A preshared secret is most conveniently represented as a sequence of characters, which is delimited by double-quote characters ("). The sequence cannot contain newline or double-quote characters.
Alternatively, preshared secrets can be represented as hexadecimal or Base64 encoded binary values. A character sequence beginning with 0x is interpreted as sequence hexadecimal digits. Similarly, a character sequence beginning with 0s is interpreted as Base64 encoded binary data.
[ <id selectors> ] : PSK <secret>
@moon.strongswan.org @sun.strongswan.org : PSK 0sv+NkxY9LLZvwj4qCC2o/gGrWDF2d21jL @moon.strongswan.org : PSK 0sFpZAZqEN6Ti9sqt4ZP5EWcqx @sun.strongswan.org : PSK "This is a strong password" firstname.lastname@example.org : PSK "0sFpZAZqEN6Ti9sqt4ZP5EWcqx" : PSK 0sv+NkxY9LLZvwj4qCC2o/gGrWDF2d21jL