, to create the 128 bits randomly, or manually enter the 128 bits in the form of a hexidecimal string (i.e. a 32 character hex string, left-padded with 0x making it 34 characters total). In all cases the tool always computes the required checksum which is determinisitc and derived from the initial entropy, therefore, for user-supplied entropy the checksum should not be included as it will be automatically computed by the tool and appended to the end of the string before the final word group is derived.

Note: The palindromic 'reversible' mnemonics are simply regular BIP39-compliant ones that happen to also have the ability to reverse the order of their words and still be BIP39-compliant, this is only possible for certain mnemonics that meet specific criteria, and the author does not believe that there is any security loss for these reversible ones, as one would still need to brute-force the range of valid mnemonics in order to find ones that are also reversible.

IMPORTANT: The above entropy values shown in the above example should never be used with any real funds even when testing.