arno/bitcoinbook
1
0
Fork 0
mirror of https://github.com/bitcoinbook/bitcoinbook synced 2024-11-26 18:08:31 +00:00
Code Issues Releases Wiki Activity

Edited ch05.asciidoc with Atlas code editor

Browse Source
This commit is contained in:
judymcconville@roadrunner.com 2017-04-28 12:47:52 -07:00
parent 25f78bef72
commit 778fabc590
1 changed files with 1 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
ch05.asciidoc
View File

@ -422,7 +422,7 @@ Gabriel copies the xpub to his web store's bitcoin shop software. He uses _Mycel
===== Hardened child key derivation
The ability to derive a branch of public keys from an extended public key is very useful, but it comes with a potential risk. Access to an extended public key does not give access to child private keys. However, because the extended public key contains the chain code, if a child private key is known, or somehow leaked, it can be used with the chain code to derive all the other child private keys. A single leaked child private key, together with a parent chain code, reveals all the private keys of all the children. Worse, the child private key together with a parent chain code can be used to deduce the parent private key.
((("public and private keys", "hardened child key derivation")))((("hardened derivation")))The ability to derive a branch of public keys from an extended public key is very useful, but it comes with a potential risk. Access to an extended public key does not give access to child private keys. However, because the extended public key contains the chain code, if a child private key is known, or somehow leaked, it can be used with the chain code to derive all the other child private keys. A single leaked child private key, together with a parent chain code, reveals all the private keys of all the children. Worse, the child private key together with a parent chain code can be used to deduce the parent private key.
To counter this risk, HD wallets use an alternative derivation function called _hardened derivation_, which "breaks" the relationship between parent public key and child chain code. The hardened derivation function uses the parent private key to derive the child chain code, instead of the parent public key. This creates a "firewall" in the parent/child sequence, with a chain code that cannot be used to compromise a parent or sibling private key. The hardened derivation function looks almost identical to the normal child private key derivation, except that the parent private key is used as input to the hash function, instead of the parent public key, as shown in the diagram in <<CKDprime>>.