diff options
| -rw-r--r-- | doc/ledger3.texi | 53 |
1 files changed, 40 insertions, 13 deletions
diff --git a/doc/ledger3.texi b/doc/ledger3.texi index ad41b985..494847ca 100644 --- a/doc/ledger3.texi +++ b/doc/ledger3.texi @@ -6756,19 +6756,46 @@ $ ledger reg Expenses --group-by "payee" --group-title-format "----------------- @end smallexample @item --hashes @var{ALGO} -Record the hash of each transaction in a @var{Hash} metadata value, -according to the hashing algorithm given by the @var{ALGO} -argument. Note that if a @var{Hash} metadata value is explicitly -provided and does not match what would have been generated, an error is -reported. This provided value can also just be a prefix, at whatever -length the user wishes, in which case only this amount of text is -compared to the generated hash. Printing the entry with hashes enabled -will display both this explicit metadata setting and the internally -generated hash value. - -Hashes depend on previous entries, such that setting a single hash value -is sufficient to guarantee the shape of the entire history leading up to -that entry. +Records the chained hash of each transaction in a @var{Hash} metadata +value, according to the hashing algorithm given by the @var{ALGO} +argument (at the moment, only @code{sha512} is supported). To use this, +record the @var{Hash} metadata explicitly in some of your transactions; +these will be checked against the hashes calculated internally, and if +they do not match, an error is reported. You may also write just a +prefix of the @var{Hash}, which is less verbose but still gives quite +good assurance. + +Somewhat like balance assertions, which give assurance that previous +posting amounts are correct, these @var{Hash} tags give assurance that +all previous journal entries (in parse order) are unchanged (or at +least, their combined hash matches the Hash tag currently appearing in +the journal). + +These hashes depend on the hashes of previous transactions, such that +the single hash value of the final transaction is sufficient to +guarantee the shape of the entire history leading up to it. + +The other details that the hash depends on are the following details +from each posting in the transaction: + +@itemize +@item fullname of the account +@item amount value +@end itemize + +In addition, these details are hashed from the transaction itself: + +@itemize +@item actual date +@item auxiliary date (if provided) +@item code (if provided) +@item payee +@end itemize + +This list also means that changes in the comments of postings or +transactions, or in the ordering of the postings within a transaction, +will not affect the hash. The ordering of the transactions does matter, +however, the same way as it does for balance assertions. @item --head @var{INT} @itemx --first @var{INT} |