[atyiah]

I have the plain text and the encrypted text how can I get the key?

encrypted text                                                  Plain Text
i8kgbe4ZQVwBgYJ\\/oYNYBg==   ..........>>        1111
mPQuKLXlZg5SaliUA\\/V+3A==   ..........>>        1110
+TKOfEP4\\/20zxhqOtGR7fQ==   ..........>>        1112
uGVqCbilH8wpQD4ugbbUVQ==   ..........>>        1113
PxSiMQ9tEnvt+sAyup\\/xEw==   ..........>>        1114
dLYLFxwmWWAbfUCFzsso6A==   ..........>>        1115
2aeClPuwDTYbvC7IDPz4SQ==   ..........>>         1116
8YeTfo+Vt1iaQ23KtxhtuA==   ..........>>       1117
ZliAfkFY8byJoQYzwKk6cg==   ..........>>        1118
xiJO6Rew2n7EIqSlEEkt2A==   ..........>>        1119
VqeHgj+FXTb5MNoQZhT3aQ==   ..........>>        0000

[3DES]

If its proper encryption you cannot

[blauskaerm]

Its really hard to tell, which it should be with encryption.
The strings are however not of the same length so its hard to tell if its a common encryption algorithm. The last six does however have the same size of 128 bits so it could mean a 128-bit block cipher like AES or a MD5 hash sum which has been salted.

Found this tread, it might help you: security.stackexchange.com/questions/3989/how-to-determine-what-type-of-encoding-encryption-has-been-used