bip85keys/README.md

@@ -23,13 +23,15 @@ The mnemonic is turned into a key like this:
 The path is:
 
 ```
-m/83696968'/592366788'/<app>'/<n>'
+m/83696968'/<app>'/<n>'
 ```
 
 - `83696968` is the fixed BIP-85 purpose.
-- `592366788` is the vendor id, `sha256("berlin.sneak") & 0x7fffffff`, the same
-  one `agehd` uses.
-- `app` is the application id of the key type; each type has its own.
+- `app` is the application number of the key type. There is no vendor id: the
+  path is meant as a standard any implementation can follow, not something tied
+  to one tool. Each key type's number is spelled the way BIP-85 spells its own
+  RSA application (`828365` is the ASCII codes of `R`, `S`, `A` written out):
+  SSH is `838372` (`S` `S` `H`), age is `657169` (`A` `G` `E`).
 - `n` is the key index: flag `--index` / `-n`, default `0`.
 
 ## Giving it the mnemonic
@@ -55,17 +57,16 @@ Every command takes `--index` / `-n` and `--mnemonic-command`, and has `--help`.
 
 ## SSH keys: `bip85keys ssh`
 
-Only ed25519 keys are produced. The application id is `1822331379`,
-`sha256("bip85ssh") & 0x7fffffff`, so the path is
-`m/83696968'/592366788'/1822331379'/<n>'`. The 32 bytes from step 4 are the
-ed25519 seed.
+Only ed25519 keys are produced. The application number is `838372`, so the
+path is `m/83696968'/838372'/<n>'`. The 32 bytes from step 4 are the ed25519
+seed.
 
 Test vector, mnemonic
 `abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about`:
 
 ```
-index 0: ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIA1esgfi4OeaywgKh0o5r/8lMOUlUD/N+YoAiC8SNEML
-index 1: ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIB26T7hdDuUF6wfTQ7NpIpyeTgGha4NlhQjaAhap5dqs
+index 0: ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIJZOtOczrc/7CQytcuFwt7s4r8KjkZWkwjLZWBaFKD+7
+index 1: ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIOEWY8+/gmHYVC4u0Y0I4FKs+eVUulTPHfk9VtXw1tMF
 ```
 
 ### `bip85keys ssh pub`
@@ -97,7 +98,7 @@ It then prints `added` or `already present`. How this `ssh` connection
 authenticates is up to the user's normal `ssh` setup (existing keys, agent,
 password). Anything after `--` is passed to `ssh` unchanged.
 
-### `bip85keys ssh ssh <host> [ssh arguments...]`
+### `bip85keys ssh to <host> [ssh arguments...]`
 
 Derives the key, serves it from an SSH agent that runs inside the tool on a unix
 socket in a new private `0700` temporary directory, then runs the system `ssh`
@@ -108,13 +109,12 @@ socket and directory on the way out. The private key is never written to disk.
 ## age identities: `bip85keys age` (planned)
 
 Not in this PR, which delivers the SSH type first; it is the next type to add.
-`bip85keys age pub` and `bip85keys age priv` will derive exactly what
-`sneak/secret` derives with its `agehd` package: application id `733482323`
-(`sha256("secret") & 0x7fffffff`), so the path is
-`m/83696968'/592366788'/733482323'/<n>'`; the 32 bytes from step 4 are clamped
-as X25519 requires and encoded as an `AGE-SECRET-KEY-1...` identity. An age key
-from this tool for a given mnemonic and index will equal the one `secret`
-derives.
+`bip85keys age pub` and `bip85keys age priv` will use application number
+`657169`, path `m/83696968'/657169'/<n>'`; the 32 bytes from step 4 are clamped
+as X25519 requires and encoded as an `AGE-SECRET-KEY-1...` identity, the same
+steps `sneak/secret` takes in its `agehd` package. `secret` derives at a
+vendor-specific path today; for its keys to equal this tool's it moves to this
+path, which is a change in `secret`, not here.
 
 ## Adding a key type
 
@@ -124,7 +124,7 @@ groups its commands.
 
 ## Errors
 
-Errors go to standard error and the exit status is 1, except for `ssh ssh`,
+Errors go to standard error and the exit status is 1, except for `ssh to`,
 which passes through `ssh`'s own exit status.
 
 ## Building and running
@@ -140,5 +140,5 @@ Examples:
 bip85keys ssh pub -n 3 --mnemonic-command 'secret get foo'
 bip85keys ssh priv -n 3 > ~/.ssh/id_bip85_3
 bip85keys ssh install -n 3 user@example.com
-bip85keys ssh ssh -n 3 user@example.com uptime
+bip85keys ssh to -n 3 user@example.com uptime
 ```