bash对字符串做简单加解密及应用

一、生成密码及加解密
1、原代码
cat gen_en_de_pswd.sh

#!/bin/bash

case $1 in
1 )
# 随机产生n位数字符串
echo -e "Enter your password length: "
read length
if [ $length -gt 10 ] ;then
pw=`cat /dev/urandom | head -n 10 | md5sum | head -c $length`
echo "The password is:" $pw
elif [ $length -le 10 ] && [ $length -ge 5 ]; then
pw=`cat /dev/urandom |head -n 10000| sed 's/[^a-zA-Z0-9]//g' | strings -n $length |head -c $length`
echo "The password is:" $pw
else
echo "Your password is too short,Please try again!"
fi
;;

2 )
# 对字符串做简单的加密
echo -e "Enter your password which need to encrypt: "
read passwd
en_tmp=`echo $passwd|tr '0123456789ANzmGT#$&*' 'ANzmGT#$&*0123456789'|tr 'BCDEFHIJKLMOPQRSUVWXYZabcdefghijklnopqrstuvwxy' 'OPQRSUVWXYZBCDEFHIJKLMnopqrstuvwxyabcdefghijkl'`
len=`echo ${#en_tmp}`
if [ $len -lt 10 ] ;then
suf_len=`expr 10 - $len`
suffixal=`cat /dev/urandom |head -n 1000| sed 's/[^a-zA-Z0-9]//g' | strings -n $suf_len |head -n 1|head -c $suf_len`
en_pw=`echo ${suf_len}${en_tmp}${suffixal}|rev`
# echo $en_pw
elif [ $len -eq 10 ]; then
suf_len=0
en_pw=`echo ${suf_len}${en_tmp}|rev`
elif [ $len -eq 11 ]; then
suf_len=$
en_pw=`echo ${suf_len}${en_tmp}${suf_len}|rev`
else
en_pw=`echo $en_tmp|rev`
# echo $en_pw
fi

encrypt_pswd=''
for i in `seq ${#en_pw}`
do

if [ -n "$(echo ${en_pw:$i-1:1}| sed -n "/^[A-Z]\+$/p")" ];then

str=`echo ${en_pw:$i-1:1} | awk -v letter_cnt=26 '
BEGIN{
i = 0;
for(i = 0; i < letter_cnt; i++)
{
ch = sprintf("%c", i+65);
trans_table[ch] = i;
trans[25-i]=ch

}
}
{
if(NF == 1)
{
a=trans_table[$1]
printf("%c", trans[a]);
# printf("%d", trans_table[$1]);
}
}'`
else

str=${en_pw:$i-1:1}
fi

encrypt_pswd=${encrypt_pswd}${str}
done

echo "Your encrypt password is:" $encrypt_pswd
;;

3 )
# 对上述2项加密的字符串进行解密
echo -e "Enter your password which need to decode: "
read passwd
decode_pd=''
for i in `seq ${#passwd}`
do
if [ -n "$(echo ${passwd:$i-1:1}| sed -n "/^[A-Z]\+$/p")" ];then

str=`echo ${passwd:$i-1:1} | awk -v letter_cnt=26 '
BEGIN{
i = 0;
for(i = 0; i < letter_cnt; i++)
{
ch = sprintf("%c", i+65);
trans_table[ch] = i;
trans[25-i]=ch

}
}
{
if(NF == 1)
{
a=trans_table[$1]
printf("%c", trans[a]);
# printf("%d", trans_table[$1]);
}
}'`
else

str=${passwd:$i-1:1}
fi

decode_pd=${decode_pd}${str}
# echo $decode_pd

done

first_str=${decode_pd:0:1}
last_str=${decode_pd: -1}

if [ ${#decode_pd} -eq 11 ] ;then
tmp=`echo $decode_pd`
redundancy=${tmp: -1}
len=`expr 10 - $redundancy`
de_pw=`echo ${tmp:${redundancy}:${len}}|rev|tr '0123456789ANzmGT#$&*' 'ANzmGT#$&*0123456789'|tr 'BCDEFHIJKLMOPQRSUVWXYZabcdefghijklnopqrstuvwxy' 'OPQRSUVWXYZBCDEFHIJKLMnopqrstuvwxyabcdefghijkl'`

elif [ ${#decode_pd} -eq 13 ] && [ $first_str == '$' ] && [ $last_str == '$' ]; then
de_pw=`echo ${decode_pd:1:11}|rev|tr '0123456789ANzmGT#$&*' 'ANzmGT#$&*0123456789'|tr 'BCDEFHIJKLMOPQRSUVWXYZabcdefghijklnopqrstuvwxy' 'OPQRSUVWXYZBCDEFHIJKLMnopqrstuvwxyabcdefghijkl'`

else
de_pw=`echo $decode_pd|rev|tr '0123456789ANzmGT#$&*' 'ANzmGT#$&*0123456789'|tr 'BCDEFHIJKLMOPQRSUVWXYZabcdefghijklnopqrstuvwxy' 'OPQRSUVWXYZBCDEFHIJKLMnopqrstuvwxyabcdefghijkl'`

fi

echo "Your decode password is:" $de_pw
;;
* )
echo "Please enter one parameter,choose the number.
1.generate code 2.encrypt passwd 3.decode passwd 4.Nothing"
;;
esac


