diffie-hellman-group1-sha1
```

`--sftp=cipher-algos=...` specifies the allowed cipher algorithms. 
If unspecified then a sensible default is used.

Valid values: 
```
aes128-ctr
aes192-ctr
aes256-ctr
******@****.***
******@****.***
******@****.***
arcfour256
arcfour128
arcfour
aes128-cbc
3des-cbc
```

// addressed. Which is expected to be one of 11-13, 21-23, 31, 32,
// and y.val() should be equal to which and y.p.val() should
// be equal to z.val().  Also, x(.p)**8 == x; that is, the
// autos are all linked into a ring.
//
//go:noinline
func (v V) autos_ssa(which, w1, x1, w2, x2 int64) (y, z V) {
	fill_ssa(v.w, v.x, &v, v.p) // gratuitous no-op to force addressing
	var a, b, c, d, e, f, g, h V