{'fraction_non_alphanumeric': 0.019409937888198756, 'fraction_numerical': 0.0015527950310559005, 'mean_word_length': 5.080188679245283, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Many-Time Restrictive Blind Signatures

Probably the most successful application of blind signatures is electronic cash. In order to avoid multiple copies of the same electronic coin, one-time blind signatures are of particular importance, i.e., a recipient can obtain a signature for at most one message from each interaction with a signer. In offline electronic cash, customers who spend their electronic coins more than a specified number of times should get identified at least after the fact. This can be ensured by one-time restrictive blind signatures. Another important application of blind signatures are untraceable membership cards that can be used arbitrarily often, but only by their respective owners. An efficient cryptographic approach was presented at the Information Hiding Workshop ’98. At its heart, a special signature scheme is specified and used for which no implementation has been given yet. It turns out that many-time restrictive blind signatures meet this specification. We present a first implementation of this new class of signature schemes. It uses no hash function, is about half as efficient as previous one-time restrictive blind signatures and its security rests on a similar assumption as selective unforgeability of the pure ElGamal signature scheme.