user84640: I used bitcoinj library for wallet and it generates 12 word mnemonic seed.
But I made changes in it and created 24 word mnemonic seed.
But I need to convert old 12 word mnemonic seed into new 24 word mnemonic seed.
Please help me with this.

user7272: This is not possible.
The mnemonic words are an encoding of the entropy used in the seed, essentially. A 12 word seed has less entropy than a 24 word one, so you cannot get 24 words out of it. Similarly, you cannot get a 24 word seed to turn into a 12 word one.
Your best bet is to generate a new 24 word seed and move funds over.

84640: <p>I used bitcoinj library for wallet and it generates 12 word mnemonic seed.</p>

<p>But I made changes in it and created 24 word mnemonic seed.</p>

<p>But I need to convert old 12 word mnemonic seed into new 24 word mnemonic seed.</p>

<p>Please help me with this.</p>
 7272: <p>This is not possible.</p>

<p>The mnemonic words are an encoding of the entropy used in the seed, essentially. A 12 word seed has less entropy than a 24 word one, so you cannot get 24 words out of it. Similarly, you cannot get a 24 word seed to turn into a 12 word one.</p>

<p>Your best bet is to generate a new 24 word seed and move funds over.</p>
