Mnemonic phrases in BIP39 are not "selected words" chosen randomly, but rather:
The wallet uses high-quality random numbers (entropy).
The entropy is divided into several segments, each 11 bits.
Each segment corresponds to a word from the BIP39 fixed list of 2048 words.
Since each segment is independently random, it's possible for different segments to correspond to the same word → the appearance of repeated words is normal.
Probability of Repetition
Since each selection is made randomly from the same list of 2048 words, it is theoretically possible to select the same word, leading to repetition.
This is similar to "drawing cards": drawing 12/24 times from a deck of 2048 cards, drawing a duplicate card is completely normal.
Mnemonic Phrase Length | Probability of "at least one repeated word" |
12 Words | ≈ 3% (approx. 1/33) |
24 Words | ≈ 12% (approx. 1/8) |
In other words: for a 24-word phrase, the probability of repetition is ≈ 1 in 8 generations.
The security of a mnemonic phrase comes from the underlying number of random entropy bits (128 / 256 bits), not from whether the words are repeated. Even if repetitions occur, the randomness remains intact. Repetitions are merely a "natural manifestation of randomness" and do not weaken security.
Why is the Randomness of OneKey Hardware Wallet Mnemonic Phrases Reliable?
OneKey's Advantages:
✅ Open Source: Firmware and code are publicly auditable, ensuring transparent security.
✅ Uses EAL6+ Security Chip
Provides True Random Numbers (TRNG) at the hardware level.
Entropy quality is certified and evaluated.
Additionally, if you are not satisfied with the generated mnemonic phrase, you can regenerate a completely new set of mnemonic phrases on your OneKey hardware wallet and back them up properly.