Create self-decrypting encrypted files using your ssh public key. The self decrypting file will only decrypt if you have the private key. Only works on small files like short messages.

makesmsg.sh

#!/bin/bash

if [[ "$#" == 1 ]]; then
    PUBKEYFILE="${HOME}/.ssh/id_rsa.pub"
    INFILE="$1"
    OUTFILE="${1}.sh"
elif [[ "$#" == 2 ]]; then
    PUBKEYFILE="${HOME}/.ssh/id_rsa.pub"
    INFILE="$1"
    OUTFILE="$2"
elif [[ "$#" == 3 ]]; then
    PUBKEYFILE="$1"
    INFILE="$2"
    OUTFILE="$3"
else
    PUBKEYFILE="--help"
fi

[ "${PUBKEYFILE}" == "--help" ] && exec echo "Usage: makesmsg.sh [ <ssh rsa public key file> ] <infile> [ <outfile.sh> ]"
(
cat <<END
#!/bin/bash

openssl rsautl -decrypt -inkey ~/.ssh/id_rsa -in <(
END
echo "echo \"$(openssl enc -base64 -in <(openssl rsautl -encrypt -inkey <(
php_cwd=`/usr/bin/env php <<EOF
<?php
echo openssh2pem("$PUBKEYFILE");

function len(\\$s)
{
    \\$len = strlen(\\$s);

    if (\\$len < 0x80) {
        return chr(\\$len);
    }

    \\$data = dechex(\\$len);
    \\$data = pack('H*', (strlen(\\$data) & 1 ? '0' : '') . \\$data);
    return chr(strlen(\\$data) | 0x80) . \\$data;
}

function openssh2pem(\\$file)
{
    list(,\\$data) = explode(' ', trim(file_get_contents(\\$file)), 3);
    \\$data = base64_decode(\\$data);

    list(,\\$alg_len) = unpack('N', substr(\\$data, 0, 4));
    \\$alg = substr(\\$data, 4, \\$alg_len);

    if (\\$alg !== 'ssh-rsa') {
        return FALSE;
    }

    list(,\\$e_len) = unpack('N', substr(\\$data, 4 + strlen(\\$alg), 4));
    \\$e = substr(\\$data, 4 + strlen(\\$alg) + 4, \\$e_len);
    list(,\\$n_len) = unpack('N', substr(\\$data, 4 + strlen(\\$alg) + 4 + strlen(\\$e), 4));
    \\$n = substr(\\$data, 4 + strlen(\\$alg) + 4 + strlen(\\$e) + 4, \\$n_len);

    \\$algid = pack('H*', '06092a864886f70d0101010500');                // algorithm identifier (id, null)
    \\$algid = pack('Ca*a*', 0x30, len(\\$algid), \\$algid);                // wrap it into sequence
    \\$data = pack('Ca*a*Ca*a*', 0x02, len(\\$n), \\$n, 0x02, len(\\$e), \\$e); // numbers
    \\$data = pack('Ca*a*', 0x30, len(\\$data), \\$data);                   // wrap it into sequence
    \\$data = "\x00" . \\$data;                                           // don't know why, but needed
    \\$data = pack('Ca*a*', 0x03, len(\\$data), \\$data);                   // wrap it into bitstring
    \\$data = \\$algid . \\$data;                                           // prepend algid
    \\$data = pack('Ca*a*', 0x30, len(\\$data), \\$data);                   // wrap it into sequence

    return "-----BEGIN PUBLIC KEY-----\n" .
           chunk_split(base64_encode(\\$data), 64, "\n") .
           "-----END PUBLIC KEY-----\n";
}
?>
EOF`
echo "$php_cwd"
) -pubin -in $INFILE))\"|openssl enc -base64 -d
) 2>&-"
) > "$OUTFILE"
if [[ -e "$OUTFILE" ]]; then
    chmod a+x "$OUTFILE"
fi