2、如何使用
2.1 生成随机密码（密码长度自己输入）
[oracle@hyhxdb ~]$ sh gen_en_de_pswd.sh 1
Enter your password length:
8
The password is: rK92pdQR
[oracle@hyhxdb ~]$ sh gen_en_de_pswd.sh 1
Enter your password length:
11
The password is: 584253ce235

2.2 对生成的字符串加密
[oracle@hyhxdb ~]$ sh gen_en_de_pswd.sh 2
Enter your password which need to encrypt:
rK92pdQR
Your encrypt password is: 0KVWqcz*Ce2
[oracle@hyhxdb ~]$ sh gen_en_de_pswd.sh 2
Enter your password which need to encrypt:
584253ce235
Your encrypt password is: $GmzrpmGzT&G$

2.3 对加密字符串进行解密
[oracle@hyhxdb ~]$ sh gen_en_de_pswd.sh 3
Enter your password which need to decode:
0KVWqcz*Ce2
Your decode password is: rK92pdQR
[oracle@hyhxdb ~]$ sh gen_en_de_pswd.sh 3
Enter your password which need to decode:
$GmzrpmGzT&G$
Your decode password is: 584253ce235

二、简单的应用
1、源代码
cat example.sh
#!/bin/bash
function de_passwd()
{
passwd=$1
decode_pd=''
for i in `seq ${#passwd}`
do
if [ -n "$(echo ${passwd:$i-1:1}| sed -n "/^[A-Z]\+$/p")" ];then

str=`echo ${passwd:$i-1:1} | awk -v letter_cnt=26 '
BEGIN{
i = 0;
for(i = 0; i < letter_cnt; i++)
{
ch = sprintf("%c", i+65);
trans_table[ch] = i;
trans[25-i]=ch

}
}
{
if(NF == 1)
{
a=trans_table[$1]
printf("%c", trans[a]);
}
}'`
else

str=${passwd:$i-1:1}
fi

decode_pd=${decode_pd}${str}

done

first_str=${decode_pd:0:1}
last_str=${decode_pd: -1}

if [ ${#decode_pd} -eq 11 ] ;then
tmp=`echo $decode_pd`
redundancy=${tmp: -1}
len=`expr 10 - $redundancy`
de_pw=`echo ${tmp:${redundancy}:${len}}|rev|tr '0123456789ANzmGT#$&*' 'ANzmGT#$&*0123456789'|tr 'BCDEFHIJKLMOPQRSUVWXYZabcdefghijklnopqrstuvwxy' 'OPQRSUVWXYZBCDEFHIJKLMnopqrstuvwxyabcdefghijkl'`

elif [ ${#decode_pd} -eq 13 ] && [ $first_str == '$' ] && [ $last_str == '$' ]; then
de_pw=`echo ${decode_pd:1:11}|rev|tr '0123456789ANzmGT#$&*' 'ANzmGT#$&*0123456789'|tr 'BCDEFHIJKLMOPQRSUVWXYZabcdefghijklnopqrstuvwxy' 'OPQRSUVWXYZBCDEFHIJKLMnopqrstuvwxyabcdefghijkl'`

else
de_pw=`echo $decode_pd|rev|tr '0123456789ANzmGT#$&*' 'ANzmGT#$&*0123456789'|tr 'BCDEFHIJKLMOPQRSUVWXYZabcdefghijklnopqrstuvwxy' 'OPQRSUVWXYZBCDEFHIJKLMnopqrstuvwxyabcdefghijkl'`
fi
echo $de_pw
}
pswd=`de_passwd 'iImzMqtcuf2'`
# echo $pswd

sqlplus -s shpgd/${pswd}@shopguide <select sysdate from dual;
exit
EOF

2、如何使用
2.1 先对原密码加密
[oracle@hyhxdb ~]$ sh gen_en_de_pswd.sh 2
Enter your password which need to encrypt:
shpgd123
Your encrypt password is: iImzMqtcuf2

2.2 如何应用
在源代码中修改如下的参数即可
pswd=`de_passwd 'iImzMqtcuf2'`

执行脚本即可

[oracle@hyhxdb ~]$ sh example.sh

SYSDATE
-------------------
2017-11-07 11:59:59

注：这只是简单的加密，在有源码情况下其实没什么效果，后续有待完善，学习中。