a seed which is a bunch of human-readable phrases.
There’s a distinction between a “seed phrase” and a “seed quantity”. The latter is generated from the previous (or generated randomly if no seed phrase is used).
Electrum doeesn’t at all times comply with the standard BIPs however we are able to have a look at BIP-39 to see how a seed could be generated from a seed-phrase
To create a binary seed from the mnemonic, we use the PBKDF2 operate with a mnemonic sentence (in UTF-8 NFKD) used because the password and the string “mnemonic” + passphrase (once more in UTF-8 NFKD) used because the salt. The iteration rely is about to 2048 and HMAC-SHA512 is used because the pseudo-random operate. The size of the derived secret’s 512 bits (= 64 bytes).
Notice that 64 bytes could be written as 128 hexadecimal characters.
Notice additionally the excellence between seed-phrase and passphrase. These are two various things which can be each used (although the passphrase could also be empty).
the seed is sort of a 129-length string, it seems like a hash. Is {that a} hash?
In keeping with Wikipedia
PBKDF2 applies a pseudorandom operate, reminiscent of hash-based message authentication code (HMAC), to the enter password or passphrase together with a salt worth and repeats the method many occasions to provide a derived key,
So sure, hashing operations are concerned. The seed is not a easy hash of the seed-phase although.
Can [the seed number] be used to revive an Electrum pockets?
As far as I can inform, Electrum offers a method to restore from a seed-phrase however not from a seed quantity.