暗号化しなければ署名鍵が見える。それはそうよね。
$ echo Hello, World! | gpg --sign --default-key zundan@gmail.com | gpg --list-packets --verbose 2>/dev/null
:
# …
:compressed packet: algo=1
# off=2 ctb=90 tag=4 hlen=2 plen=13
:onepass_sig packet: keyid B56C20316D6E8279
version 3, sigclass 0x00, digest 10, pubkey 1, last=1
# …
:literal data packet:
mode b (62), created 1709581369, name="",
raw data: 14 bytes
# … :signature packet: algo 1, keyid B56C20316D6E8279
version 4, created 1709581369, md5len 0, sigclass 0x00
digest algo 10, begin of digest 94 5b
hashed subpkt 33 len 21 (issuer fpr v4 F60960D80B224382CA8D831CB56C20316D6E8279)
hashed subpkt 2 len 4 (sig created 2024-03-04)
hashed subpkt 28 len 16 (signer's user ID)
subpkt 16 len 8 (issuer key ID B56C20316D6E8279)
data: …
$ gpg --list-keys B56C20316D6E8279
pub rsa3072 2020-06-24 [SC] [expires: 2024-06-25]
F60960D80B224382CA8D831CB56C20316D6E8279
uid [ultimate] zunda <zundan@gmail.com>
sub rsa3072 2020-06-24 [E] [expires: 2024-06-25]