gpg: NOTE: cipher algorithm 9 not found in preferences

[Lionel Elie Mamane]

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On Mon, Mar 12, 2001 at 10:10:14AM -0800, Nick Andriash wrote:

> BTW, what is the command to see the default list?

gpg --edit-key 0x7BA3FDCE
pref

Will see a line that looks like:

S7 S10 S3 S4 H3 H2 Z2 Z1

Hn (where n is an integer) is the preference for the Hash
Zn (where n is an integer) is the preference for the Compression
Sn (where n is an integer) is the preference for the cipher

Here is the key to the values of n:

#define CIPHER_ALGO_NONE         0
#define CIPHER_ALGO_IDEA         1
#define CIPHER_ALGO_3DES         2
#define CIPHER_ALGO_CAST5        3
#define CIPHER_ALGO_BLOWFISH     4  /* blowfish 128 bit key */
#define CIPHER_ALGO_SAFER_SK128  5
#define CIPHER_ALGO_DES_SK       6
#define CIPHER_ALGO_RIJNDAEL     7
#define CIPHER_ALGO_RIJNDAEL192  8
#define CIPHER_ALGO_RIJNDAEL256  9
#define CIPHER_ALGO_TWOFISH     10  /* twofish 256 bit */
#define CIPHER_ALGO_SKIPJACK   101  /* experimental: skipjack */
#define CIPHER_ALGO_TWOFISH_OLD 102 /* experimental: twofish 128 bit */
#define CIPHER_ALGO_DUMMY      110  /* no encryption at all */

#define DIGEST_ALGO_MD5       1
#define DIGEST_ALGO_SHA1      2
#define DIGEST_ALGO_RMD160    3
#define DIGEST_ALGO_TIGER     6

So, e.g., the line given above means:

RIJNDAEL, TWOFISH, CAST5, BLOWFISH (implicit 3DES)
RMD160, SHA1

> With reference to *sending* encrypted messages, my preference again
> would be Rijndael-256. If however, the Recipient cannot accept that
> Algorithm, does GnuPG use the first of the preferred Algorithms on
> the Recipients Key Preferences...

If you specify a cipher-algo option, no. If you don't specify a
cipher-algo optiuon, it will pick an algorithm from the Recipients Key
Preferences.

> which I presume is hidden somewhere in his self-signature...

Hmm... Not quite "hidden", but that's where it is, indeed.

> or am I *forcing* the Recipient to accept encrypted messages using
> Rijndael-256?

By specifying "cipher-algo RIJNDAEL-256", you are forcing him.

--=20
Lionel Elie Mamane
RFC 1991 (PGP 2.x) 2048 bits Key Fingerprint (KeyID: 20C897E9):
    85CF 986F 263E 8CD0 80FD 4B8C F5F9 C17D
OpenPGP DH/DSS 4096/1024 Key Fingerprint (KeyID: 3E7B4B73):
	9DAD 3131 3ADA F50B D096 002A B1C4 7317 3E7B 4B73

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